Patent Application
20210231665
Incorporated by reference in its entirety herein is a computer-readable nucleotide/amino acid sequence listing submitted concurrently herewith and identified as follows: One 237,978 Byte ASCII (Text) file named “34340-308_ST25.txt,” created on Apr. 15, 2021.
The present disclosure provides detection methods employing HCV core lipid binding domain and DNA binding domain monoclonal antibodies. In certain embodiments, the lipid binding domain monoclonal antibody recognizes an epitope in amino acids 141 to 161 of HCV core protein.
According to WHO statistics, as many as 170 million people worldwide are infected by hepatitis C virus (HCV), a viral infection of the liver. 75 to 85% of persons infected with HCV progress to chronic infection, approximately 20% of these cases develop complications of chronic hepatitis C, including cirrhosis of the liver or hepatocellular carcinoma after 20 years of infection. The current recommended treatment for HCV infections is a combination of interferon and ribavirin drugs, however the treatment is not effective in all cases and the liver transplantation is indicated in hepatitis C-related end-stage liver disease. At present, there is no vaccine available to prevent HCV infection, therefore all precautions to avoid infection must be taken.
Thus, patient care, as well as the prevention of transmission of Hepatitis C Virus (HCV) by blood and blood products or by close personal contact requires extreme vigilance using sensitive detection assays. This creates a need for specific methods for screening and identifying carriers of HCV and HCV-contaminated blood or blood products. Serological determination of HCV exposure relies on the detection of HCV present in human blood plasma or sera. This can be accomplished by detection of distinct structural and non-structural proteins encoded by the virus.
The HCV virus is a (+) sense single-stranded enveloped RNA virus in the Hepacivirus genus of the Flaviviridae family. The viral genome is approximately 10 kb in length and encodes a 3011 amino acid polyprotein precursor. The HCV genome has a large single open reading frame (ORF) coding for a unique polyprotein. This polyprotein is co- and post-translationally processed by cellular and viral proteases into three structural proteins, i.e., core, E1 and E2 and at least six non-structural NS2, NS3, NS4A, NS4B, NS5A and NS5B proteins. (Choo et al., Science 244: 359-362 (1989)).
Following HCV exposure, the virus enters a susceptible hepatocyte and viral replication occurs. During an eclipse phase period of approximately 10 days, viral presence is not evident (i.e., viral RNA cannot be detected), serum transaminase levels are within normal limits, and no evidence exists of an immune response to HCV (Busch et al., Transfusion 40:143 (2000)). Typically, about 10 days following exposure, HCV RNA can be detected, often with viral loads between 100,000-120,000,000 HCV RNA copies per ml of serum. Typically several weeks later, an increase in ALT levels is observed, indicating inflammation of the liver; antibodies are detected an average of about 70 days after exposure.
Screening of blood for exposure to HCV, either by the detection of antibodies to HCV or by the detection of viral-specific molecules (e.g., HCV RNA or HCV core proteins) in serum/plasma is an integral and important part of patient care. Blood or blood products derived from individuals identified as having been exposed to HCV, by these tests, are removed from the blood supply and are not utilized for distribution to recipients of blood products (see, e.g., U.S. Pat. No. 6,172,189). These tests may also be utilized in the clinical setting to diagnose liver disease attributable to HCV infection.
Serologic antibody tests rely on the use of recombinant antigens or synthetic peptides, representing selected fragments of the viral polyprotein. The first generation anti-HCV screening tests were based on detection of antibodies directed against a recombinant protein (HCV genotype la) originating from sequences located in the nonstructural NS-4 protein (C100-3) (Choo et al., Science 244:359 (1989); Kuo et al., Science 244:362 (1989)). The first generation assays failed to detect antibodies in approximately 10% of individuals having chronic HCV infection and up to 10-30% of individuals presenting with acute HCV infection. The second generation anti-HCV assays have incorporated recombinant proteins from three different regions of the HCV genome (HCV genotype 1a), including amino acid sequences from the core, NS3, and NS4 protein (Mimms et al., Lancet 336:1590 (1990); Bresters et al., Vox Sang 62:213 (1992)), allowing a marked improvement over the first generation tests in identifying HCV infected blood donors (Aach et al., N Engl J Med 325:1325 (1991); Kleinman et al., Transfusion 32:805 (1992). The second-generation assays detect antibodies in close to 100% of chronic HCV cases (Hino K., Intervirology 37:77 (1994)) and in nearly 100% of the acute cases by 12 weeks post infection (Alter et al., N Engl J Med 327:1899 (1992); Bresters et al., Vox Sang 62:213 (1992)). The third generation test includes a recombinant protein expressing amino acid sequences from the NS5 region, as well as antigens from the core, NS3 and NS4. Some studies have indicated a slight improvement in sensitivity in comparing the third generation tests to second generation tests (Lee et al., Transfusion 35:845 (1995); Courouce et al. Transfusion 34:790-795 (1994)), but this improvement is largely attributed to changes in the NS3 protein rather than the inclusion of NS5 (Courouce et al., Lancet 343:853 (1994)).
In general, the second and third generation HCV antibody tests detect exposure to HCV about 70 days after exposure. Since HCV establishes persistent, and in many cases lifelong infection, the detection of antibodies to HCV represents a very efficient method for determining exposure to HCV. However, antibody testing alone will frequently fail to detect HCV infected individuals during the first 70 days after exposure.
It has been suggested that testing for HCV antigen detects exposure to HCV significantly earlier than antibody testing and represents an alternative to nucleic acid testing for detecting exposure to HCV during the pre-seroconversion period. The HCV antigen detection test is rapid, simple, may-not require sample extraction or other pretreatment, and is not as prone to handling errors (e.g., contamination) as may occur in the HCV RNA tests. Thus, HCV core antigen tests present a practical alternative to HCV RNA for screening blood donors or for monitoring antiviral therapy.
Existing HCV antigen tests rely on detecting the presence of the HCV core antigen in serum or plasma. HCV core protein is a structural protein of HCV comprising the first 191 amino acids of the polyprotein and that forms the internal viral coat encapsidating the genomic RNA. Two different types of serologic assays have been developed which permit detection of HCV core antigens in serum. One assay format detects HCV core antigens in subjects prior to seroconversion and is utilized in screening blood donors, while the other assay format detects core antigens only in hepatitis C patients, regardless of their HCV antibody status, and is utilized in clinical laboratories to diagnose exposure to HCV or to monitor antiviral therapy. The currently available core antigen detection assays all use antibodies against the DNA binding domain of HCV core which is located at amino acids 1-125 of the core protein. The core protein also contains a lipid binding domain that is located between amino acids 134-171. To date there have been no antigens described from that section of core protein and until now it has been assumed that core detection required antibodies against the DNA binding domain.
Thus, binding proteins that can readily detect HCV core antigen will markedly improve the available methods of detection of HCV exposure in a patient. Thus, there is a recognized need for new antibodies that can readily be employed in screening tests.
The present disclosure provides detection methods employing HCV core lipid binding domain and DNA binding domain monoclonal antibodies. In certain embodiments, the lipid binding domain monoclonal antibody recognizes an epitope in amino acids 141 to 161 of HCV core protein.
In certain embodiments, the present invention provides a monoclonal antibody that is specifically immunoreactive with the lipid binding domain of HCV core antigen. More particularly, the HCV core antigen is amino acid residues 134-171 of HCV. In more particular embodiments, the antibody specifically binds at least one epitope formed by amino acid sequence MGYIPLVGAPLGGAARALAHGVRVLEDGVNYATGNLPG (SEQ ID NO:578). In more specific embodiments, the antibody is immunoreactive with an epitope formed by amino acids 141-161, 134-154 and 151-171 of HCV core antigen.
Another aspect of the invention provides a monoclonal antibody that is specifically immunoreactive with the lipid binding domain of HCV core antigen, wherein said monoclonal antibody has a heavy chain variable domain selected from the group consisting of the antibodies listed in
It is contemplated that any of the antibodies described herein may be prepared as immunoassay reagents, more particularly, such reagents preferably are labeled with a detectable label.
In still other embodiments, immunoassay reagents of the invention comprise one or more of the antibodies disclosed herein being bound to a solid phase.
The immunoassay reagents comprising the antibodies of the invention may further comprise an additional antibody against an HCV antigen. For example, such an additional antibody is an additional anti-core antibody.
A further aspect of the invention is directed to an immunoassay for the detection of HCV in a test sample, said immunoassay comprising:
(i) contacting a test sample suspected of containing HCV with a first antibody directed against HCV core antigen to form a complex between said first antibody and antigen located within said test sample;
(ii) contacting said complex formed in step (i) with an antibody to a core lipid binding domain, to form a complex between said antibody to a core lipid binding domain and antigen in the complex formed in step (i) wherein said antibody to a core lipid binding domain is detectably labeled and
(iii) detecting the label of the complex formed in step (ii).
In more specific embodiments, the immunoassay may further be characterized in that the first antibody is directed to the DNA binding domain of HCV core antigen. In more particular embodiments the antibody employed in step (ii) is labeled with a fluorescent label. In exemplary embodiments, the label is acridinium.
In some embodiments, the immunoassay is one in which the antibody of step (i) is coated on solid phase. In specific preferred embodiments, the antibody of step (i) comprises an antibody that is distinct from the antibody of step (ii). Alternatively, the immunoassay is one in which the antibody of step (i) comprises an antibody that is the same as the antibody of step (ii).
Any of the immunoassays of the invention may be used on a test sample obtained from a patient and the method further comprises diagnosing, prognosticating, or assessing the efficacy of a therapeutic/prophylactic treatment of the patient, wherein, if the method further comprises assessing the efficacy of a therapeutic/prophylactic treatment of the patient, the method optionally further comprises modifying the therapeutic/prophylactic treatment of the patient as needed to improve efficacy.
As will be described in further detail herein, it will be understood by those skilled in the art that any of the immunoassays of the invention may be readily adapted for use in an automated system or a semi-automated system.
The present disclosure provides detection methods employing HCV core lipid binding domain and DNA binding domain monoclonal antibodies. In certain embodiments, the lipid binding domain monoclonal antibody recognizes an epitope in amino acids 141 to 161 of HCV core protein.
In some embodiments, the present invention describes the development of monoclonal antibodies directed against the Hepatitis C Virus core antigen, specifically, the lipid binding domain of core antigen between amino acids 134-171. The immunogen used was a synthetic peptide and screening of hybridomas utilized both the immunogen peptide and a set of three overlapping smaller peptides within the 134-171 region. In addition, a recombinant core antigen representing amino acids 1-169 was used for screening to determine the efficacy of the identified monoclonal antibodies as reactive with HCV core protein. The antibodies are delineated by their reactivity to the antigen, the immunogen peptide, and smaller overlapping peptides comprising the immunogen. Binding kinetics of the antibodies to the immunogen peptide were determined by SPR (surface plasmon resonance) using a BIAcore 4000 instrument. Immunoreactivity to the recombinant core antigen was determined by standard ELISA.
In addition, to show that the monoclonal antibodies of the present invention were useful in analyzing the presence of core antigen, core antigen capture microtiter plate assays were performed by using monoclonal antibodies directed to epitopes within the DNA binding domain of HCV core (e.g. amino acids 1-125) as the capture reagent and the 134-171-directed antibodies of the present invention as detection reagents. These assays produced results to demonstrate the utility of the 134-171-directed antibodies of the invention for HCV core antigen detection immunoassays. This is the first demonstration of an antigen capture assay that independently targets two major domains of HCV core for capture and detection. Previously reported core antigen detection assays use antibodies that bind to epitopes within the DNA binding domain (e.g., amino acids 1-125).
To produce the antibodies of the present invention, mice were immunized with a synthetic peptide comprised of HCV core genotype 1 consensus sequence from amino acids 134-171 linked to BSA. More specifically, the immunogen had the sequence of:
MGYIPLVGAPLGGAARALAHGVRVLEDGVNYATGNLPG (SEQ ID NO:578).
In addition, the binding of the monoclonal antibodies to three specific N-terminally biotinylated epitope regions also was characterized and is further discussed in the Examples. Specifically, the three overlapping epitopes were derived from the above region and had the sequences of:
HCVc 134-154 MGYIPLVGAPLGGAARALAHG (SEQ ID NO:573)
HCVc 141-161 GAPLGGAARALAHGVRVLEDG (SEQ ID NO:574)
HCVc 151-171 LAHGVRVLEDGVNYATGNLPG (SEQ ID NO:575)
The immunogen was conjugated to BSA to produce the antibodies. In other embodiments, the immunogen was conjugated to TT and fibrils. The TT sequence is often used to provide a more robust immune response in mice. The sequence of the TT conjugate was:
Ac-Met-Gly-Tyr-Ile-Pro-Leu-Val-Gly-Ala-Pro-Leu-Gly-Gly-Ala-Ala-Arg-Ala-Leu-Ala-His-Gly-Val-Arg-Val-Leu-Glu-Asp-Gly-Val-Asn-Tyr-Ala-Thr-Gly-Asn-Leu-Pro-Gly-Gln-Tyr-Ile-Lys-Ala-Asn-Ser-Lys-Phe-Ile-Gly-Ile-Thr-Glu-Leu-NH2 (SEQ ID NO:577).
The sequence of the fibrils conjugate was:
Ac-Met-Gly-Tyr-Ile-Pro-Leu-Val-Gly-Ala-Pro-Leu-Gly-Gly-Ala-Ala-Arg-Ala-Leu-Ala-His-Gly-Val-Arg-Val-Leu-Glu-Asp-Gly-Val-Asn-Tyr-Ala-Thr-Gly-Asn-Leu-Pro-Gly-Gln-Gln-Lys-Phe-Gln-Phe-Gln-Phe-Glu-Gln-Gln-NH2 (SEQ ID NO:579).
B-lymphocytes were fused with a myeloma fusion partner to create hybridomas that were then screened for reactivity against the immunogen peptide, three overlapping peptides within the immunogen peptide sequence, and a recombinant HCV core antigen. Kinetic profiling using a Biacore 4000 allowed for identification of clusters of antibodies wherein the clusters are defined by their ability to bind to the immunogen peptide, or shorter peptides overlapping the 134-171 region. Combining these results with immunoreactivity, or lack thereof, for the recombinant antigen as determined by ELISA, allowed further delineation of the antibodies into groups with similar characteristics (specificities).
To briefly summarize the screening results discussed in further detail in the Examples, the greatest immune response was seen in mice immunized with the peptide linked to BSA. Additionally, the response from these mice was predominantly focused on the amino acid 141-161 region, although there was also some response to the amino acid 134-154 and 151-171 regions as well. With the HCV peptide linked to TT, an immune response was seen, however, this response was not as strong as with BSA. The response was spread over all 3 epitope regions. On the other hand, mice immunized using the amino acid 134-171 peptide linked to a peptide that would form fibril networks failed to show a significant immune response. The antibodies of the present invention are described in further detail in
The HCV core antigen used for these studies was expressed in E. coli and purified in a two-step process using IMAC followed by reverse-phase HPLC based on previously published methods (Boulant et al., J. Virol. (2005), 79(17):11353-11365).
In this manner a significant array of monoclonal antibodies that are specific for the lipid binding domain of HCV core have been produced. These monoclonal antibodies have utility in development of diagnostic assays for the detection of HCV core antigen in the serum and plasma of infected individuals. Prior to the present invention, there has been no reported generation of monoclonal antibodies to the multiple epitopes within the core amino acid 134-171 region that have shown binding activity to the HCV full length core peptide. The availability of the monoclonal antibodies of the present invention allows for the development of immunoassays for core antigen detection wherein two major domains of HCV core antigen are targeted. Previous core antigen assays described the use of monoclonals directed to epitopes within amino acid 1-125 (nucleic acid binding domain). Because the previously described monoclonal antibodies were only able to target the nucleic acid binding domain of HCV core, they were at best inefficient and often ineffective at detection of core protein fragments, break-down products, or smaller core proteins derived by internal translation initiation. The present invention for the first time overcomes these inadequacies in the previous assays by providing specific monoclonal antibodies that can be used as reagents to more efficiently and rapidly detect HCV core present in a test sample.
More particularly, the antibodies described herein are reagents useful for detection of HCV core antigen and are useful reagents to facilitate investigation of the life cycle of HCV. As noted above, HCV encoded proteins are expressed in a concerted process in which ribosomes bind to the internal ribosome entry site (IRES) and initiate translation, leading to synthesis of the viral polyprotein, which is cleaved to produce the classical HCV proteins, p21 core, E1, E2, p7, and the nonstructural proteins. None of the viral enzymes, including the viral polymerase, can be made without the initiation of translation in the core gene region. Because of this temporal relationship, it is believed that translation events in this region control the expression all HCV proteins. Hence, a complete understanding of the core gene and its gene products is essential to understanding the life cycle of the virus and may shed light on our understanding of mechanisms of virus pathogenicity. Recently, a new family of conserved viral proteins, referred to as minicores have been described (Eng et al., J Virol. 2009 April; 83(7):3104-3114). These proteins are encoded in the same reading frame as the core gene but, are believed to be derived from internal translation initiation events rather than post-translational processing of the full-length core protein. One of the minicore proteins described is termed “91 minicore” named for the presumed initiator codon within core. It is hypothesized that “134 minicore” also exists, being derived from translation initiation at codon 134 which encodes a methionine in many HCV isolates. However, reagents are not available that allow detection of minicores that are, essentially, derived from the lipid binding domain. Such proteins may play an important role in HCV persistence.
Since the monoclonal antibodies were raised against a linear, synthetic peptide derived from HCV core 134-171, it is unknown whether they will bind to the native, complete core antigen or processed forms of HCV core that exist in infected individuals. However, provided that the monoclonal antibodies of the present invention are able at least to bind one or more epitopes presented by the linear HCV core region from amino acids 134-171, it is contemplated that such binding will be sufficient to render these monoclonal antibodies significantly useful in HCV detection assays. Some of the monoclonal antibodies of the present invention react with recombinant core antigen while others do not, suggesting that within the core amino acid 134-171 region, there are both linear and conformational epitopes. Antibodies recognizing either linear or conformational epitopes are very useful tools for the study of virus assembly within infected cells and the virus life cycle generally.
Finally, these reagents can also be used in immunoassays where it is desirable to determine the presence of only the lipid binding domain. Since little is known about circulating levels of minicores in infected individuals it is possible that they are present at much higher levels than core proteins containing the region of amino acids 1-125. In providing antibodies that detect HCV core peptides outside of the region of amino acids 1-125, the present invention provides HCV core antigen detection assays with much greater sensitivity than those currently available.
The terms “specific binding” or “specifically binding”, as used herein, in reference to the interaction of an antibody, a protein, or a peptide with a second chemical species, mean that the interaction is dependent upon the presence of a particular structure (e.g., an antigenic determinant or epitope) on the chemical species; for example, an antibody recognizes and binds to a specific protein structure rather than to proteins generally. If an antibody is specific for epitope “A”, the presence of a molecule containing epitope A (or free, unlabeled A), in a reaction containing labeled “A” and the antibody, will reduce the amount of labeled A bound to the antibody.
The term “antibody”, as used herein, broadly refers to any immunoglobulin (Ig) molecule comprised of four polypeptide chains, two heavy (H) chains and two light (L) chains, or any functional fragment, mutant, variant, or derivation thereof, which retains the essential epitope binding features of an Ig molecule. Such mutant, variant, or derivative antibody formats are known in the art. Nonlimiting embodiments of which are discussed below.
In a full-length antibody, each heavy chain is comprised of a heavy chain variable region (abbreviated herein as HCVR or VH) and a heavy chain constant region. The heavy chain constant region is comprised of three domains, CHL CH2 and CH3. Each light chain is comprised of a light chain variable region (abbreviated herein as LCVR or VL) and a light chain constant region. The light chain constant region is comprised of one domain, CL. The VH and VL regions can be further subdivided into regions of hypervariability, termed complementarity determining regions (CDR), interspersed with regions that are more conserved, termed framework regions (FR). Each VH and VL is composed of three CDRs and four FRs, arranged from amino-terminus to carboxy-terminus in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4. Immunoglobulin molecules can be of any type (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgG 1, IgG2, IgG 3, IgG4, IgA1 and IgA2) or subclass.
The term “Fc region” is used to define the C-terminal region of an immunoglobulin heavy chain, which may be generated by papain digestion of an intact antibody. The Fc region may be a native sequence Fc region or a variant Fc region. The Fc region of an immunoglobulin generally comprises two constant domains, a CH2 domain and a CH3 domain, and optionally comprises a CH4 domain. Replacements of amino acid residues in the Fc portion to alter antibody effector function are known in the art (Winter, et al. U.S. Pat. Nos. 5,648,260 and 5,624,821). The Fc portion of an antibody mediates several important effector functions e.g., cytokine induction, ADCC, phagocytosis, complement dependent cytotoxicity (CDC) and half-life/clearance rate of antibody and antigen-antibody complexes. In some cases these effector functions are desirable for therapeutic antibody but in other cases might be unnecessary or even deleterious, depending on the therapeutic objectives. Certain human IgG isotypes, particularly IgG1 and IgG3, mediate ADCC and CDC via binding to Fc.gamma.R5 and complement Clq, respectively. Neonatal Fc receptors (FcRn) are the critical components determining the circulating half-life of antibodies. At least one amino acid residue is replaced in the constant region of the antibody, for example the Fc region of the antibody, such that effector functions of the antibody are altered. The dimerization of two identical heavy chains of an immunoglobulin is mediated by the dimerization of CH3 domains and is stabilized by the disulfide bonds within the hinge region (Huber et al. Nature; 264: 415-20; Thies et al 1999 J Mol Biol; 293: 67-79.). Mutation of cysteine residues within the hinge regions to prevent heavy chain-heavy chain disulfide bonds will destabilize dimerization of CH3 domains. Residues responsible for CH3 dimerization have been identified (Dall'Acqua 1998 Biochemistry 37: 9266-73.). Therefore, it is possible to generate a monovalent half-Ig. Interestingly, these monovalent half Ig molecules have been found in nature for both IgG and IgA subclasses (Seligman 1978 Ann Immunol 129: 855-70; Biewenga et al 1983 Clin Exp Immunol 51: 395-400). The stoichiometry of FcRn: Ig Fc region has been determined to be 2:1 (West et al. 2000 Biochemistry 39: 9698-708), and half Fc is sufficient for mediating FcRn binding (Kim et al 1994 Eur J Immunol; 24: 542-548.). Mutations to disrupt the dimerization of CH3 domain may not have greater adverse effect on its FcRn binding as the residues important for CH3 dimerization are located on the inner interface of CH3 b sheet structure, whereas the region responsible for FcRn binding is located on the outside interface of CH2-CH3 domains. However the half Ig molecule may have certain advantage in tissue penetration due to its smaller size than that of a regular antibody. At least one amino acid residue may be replaced in the constant region of the binding protein of the present disclosure, for example the Fc region, such that the dimerization of the heavy chains is disrupted, resulting in half DVD Ig molecules. The anti-inflammatory activity of IgG is completely dependent on sialylation of the N-linked glycan of the IgG Fc fragment. The precise glycan requirements for anti-inflammatory activity has been determined, such that an appropriate IgG1 Fc fragment can be created, thereby generating a fully recombinant, sialylated IgG1 Fc with greatly enhanced potency (Anthony, R. M., et al. (2008) Science 320:373-376).
The term “antigen-binding portion” of an antibody (or simply “antibody portion”), as used herein, refers to one or more fragments of an antibody that retain the ability to specifically bind to an antigen. It has been shown that the antigen-binding function of an antibody can be performed by fragments of a full-length antibody. Such antibody embodiments may also be bispecific, dual specific, or multi-specific formats; specifically binding to two or more different antigens. Examples of binding fragments encompassed within the term “antigen-binding portion” of an antibody include (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and CH1 domains; (ii) a F(ab′).sub.2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and CH1 domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a dAb fragment (Ward et al., (1989) Nature 341:544-546, Winter et al., PCT publication WO 90/05144 A1 herein incorporated by reference), which comprises a single variable domain; and (vi) an isolated complementarity determining region (CDR). Furthermore, although the two domains of the Fv fragment, VL and VH, are coded for by separate genes, they can be joined, using recombinant methods, by a synthetic linker that enables them to be made as a single protein chain in which the VL and VH regions pair to form monovalent molecules (known as single chain Fv (scFv); see e.g., Bird et al. (1988) Science 242:423-426; and Huston et al. (1988) Proc. Natl. Acad. Sci. USA 85:5879-5883). Such single chain antibodies are also intended to be encompassed within the term “antigen-binding portion” of an antibody. Other forms of single chain antibodies, such as diabodies are also encompassed. Diabodies are bivalent, bispecific antibodies in which VH and VL domains are expressed on a single polypeptide chain, but using a linker that is too short to allow for pairing between the two domains on the same chain, thereby forcing the domains to pair with complementary domains of another chain and creating two antigen binding sites. (See, e.g., Holliger, P., et al. (1993) Proc. Natl. Acad. Sci. USA 90:6444-6448; Poljak, R. J., et al. (1994) Structure 2:1121-1123). Such antibody binding portions are known in the art. (See, e.g., Kontermann and Dubel eds., Antibody Engineering (2001) Springer-Verlag. New York. 790 pp. (ISBN 3-540-41354-5)). In addition, single chain antibodies also include “linear antibodies” comprising a pair of tandem Fv segments (VH-CH1-VH-CH1) which, together with complementary light chain polypeptides, form a pair of antigen binding regions (Zapata et al., Protein Eng. 8(10):1057-1062 (1995); and U.S. Pat. No. 5,641,870).
The term “multivalent binding protein” is used throughout this specification to denote a binding protein comprising two or more antigen binding sites. In one aspect, the multivalent binding protein is engineered to have three or more antigen binding sites, and is generally not a naturally occurring antibody. Dual variable domain (DVD) binding proteins comprise two or more antigen binding sites and are tetravalent or multivalent binding proteins. DVDs as described herein can be monospecific, i.e., capable of one antigen such as HCV core protein, or multispecific, i.e. capable of binding two or more antigens. DVD binding proteins comprising two heavy chain DVD polypeptides and two light chain DVD polypeptides are referred to as DVD-Ig, and are described for example in U.S. Pat. No. 7,612,181, the disclosure of which is herein incorporated by reference in its entirety. Each half of a DVD-Ig comprises a heavy chain DVD polypeptide, and a light chain DVD polypeptide, and two antigen binding sites. Each binding site comprises a heavy chain variable domain and a light chain variable domain with a total of 6 CDRs involved in antigen binding per antigen binding site.
A “functional antigen binding site” of a binding protein is one that is capable of binding a target antigen. The antigen binding affinity of the antigen binding site is not necessarily as strong as the parent antibody from which the antigen binding site is derived, but the ability to bind antigen must be measurable using any one of a variety of methods known for evaluating antibody binding to an antigen. Moreover, the antigen binding affinity of each of the antigen binding sites of a multivalent antibody herein need not be quantitatively the same.
An “immunoglobulin constant domain” refers to a heavy or light chain constant domain. Human IgG heavy chain and light chain constant domain amino acid sequences are known in the art.
The term “monoclonal antibody” or “mAb” as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally occurring mutations that may be present in minor amounts. Monoclonal antibodies are highly specific, being directed against a single antigen. Furthermore, in contrast to polyclonal antibody preparations that typically include different antibodies directed against different determinants (epitopes), each mAb is directed against a single determinant on the antigen. The modifier “monoclonal” is not to be construed as requiring production of the antibody by any particular method.
The term “human antibody”, as used herein, is intended to include antibodies having variable and constant regions derived from human germline immunoglobulin sequences. The human antibodies of the present disclosure may include amino acid residues not encoded by human germline immunoglobulin sequences (e.g., mutations introduced by random or site-specific mutagenesis in vitro or by somatic mutation in vivo), for example in the CDRs and in particular CDR3. However, the term “human antibody”, as used herein, is not intended to include antibodies in which CDR sequences derived from the germline of another mammalian species, such as a mouse, have been grafted onto human framework sequences.
The term “recombinant human antibody”, as used herein, is intended to include all human antibodies that are prepared, expressed, created or isolated by recombinant means, such as antibodies expressed using a recombinant expression vector transfected into a host cell (described further in Section II C, below), antibodies isolated from a recombinant, combinatorial human antibody library (Hoogenboom H. R. (1997) TIB Tech. 15:62-70; Azzazy H., and Highsmith W. E. (2002) Clin. Biochem. 35:425-445; Gavilondo J. V., and Larrick J. W. (2002) BioTechniques 29:128-145; Hoogenboom H., and Chames P. (2000) Immunology Today 21:371-378), antibodies isolated from an animal (e.g., a mouse) that is transgenic for human immunoglobulin genes (see, Taylor, L. D., et al. (1992) Nucl. Acids Res. 20:6287-6295; Kellermann S-A. and Green L. L. (2002) Current Opinion in Biotechnology 13:593-597; Little M. et al. (2000) Immunology Today 21:364-370) or antibodies prepared, expressed, created or isolated by any other means that involves splicing of human immunoglobulin gene sequences to other DNA sequences. Such recombinant human antibodies have variable and constant regions derived from human germline immunoglobulin sequences. Such recombinant human antibodies can be subjected to in vitro mutagenesis (or, when an animal transgenic for human Ig sequences is used, in vivo somatic mutagenesis) such that the amino acid sequences of the VH and VL regions of the recombinant antibodies are sequences that, while derived from and related to human germline VH and VL sequences, may not naturally exist within the human antibody germline repertoire in vivo.
An “affinity matured” antibody is an antibody with one or more alterations in one or more CDRs thereof which result an improvement in the affinity of the antibody for antigen, compared to a parent antibody which does not possess those alteration(s). Exemplary affinity matured antibodies will have nanomolar or even picomolar affinities for the target antigen.
Affinity matured antibodies are produced by procedures known in the art. Marks et al. BidlTechnology 10:779-783 (1992) describes affinity maturation by VH and VL domain shuffling. Random mutagenesis of CDR and/or framework residues is described by: Barbas et al. Proc Nat. Acad. Sci, USA 91:3809-3813 (1994); Schier et al. Gene 169:147-155 (1995); Yelton et al. J. Immunol. 155:1994-2004 (1995); Jackson et al., J. Immunol. 154(7):3310-9 (1995); Hawkins et al, J. Mol. Biol. 226:889-896 (1992) and selective mutation at selective mutagenesis positions, contact or hypermutation positions with an activity enhancing amino acid residue as described in U.S. Pat. No. 6,914,128 B1.
The term “chimeric antibody” refers to antibodies which comprise heavy and light chain variable region sequences from one species and constant region sequences from another species, such as antibodies having murine heavy and light chain variable regions linked to human constant regions.
The term “CDR-grafted antibody” refers to antibodies which comprise heavy and light chain variable region sequences from one species but in which the sequences of one or more of the CDR regions of VH and/or VL are replaced with CDR sequences of another species, such as antibodies having murine heavy and light chain variable regions in which one or more of the murine CDRs (e.g., CDR3) has been replaced with human CDR sequences.
The term “humanized antibody” refers to antibodies which comprise heavy and light chain variable region sequences from a non-human species (e.g., a mouse) but in which at least a portion of the VH and/or VL sequence has been altered to be more “human-like”, i.e., more similar to human germline variable sequences. One type of humanized antibody is a CDR-grafted antibody, in which human CDR sequences are introduced into non-human VH and VL sequences to replace the corresponding nonhuman CDR sequences. Also “humanized antibody” is an antibody or a variant, derivative, analog or fragment thereof which immunospecifically binds to an antigen of interest and which comprises a framework (FR) region having substantially the amino acid sequence of a human antibody and a complementary determining region (CDR) having substantially the amino acid sequence of a non-human antibody. As used herein, the term “substantially” in the context of a CDR refers to a CDR having an amino acid sequence at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequence of a non-human antibody CDR. A humanized antibody comprises substantially all of at least one, and typically two, variable domains (Fab, Fab′, F(ab′) 2, FabC, Fv) in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin (i.e., donor antibody) and all or substantially all of the framework regions are those of a human immunoglobulin consensus sequence. In one aspect, a humanized antibody also comprises at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. In some embodiments, a humanized antibody contains both the light chain as well as at least the variable domain of a heavy chain. The antibody also may include the CH1, hinge, CH2, CH3, and CH4 regions of the heavy chain. In some embodiments, a humanized antibody only contains a humanized light chain. In some embodiments, a humanized antibody only contains a humanized heavy chain. In specific embodiments, a humanized antibody only contains a humanized variable domain of a light chain and/or humanized heavy chain.
The terms “Kabat numbering”, “Kabat definitions” and “Kabat labeling” are used interchangeably herein. These terms, which are recognized in the art, refer to a system of numbering amino acid residues which are more variable (i.e. hypervariable) than other amino acid residues in the heavy and light chain variable regions of an antibody, or an antigen binding portion thereof (Kabat et al. (1971) Ann. NY Acad, Sci. 190:382-391 and, Kabat, E. A., et al. (1991) Sequences of Proteins of Immunological Interest, Fifth Edition, U.S. Department of Health and Human Services, NIH Publication No. 91-3242). For the heavy chain variable region, the hypervariable region ranges from amino acid positions 31 to 35 for CDR1, amino acid positions 50 to 65 for CDR2, and amino acid positions 95 to 102 for CDR3. For the light chain variable region, the hypervariable region ranges from amino acid positions 24 to 34 for CDR1, amino acid positions 50 to 56 for CDR2, and amino acid positions 89 to 97 for CDR3.
As used herein, the term “CDR” refers to the complementarity determining region within antibody variable sequences. There are three CDRs in each of the variable regions of the heavy chain and the light chain, which are designated CDR1, CDR2 and CDR3, for each of the variable regions. The term “CDR set” as used herein refers to a group of three CDRs that occur in a single variable region capable of binding the antigen. The exact boundaries of these CDRs have been defined differently according to different systems. The system described by Kabat (Kabat et al., Sequences of Proteins of Immunological Interest (National Institutes of Health, Bethesda, Md. (1987) and (1991)) not only provides an unambiguous residue numbering system applicable to any variable region of an antibody, but also provides precise residue boundaries defining the three CDRs. These CDRs may be referred to as Kabat CDRs. Chothia and coworkers (Chothia & Lesk, J. Mol. Biol. 196:901-917 (1987) and Chothia et al., Nature 342:877-883 (1989)) found that certain sub-portions within Kabat CDRs adopt nearly identical peptide backbone conformations, despite having great diversity at the level of amino acid sequence. These sub-portions were designated as L1, L2 and L3 or H1, H2 and H3 where the “L” and the “H” designates the light chain and the heavy chains regions, respectively. These regions may be referred to as Chothia CDRs, which have boundaries that overlap with Kabat CDRs. Other boundaries defining CDRs overlapping with the Kabat CDRs have been described by Padlan (FASEB J. 9:133-139 (1995)) and MacCallum (J Mol Biol 262(5):732-45 (1996)). Still other CDR boundary definitions may not strictly follow one of the herein systems, but will nonetheless overlap with the Kabat CDRs, although they may be shortened or lengthened in light of prediction or experimental findings that particular residues or groups of residues or even entire CDRs do not significantly impact antigen binding. The methods used herein may utilize CDRs defined according to any of these systems, although certain embodiments use Kabat or Chothia defined CDRs.
As used herein, the term “framework” or “framework sequence” refers to the remaining sequences of a variable region minus the CDRs. Because the exact definition of a CDR sequence can be determined by different systems, the meaning of a framework sequence is subject to correspondingly different interpretations. The six CDRs (CDR-L1, -L2, and -L3 of light chain and CDR-H1, -H2, and -H3 of heavy chain) also divide the framework regions on the light chain and the heavy chain into four sub-regions (FR1, FR2, FR3 and FR4) on each chain, in which CDR1 is positioned between FR1 and FR2, CDR2 between FR2 and FR3, and CDR3 between FR3 and FR4. Without specifying the particular sub-regions as FR1, FR2, FR3 or FR4, a framework region, as referred by others, represents the combined FR's within the variable region of a single, naturally occurring immunoglobulin chain. As used herein, a FR represents one of the four sub-regions, and FRs represents two or more of the four sub-regions constituting a framework region. As used herein, the term “germline antibody gene” or “gene fragment” refers to an immunoglobulin sequence encoded by non-lymphoid cells that have not undergone the maturation process that leads to genetic rearrangement and mutation for expression of a particular immunoglobulin. (See, e.g., Shapiro et al., Crit. Rev. Immunol. 22(3): 183-200 (2002); Marchalonis et al., Adv Exp Med. Biol. 484:13-30 (2001)). One of the advantages provided by various embodiments of the present disclosure stems from the recognition that germline antibody genes are more likely than mature antibody genes to conserve essential amino acid sequence structures characteristic of individuals in the species, hence less likely to be recognized as from a foreign source when used therapeutically in that species.
As used herein, the term “humanized antibody” is an antibody or a variant, derivative, analog or fragment thereof which immunospecifically binds to an antigen of interest and which comprises a framework (FR) region having substantially the amino acid sequence of a human antibody and a complementary determining region (CDR) having substantially the amino acid sequence of a non-human antibody. As used herein, the term “substantially” in the context of a CDR refers to a CDR having an amino acid sequence at least 80%, preferably at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequence of a non-human antibody CDR. A humanized antibody comprises substantially all of at least one, and typically two, variable domains (Fab, Fab′, F(ab′) 2, FabC, Fv) in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin (i.e., donor antibody) and all or substantially all of the framework regions are those of a human immunoglobulin consensus sequence. Preferably, a humanized antibody also comprises at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin. In some embodiments, a humanized antibody contains both the light chain as well as at least the variable domain of a heavy chain. The antibody also may include the CH1, hinge, CH2, CH3, and CH4 regions of the heavy chain. In some embodiments, a humanized antibody only contains a humanized light chain. In some embodiments, a humanized antibody only contains a humanized heavy chain. In specific embodiments, a humanized antibody only contains a humanized variable domain of a light chain and/or humanized heavy chain.
As used herein, the term “neutralizing” refers to counteracting the biological activity of an antigen when a binding protein specifically binds the antigen. In one aspect, the neutralizing binding protein binds the cytokine and reduces its biologically activity by at least about 20%, 40%, 60%, 80%, 85% or more.
The term “epitope” includes any polypeptide determinant capable of specific binding to an immunoglobulin or T-cell receptor. In certain embodiments, epitope determinants include chemically active surface groupings of molecules such as amino acids, sugar side chains, phosphoryl, or sulfonyl, and, in certain embodiments, may have specific three dimensional structural characteristics, and/or specific charge characteristics. An epitope is a region of an antigen that is bound by an antibody. In certain embodiments, an antibody is said to specifically bind an antigen when it recognizes its target antigen in a complex mixture of proteins and/or macromolecules. Antibodies are said to “bind to the same epitope” if the antibodies cross-compete (one prevents the binding or modulating effect of the other). In addition structural definitions of epitopes (overlapping, similar, identical) are informative, but functional definitions are often more relevant as they encompass structural (binding) and functional (modulation, competition) parameters.
The term “surface plasmon resonance”, as used herein, refers to an optical phenomenon that allows for the analysis of real-time biospecific interactions by detection of alterations in protein concentrations within a biosensor matrix, for example using the BIAcore® system
(BIAcore International AB, a GE Healthcare company, Uppsala, Sweden and Piscataway, N.J.). For further descriptions, see Jonsson, U., et al. (1993) Ann. Biol. Clin. 51:19-26; Jonsson, U., et al. (1991) Biotechniques 11:620-627; Johnsson, B., et al. (1995) J. Mol. Recognit. 8:125-131; and Johnnson, B., et al. (1991) Anal. Biochem. 198:268-277.
The term “Kon”, as used herein, is intended to refer to the on rate constant for association of a binding protein (e.g., an antibody) to the antigen to form the, e.g., antibody/antigen complex as is known in the art. The “Kon” also is known by the terms “association rate constant”, or “ka”, as used interchangeably herein. This value indicating the binding rate of an antibody to its target antigen or the rate of complex formation between an antibody and antigen.
The term “Koff”, as used herein, is intended to refer to the off rate constant for dissociation, or “dissociation rate constant”, of a binding protein (e.g., an antibody) from the, e.g., antibody/antigen complex as is known in the art. This value indicates the dissociation rate of an antibody from its target antigen or separation of Ab-Ag complex over time into free antibody and antigen.
The term “KD” as used herein, is intended to refer to the “equilibrium dissociation constant”, and refers to the value obtained in a titration measurement at equilibrium, or by dividing the dissociation rate constant (koff) by the association rate constant (kon). The association rate constant, the dissociation rate constant and the equilibrium dissociation constant are used to represent the binding affinity of an antibody to an antigen. Methods for determining association and dissociation rate constants are well known in the art. Using fluorescence-based techniques offers high sensitivity and the ability to examine samples in physiological buffers at equilibrium. Other experimental approaches and instruments such as a BIAcore® (biomolecular interaction analysis) assay can be used (e.g., instrument available from BIAcore International AB, a GE Healthcare company, Uppsala, Sweden). Additionally, a KinExA® (Kinetic Exclusion Assay) assay, available from Sapidyne Instruments (Boise, Id.) can also be used.
“Label” and “detectable label” mean a moiety attached to a specific binding partner, such as an antibody or an analyte, e.g., to render the reaction between members of a specific binding pair, such as an antibody and an analyte, detectable, and the specific binding partner, e.g., antibody or analyte, so labeled is referred to as “detectably labeled.” Thus, the term “labeled binding protein” as used herein, refers to a protein with a label incorporated that provides for the identification of the binding protein. In one aspect, the label is a detectable marker that can produce a signal that is detectable by visual or instrumental means, e.g., incorporation of a radiolabeled amino acid or attachment to a polypeptide of biotinyl moieties that can be detected by marked avidin (e.g., streptavidin containing a fluorescent marker or enzymatic activity that can be detected by optical or colorimetric methods). Examples of labels for polypeptides include, but are not limited to, the following: radioisotopes or radionuclides (e.g., 3H, 14C, 35S, 90Y, 99Tc, 111In, 125I, 131I, 177Lu, 166Ho, or 153Sm); chromogens, fluorescent labels (e.g., FITC, rhodamine, lanthanide phosphors), enzymatic labels (e.g., horseradish peroxidase, luciferase, alkaline phosphatase); chemiluminescent markers; biotinyl groups; predetermined polypeptide epitopes recognized by a secondary reporter (e.g., leucine zipper pair sequences, binding sites for secondary antibodies, metal binding domains, epitope tags); and magnetic agents, such as gadolinium chelates. Representative examples of labels commonly employed for immunoassays include moieties that produce light, e.g., acridinium compounds, and moieties that produce fluorescence, e.g., fluorescein. Other labels are described herein. In this regard, the moiety itself may not be detectably labeled but may become detectable upon reaction with yet another moiety. Use of “detectably labeled” is intended to encompass the latter type of detectable labeling.
The term “conjugate” refers to a binding protein, such as an antibody, chemically linked to a second chemical moiety, such as a therapeutic or cytotoxic agent. The term “agent” is used herein to denote a chemical compound, a mixture of chemical compounds, a biological macromolecule, or an extract made from biological materials. In one aspect, the therapeutic or cytotoxic agents include, but are not limited to, pertussis toxin, taxol, cytochalasin B, gramicidin D, ethidium bromide, emetine, mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicin, doxorubicin, daunorubicin, dihydroxy anthracin dione, mitoxantrone, mithramycin, actinomycin D, 1-dehydrotestosterone, glucocorticoids, procaine, tetracaine, lidocaine, propranolol, and puromycin and analogs or homologs thereof. When employed in the context of an immunoassay, the conjugate antibody may be a detectably labeled antibody used as the detection antibody.
The terms “isolated polynucleotide” and “isolated nucleotide molecule” as used interchangeably herein mean a polynucleotide (e.g., of genomic, cDNA, or synthetic origin, or some combination thereof) that, is not associated with all or a portion of a polynucleotide with which the “isolated polynucleotide” or “isolated nucleotide molecule” is found in nature, or does not occur in nature as part of a larger sequence. An “isolated polynucleotide” or “isolated nucleotide molecule” may be operably linked to a polynucleotide that it is not linked to in nature.
The terms “regulate” and “modulate” as used interchangeably herein refer to a change or an alteration in the activity of a molecule of interest (e.g., the biological activity of a cytokine). Modulation may be an increase or a decrease in the magnitude of a certain activity or function of the molecule of interest. Exemplary activities and functions of a molecule include, but are not limited to, binding characteristics, enzymatic activity, cell receptor activation, and signal transduction. Correspondingly, the term “modulator,” as used herein, is a compound capable of changing or altering an activity or function of a molecule of interest (e.g., the biological activity of a cytokine). For example, a modulator may cause an increase or decrease in the magnitude of a certain activity or function of a molecule compared to the magnitude of the activity or function observed in the absence of the modulator. In certain embodiments, a modulator is an inhibitor, which decreases the magnitude of at least one activity or function of a molecule. Exemplary inhibitors include, but are not limited to, proteins, peptides, antibodies, peptibodies, carbohydrates or small organic molecules. Peptibodies are described, e.g., in WO01/83525.
“Patient” and “subject” may be used interchangeably herein to refer to an animal, such as a mammal, including a primate (for example, a human, a monkey, and a chimpanzee), a non-primate (for example, a cow, a pig, a camel, a llama, a horse, a goat, a rabbit, a sheep, a hamster, a guinea pig, a cat, a dog, a rat, a mouse, a whale), a bird (e.g., a duck or a goose), and a shark. Preferably, the patient or subject is a human, such as a human being treated or assessed for a disease, disorder or condition, a human at risk for a disease, disorder or condition, a human having a disease, disorder or condition, and/or human being treated for a disease, disorder or condition.
The term “sample”, as used herein, is used in its broadest sense. A “biological sample”, as used herein, includes, but is not limited to, any quantity of a substance from a living thing or formerly living thing. Such living things include, but are not limited to, humans, mice, rats, monkeys, dogs, rabbits and other animals. Such substances include, but are not limited to, blood, (e.g., whole blood), plasma, serum, urine, amniotic fluid, synovial fluid, endothelial cells, leukocytes, monocytes, other cells, organs, tissues, bone marrow, lymph nodes and spleen.
“Component,” “components,” and “at least one component,” refer generally to a capture antibody, a detection or conjugate antibody, a control, a calibrator, a series of calibrators, a sensitivity panel, a container, a buffer, a diluent, a salt, an enzyme, a co-factor for an enzyme, a detection reagent, a pretreatment reagent/solution, a substrate (e.g., as a solution), a stop solution, and the like that can be included in a kit for assay of a test sample, such as a patient urine, serum or plasma sample, in accordance with the methods described herein and other methods known in the art. Thus, in the context of the present disclosure, “at least one component,” “component,” and “components” can include a polypeptide or other analyte as above, such as a composition comprising an analyte such as polypeptide, which is optionally immobilized on a solid support, such as by binding to an anti-analyte (e.g., anti-polypeptide) antibody. Some components can be in solution or lyophilized for reconstitution for use in an assay.
“Control” refers to a composition known to not analyte (“negative control”) or to contain analyte (“positive control”). A positive control can comprise a known concentration of analyte. “Control,” “positive control,” and “calibrator” may be used interchangeably herein to refer to a composition comprising a known concentration of analyte. A “positive control” can be used to establish assay performance characteristics and is a useful indicator of the integrity of reagents (e.g., analytes).
“Predetermined cutoff” and “predetermined level” refer generally to an assay cutoff value that is used to assess diagnostic/prognostic/therapeutic efficacy results by comparing the assay results against the predetermined cutoff/level, where the predetermined cutoff/level already has been linked or associated with various clinical parameters (e.g., severity of disease, progression/nonprogression/improvement, etc.). While the present disclosure may provide exemplary predetermined levels, it is well-known that cutoff values may vary depending on the nature of the immunoassay (e.g., antibodies employed, etc.). It further is well within the ordinary skill of one in the art to adapt the disclosure herein for other immunoassays to obtain immunoassay-specific cutoff values for those other immunoassays based on this disclosure. Whereas the precise value of the predetermined cutoff/level may vary between assays, correlations as described herein (if any) should be generally applicable.
“Pretreatment reagent,” e.g., lysis, precipitation and/or solubilization reagent, as used in a diagnostic assay as described herein is one that lyses any cells and/or solubilizes any analyte that is/are present in a test sample. Pretreatment is not necessary for all samples, as described further herein. Among other things, solubilizing the analyte (e.g., polypeptide of interest) may entail release of the analyte from any endogenous binding proteins present in the sample. A pretreatment reagent may be homogeneous (not requiring a separation step) or heterogeneous (requiring a separation step). With use of a heterogeneous pretreatment reagent there is removal of any precipitated analyte binding proteins from the test sample prior to proceeding to the next step of the assay.
“Quality control reagents” in the context of immunoassays and kits described herein, include, but are not limited to, calibrators, controls, and sensitivity panels. A “calibrator” or “standard” typically is used (e.g., one or more, such as a plurality) in order to establish calibration (standard) curves for interpolation of the concentration of an analyte, such as an antibody or an analyte. Alternatively, a single calibrator, which is near a predetermined positive/negative cutoff, can be used. Multiple calibrators (i.e., more than one calibrator or a varying amount of calibrator(s)) can be used in conjunction so as to comprise a “sensitivity panel.”
“Risk” refers to the possibility or probability of a particular event occurring either presently or at some point in the future. “Risk stratification” refers to an array of known clinical risk factors that allows physicians to classify patients into a low, moderate, high or highest risk of developing a particular disease, disorder or condition.
“Specific” and “specificity” in the context of an interaction between members of a specific binding pair (e.g., an antigen (or fragment thereof) and an antibody (or antigenically reactive fragment thereof)) refer to the selective reactivity of the interaction. The phrase “specifically binds to” and analogous phrases refer to the ability of antibodies (or antigenically reactive fragments thereof) to bind specifically to analyte (or a fragment thereof) and not bind specifically to other entities.
“Specific binding partner” is a member of a specific binding pair. A specific binding pair comprises two different molecules, which specifically bind to each other through chemical or physical means. Therefore, in addition to antigen and antibody specific binding pairs of common immunoassays, other specific binding pairs can include biotin and avidin (or streptavidin), carbohydrates and lectins, complementary nucleotide sequences, effector and receptor molecules, cofactors and enzymes, enzyme inhibitors and enzymes, and the like. Furthermore, specific binding pairs can include members that are analogs of the original specific binding members, for example, an analyte-analog. Immunoreactive specific binding members include antigens, antigen fragments, and antibodies, including monoclonal and polyclonal antibodies as well as complexes, fragments, and variants (including fragments of variants) thereof, whether isolated or recombinantly produced.
Monoclonal Antibodies
The anti-HCV core binding proteins, including monoclonal antibodies and any derivative (e.g., a fragment or variant) thereof that comprises the CDRs of the heavy and light chains of the monoclonal antibodies described herein (see
The nucleotide (DNA) sequences and deduced protein sequences encoding the heavy and light chain variable domains of anti-HCV core monoclonal antibodies were obtained by immunizing mice with a synthetic peptide comprised of HCV core genotype 1 consensus sequence from amino acids 134-171 and a tetanus toxoid (TT) peptide sequence. In some embodiments, the amino acid 134-171 sequence was conjugated to BSA. However, in other embodiments, the synthetic peptide also was conjugated to the TT sequence as this is often used to provide a more robust immune response in mice, by methods known to those skilled in the art such as those described in detail herein below and in, for example, Goding, J. W. 1983. Monoclonal Antibodies: Principles and Practice, Pladermic Press, Inc., NY, N.Y., pp. 56 97. Briefly, to produce a human-human hybridoma, a human lymphocyte donor is selected. A donor who is known as infected with HCV (where infection has been shown for example by the presence of anti-virus antibodies in the blood or by virus culture) may serve as a suitable lymphocyte donor. Lymphocytes can be isolated from a peripheral blood sample or spleen cells may be used if the donor is subject to splenectomy. Epstein-Barr virus (EBV) can be used to immortalize human lymphocytes or a human fusion partner can be used to produce human-human hybridomas. Primary in vitro immunization with peptides can also be used in the generation of human monoclonal antibodies. Antibodies secreted by the immortalized cells are screened to determine the clones that secrete antibodies of the desired specificity. For monoclonal anti-HCV core antibodies, the antibodies must bind to HCV core protein and more specifically, the lipid binding domain of HCV core protein respectively. Cells producing antibodies of the desired specificity are selected. Other methods for obtaining monoclonal antibodies can be used, as known in the art. The Examples below describes how the anti-HCV core monoclonal antibodies were obtained and characterized following isolation of mRNA from hybridoma cells grown in cell culture. Deduced amino acid sequences of the heavy and light chain variable regions for the anti-HCV core monoclonal antibodies of the present invention are listed in
The deduced amino acid sequences of the heavy and the light chain domains were assigned SEQ ID NOs and the corresponding cDNAs sequences encoding the same are shown in the Sequence Table in Appendix A.
The cDNA sequences set forth in the Sequence Table represent exemplary embodiments of the disclosed cDNAs. Variations are contemplated in the cDNA sequences shown therein. Such variations include those that will result in a nucleic acid sequence that is capable of directing production of analogs of the corresponding protein shown in the Sequence Table. It will be understood that due to the degeneracy of the genetic code, many substitutions of nucleotides may be made that will lead to a DNA sequence that remains capable of directing production of the corresponding protein or its analogs. All such variant DNA sequences that are functionally equivalent to any of the sequences described herein, are encompassed by the present disclosure.
A variant of any of the binding proteins (as exemplified by monoclonal antibodies of the invention shown in
The antibodies of the present invention or antigen binding fragments of those antibodies (e.g., fragments that comprise the heavy and light chain CDRs of the antibodies of the present invention) may also be produced by genetic engineering. For example, the technology for expression of both heavy and light chain genes in E. coli is the subject of the PCT patent applications; publication number WO 901443, WO901443, and WO 9014424 and in Huse et al., 1989 Science 246:1275 1281. The present disclosure also encompasses an isolated recombinant vector comprising a nucleic acid molecule as described herein, as well as a host cell comprising such a recombinant vector. A vector is a nucleic acid molecule, which may be a construct, capable of transporting another nucleic acid to which it has been linked. A vector may include any preferred or required operational elements. Preferred vectors are those for which the restriction sites have been described and which contain the operational elements needed for transcription of the nucleic acid sequence. Such operational elements include for example at least one suitable promoter, at least one operator, at least one leader sequence, at least one terminator codon, and any other DNA sequences necessary or preferred for appropriate transcription and subsequent translation of the nucleic acid sequence. Such vectors contain at least one origin of replication recognized by the host organism along with at least one selectable marker and at least one promoter sequence capable of initiating transcription of the nucleic acid sequence. A vector may be a plasmid into which additional DNA segments may be ligated. A vector may be a viral vector, wherein additional DNA segments may be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) can be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operatively linked. Such vectors are referred to herein as “recombinant expression vectors” (or simply, “expression vectors”). In general, expression vectors of utility in recombinant DNA techniques are often in the form of plasmids. In the present specification, “plasmid” and “vector” may be used interchangeably as a plasmid is the most commonly used form of vector. However, the present disclosure is intended to include such other forms of expression vectors, such as viral vectors (e.g., replication defective retroviruses, adenoviruses and adeno-associated viruses), which serve equivalent functions.
Sequences that are operably linked are in a relationship permitting them to function in their intended manner. A control sequence operably linked to a coding sequence is ligated in such a way that expression of the coding sequence is achieved under conditions compatible with the control sequences. Operably linked sequences include both expression control sequences that are contiguous with the gene of interest and expression control sequences that act in trans or at a distance to control the gene of interest. Expression control sequences are polynucleotide sequences that are necessary to effect the expression and processing of coding sequences to which they are ligated. Expression control sequences include appropriate transcription initiation, termination, promoter and enhancer sequences; efficient RNA processing signals such as splicing and polyadenylation signals; sequences that stabilize cytoplasmic mRNA; sequences that enhance translation efficiency (i.e., Kozak consensus sequence); sequences that enhance protein stability; and when desired, sequences that enhance protein secretion. The nature of such control sequences differs depending upon the host organism; in prokaryotes, such control sequences generally include promoter, ribosomal binding site, and transcription termination sequence; in eukaryotes, generally, such control sequences include promoters and transcription termination sequence. Control sequences include components whose presence is essential for expression and processing, and can also include additional components whose presence is advantageous, for example, leader sequences and fusion partner sequences.
A host cell may be transformed with a vector that introduces exogenous DNA into a host cell in order to render that cell one that recombinantly produces the antibodies of the present invention. Transformation may occur under natural or artificial conditions using various methods well known in the art. Transformation may rely on any known method for the insertion of foreign nucleic acid sequences into a prokaryotic or eukaryotic host cell. The method is selected based on the host cell being transformed and may include, but is not limited to, viral infection, electroporation, lipofection, and particle bombardment. Transformed cells include stably transformed cells in which the inserted DNA is capable of replication either as an autonomously replicating plasmid or as part of the host chromosome, and cells which transiently express the inserted DNA or RNA for limited periods of time.
Suitable host organisms include for example a eukaryotic cell system such as but not limited to cell lines such as HeLa, MRC-5 or CV-1. Host organisms such as host cells are cultured under conditions appropriate for amplification of the vector and expression of the protein, as well known in the art. Expressed recombinant proteins may be detected by any of a number of methods also well known in the art.
Although the HCV detection aspects of the present invention merely need the antibodies to be monoclonal antibodies such that they specifically recognize HCV core antigen, it may in some embodiments be desirable to produce humanized versions of the antibodies of the present invention. Humanized” antibodies and production thereof is well known to those of skill in the art. General reviews of “humanized” antibodies are provided by Morrison S., 1985 Science 229:1202 and by Oi et al., 1986 BioTechniques 4:214. Suitable “humanized” antibodies can be alternatively produced by CDR or CEA substitution (Jones et al., 1986 Nature 321:552; Verhoeyan et al., 1988 Science 239:1534; Biedler et al. 1988 J. Immunol. 141:4053, the entire disclosures of which are incorporated herein by reference).
In other embodiments, the monoclonal antibodies of the present invention may serve as useful starting materials for the production of engineered and derivatized binding proteins including dual variable domain immunoglobulin (DVD-Ig) binding proteins comprising one or more anti-HCV monoclonal antibodies as described herein. For example, DVD-Ig's with unique binding affinities for HCV core protein may be produced, as described for example in U.S. Pat. No. 7,612,181, the entire disclosure of which is hereby incorporated by reference. DVD-Ig binding proteins are capable of binding one or more targets. Preferably the binding protein comprises a polypeptide chain comprising VD1-(X1)n-VD2-C-(X2)n, wherein VD1 is a first variable domain, VD2 is a second variable domain, C is a constant domain, X1 represents an amino acid or polypeptide, X2 represents an Fc region and n is 0 or 1. The binding protein can be generated using various techniques.
In exemplary techniques, the DVD-Ig can be formed with four polypeptide chains which form four functional antigen binding sites. Thus, for example, the DVD-Ig is capable of binding HCV core protein. The binding protein can be capable of modulating a biological function of HCV core protein, or of neutralizing HCV core protein. Exemplary such binding proteins have at least one heavy chain variable domain comprising an amino acid sequence of at least 90% identity with one of the antibodies of the present invention and at least the corresponding light chain variable domain comprising an amino acid sequence having at least 90% identity with a sequence of that light chain variable domain.
The variable domains of a DVD binding protein can be obtained from parent antibodies, including polyclonal and monoclonal antibodies capable of binding antigens of interest. The monoclonal antibodies that specifically bind to HCV core protein described herein are suitable parent antibodies. Generally, antibodies used for the DVD binding protein may be naturally occurring or may be generated by recombinant technology.
Monoclonal antibodies can be prepared using a wide variety of techniques known in the art including the use of hybridoma, recombinant, and phage display technologies, or a combination thereof. For example, monoclonal antibodies can be produced using hybridoma techniques including those as described herein for preparing the anti-HCV core protein monoclonal antibodies, and those known in the art and taught, for example, in Harlow et al., Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press, 2nd ed. 1988); Hammerling, et al., in: Monoclonal Antibodies and T-Cell Hybridomas 563-681 (Elsevier, N.Y., 1981) (said references incorporated by reference in their entireties). The term “monoclonal antibody” as used herein is not limited to antibodies produced through hybridoma technology. The term “monoclonal antibody” refers to an antibody that is derived from a single clone, including any eukaryotic, prokaryotic, or phage clone, and not the method by which it is produced. Hybridomas are selected, cloned and further screened for desirable characteristics, including robust hybridoma growth, high antibody production and desirable antibody characteristics, as discussed in Example 1 below. Hybridomas may be cultured and expanded in vivo in syngeneic animals, in animals that lack an immune system, e.g., nude mice, or in cell culture in vitro. Methods of selecting, cloning and expanding hybridomas are well known to those of ordinary skill in the art. In a preferred embodiment, the hybridomas are mouse hybridomas. In another preferred embodiment, the hybridomas are produced in a non-human, non-mouse species such as rats, sheep, pigs, goats, cattle or horses. In another embodiment, the hybridomas are human hybridomas, in which a human non-secretory myeloma is fused with a human cell expressing an antibody capable of binding a specific antigen.
Recombinant monoclonal antibodies are also generated from single, isolated lymphocytes using a procedure referred to in the art as the selected lymphocyte antibody method (SLAM), as described in U.S. Pat. No. 5,627,052, PCT Publication WO 92/02551 and Babcock, J. S. et al. (1996) Proc. Natl. Acad. Sci. USA 93:7843-7848. In this method, single cells secreting antibodies of interest, e.g., lymphocytes derived from an immunized animal, are identified, and, heavy- and light-chain variable region cDNAs are rescued from the cells by reverse transcriptase-PCR and these variable regions can then be expressed, in the context of appropriate immunoglobulin constant regions (e.g., human constant regions), in mammalian host cells, such as COS or CHO cells. The host cells transfected with the amplified immunoglobulin sequences, derived from in vivo selected lymphocytes, can then undergo further analysis and selection in vitro, for example by panning the transfected cells to isolate cells expressing antibodies to the antigen of interest. The amplified immunoglobulin sequences further can be manipulated in vitro, such as by in vitro affinity maturation methods such as those described in PCT Publication WO 97/29131 and PCT Publication WO 00/56772.
Monoclonal antibodies are also produced by immunizing a non-human animal comprising some, or all, of the human immunoglobulin locus with an antigen of interest. In a preferred embodiment, the non-human animal is a XENOMOUSE® transgenic mouse, an engineered mouse strain that comprises large fragments of the human immunoglobulin loci and is deficient in mouse antibody production. See, e.g., Green et al. Nature Genetics 7:13-21 (1994) and U.S. Pat. Nos. 5,916,771, 5,939,598, 5,985,615, 5,998,209, 6,075,181, 6,091,001, 6,114,598 and 6,130,364. See also WO 91/10741, published Jul. 25, 1991, WO 94/02602, published Feb. 3, 1994, WO 96/34096 and WO 96/33735, both published Oct. 31, 1996, WO 98/16654, published Apr. 23, 1998, WO 98/24893, published Jun. 11, 1998, WO 98/50433, published Nov. 12, 1998, WO 99/45031, published Sep. 10, 1999, WO 99/53049, published Oct. 21, 1999, WO 00 09560, published Feb. 24, 2000 and WO 00/037504, published Jun. 29, 2000. The XENOMOUSE™ transgenic mouse produces an adult-like human repertoire of fully human antibodies, and generates antigen-specific human Mabs. The XENOMOUSE® transgenic mouse contains approximately 80% of the human antibody repertoire through introduction of megabase sized, germline configuration YAC fragments of the human heavy chain loci and x light chain loci. See Mendez et al., Nature Genetics 15:146-156 (1997), Green and Jakobovits J. Exp. Med. 188:483-495 (1998), the disclosures of which are hereby incorporated by reference.
In vitro methods also can be used to make the parent antibodies, wherein an antibody library is screened to identify an antibody having the desired binding specificity. Methods for such screening of recombinant antibody libraries are well known in the art and include methods described in, for example, Ladner et al. U.S. Pat. No. 5,223,409; Kang et al. PCT Publication No. WO 92/18619; Dower et al. PCT Publication No. WO 91/17271; Winter et al. PCT Publication No. WO 92/20791; Markland et al. PCT Publication No. WO 92/15679; Breitling et al. PCT Publication No. WO 93/01288; McCafferty et al. PCT Publication No. WO 92/01047; Garrard et al. PCT Publication No. WO 92/09690; Fuchs et al. (1991) Bio/Technology 9:1370-1372; Hay et al. (1992) Hum Antibod Hybridomas 3:81-85; Huse et al. (1989) Science 246:1275-1281; McCafferty et al., Nature (1990) 348:552-554; Griffiths et al. (1993) EMBO J. 12:725-734; Hawkins et al. (1992) J Mol Biol 226:889-896; Clackson et al. (1991) Nature 352:624-628; Gram et al. (1992) PNAS 89:3576-3580; Garrad et al. (1991) Bio/Technology 9:1373-1377; Hoogenboom et al. (1991) Nuc Acid Res 19:4133-4137; and Barbas et al. (1991) PNAS 88:7978-7982, US patent application publication 20030186374, and PCT Publication No. WO 97/29131, the contents of each of which are incorporated herein by reference.
Parent antibodies can also be generated using various phage display methods known in the art. In phage display methods, functional antibody domains are displayed on the surface of phage particles that carry the polynucleotide sequences encoding them. In a particular, such phage can be utilized to display antigen-binding domains expressed from a repertoire or combinatorial antibody library (e.g., human or murine). Phage expressing an antigen binding domain that binds the antigen of interest can be selected or identified with antigen, e.g., using labeled antigen or antigen bound or captured to a solid surface or bead. Phage used in these methods are typically filamentous phage including fd and M13 binding domains expressed from phage with Fab, Fv or disulfide stabilized Fv antibody domains recombinantly fused to either the phage gene III or gene VIII protein. Examples of phage display methods that can be used to make the antibodies as described herein include those disclosed in Brinkman et al., J. Immunol. Methods 182:41-50 (1995); Ames et al., J. Immunol. Methods 184:177-186 (1995); Kettleborough et al., Eur. J. Immunol. 24:952-958 (1994); Persic et al., Gene 187 9-18 (1997); Burton et al., Advances in Immunology 57:191-280 (1994); PCT application No. PCT/GB91/01134; PCT publications WO 90/02809; WO 91/10737; WO 92/01047; WO 92/18619; WO 93/11236; WO 95/15982; WO 95/20401; and U.S. Pat. Nos. 5,698,426; 5,223,409; 5,403,484; 5,580,717; 5,427,908; 5,750,753; 5,821,047; 5,571,698; 5,427,908; 5,516,637; 5,780,225; 5,658,727; 5,733,743 and 5,969,108; each of which is incorporated herein by reference in its entirety.
As described in the above references, after phage selection, the antibody coding regions from the phage can be isolated and used to generate whole antibodies including human antibodies or any other desired antigen binding fragment, and expressed in any desired host, including mammalian cells, insect cells, plant cells, yeast, and bacteria, e.g., as described in detail below. For example, techniques to recombinantly produce Fab, Fab′ and F(ab′)2 fragments can also be employed using methods known in the art such as those disclosed in PCT publication WO 92/22324; Mullinax et al., BioTechniques 12(6):864-869 (1992); and Sawai et al., AJRI 34:26-34 (1995); and Better et al., Science 240:1041-1043 (1988) (said references incorporated by reference in their entireties). Examples of techniques which can be used to produce single-chain Fvs and antibodies include those described in U.S. Pat. Nos. 4,946,778 and 5,258,498; Huston et al., Methods in Enzymology 203:46-88 (1991); Shu et al., PNAS 90:7995-7999 (1993); and Skerra et al., Science 240:1038-1040 (1988).
Alternative to screening of recombinant antibody libraries by phage display, other methodologies known in the art for screening large combinatorial libraries can be applied to the identification of parent antibodies. One type of alternative expression system is one in which the recombinant antibody library is expressed as RNA-protein fusions, as described in PCT Publication No. WO 98/31700 by Szostak and Roberts, and in Roberts, R. W. and Szostak, J. W. (1997) Proc. Natl. Acad. Sci. USA 94:12297-12302. In this system, a covalent fusion is created between an mRNA and the peptide or protein that it encodes by in vitro translation of synthetic mRNAs that carry puromycin, a peptidyl acceptor antibiotic, at their 3′ end. Thus, a specific mRNA can be enriched from a complex mixture of mRNAs (e.g., a combinatorial library) based on the properties of the encoded peptide or protein, e.g., antibody, or portion thereof, such as binding of the antibody, or portion thereof, to the dual specificity antigen. Nucleic acid sequences encoding antibodies, or portions thereof, recovered from screening of such libraries can be expressed by recombinant means as described above (e.g., in mammalian host cells) and, moreover, can be subjected to further affinity maturation by either additional rounds of screening of mRNA-peptide fusions in which mutations have been introduced into the originally selected sequence(s), or by other methods for affinity maturation in vitro of recombinant antibodies, as described above.
In another approach the parent antibodies can also be generated using yeast display methods known in the art. In yeast display methods, genetic methods are used to tether antibody domains to the yeast cell wall and display them on the surface of yeast. In particular, such yeast can be utilized to display antigen-binding domains expressed from a repertoire or combinatorial antibody library (e.g., human or murine). Examples of yeast display methods that can be used to make the parent antibodies include those disclosed in Wittrup, et al. U.S. Pat. No. 6,699,658 incorporated herein by reference.
The monoclonal antibodies described herein can be further modified to generate CDR grafted and Humanized parent antibodies. CDR-grafted parent antibodies comprise heavy and light chain variable region sequences from a human antibody wherein one or more of the CDR regions of VH and/or VL are replaced with CDR sequences of murine antibodies capable of binding antigen of interest. A framework sequence from any human antibody may serve as the template for CDR grafting. However, straight chain replacement onto such a framework often leads to some loss of binding affinity to the antigen. The more homologous a human antibody is to the original murine antibody, the less likely the possibility that combining the murine CDRs with the human framework will introduce distortions in the CDRs that could reduce affinity. Therefore, it is preferable that the human variable framework that is chosen to replace the murine variable framework apart from the CDRs has at least a 65% sequence identity with the murine antibody variable region framework. It is more preferable that the human and murine variable regions apart from the CDRs have at least 70% sequence identify. It is even more preferable that the human and murine variable regions apart from the CDRs have at least 75% sequence identity. It is most preferable that the human and murine variable regions apart from the CDRs have at least 80% sequence identity. Methods for producing such antibodies are known in the art (see EP 239,400; PCT publication WO 91/09967; U.S. Pat. Nos. 5,225,539; 5,530,101; and 5,585,089), veneering or resurfacing (EP 592,106; EP 519,596; Padlan, Molecular Immunology 28(4/5):489-498 (1991); Studnicka et al., Protein Engineering 7(6):805-814 (1994); Roguska et al., PNAS 91:969-973 (1994)), and chain shuffling (U.S. Pat. No. 5,565,352).
Humanized antibodies are antibody molecules from non-human species antibody that binds the desired antigen having one or more complementarity determining regions (CDRs) from the non-human species and framework regions from a human immunoglobulin molecule. Known human Ig sequences are disclosed, e.g., www.ncbi.nlm.nih.gov/entrez-/query.fcgi; www.atcc.org/phage/hdb.html; www.sciquest.com/; www.abcam.com/; www.antibodyresource.com/onlinecomp.html; www.public.iastate.edu/.about.pedro/research tools.html; www.mgen.uni-heidelberg.de/SD/IT/IT.html; www.whfreeman.com/immunology/CH-05/kuby05.html; www.library.thinkquest.org/12429/Immune/Antibody.html; www.hhmi.org/grants/lectures/1996/vlab/; www.path.cam.ac.uk/.about.mrc7/m-ikeimages.html; www.antibodyresource.com/; mcb.harvard.edu/BioLinks/Immunology.html.www.immunologylink.com/; pathbox.wustl.edu/.about.hcenter/index.-html; www.biotech.ufl.edu/.about.hcl/; www.pebio.com/pa/340913/340913.html-; www.nal.usda.gov/awic/pubs/antibody/; www.m.ehime-u.acjp/.about.yasuhito-/Elisa.html; www.biodesign.com/table.asp; www.icnet.uk/axp/facs/davies/lin-ks.html; www.biotech.ufl.edu/.about.fccl/protocol.html; www.isac-net.org/sites_geo.html; aximtl.imt.uni-marburg.de/.about.rek/AEP-Start.html; baserv.uci.kun.nl/.aboutjraats/linksl.html; www.recab.uni-hd.de/immuno.bme.nwu.edu/; www.mrc-cpe.cam.ac.uk/imt-doc/pu-blic/INTRO.html; www.ibt.unam.mx/virV_-mice.html; imgt.cnusc.fr:8104/; www.biochem.ucl.ac.uk/.about.martin/abs/index.html; antibody.bath.ac.uk/; abgen.cvm.tamu.edu/lab/wwwabgen.html; www.unizh.ch/.about.honegger/AHOseminar/Slide01.html; www.cryst.bbk.ac.ukfabout.ubcg07s/; www.nimr.mrc.ac.uk/CC/ccaewg/ccaewg.htm; www.path.cam.ac.uk/.about.mrc7/humanisation/TAHHP.html; www.ibt.unam.mx/vir/structure/stataim.html; www.biosci.missouri.edu/smithgp/index.html; www. cryst.bioc.cam.ac.uk/.abo-ut.fmolina/Webpages/Pept/spottech.html;wwwjerini.de/fr roducts.htm; www.patents.ibm.con/ibm.html.Kabat et al., Sequences of Proteins of Immunological Interest, U.S. Dept. Health (1983), each entirely incorporated herein by reference. Such imported sequences can be used to reduce immunogenicity or reduce, enhance or modify binding, affinity, on-rate, off-rate, avidity, specificity, half-life, or any other suitable characteristic, as known in the art.
Framework residues in the human framework regions may be substituted with the corresponding residue from the CDR donor antibody to alter, preferably improve, antigen binding. These framework substitutions are identified by methods well known in the art, e.g., by modeling of the interactions of the CDR and framework residues to identify framework residues important for antigen binding and sequence comparison to identify unusual framework residues at particular positions. (See, e.g., Queen et al., U.S. Pat. No. 5,585,089; Riechmann et al., Nature 332:323 (1988), which are incorporated herein by reference in their entireties.) Three-dimensional immunoglobulin models are commonly available and are familiar to those skilled in the art. Computer programs are available which illustrate and display probable three-dimensional conformational structures of selected candidate immunoglobulin sequences. Inspection of these displays permits analysis of the likely role of the residues in the functioning of the candidate immunoglobulin sequence, i.e., the analysis of residues that influence the ability of the candidate immunoglobulin to bind its antigen. In this way, FR residues can be selected and combined from the consensus and import sequences so that the desired antibody characteristic, such as increased affinity for the target antigen(s), is achieved. In general, the CDR residues are directly and most substantially involved in influencing antigen binding. Antibodies can be humanized using a variety of techniques known in the art, such as but not limited to those described in Jones et al., Nature 321:522 (1986); Verhoeyen et al., Science 239:1534 (1988)), Sims et al., J. Immunol. 151: 2296 (1993); Chothia and Lesk, J. Mol. Biol. 196:901 (1987), Carter et al., Proc. Natl. Acad. Sci. U.S.A. 89:4285 (1992); Presta et al., J. Immunol. 151:2623 (1993), Padlan, Molecular
Immunology 28(4/5):489-498 (1991); Studnicka et al., Protein Engineering 7(6):805-814 (1994); Roguska. et al., PNAS 91:969-973 (1994); PCT publication WO 91/09967, PCT/: US98/16280, US96/18978, US91/09630, US91/05939, US94/01234, GB89/01334, GB91/01134, GB92/01755; W090/14443, W090/14424, W090/14430, EP 229246, EP 592,106; EP 519,596, EP 239,400, U.S. Pat. Nos. 5,565,332, 5,723,323, 5,976,862, 5,824,514, 5,817,483, 5,814,476, 5,763,192, 5,723,323, 5,766,886, 5,714,352, 6,204,023, 6,180,370, 5,693,762, 5,530,101, 5,585,089, 5,225,539; 4,816,567, each entirely incorporated herein by reference, included references cited therein.
Parent monoclonal antibodies may be selected from various monoclonal antibodies capable of binding specific targets including, or in addition to, HCV proteins, as well known in the art.
Parent monoclonal antibodies may also be selected from various therapeutic antibodies approved for use, in clinical trials, or in development for clinical use, particularly those that may be applicable in treating symptoms of HCV infection, or in treating conditions or diseases that co-exist with HCV infection, such as cancer, including particularly hepatocellular carcinoma.
As noted throughout the present invention, it may be desirable to label the antibodies of the present invention. A labeled antibody (or a binding protein derived from one of the antibodies of the present invention) comprises the antibody, which is derivatized or linked to another functional molecule (e.g., another peptide or protein). For example, the monoclonal antibody can be derivatized by functionally linking it (by chemical coupling, genetic fusion, noncovalent association or otherwise) to one or more other molecular entities, such as another antibody (e.g., a bispecific antibody or a diabody), a detectable agent, a cytotoxic agent, a pharmaceutical agent, and/or a protein or peptide that can mediate association of the binding protein with another molecule (such as a streptavidin core region or a polyhistidine tag).
Useful detectable agents with which monoclonal antibody may be derivatized include fluorescent compounds. Exemplary fluorescent detectable agents include fluorescein, fluorescein isothiocyanate, rhodamine, 5-dimethylamine-l-napthalenesulfonyl chloride, phycoerythrin and the like. The antibody may also be derivatized with detectable enzymes, such as alkaline phosphatase, horseradish peroxidase, glucose oxidase and the like. When derivatized with a detectable enzyme, the detection is achieved by adding additional reagents that the enzyme uses to produce a detectable reaction product. For example, when the detectable agent horseradish peroxidase is present, the addition of hydrogen peroxide and diaminobenzidine leads to a colored reaction product, which is detectable. A monoclonal antibody of the invention may also be derivatized with biotin, and detected through indirect measurement of avidin or streptavidin binding, or vice versa.
While the compositions of the present invention have demonstrated use in diagnostic applications for determining the presence of HCV core antigen in a test sample, it is contemplated that the compositions of the present invention also may serve a diagnostic or therapeutic purpose for in vivo administration to a mammal. Thus, in some embodiments, the present invention provides pharmaceutical and diagnostic compositions comprising one or more anti-HCV core binding proteins disclosed herein as an active ingredient. Pharmaceutical or diagnostic compositions may comprise any monoclonal antibody described herein, or any combination thereof, and a pharmaceutically acceptable carrier, diluent and/or excipient. Generally, the pharmaceutical and diagnostic compositions are prepared by combining the active ingredient with the carrier, diluent and/or excipient.
The compositions comprising binding proteins as described herein are for use in, but not limited to, diagnosing, detecting, or monitoring a disorder, but may also find use in preventing, treating, managing, or ameliorating of a disorder or one or more symptoms thereof, and/or in research. In a specific embodiment, a composition comprises one or more monoclonal antibodies of the present invention or a binding protein derived from one or more of the monoclonal antibodies of the present invention. In another embodiment, the composition comprises one or more monoclonal antibodies or binding proteins derived therefrom as described herein and one or more diagnostic, prophylactic or therapeutic agents other than monoclonal antibodies or binding proteins derived therefrom as described herein.
Immunoassays
Immunoassays according to the present disclosure include such techniques commonly recognized in the art, including for example radioimmunoassay, Western blot assay, immunofluorescent assay, enzyme immunoassay, chemiluminescent assay, immunohistochemical assay, immunoprecipitation and the like. Standard techniques known in the art for ELISA are well-known and described for example in Methods in Immunodiagnosis, 2nd Edition, Rose and Bigazzi, eds., John Wiley and Sons, 1980 and Campbell et al., Methods of Immunology, W. A. Benjamin, Inc., 1964, both of which are incorporated herein by reference
Immunoassays may be a direct, indirect, competitive, or noncompetitive immunoassay as described in the art (Oellerich, M. 1984. J. Clin. Chem. Clin. BioChem 22:895 904). Biological samples appropriate for such detection assays include, but are not limited to blood, plasma, serum, liver, saliva, lymphocytes or other mononuclear cells.
In preferred embodiments, the antibodies described herein are used in immunoassays specific for the detection of HCV. Examples include, but are not limited to, sandwich immunoassay, radioisotope detection (radioimmunoassay (RIA)) and enzyme detection (enzyme immunoassay (EIA) or enzyme-linked immunosorbent assay (ELISA) (e.g., Quantikine ELISA assays, R&D Systems, Minneapolis, Minn.)), competitive inhibition immunoassay (e.g., forward and reverse), fluorescence polarization immunoassay (FPIA), enzyme multiplied immunoassay technique (EMIT), bioluminescence resonance energy transfer (BRET), and homogeneous chemiluminescent assay, etc. In a SELDI-based immunoassay, a capture reagent that specifically binds an analyte of interest such as HCV core (or a fragment thereof) is attached to the surface of a mass spectrometry probe, such as a pre-activated protein chip array. The analyte (or a fragment thereof) is then specifically captured on the biochip, and the captured analyte (or a fragment thereof) is detected by mass spectrometry. Alternatively, the analyte (or a fragment thereof) can be eluted from the capture reagent and detected by traditional MALDI (matrix-assisted laser desorption/ionization) or by SELDI. A chemiluminescent microparticle immunoassay, in particular one employing the ARCHITECT®automated analyzer (Abbott Laboratories, Abbott Park, Ill.), is an example of a preferred immunoassay.
An immunoassay for determining the presence or amount of human hepatitis C virus in a sample may comprise, for example, combining an HCV core protein binding protein with the sample for a time sufficient for the binding protein to bind to any human hepatitis C virus that may be present in the sample, and determining the presence or amount of human hepatitis C virus present in the sample based on specific binding of the binding protein to the human hepatitis C virus core protein. The disclosure also encompasses an immunoassay device for detecting the presence or absence of human HCV in a sample, wherein the device comprises any of the antibodies described herein immobilized on a solid support. The anti-HCV core antibodies and any analogs thereof may be prepared in the form of a kit, alone, or in combinations with other reagents such as secondary antibodies, for use in immunoassays.
Methods well-known in the art for collecting, handling and processing urine, blood, serum and plasma, and other body fluids, are used in the practice of the present disclosure, for instance, when an anti-HCV core antibody of the present invention is employed as an immunodiagnostic reagent and/or in an analyte immunoassay kit. The test sample can comprise further moieties in addition to the HCV core antigen, including for example, antibodies, antigens, haptens, hormones, drugs, enzymes, receptors, proteins, peptides, polypeptides, oligonucleotides and/or polynucleotides. For example, the sample can be a whole blood sample obtained from a subject. It can be necessary or desired that a test sample, particularly whole blood, be treated prior to immunoassay as described herein, e.g., with a pretreatment reagent. Even in cases where pretreatment is not necessary (e.g., most urine samples), pretreatment optionally may be performed (e.g., as part of a regimen on a commercial platform).
The pretreatment reagent can be any reagent appropriate for use with the immunoassay and kits of the present disclosure. The pretreatment optionally comprises: (a) one or more solvents (e.g., methanol and ethylene glycol) and optionally, salt, (b) one or more solvents and salt, and optionally, detergent, (c) detergent, or (d) detergent and salt. Pretreatment reagents are known in the art, and such pretreatment can be employed as has been previously described, e.g., as used for assays on Abbott TDx, AxSYM®, and ARCHITECT® analyzers (Abbott Laboratories, Abbott Park, Ill.), as described in the literature (see, e.g., Yatscoff et al., Abbott TDx Monoclonal Antibody Assay Evaluated for Measuring Cyclosporine in Whole Blood, Clin. Chem. 36: 1969-1973 (1990), and Wallemacq et al., Evaluation of the New AxSYM Cyclosporine Assay Comparison with TDx Monoclonal Whole Blood and EMIT Cyclosporine Assays, Clin. Chem. 45: 432-435 (1999)), and/or as commercially available. Additionally, pretreatment can be performed as described in U.S. Pat. No. 5,135,875, European Patent Pub. No. 0 471 293, U.S. Provisional Patent App. 60/878,017, filed Dec. 29, 2006, and U.S. Patent App. Pub. No. 2008/0020401 (incorporated by reference in its entirety for its teachings regarding pretreatment).
With use of a pretreatment reagent the assay is rendered more sensitive by disruption of preformed/preexisting immune complexes or viral particles in the test sample. In such a pretreated test sample, the anti-HCV core antibody in the sample is separated from the antigen and the remaining antigen in the sample is then tested for the presence of HCV core antigen using the monoclonal antibodies of the present invention. The HCV core antigen in the test sample is thus subjected to an antibody capture step to capture any HCV antigen present in the test sample.
In some other embodiments, use of the pretreatment does not require such a separation step. The entire mixture of test sample and pretreatment reagent are contacted with an antibody specific for the targeted antigen (in this case HCV core antigen, or more particularly, HCV core antigen lipid binding domain). The pretreatment reagent employed for such an assay typically is diluted in the pretreated test sample mixture, either before or during capture by the first antibody that is used to capture the HCV antigen. Despite such dilution, a certain amount of the pretreatment reagent may still be present in the test sample mixture during capture. The capture reagents may be an antibody of the present invention, alternatively, it may be another anti-HCV core antigen antibody or indeed it may be an antibody directed against a non-core protein antigen of HCV (e.g., an antibody against an envelope protein, E1, or E2 or other portion of HCV).
In one assay format, after the test sample is obtained from a subject, a first mixture is prepared. The mixture contains the test sample being assessed for the presence of a given antigen (e.g., in the present case, for the presence of HCV core antigen) and a first specific binding partner (typically an antibody that recognizes an HCV epitope), wherein the first specific binding partner and any HCV antigen contained in the test sample form a first antibody-antigen complex. The order in which the test sample and the first specific binding partner are added to form the mixture is not critical. The first specific binding partner may be immobilized on a solid phase, but in alternative embodiments, the first specific binding partner may be in a solution phase. The solid phase used in the immunoassay (for the first specific binding partner and, optionally, the second specific binding partner) can be any solid phase known in the art, such as, but not limited to, a magnetic particle, a bead, a test tube, a microtiter plate, a cuvette, a membrane, a scaffolding molecule, a film, a filter paper, a disc and a chip.
The methods described are amenable for adaption to systems that utilize microparticle technology including in automated and semi-automated systems wherein the solid phase comprises a microparticle. Such systems include those described in pending U.S. patent application Ser. Nos. 425,651 and 425,643, which correspond to published EPO applications Nos. EP 0 425 633 and EP 0 424 634, respectively, which are incorporated herein by reference.
After the mixture containing the first specific binding partner-analyte complex is formed, any unbound analyte is removed from the complex using any technique known in the art. For example, the unbound analyte can be removed by washing. Desirably, however, the first specific binding partner is present in excess of any analyte present in the test sample in order to optimize maximal binding of the analyte present in the test sample by the first specific binding partner.
After removal of unbound analyte, a second specific binding partner is added to the mixture to form a first specific binding partner-analyte-second specific binding partner complex. The second specific binding partner is preferably an anti-analyte antibody that binds to an epitope on the analyte that differs from the epitope on analyte bound by the first specific binding partner. Simply by way of example, assuming that the assay is for detection of HCV core antigen, a first “capture” antibody is used that is specific for the DNA binding domain of HCV core antigen (alternatively, the first antibody is an anti HCV core antibody that is specific for the HCV core antigen lipid binding domain, such as the antibodies described herein), once this first capture antibody captures HCV core protein from the sample, a second anti-core antigen antibody that binds the lipid binding domain of HCV core antigen (where the first antibody bound the DNA binding domain, or alternatively, where the first antibody is first antibody is specific for the HCV core antigen lipid binding domain, the second antibody could be specific for the DNA binding domain of HCV core antigen). Preferably, in such embodiments, the second specific binding partner is labeled with or contains a detectable label as described above in order to facilitate detection of the (capture antibody-antigen-second antibody) complex.
Any suitable detectable label as is known in the art can be used. For example, the detectable label can be a radioactive label (such as 3H, 125I, 35S, 14C, 32P, and 33P), an enzymatic label (such as horseradish peroxidase, alkaline peroxidase, glucose 6-phosphate dehydrogenase, and the like), a chemiluminescent label (such as acridinium esters, thioesters, or sulfonamides; luminol, isoluminol, phenanthridinium esters, and the like), a fluorescent label (such as fluorescein (e.g., 5-fluorescein, 6-carboxyfluorescein, 3′6-carboxyfluorescein, 5(6)-carboxyfluorescein, 6-hexachloro-fluorescein, 6-tetrachlorofluorescein, fluorescein isothiocyanate, and the like)), rhodamine, phycobiliproteins, R-phycoerythrin, quantum dots (e.g., zinc sulfide-capped cadmium selenide), a thermometric label, or an immuno-polymerase chain reaction label. An introduction to labels, labeling procedures and detection of labels is found in Polak and Van Noorden, Introduction to Immunocytochemistry, 2nd ed., Springer Verlag, N.Y. (1997), and in Haugland, Handbook of Fluorescent Probes and Research Chemicals (1996), which is a combined handbook and catalogue published by Molecular Probes, Inc., Eugene, Oreg. A fluorescent label can be used in FPIA (see, e.g., U.S. Pat. Nos. 5,593,896, 5,573,904, 5,496,925, 5,359,093, and 5,352,803, which are hereby incorporated by reference in their entireties). An acridinium compound can be used as a detectable label in a homogeneous chemiluminescent assay (see, e.g., Adamczyk et al., Bioorg. Med. Chem. Lett. 16: 1324-1328 (2006); Adamczyk et al., Bioorg. Med. Chem. Lett. 4: 2313-2317 (2004); Adamczyk et al., Biorg. Med. Chem. Lett. 14: 3917-3921 (2004); and Adamczyk et al., Org. Lett. 5: 3779-3782 (2003)).
A preferred acridinium compound is an acridinium-9-carboxamide. Methods for preparing acridinium 9-carboxamides are described in Mattingly, J. Biolumin. Chemilumin. 6: 107-114 (1991); Adamczyk et al., J. Org. Chem. 63: 5636-5639 (1998); Adamczyk et al., Tetrahedron 55: 10899-10914 (1999); Adamczyk et al., Org. Lett. 1: 779-781 (1999); Adamczyk et al., Bioconjugate Chem. 11: 714-724 (2000); Mattingly et al., In Luminescence Biotechnology: Instruments and Applications; Dyke, K. V. Ed.; CRC Press: Boca Raton, pp. 77-105 (2002); Adamczyk et al., Org. Lett. 5: 3779-3782 (2003); and U.S. Pat. Nos. 5,468,646, 5,543,524 and 5,783,699 (each of which is incorporated herein by reference in its entirety for its teachings regarding same).
Another preferred acridinium compound is an acridinium-9-carboxylate aryl ester. An example of an acridinium-9-carboxylate aryl ester of formula II is 10-methyl-9-(phenoxycarbonyl)acridinium fluorosulfonate (available from Cayman Chemical, Ann Arbor, Mich.). Methods for preparing acridinium 9-carboxylate aryl esters are described in McCapra et al., Photochem. Photobiol. 4: 1111-21 (1965); Razavi et al., Luminescence 15: 245-249 (2000); Razavi et al., Luminescence 15: 239-244 (2000); and U.S. Pat. No. 5,241,070 (each of which is incorporated herein by reference in its entirety for its teachings regarding same). Such acridinium-9-carboxylate aryl esters are efficient chemiluminescent indicators for hydrogen peroxide produced in the oxidation of an analyte by at least one oxidase in terms of the intensity of the signal and/or the rapidity of the signal. The course of the chemiluminescent emission for the acridinium-9-carboxylate aryl ester is completed rapidly, i.e., in under 1 second, while the acridinium-9-carboxamide chemiluminescent emission extends over 2 seconds. Acridinium-9-carboxylate aryl ester, however, loses its chemiluminescent properties in the presence of protein. Therefore, its use requires the absence of protein during signal generation and detection. Methods for separating or removing proteins in the sample are well-known to those skilled in the art and include, but are not limited to, ultrafiltration, extraction, precipitation, dialysis, chromatography, and/or digestion (see, e.g., Wells, High Throughput Bioanalytical Sample Preparation. Methods and Automation Strategies, Elsevier (2003)). The amount of protein removed or separated from the test sample can be about 40%, about 45%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95%. Further details regarding acridinium-9-carboxylate aryl ester and its use are set forth in U.S. patent application Ser. No. 11/697,835, filed Apr. 9, 2007, and published on Oct. 9, 2008, as U.S. Pat. App. Pub. No. 2008/0248493. Acridinium-9-carboxylate aryl esters can be dissolved in any suitable solvent, such as degassed anhydrous N,N-dimethylformamide (DMF) or aqueous sodium cholate.
Chemiluminescent assays can be performed in accordance with the methods described in Adamczyk et al., Anal. Chim. Acta 579(1): 61-67 (2006). While any suitable assay format can be used, a microplate chemiluminometer (Mithras LB-940, Berthold Technologies U.S.A., LLC, Oak Ridge, Tenn.) enables the assay of multiple samples of small volumes rapidly. The chemiluminometer can be equipped with multiple reagent injectors using 96-well black polystyrene microplates (Costar #3792). Each sample can be added into a separate well, followed by the simultaneous/sequential addition of other reagents as determined by the type of assay employed. Desirably, the formation of pseudobases in neutral or basic solutions employing an acridinium aryl ester is avoided, such as by acidification. The chemiluminescent response is then recorded well-by-well. In this regard, the time for recording the chemiluminescent response will depend, in part, on the delay between the addition of the reagents and the particular acridinium employed.
The order in which the test sample and the specific binding partner(s) are added to form the mixture for chemiluminescent assay is not critical. If the first specific binding partner is detectably labeled with a chemiluminescent agent such as an acridinium compound, detectably labeled first specific binding partner-analyte complexes form. Alternatively, if a second specific binding partner is used and the second specific binding partner is detectably labeled with a chemiluminescent agent such as an acridinium compound, detectably labeled first specific binding partner-analyte-second specific binding partner complexes form. Any unbound specific binding partner, whether labeled or unlabeled, can be removed from the mixture using any technique known in the art, such as washing.
Hydrogen peroxide can be generated in situ in the mixture or provided or supplied to the mixture (e.g., the source of the hydrogen peroxide being one or more buffers or other solutions that are known to contain hydrogen peroxide) before, simultaneously with, or after the addition of an above-described acridinium compound. Hydrogen peroxide can be generated in situ in a number of ways such as would be apparent to one skilled in the art.
Upon the simultaneous or subsequent addition of at least one basic solution to the sample, a detectable signal, namely, a chemiluminescent signal, indicative of the presence of analyte is generated. The basic solution contains at least one base and has a pH greater than or equal to 10, preferably, greater than or equal to 12. Examples of basic solutions include, but are not limited to, sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonium hydroxide, magnesium hydroxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, calcium carbonate, and calcium bicarbonate. The amount of basic solution added to the sample depends on the concentration of the basic solution. Based on the concentration of the basic solution used, one skilled in the art can easily determine the amount of basic solution to add to the sample.
The chemiluminescent signal that is generated can be detected using routine techniques known to those skilled in the art. Based on the intensity of the signal generated, the amount of analyte in the sample can be quantified. Specifically, the amount of analyte in the sample is proportional to the intensity of the signal generated. The amount of analyte present can be quantified by comparing the amount of light generated to a standard curve for analyte or by comparison to a reference standard. The standard curve can be generated using serial dilutions or solutions of known concentrations of analyte by mass spectroscopy, gravimetric methods, and other techniques known in the art. While the above is described with emphasis on use of an acridinium compound as the chemiluminescent agent, one of ordinary skill in the art can readily adapt this description for use of other chemiluminescent agents.
Analyte immunoassays generally can be conducted using any format known in the art, such as, but not limited to, a sandwich format. Specifically, in one immunoassay format, at least two antibodies are employed to capture and quantify analyte, such as human analyte, or a fragment thereof in a sample. More specifically, preferably, the at least two antibodies bind to different epitopes on an analyte (or a fragment thereof) forming an immune complex, which is referred to as a “sandwich.” Generally, in the immunoassays one or more antibodies can be used to capture the analyte (or a fragment thereof) in the test sample (these antibodies are frequently referred to as a “capture” antibody or “capture” antibodies) and one or more antibodies can be used to bind a detectable (namely, quantifiable) label to the sandwich (these antibodies are frequently referred to as the “detection antibody,” the “detection antibodies,” the “conjugate,” or the “conjugates”). Thus, in the context of a sandwich immunoassay format, an anti-HCV core antibody of the present invention can be used as a capture antibody, a detection antibody, or both. For example, one anti-HCV core antibody having a domain that can bind a first epitope (e.g., the lipid binding domain of HCV core antigen) on an analyte can be used as a capture antibody and/or another anti-HCV core antibody having a domain that can bind a second epitope (e.g., the DNA binding domain of HCV core antigen) can be used as a detection antibody, or vice versa. Alternatively, one antibody having a first domain that can bind an epitope on a HCV core antigen and a second antibody that binds an epitope on a different HCV antigen can be used as a capture antibody and/or a detection antibody to detect, and optionally quantify, two or more analytes.
Generally speaking, a sample being tested for (for example, suspected of containing) analyte can be contacted with at least one capture antibody (or antibodies) and at least one detection antibody (which can be a second detection antibody or a third detection antibody or even a successively numbered antibody, e.g., as where the capture and/or detection antibody comprise multiple antibodies) either simultaneously or sequentially and in any order. For example, the test sample can be first contacted with at least one capture antibody and then (sequentially) with at least one detection antibody. Alternatively, the test sample can be first contacted with at least one detection antibody and then (sequentially) with at least one capture antibody. In yet another alternative, the test sample can be contacted simultaneously with a capture antibody and a detection antibody.
In the sandwich assay format, a sample suspected of containing analyte (or a fragment thereof) is first brought into contact with at least one first capture antibody under conditions that allow the formation of a first antibody/analyte complex. If more than one capture antibody is used, a first capture antibody/analyte complex comprising two or more capture antibodies is formed. In a sandwich assay, the antibodies, i.e., preferably, the at least one capture antibody, are used in molar excess amounts of the maximum amount of analyte (or a fragment thereof) expected in the test sample. For example, from about 5 ug to about 1 mg of antibody per mL of buffer (e.g., microparticle coating buffer) can be used.
Competitive inhibition immunoassays, which are often used to measure small analytes because binding by only one antibody is required, comprise sequential and classic formats. In a sequential competitive inhibition immunoassay a capture antibody to an analyte of interest is coated onto a well of a microtiter plate or other solid support. When the sample containing the analyte of interest is added to the well, the analyte of interest binds to the capture antibody. After washing, a known amount of labeled (e.g., biotin or horseradish peroxidase (HRP)) analyte is added to the well. A substrate for an enzymatic label is necessary to generate a signal. An example of a suitable substrate for HRP is 3,3′,5,5′-tetramethylbenzidine (TMB). After washing, the signal generated by the labeled analyte is measured and is inversely proportional to the amount of analyte in the sample. In a classic competitive inhibition immunoassay an antibody to an analyte of interest is coated onto a solid support (e.g., a well of a microtiter plate). However, unlike the sequential competitive inhibition immunoassay, the sample and the labeled analyte are added to the well at the same time. Any analyte in the sample competes with labeled analyte for binding to the capture antibody. After washing, the signal generated by the labeled analyte is measured and is inversely proportional to the amount of analyte in the sample.
Optionally, prior to contacting the test sample with the at least one capture antibody (for example, the first capture antibody), the at least one capture antibody can be bound to a solid support, which facilitates the separation of the first antibody/analyte (or a fragment thereof) complex from the test sample. The substrate to which the capture antibody is bound can be any suitable solid support or solid phase that facilitates separation of the capture antibody-analyte complex from the sample.
Examples of solid phases or supports are well known to those of skill in the art and include a well of a plate, such as a microtiter plate, a test tube, a porous gel (e.g., silica gel, agarose, dextran, or gelatin), a polymeric film (e.g., polyacrylamide), beads (e.g., polystyrene beads or magnetic beads), a strip of a filter/membrane (e.g., nitrocellulose or nylon), microparticles (e.g., latex particles, magnetizable microparticles (e.g., microparticles having ferric oxide or chromium oxide cores and homo- or hetero-polymeric coats and radii of about 1-10 microns). The substrate can comprise a suitable porous material with a suitable surface affinity to bind antigens and sufficient porosity to allow access by detection antibodies. A microporous material is generally preferred, although a gelatinous material in a hydrated state can be used. Such porous substrates are preferably in the form of sheets having a thickness of about 0.01 to about 0.5 mm, preferably about 0.1 mm. While the pore size may vary quite a bit, preferably the pore size is from about 0.025 to about 15 microns, more preferably from about 0.15 to about 15 microns. The surface of such substrates can be activated by chemical processes that cause covalent linkage of an antibody to the substrate. Irreversible binding, generally by adsorption through hydrophobic forces, of the antigen or the antibody to the substrate results;
alternatively, a chemical coupling agent or other means can be used to bind covalently the antibody to the substrate, provided that such binding does not interfere with the ability of the antibody to bind to analyte. Alternatively, the antibody can be bound with microparticles, which have been previously coated with streptavidin (e.g., DYNAL® Magnetic Beads, Invitrogen, Carlsbad, Calif) or biotin (e.g., using Power-Bind™-SA-MP streptavidin-coated microparticles (Seradyn, Indianapolis, Ind.)) or anti-species-specific monoclonal antibodies. If necessary, the substrate can be derivatized to allow reactivity with various functional groups on the antibody. Such derivatization requires the use of certain coupling agents, examples of which include, but are not limited to, maleic anhydride, N-hydroxysuccinimide, and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. If desired, one or more capture reagents, such as antibodies (or fragments thereof), each of which is specific for analyte(s) can be attached to solid phases in different physical or addressable locations (e.g., such as in a biochip configuration (see, e.g., U.S. Pat. No. 6,225,047; Int'l Patent App. Pub. No. WO 99/51773; U.S. Pat. No. 6,329,209; International Patent App. Pub. No. WO 00/56934, and U.S. Pat. No. 5,242,828). If the capture reagent is attached to a mass spectrometry probe as the solid support, the amount of analyte bound to the probe can be detected by laser desorption ionization mass spectrometry. Alternatively, a single column can be packed with different beads, which are derivatized with the one or more capture reagents, thereby capturing the analyte in a single place (see, antibody-derivatized, bead-based technologies, e.g., the xMAP technology of Luminex (Austin, Tex.)).
After the test sample being assayed for analyte (or a fragment thereof) is brought into contact with the at least one capture antibody (for example, the first capture antibody), the mixture is incubated in order to allow for the formation of a first antibody (or multiple antibody)-analyte (or a fragment thereof) complex. The incubation can be carried out at a pH of from about 4.5 to about 10.0, at a temperature of from about 2° C. to about 45° C., and for a period from at least about one (1) minute to about eighteen (18) hours, preferably from about 1 to about 24 minutes, most preferably for about 4 to about 18 minutes. The immunoassay described herein can be conducted in one step (meaning the test sample, at least one capture antibody and at least one detection antibody are all added sequentially or simultaneously to a reaction vessel) or in more than one step, such as two steps, three steps, etc.
After formation of the (first or multiple) capture antibody/analyte complex, the complex is then contacted with at least one detection antibody under conditions which allow for the formation of a (first or multiple) capture antibody/analyte/second detection antibody complex).
While captioned for clarity as the “second” antibody (e.g., second detection antibody), in fact, where multiple antibodies are used for capture and/or detection, the at least one detection antibody can be the second, third, fourth, etc. antibodies used in the immunoassay. If the capture antibody/analyte complex is contacted with more than one detection antibody, then a (first or multiple) capture antibody/analyte (or a fragment thereof)/(multiple) detection antibody complex is formed. As with the capture antibody (e.g., the first capture antibody), when the at least one (e.g., second and any subsequent) detection antibody is brought into contact with the capture antibody/analyte (or a fragment thereof) complex, a period of incubation under conditions similar to those described above is required for the formation of the (first or multiple) capture antibody/analyte/(second or multiple) detection antibody complex. Preferably, at least one detection antibody contains a detectable label. The detectable label can be bound to the at least one detection antibody (e.g., the second detection antibody) prior to, simultaneously with, or after the formation of the (first or multiple) capture antibody/analyte/(second or multiple) detection antibody complex. Any detectable label known in the art can be used (see discussion above).
The detectable label can be bound to the antibodies either directly or through a coupling agent. An example of a coupling agent that can be used is EDAC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, hydrochloride), which is commercially available from Sigma-Aldrich, St. Louis, Mo. Other coupling agents that can be used are known in the art. Methods for binding a detectable label to an antibody are known in the art. Additionally, many detectable labels can be purchased or synthesized that already contain end groups that facilitate the coupling of the detectable label to the antibody, such as CPSP-Acridinium Ester (i.e., 9-[N- to syl-N-(3-carboxypropyl)]-10-(3-sulfopropyl)acridinium carboxamide) or SP SP-Acridinium Ester (i.e., N10-(3-sulfopropyl)-N-(3-sulfopropyl)-acridinium-9-carboxamide).
The (first or multiple) capture antibody/analyte/(second or multiple) detection antibody complex can be, but does not have to be, separated from the remainder of the test sample prior to quantification of the label. For example, if the at least one capture antibody (e.g., the first capture antibody) is bound to a solid support, such as a well or a bead, separation can be accomplished by removing the fluid (of the test sample) from contact with the solid support. Alternatively, if the at least first capture antibody is bound to a solid support, it can be simultaneously contacted with the analyte-containing sample and the at least one second detection antibody to form a first (multiple) antibody/analyte/second (multiple) antibody complex, followed by removal of the fluid (test sample) from contact with the solid support. If the at least one first capture antibody is not bound to a solid support, then the (first or multiple) capture antibody/analyte/(second or multiple) detection antibody complex does not have to be removed from the test sample for quantification of the amount of the label.
After formation of the labeled capture antibody/analyte/detection antibody complex (e.g., the first capture antibody/analyte/second detection antibody complex), the amount of label in the complex is quantified using techniques known in the art. For example, if an enzymatic label is used, the labeled complex is reacted with a substrate for the label that gives a quantifiable reaction such as the development of color. If the label is a radioactive label, the label is quantified using appropriate means, such as a scintillation counter. If the label is a fluorescent label, the label is quantified by stimulating the label with a light of one color (which is known as the “excitation wavelength”) and detecting another color (which is known as the “emission wavelength”) that is emitted by the label in response to the stimulation. If the label is a chemiluminescent label, the label is quantified by detecting the light emitted either visually or by using luminometers, x-ray film, high speed photographic film, a CCD camera, etc. Once the amount of the label in the complex has been quantified, the concentration of analyte or a fragment thereof in the test sample is determined by appropriate means, such as by use of a standard curve that has been generated using serial dilutions of analyte or a fragment thereof of known concentration. Other than using serial dilutions of analyte or a fragment thereof, the standard curve can be generated gravimetrically, by mass spectroscopy and by other techniques known in the art.
In a chemiluminescent microparticle assay employing the ARCHITECT® analyzer, the conjugate diluent pH should be about 6.0+/−0.2, the microparticle coating buffer should be maintained at about room temperature (i.e., at from about 17 to about 27° C.), the microparticle coating buffer pH should be about 6.5+/−0.2, and the microparticle diluent pH should be about 7.8+/−0.2. Solids preferably are less than about 0.2%, such as less than about 0.15%, less than about 0.14%, less than about 0.13%, less than about 0.12%, or less than about 0.11%, such as about 0.10%.
FPIAs are based on competitive binding immunoassay principles. A fluorescently labeled compound, when excited by a linearly polarized light, will emit fluorescence having a degree of polarization inversely proportional to its rate of rotation. When a fluorescently labeled tracer-antibody complex is excited by a linearly polarized light, the emitted light remains highly polarized because the fluorophore is constrained from rotating between the time light is absorbed and the time light is emitted. When a “free” tracer compound (i.e., a compound that is not bound to an antibody) is excited by linearly polarized light, its rotation is much faster than the corresponding tracer-antibody conjugate produced in a competitive binding immunoassay. FPIAs are advantageous over RIAs inasmuch as there are no radioactive substances requiring special handling and disposal. In addition, FPIAs are homogeneous assays that can be easily and rapidly performed.
In view of the above, a method of determining the presence, amount, or concentration of HCV core (or a fragment thereof) in a test sample is provided. The method comprises assaying the test sample for an HCV core antigen (or a fragment thereof) by an assay (i) employing (i′) at least one of an antibody, a fragment of an antibody that can bind to an analyte, a variant of an antibody that can bind to an analyte, a fragment of a variant of an antibody that can bind to an analyte, or a DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof) that can bind to an HCV core antigen, and (ii′) at least one detectable label and (ii) comprising comparing a signal generated by the detectable label as a direct or indirect indication of the presence, amount or concentration of the HCV core antigen (or a fragment thereof) in the test sample to a signal generated as a direct or indirect indication of the presence, amount or concentration of HCV core antigen (or a fragment thereof) in a control or calibrator. The calibrator is optionally part of a series of calibrators, in which each of the calibrators differs from the other calibrators by the concentration of analyte.
The method can comprise (i) contacting the test sample with at least one first specific binding partner for HCV core (or a fragment thereof) selected from the group consisting of an antibody of the present invention, a fragment of such an antibody that can bind to an HCV core antigen, a variant of an antibody that can bind to an HCV core antigen, a fragment of a variant of an antibody that can bind to an HCV core antigen, or a DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof) that can bind to an HCV core antigen so as to form a first specific binding partner/HCV core antigen (or fragment thereof) complex, (ii) contacting the first specific binding partner/HCV core antigen (or fragment thereof) complex with at least one second specific binding partner for the HCV core antigen (or fragment thereof) selected from the group consisting of a detectably labeled anti-HCV core antibody, a detectably labeled fragment of an anti-HCV core antibody that can bind to HCV core antigen, a detectably labeled variant of an anti-HCV core antibody that can bind to HCV core antigen, a detectably labeled fragment of a variant of an anti-HCV core antibody that can bind to HCV core antigen, and a detectably labeled DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof) so as to form a first specific binding partner/HCV core antigen (or fragment thereof)/second specific binding partner complex, and (iii) determining the presence, amount or concentration of HCV core antigen in the test sample by detecting or measuring the signal generated by the detectable label in the first specific binding partner/HCV core antigen (or fragment thereof)/second specific binding partner complex formed in (ii).
Alternatively, the method can comprise contacting the test sample with at least one first specific binding partner for HCV core (or a fragment thereof) selected from the group consisting of an antibody, a fragment of an antibody that can bind to an HCV core, a variant of an antibody that can bind to an HCV core, a fragment of a variant of an antibody that can bind to an HCV core, and a DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof) and simultaneously or sequentially, in either order, contacting the test sample with at least one second specific binding partner, which can compete with HCV core (or a fragment thereof) for binding to the at least one first specific binding partner and which is selected from the group consisting of a detectably labeled HCV core, a detectably labeled fragment of HCV core that can bind to the first specific binding partner, a detectably labeled variant of HCV core that can bind to the first specific binding partner, and a detectably labeled fragment of a variant of HCV core that can bind to the first specific binding partner. Any HCV core (or a fragment thereof) present in the test sample and the at least one second specific binding partner compete with each other to form a first specific binding partner/HCV core (or fragment thereof) complex and a first specific binding partner/second specific binding partner complex, respectively. The method further comprises determining the presence, amount or concentration of HCV core in the test sample by detecting or measuring the signal generated by the detectable label in the first specific binding partner/second specific binding partner complex formed in (ii), wherein the signal generated by the detectable label in the first specific binding partner/second specific binding partner complex is inversely proportional to the amount or concentration of HCV core in the test sample.
The above methods can further comprise diagnosing, prognosticating, or assessing the efficacy of a therapeutic/prophylactic treatment of a patient from whom the test sample was obtained. If the method further comprises assessing the efficacy of a therapeutic/prophylactic treatment of the patient from whom the test sample was obtained, the method optionally further comprises modifying the therapeutic/prophylactic treatment of the patient as needed to improve efficacy. The method can be adapted for use in an automated system or a semi-automated system.
With regard to the methods of assay (and kit therefor), it may be possible to employ commercially available anti-HCV core antibodies or methods for production of anti-HCV core as described in the literature. Commercial supplies of various antibodies include, but are not limited to, Santa Cruz Biotechnology Inc. (Santa Cruz, Calif.), GenWay Biotech, Inc. (San Diego, Calif.), and R&D Systems (RDS; Minneapolis, Minn.).
Generally, a predetermined level can be employed as a benchmark against which to assess results obtained upon assaying a test sample for HCV core or a fragment thereof, e.g., for detecting disease or risk of disease. Generally, in making such a comparison, the predetermined level is obtained by running a particular assay a sufficient number of times and under appropriate conditions such that a linkage or association of HCV core presence, amount or concentration with a particular stage or endpoint of a disease, disorder or condition or with particular clinical indicia can be made. Typically, the predetermined level is obtained with assays of reference subjects (or populations of subjects). The HCV core measured can include fragments thereof, degradation products thereof, and/or enzymatic cleavage products thereof.
In particular, with respect to a predetermined level as employed for monitoring HCV disease progression and/or treatment, the amount or concentration of analyte or a fragment thereof may be “unchanged,” “favorable” (or “favorably altered”), or “unfavorable” (or “unfavorably altered”). “Elevated” or “increased” refers to an amount or a concentration in a test sample that is higher than a typical or normal level or range (e.g., predetermined level), or is higher than another reference level or range (e.g., earlier or baseline sample). The term “lowered” or “reduced” refers to an amount or a concentration in a test sample that is lower than a typical or normal level or range (e.g., predetermined level), or is lower than another reference level or range (e.g., earlier or baseline sample). The term “altered” refers to an amount or a concentration in a sample that is altered (increased or decreased) over a typical or normal level or range (e.g., predetermined level), or over another reference level or range (e.g., earlier or baseline sample).
The typical or normal level or range for HCV core antigen is defined in accordance with standard practice. Because the levels of HCV core in some instances will be very low, a so-called altered level or alteration can be considered to have occurred when there is any net change as compared to the typical or normal level or range, or reference level or range, that cannot be explained by experimental error or sample variation. Thus, the level measured in a particular sample will be compared with the level or range of levels determined in similar samples from a so-called normal subject. In this context, a “normal subject” is an individual with no detectable disease, for example, and a “normal” (sometimes termed “control”) patient or population is/are one(s) that exhibit(s) no detectable disease, respectively, for example. Furthermore, given that HCV core is not routinely found at a high level in the majority of the human population, a “normal subject” can be considered an individual with no substantial detectable increased or elevated amount or concentration of HCV core, and a “normal” (sometimes termed “control”) patient or population is/are one(s) that exhibit(s) no substantial detectable increased or elevated amount or concentration of HCV core. An “apparently normal subject” is one in which HCV core has not yet been or currently is being assessed. The level of an HCV core is said to be “elevated” when the HCV core is normally undetectable (e.g., the normal level is zero, or within a range of from about 25 to about 75 percentiles of normal populations), but is detected in a test sample, as well as when the HCV core is present in the test sample at a higher than normal level.
Thus, inter alia, the disclosure provides a method of screening for a subject having, or at risk of having, a particular disease, disorder, or condition. The method of assay can also involve the assay of other markers and the like.
Accordingly, the methods described herein also can be used to determine whether or not a subject has or is at risk of developing a HCV disease, disorder or condition. Specifically, such a method can comprise the steps of:
(a) determining the concentration or amount in a test sample from a subject of HCV core (or a fragment thereof) (e.g., using the methods described herein, or methods known in the art); and
(b) comparing the concentration or amount of HCV core (or a fragment thereof) determined in step (a) with a predetermined level, wherein, if the concentration or amount of HCV core determined in step (a) is favorable with respect to a predetermined level, then the subject is determined not to have or be at risk for a given disease, disorder or condition. However, if the concentration or amount of HCV core determined in step (a) is unfavorable with respect to the predetermined level, then the subject is determined to have or be at risk for a given disease, disorder or condition.
Additionally, provided herein is method of monitoring the progression of disease in a subject. Optimally the method comprising the steps of:
(a) determining the concentration or amount in a test sample from a subject of HCV core;
(b) determining the concentration or amount in a later test sample from the subject of HCV core; and
(c) comparing the concentration or amount of HCV core as determined in step (b) with the concentration or amount of HCV core determined in step (a), wherein if the concentration or amount determined in step (b) is unchanged or is unfavorable when compared to the concentration or amount of HCV core determined in step (a), then the disease in the subject is determined to have continued, progressed or worsened. By comparison, if the concentration or amount of HCV core as determined in step (b) is favorable when compared to the concentration or amount of HCV core as determined in step (a), then the disease in the subject is determined to have discontinued, regressed or improved.
Optionally, the method further comprises comparing the concentration or amount of HCV core as determined in step (b), for example, with a predetermined level. Further, optionally the method comprises treating the subject with one or more pharmaceutical compositions for a period of time if the comparison shows that the concentration or amount of HCV core as determined in step (b), for example, is unfavorably altered with respect to the predetermined level.
In still other embodiments, any of the assays described herein for monitoring presence or levels of HCV core antigen can advantageously be combined with other assays that also determine HCV infection. For example, any of the HCV core determining methods of the invention may further comprise determining the level of another HCV antigen or HCV antibody directed to an antigen other than core protein, including but not limited to determining the presence of HCV Core, E1, E2, NS2, NS3, NS4a, NS4b and NS5.
Still further, the methods can be used to monitor treatment in a subject receiving treatment with one or more pharmaceutical compositions. Specifically, such methods involve providing a first test sample from a subject before the subject has been administered one or more pharmaceutical compositions. Next, the concentration or amount in a first test sample from a subject of HCV core is determined (e.g., using the methods described herein or as known in the art). After the concentration or amount of HCV core is determined, optionally the concentration or amount of HCV core is then compared with a predetermined level. If the concentration or amount of HCV core as determined in the first test sample is lower than the predetermined level, then the subject is not treated with one or more pharmaceutical compositions. However, if the concentration or amount of HCV core as determined in the first test sample is higher than the predetermined level, then the subject is treated with one or more pharmaceutical compositions for a period of time. The period of time that the subject is treated with the one or more pharmaceutical compositions can be determined by one skilled in the art (for example, the period of time can be from about seven (7) days to about two years, preferably from about fourteen (14) days to about one (1) year).
During the course of treatment with the one or more pharmaceutical compositions, second and subsequent test samples are then obtained from the subject. The number of test samples and the time in which said test samples are obtained from the subject are not critical. For example, a second test sample could be obtained seven (7) days after the subject is first administered the one or more pharmaceutical compositions, a third test sample could be obtained two (2) weeks after the subject is first administered the one or more pharmaceutical compositions, a fourth test sample could be obtained three (3) weeks after the subject is first administered the one or more pharmaceutical compositions, a fifth test sample could be obtained four (4) weeks after the subject is first administered the one or more pharmaceutical compositions, etc.
After each second or subsequent test sample is obtained from the subject, the concentration or amount of HCV core is determined in the second or subsequent test sample is determined (e.g., using the methods described herein or as known in the art). The concentration or amount of HCV core as determined in each of the second and subsequent test samples is then compared with the concentration or amount of HCV core as determined in the first test sample (e.g., the test sample that was originally optionally compared to the predetermined level). If the concentration or amount of HCV core as determined in step (c) is favorable when compared to the concentration or amount of HCV core as determined in step (a), then the disease in the subject is determined to have discontinued, regressed or improved, and the subject should continue to be administered the one or pharmaceutical compositions of step (b). However, if the concentration or amount determined in step (c) is unchanged or is unfavorable when compared to the concentration or amount of HCV core as determined in step (a), then the disease in the subject is determined to have continued, progressed or worsened, and the subject should be treated with a higher concentration of the one or more pharmaceutical compositions administered to the subject in step (b) or the subject should be treated with one or more pharmaceutical compositions that are different from the one or more pharmaceutical compositions administered to the subject in step (b). Specifically, the subject can be treated with one or more pharmaceutical compositions that are different from the one or more pharmaceutical compositions that the subject had previously received to decrease or lower said subject's HCV core level.
Generally, for assays in which repeat testing may be done (e.g., monitoring disease progression and/or response to treatment), a second or subsequent test sample is obtained at a period in time after the first test sample has been obtained from the subject. Specifically, a second test sample from the subject can be obtained minutes, hours, days, weeks or years after the first test sample has been obtained from the subject. For example, the second test sample can be obtained from the subject at a time period of about 1 minute, about 5 minutes, about 10 minutes, about 15 minutes, about 30 minutes, about 45 minutes, about 60 minutes, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 15 hours, about 16 hours, about 17 hours, about 18 hours, about 19 hours, about 20 hours, about 21 hours, about 22 hours, about 23 hours, about 24 hours, about 2 days, about 3 days, about 4 days, about 5 days, about 6 days, about 7 days, about 2 weeks, about 3 weeks, about 4 weeks, about 5 weeks, about 6 weeks, about 7 weeks, about 8 weeks, about 9 weeks, about 10 weeks, about 11 weeks, about 12 weeks, about 13 weeks, about 14 weeks, about 15 weeks, about 16 weeks, about 17 weeks, about 18 weeks, about 19 weeks, about 20 weeks, about 21 weeks, about 22 weeks, about 23 weeks, about 24 weeks, about 25 weeks, about 26 weeks, about 27 weeks, about 28 weeks, about 29 weeks, about 30 weeks, about 31 weeks, about 32 weeks, about 33 weeks, about 34 weeks, about 35 weeks, about 36 weeks, about 37 weeks, about 38 weeks, about 39 weeks, about 40 weeks, about 41 weeks, about 42 weeks, about 43 weeks, about 44 weeks, about 45 weeks, about 46 weeks, about 47 weeks, about 48 weeks, about 49 weeks, about 50 weeks, about 51 weeks, about 52 weeks, about 1.5 years, about 2 years, about 2.5 years, about 3.0 years, about 3.5 years, about 4.0 years, about 4.5 years, about 5.0 years, about 5.5. years, about 6.0 years, about 6.5 years, about 7.0 years, about 7.5 years, about 8.0 years, about 8.5 years, about 9.0 years, about 9.5 years or about 10.0 years after the first test sample from the subject is obtained.
When used to monitor disease progression, the above assay can be used to monitor the progression of disease in subjects suffering from acute conditions. Acute conditions, also known as critical care conditions, refer to acute, life-threatening diseases or other critical medical conditions involving, for example, the cardiovascular system or excretory system. Typically, critical care conditions refer to those conditions requiring acute medical intervention in a hospital-based setting (including, but not limited to, the emergency room, intensive care unit, trauma center, or other emergent care setting) or administration by a paramedic or other field-based medical personnel. For critical care conditions, repeat monitoring is generally done within a shorter time frame, namely, minutes, hours or days (e.g., about 1 minute, about 5 minutes, about 10 minutes, about 15 minutes, about 30 minutes, about 45 minutes, about 60 minutes, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 15 hours, about 16 hours, about 17 hours, about 18 hours, about 19 hours, about 20 hours, about 21 hours, about 22 hours, about 23 hours, about 24 hours, about 2 days, about 3 days, about 4 days, about 5 days, about 6 days or about 7 days), and the initial assay likewise is generally done within a shorter timeframe, e.g., about minutes, hours or days of the onset of the disease or condition.
The assays also can be used to monitor the progression of disease in subjects suffering from chronic or non-acute conditions. Non-critical care or, non-acute conditions, refers to conditions other than acute, life-threatening disease or other critical medical conditions involving, for example, the cardiovascular system and/or excretory system. Typically, non-acute conditions include those of longer-term or chronic duration. For non-acute conditions, repeat monitoring generally is done with a longer timeframe, e.g., hours, days, weeks, months or years (e.g., about 1 hour, about 2 hours, about 3 hours, about 4 hours, about 5 hours, about 6 hours, about 7 hours, about 8 hours, about 9 hours, about 10 hours, about 11 hours, about 12 hours, about 13 hours, about 14 hours, about 15 hours, about 16 hours, about 17 hours, about 18 hours, about 19 hours, about 20 hours, about 21 hours, about 22 hours, about 23 hours, about 24 hours, about 2 days, about 3 days, about 4 days, about 5 days, about 6 days, about 7 days, about 2 weeks, about 3 weeks, about 4 weeks, about 5 weeks, about 6 weeks, about 7 weeks, about 8 weeks, about 9 weeks, about 10 weeks, about 11 weeks, about 12 weeks, about 13 weeks, about 14 weeks, about 15 weeks, about 16 weeks, about 17 weeks, about 18 weeks, about 19 weeks, about 20 weeks, about 21 weeks, about 22 weeks, about 23 weeks, about 24 weeks, about 25 weeks, about 26 weeks, about 27 weeks, about 28 weeks, about 29 weeks, about 30 weeks, about 31 weeks, about 32 weeks, about 33 weeks, about 34 weeks, about 35 weeks, about 36 weeks, about 37 weeks, about 38 weeks, about 39 weeks, about 40 weeks, about 41 weeks, about 42 weeks, about 43 weeks, about 44 weeks, about 45 weeks, about 46 weeks, about 47 weeks, about 48 weeks, about 49 weeks, about 50 weeks, about 51 weeks, about 52 weeks, about 1.5 years, about 2 years, about 2.5 years, about 3.0 years, about 3.5 years, about 4.0 years, about 4.5 years, about 5.0 years, about 5.5. years, about 6.0 years, about 6.5 years, about 7.0 years, about 7.5 years, about 8.0 years, about 8.5 years, about 9.0 years, about 9.5 years or about 10.0 years), and the initial assay likewise generally is done within a longer time frame, e.g., about hours, days, months or years of the onset of the disease or condition.
Furthermore, the above assays can be performed using a first test sample obtained from a subject where the first test sample is obtained from one source, such as urine, serum or plasma.
Optionally, the above assays can then be repeated using a second test sample obtained from the subject where the second test sample is obtained from another source. For example, if the first test sample was obtained from urine, the second test sample can be obtained from serum or plasma. The results obtained from the assays using the first test sample and the second test sample can be compared. The comparison can be used to assess the status of a disease or condition in the subject.
Moreover, the present disclosure also relates to methods of determining whether a subject predisposed to or suffering from a given disease, disorder or condition will benefit from treatment. In particular, the disclosure relates to HCV core companion diagnostic methods and products. Thus, the method of “monitoring the treatment of disease in a subject” as described herein further optimally also can encompass selecting or identifying candidates for therapy.
Thus, in particular embodiments, the disclosure also provides a method of determining whether a subject having, or at risk for, a given disease, disorder or condition is a candidate for therapy. Generally, the subject is one who has experienced some symptom of a given disease, disorder or condition or who has actually been diagnosed as having, or being at risk for, a given disease, disorder or condition, and/or who demonstrates an unfavorable concentration or amount of HCV core or a fragment thereof, as described herein.
The method optionally comprises an assay as described herein, where HCV core is assessed before and following treatment of a subject with one or more pharmaceutical compositions (e.g., particularly with a pharmaceutical related to a mechanism of action involving HCV core), with immunosuppressive therapy, or by immunoabsorption therapy, or where HCV core is assessed following such treatment and the concentration or the amount of HCV core is compared against a predetermined level. An unfavorable concentration of amount of HCV core observed following treatment confirms that the subject will not benefit from receiving further or continued treatment, whereas a favorable concentration or amount of HCV core observed following treatment confirms that the subject will benefit from receiving further or continued treatment. This confirmation assists with management of clinical studies, and provision of improved patient care.
The method of assay also can be used to identify a compound that ameliorates a given disease, disorder or condition. For example, a cell that expresses HCV core can be contacted with a candidate compound. The level of expression of HCV core in the cell contacted with the compound can be compared to that in a control cell using the method of assay described herein.
In yet another detection method, each of the binding proteins as described herein can be employed in the detection of HCV antigens in fixed tissue sections, as well as fixed cells by immunohistochemical analysis.
In addition, these binding proteins can be bound to matrices similar to CNBr-activated Sepharose and used for the affinity purification of specific HCV proteins from cell cultures, or biological tissues such as blood and liver.
The monoclonal antibodies as described herein can also be used for the generation of chimeric antibodies for therapeutic use, or other similar applications. In addition, as discussed herein throughout the antibodies also could be used in the production of DVD-Ig molecules.
The monoclonal antibodies or fragments thereof can be provided individually to detect HCV core antigens. It is contemplated that combinations of the monoclonal antibodies (and fragments thereof) provided herein also may be used together as components in a mixture or “cocktail” of at least one anti-HCV core antibody as described herein with antibodies to other
HCV regions, each having different binding specificities. Thus, this cocktail can include the monoclonal antibodies as described herein, which are directed to HCV core protein, and other monoclonal antibodies to other antigenic determinants of the HCV genome. Examples of other monoclonal antibodies useful for these contemplated cocktails include those to HCV C-100, HCV 33C, HCV CORE, HCV NS5 and/or HCV putative ENV, which are disclosed in, for example, U.S. Ser. No. 07/610,175 entitled MONOCLONAL ANTIBODIES TO HEPATITIS C VIRUS AND METHOD FOR USING SAME, U.S. Ser. No. 07/610,175 entitled MONOCLONAL ANTIBODIES TO HCV 33C PROTEINS AND METHODS FOR USING SAME, U.S. Ser. No. 07/648,475 entitled MONOCLONAL ANTIBODIES TO PUTATIVE HCV ENVELOPE REGION AND METHODS FOR USING SAME, U.S. Ser. No. 07/648,473 entitled MONOCLONAL ANTIBODIES TO HCV CORE PROTEINS AND METHODS FOR USING SAME and in co-filed patent application entitled MONOCLONAL ANTIBODIES TO HCV NS5 PROTEIN AND METHODS FOR USING SAME, U.S. Ser. No. 07/748,563, all of which enjoy common ownership and are incorporated herein by reference. This cocktail of monoclonal antibodies as described herein would be used in the assay formats detailed herein in place of the monoclonal antibody to HCV core, and thus would be able to detect the HCV core and other HCV antigens.
The polyclonal antibody or fragment thereof which can be used in the assay formats should specifically bind to HCV core or other HCV proteins used in the assay, such as HCV C-100 protein, HCV 33C protein, HCV ENV, HCV E2/NS1 or HCV NS5 protein. The polyclonal antibody used preferably is of mammalian origin; human, goat, rabbit or sheep anti-HCV polyclonal antibody can be used. Most preferably, the polyclonal antibody is rabbit polyclonal anti-HCV antibody. The polyclonal antibodies used in the assays can be used either alone or as a cocktail of polyclonal antibodies. Since the cocktails used in the assay formats are comprised of either monoclonal antibodies or polyclonal antibodies having different HCV specificity, they would be useful for diagnosis, evaluation and prognosis of HCV infection, as well as for studying HCV protein differentiation and specificity.
As noted elsewhere herein throughout, the test samples which can be tested by the methods as described herein described herein include human and animal body fluids such as whole blood, serum, plasma, cerebrospinal fluid, urine, biological fluids such as cell culture supernatants, fixed tissue specimens and fixed ceil specimens.
The indicator reagent comprises a signal-generating compound (label) that is capable of generating a measurable signal detectable by external means conjugated (attached) to a specific binding member for HCV core. “Specific binding member” as used herein means a member of a specific binding pair. That is, two different molecules where one of the molecules through chemical or physical means specifically binds to the second molecule. In addition to being an antibody member of a specific binding pair for HCV core, the indicator reagent also can be a member of any specific binding pair, including either hapten-anti-hapten systems such as biotin or anti-biotin, avidin or biotin, a carbohydrate or a lectin, a complementary nucleotide sequence, an effector or a receptor molecule, an enzyme cofactor and an enzyme, an enzyme inhibitor or an enzyme, and the like. An immunoreactive specific binding member can be an antibody, an antigen, or an antibody/antigen complex that is capable of binding either to HCV core as in a sandwich assay, to the capture reagent as in a competitive assay, or to the ancillary specific binding member as in an indirect assay.
The various signal generating compounds (labels) contemplated include chromogens, catalysts such as enzymes, luminescent compounds such as fluorescein and rhodamine, chemiluminescent compounds such as acridinium, phenanthridinium and dioxetane compounds, radioactive elements, and direct visual labels. Examples of enzymes include alkaline phosphatase, horseradish peroxidase, beta-galactosidase, and the like. The selection of a particular label is not critical, but it will be capable of producing a signal either by itself or in conjunction with one or more additional substances.
The use of scanning probe microscopy (SPM) for immunoassays also is a technology to which the monoclonal antibodies as described herein are easily adaptable. In scanning probe microscopy, in particular in atomic force microscopy, the capture phase, for example, at least one of the monoclonal antibodies as described herein, is adhered to a solid phase and a scanning probe microscope is utilized to detect antigen/antibody complexes which may be present on the surface of the solid phase. The use of scanning tunnelling microscopy eliminates the need for labels that normally must be utilized in many immunoassay systems to detect antigen/antibody complexes. Such a system is described in pending U.S. patent application Ser. No. 662,147, which enjoys common ownership and is incorporated herein by reference.
The use of SPM to monitor specific binding reactions can occur in many ways. In one embodiment, one member of a specific binding partner (the HCV core specific substance, which is the monoclonal antibody as described herein) is attached to a surface suitable for scanning. The attachment of the HCV core specific substance may be by adsorption to a test piece, which comprises a solid phase of a plastic or metal surface, following methods known to those of ordinary skill in the art. Or, covalent attachment of a specific binding partner (HCV core specific substance) to a test piece which test piece comprises a solid phase of derivatized plastic, metal, silicon, or glass may be utilized. Covalent attachment methods are known to those skilled in the art and include a variety of means to irreversibly link specific binding partners to the test piece. If the test piece is silicon or glass, the surface must be activated prior to attaching the specific binding partner. Activated silane compounds such as triethoxy amino propyl silane (available from Sigma Chemical Co., St. Louis, Mo.), triethoxy vinyl silane (Aldrich Chemical Co., Milwaukee, Wis.), and (3-mercapto-propyl)trimethoxy silane (Sigma Chemical Co., St. Louis, Mo.) can be used to introduce reactive groups such as amino-, vinyl, and thiol, respectively. Such activated surfaces can be used to link the binding partner directly (in the cases of amino or thiol) or the activated surface can be further reacted with linkers such as glutaraldehyde, bis(succinimidyl) suberate, SPPD 9 succinimidyl 3[2-pyridyldithio]propionate), SMCC (succinimidyl-4-[N-maleimidomethyl]cyclohexane-1-carboxylate), SLAB (succinimidyl [4-iodoacetyl]aminobenzoate), and SMPB (succinimidyl 4[1-maleimidophenyl]butyrate) to separate the binding partner from the surface. The vinyl group can be oxidized to provide a means for covalent attachment. It also can be used as an anchor for the polymerization of various polymers such as poly acrylic acid, which can provide multiple attachment points for specific binding partners. The amino surface can be reacted with oxidized dextrans of various molecular weights to provide hydrophilic linkers of different size and capacity. Examples of oxidizable dextrans include Dextran T-40 (molecular weight 40,000 daltons), Dextran T-110 (molecular weight 110,000 daltons), Dextran T-500 (molecular weight 500,000 daltons), Dextran T-2M (molecular weight 2,000,000 daltons) (all of which are available from Pharmacia, Piscataway, N.J.), or Ficoll (molecular weight 70,000 daltons (available from Sigma Chemical Co., St. Louis, Mo.). Also, polyelectrolyte interactions may be used to immobilize a specific binding partner on a surface of a test piece by using techniques and chemistries described by pending U.S. patent application Ser. Nos. 150,278, filed Jan. 29, 1988, and Ser. No. 375,029, filed Jul. 7, 1989, each of which enjoys common ownership and each of which is incorporated herein by reference. The preferred method of attachment is by covalent means. Following attachment of a specific binding member, the surface may be further treated with materials such as serum, proteins, or other blocking agents to minimize non-specific binding. The surface also may be scanned either at the site of manufacture or point of use to verify its suitability for assay purposes. The scanning process is not anticipated to alter the specific binding properties of the test piece.
While the present disclosure expresses a preference for the use of solid phases, it is contemplated that the monoclonal antibodies as described herein can be utilized in non-solid phase assay systems. These assay systems are known to those skilled in the art, and are considered to be within the scope of the disclosure.
It is contemplated that the reagent employed for the assay can be provided in the form of a kit with one or more containers such as vials or bottles, with each container containing a separate reagent such as a monoclonal antibody, or a cocktail of monoclonal antibodies, detection reagents and washing reagents employed in the assay.
The antibodies can also be used as a means of enhancing the immune response. The antibodies can be administered in amount similar to those used for other therapeutic administrations of antibody. For example, normal immune globulin is administered at 0.02 0.1 ml/lb body weight during the early incubation period of other viral diseases such as rabies, measles, and hepatitis B to interfere with viral entry into cells. Thus, antibodies reactive with the HCV core proteins can be passively administered alone or in conjunction with another anti-viral agent to a host infected with an HCV to enhance the immune response and/or the effectiveness of an antiviral drug.
When used as a means of inducing anti-HCV virus antibodies in an animal, the manner of injecting the antibody is the same as for vaccination purposes, namely intramuscularly, intraperitoneally, subcutaneously or the like in an effective concentration in a physiologically suitable diluent with or without adjuvant. One or more booster injections may be desirable.
Kits
Also contemplated herein are kits for assaying a test sample for the presence, amount or concentration of HCV core protein (or a fragment thereof) in a test sample. Such a kit comprises at least one component for assaying the test sample for HCV core protein (or a fragment thereof) and instructions for assaying the test sample for the HCV core (or a fragment thereof). The at least one component for assaying the test sample for the HCV core (or a fragment thereof) can include a composition comprising an anti-HCV core protein monoclonal antibody or an anti-HCV core protein DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof), which is optionally immobilized or capable of being immobilized on a solid phase.
The kit can comprise at least one component for assaying the test sample for HCV core protein by immunoassay, e.g., chemiluminescent microparticle immunoassay, and instructions for assaying the test sample for an HCV core by immunoassay, e.g., chemiluminescent microparticle immunoassay. For example, the kit can comprise at least one specific binding partner for an HCV core, such as an anti-HCV core, monoclonal/polyclonal antibody (or a fragment thereof that can bind to the HCV core, a variant thereof that can bind to the HCV core, or a fragment of a variant that can bind to the HCV core) or an anti-HCV core DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof), either of which can be detectably labeled. Alternatively or additionally, the kit can comprise detectably labeled HCV core (or a fragment thereof that can bind to an anti-HCV core, monoclonal/polyclonal antibody or an anti-HCV core DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof)), which can compete with any HCV core in a test sample for binding to an anti-HCV core, monoclonal/polyclonal antibody (or a fragment thereof that can bind to the HCV core, a variant thereof that can bind to the HCV core, or a fragment of a variant that can bind to the HCV core) or an anti-HCV core DVD-Ig (or a fragment, a variant, or a fragment of a variant thereof), either of which can be immobilized on a solid support. The kit can comprise a calibrator or control, e.g., isolated or purified HCV core. The kit can comprise at least one container (e.g., tube, microtiter plates or strips, which can be already coated with a first specific binding partner, for example) for conducting the assay, and/or a buffer, such as an assay buffer or a wash buffer, either one of which can be provided as a concentrated solution, a substrate solution for the detectable label (e.g., an enzymatic label), or a stop solution. Preferably, the kit comprises all components, i.e., reagents, standards, buffers, diluents, etc., which are necessary to perform the assay. The instructions can be in paper form or computer-readable form, such as a disk, CD, DVD, or the like.
Any antibodies, such as an anti-HCV core antibody or an anti-HCV core DVD-Ig, or tracer can incorporate a detectable label as described herein, such as a fluorophore, a radioactive moiety, an enzyme, a biotin/avidin label, a chromophore, a chemiluminescent label, or the like, or the kit can include reagents for carrying out detectable labeling. The antibodies, calibrators and/or controls can be provided in separate containers or pre-dispensed into an appropriate assay format, for example, into microtiter plates.
Optionally, the kit includes quality control components (for example, sensitivity panels, calibrators, and positive controls). Preparation of quality control reagents is well-known in the art and is described on insert sheets for a variety of immunodiagnostic products. Sensitivity panel members optionally are used to establish assay performance characteristics, and further optionally are useful indicators of the integrity of the immunoassay kit reagents, and the standardization of assays.
The kit can also optionally include other reagents required to conduct a diagnostic assay or facilitate quality control evaluations, such as buffers, salts, enzymes, enzyme co-factors, enzyme substrates, detection reagents, and the like. Other components, such as buffers and solutions for the isolation and/or treatment of a test sample (e.g., pretreatment reagents), also can be included in the kit. The kit can additionally include one or more other controls. One or more of the components of the kit can be lyophilized, in which case the kit can further comprise reagents suitable for the reconstitution of the lyophilized components.
The various components of the kit optionally are provided in suitable containers as necessary, e.g., a microtiter plate. The kit can further include containers for holding or storing a sample (e.g., a container or cartridge for a urine sample). Where appropriate, the kit optionally also can contain reaction vessels, mixing vessels, and other components that facilitate the preparation of reagents or the test sample. The kit can also include one or more instruments for assisting with obtaining a test sample, such as a syringe, pipette, forceps, measured spoon, or the like.
If the detectable label is at least one acridinium compound, the kit can comprise at least one acridinium-9-carboxamide, at least one acridinium-9-carboxylate aryl ester, or any combination thereof If the detectable label is at least one acridinium compound, the kit also can comprise a source of hydrogen peroxide, such as a buffer, a solution, and/or at least one basic solution. If desired, the kit can contain a solid phase, such as a magnetic particle, bead, test tube, microtiter plate, cuvette, membrane, scaffolding molecule, film, filter paper, disc or chip.
The kit (or components thereof), as well as the method of determining the presence, amount or concentration of an HCV core in a test sample by an assay, such as an immunoassay as described herein, can be adapted for use in a variety of automated and semi-automated systems (including those wherein the solid phase comprises a microparticle), as described, e.g., in U.S. Pat. Nos. 5,089,424 and 5,006,309, and as commercially marketed, e.g., by Abbott Laboratories (Abbott Park, Ill.) as ARCHITECT®.
Some of the differences between an automated or semi-automated system as compared to a non-automated system (e.g., ELISA) include the substrate to which the first specific binding partner (e.g., an anti-HCV core, monoclonal/polyclonal antibody (or a fragment thereof, a variant thereof, or a fragment of a variant thereof) or an anti-HCV core DVD-Ig (or a fragment thereof, a variant thereof, or a fragment of a variant thereof) is attached; either way, sandwich formation and HCV core reactivity can be impacted), and the length and timing of the capture, detection and/or any optional wash steps. Whereas a non-automated format, such as an ELISA, may require a relatively longer incubation time with sample and capture reagent (e.g., about 2 hours), an automated or semi-automated format (e.g., ARCHITECT®, Abbott Laboratories) may have a relatively shorter incubation time (e.g., approximately 18 minutes for ARCHITECT®). Similarly, whereas a non-automated format, such as an ELISA, may incubate a detection antibody, such as the conjugate reagent, for a relatively longer incubation time (e.g., about 2 hours), an automated or semi-automated format (e.g., ARCHITECT®) may have a relatively shorter incubation time (e.g., approximately 4 minutes for the ARCHITECT®).
Other platforms available from Abbott Laboratories include, but are not limited to, AxSYM®, IMx® (see, e.g., U.S. Pat. No. 5,294,404, which is hereby incorporated by reference in its entirety), PRISM®, EIA (bead), and Quantum™ II, as well as other platforms. Additionally, the assays, kits and kit components can be employed in other formats, for example, on electrochemical or other hand-held or point-of-care assay systems. The present disclosure is, for example, applicable to the commercial Abbott Point of Care (i-STAT®, Abbott Laboratories) electrochemical immunoassay system that performs sandwich immunoassays Immunosensors and their methods of manufacture and operation in single-use test devices are described, for example in, U.S. Pat. No. 5,063,081, U.S. Patent App. Pub. No. 2003/0170881, U.S. Patent App. Pub. No. 2004/0018577, U.S. Patent App. Pub. No. 2005/0054078, and U.S. Patent App. Pub. No. 2006/0160164, which are incorporated in their entireties by reference for their teachings regarding same.
In particular, with regard to the adaptation of an HCV core assay to the I-STAT® system, the following configuration is preferred. A microfabricated silicon chip is manufactured with a pair of gold amperometric working electrodes and a silver-silver chloride reference electrode. On one of the working electrodes, polystyrene beads (0.2 mm diameter) with immobilized anti-HCV core, monoclonal/polyclonal antibody (or a fragment thereof, a variant thereof, or a fragment of a variant thereof) or anti-HCV core DVD-Ig (or a fragment thereof, a variant thereof, or a fragment of a variant thereof), are adhered to a polymer coating of patterned polyvinyl alcohol over the electrode. This chip is assembled into an I-STAT® cartridge with a fluidics format suitable for immunoassay. On a portion of the wall of the sample-holding chamber of the cartridge there is a layer comprising a specific binding partner for an HCV core, such as an anti-HCV core, monoclonal/polyclonal antibody (or a fragment thereof, a variant thereof, or a fragment of a variant thereof that can bind the HCV core) or an anti-HCV core DVD-Ig (or a fragment thereof, a variant thereof, or a fragment of a variant thereof that can bind the HCV core), either of which can be detectably labeled. Within the fluid pouch of the cartridge is an aqueous reagent that includes p-aminophenol phosphate.
In operation, a sample suspected of containing an HCV core is added to the holding chamber of the test cartridge, and the cartridge is inserted into the I-STAT® reader. After the specific binding partner for an HCV core has dissolved into the sample, a pump element within the cartridge forces the sample into a conduit containing the chip. Here it is oscillated to promote formation of the sandwich. In the penultimate step of the assay, fluid is forced out of the pouch and into the conduit to wash the sample off the chip and into a waste chamber. In the final step of the assay, the alkaline phosphatase label reacts with p-aminophenol phosphate to cleave the phosphate group and permit the liberated p-aminophenol to be electrochemically oxidized at the working electrode. Based on the measured current, the reader is able to calculate the amount of HCV core in the sample by means of an embedded algorithm and factory-determined calibration curve.
It further goes without saying that the methods and kits as described herein necessarily encompass other reagents and methods for carrying out the immunoassay. For instance, encompassed are various buffers such as are known in the art and/or which can be readily prepared or optimized to be employed, e.g., for washing, as a conjugate diluent, microparticle diluent, and/or as a calibrator diluent. An exemplary conjugate diluent is ARCHITECT® conjugate diluent employed in certain kits (Abbott Laboratories, Abbott Park, Ill.) and containing 2-(N-morpholino)ethanesulfonic acid (MES), a salt, a protein blocker, an antimicrobial agent, and a detergent. An exemplary calibrator diluent is ARCHITECT® human calibrator diluent employed in certain kits (Abbott Laboratories, Abbott Park, Ill.), which comprises a buffer containing IVIES, other salt, a protein blocker, and an antimicrobial agent. Additionally, as described in U.S. Patent Application No. 61/142,048 filed Dec. 31, 2008, improved signal generation may be obtained, e.g., in an I-Stat cartridge format, using a nucleic acid sequence linked to the signal antibody as a signal amplifier.
It will be readily apparent to those skilled in the art that other suitable modifications and adaptations of the methods of the invention described herein are obvious and may be made using suitable equivalents without departing from the scope of the invention or the embodiments disclosed herein. Having now described the present invention in detail, the same will be more clearly understood by reference to the following examples, which are included for purposes of illustration only and are not intended to be limiting of the invention.
Animal Immunizations.
Female CAF1/J and RBF/DnJ mice (both from The Jackson Laboratory, Bar Harbor, Me.) were immunized on weeks 0, 4 and 10 with 50 μg of an HCV core peptide corresponding to amino acids (all numbering per HCV-1) 134-171 covalently linked to BSA (ALRZ-8 immunogen).
HCV core peptide-BSA was prepared by AnaSpec, Inc. (Fremont, Calif.). The immunogen peptide was emulsified in Complete or Incomplete Adjulite Freund's Adjuvant (Pacific Immunology, Ramona, Calif.). Complete Freund's adjuvant was used for the primary immunization and Incomplete Freund's adjuvant for the second and third immunizations. Each inoculum was prepared by first diluting the HCV peptide-BSA to the appropriate concentration in sterile saline (0.9% sodium chloride), adding an equal volume of adjuvant and then mixing by passing back and forth between two syringes via a 3-way stopcock until a thick, stable emulsion was formed. Sera samples were taken 10-14 days following the 3rd immunization. On the 4th and 3rd days prior to B cell harvest, RBF/DnJ mice #306 and 315 were administered 50 μg peptide-BSA diluted in sterile saline. This inoculum was delivered into the body cavity near the spleen.
ALRZ-8 Immunogen
Ac-MGYIPLVGAPLGGAARALAHGVRVLEDGVNYATGNLPGC-B SA (SEQ ID NO:576).
Screening of mouse sera for antigen immunoreactivity.
Mouse sera samples collected 7-10 days after their final immunization were first tested in a 96-well micro titer enzyme immunoassay (EIA) for reactivity to each of three synthetic
(Anaspec, Inc.) carboxy-terminal biotinylated HCV core peptides. The peptides used for screening were derived from the immunogen sequence described in Example 1 and had the following designations and sequences: Peptide 1 (all numbering per HCV-1), amino acids 134-151: MGYIPLVGAPLGGAARALAHG (SEQ ID NO:573); Peptide 2, amino acids 141-161: GAPLGGAARALAHGVRVLEDG (SEQ ID NO:574), Peptide 3, amino acids 151-171, LAHGVRVLEDGVNYATGNLPG (SEQ ID NO:575). Assay plates (NUNC Corporation, Naperville, Ill.) were coated with 100 μL/well of sheep anti-mouse IgG Fc specific antibody (Jackson ImmunoResearch, West Grove, Pa.) diluted to 2 μg/mL in phosphate-buffered saline (PBS). Plates were incubated at 37 deg C for about 2 hours and then at about 21 deg C for about 2 hours. The capture antibody was then removed and 200 μL/well of blocking solution (3% w/v [weight/volume] bovine serum albumin (BSA) and 0.5% v/v [volume/volume] polysorbate-20 diluted in PBS added. The plates were incubated for about 30 minutes and then washed with distilled water. Next, serial dilutions (in block solution) of the mouse sera or a positive control were added to the assay plates (100 μL/well), incubated for between 2 and 20 hours and then washed with dH2O. Next, 100 μL/well of normal serum solution (NSS; block solution containing 2% v/v normal mouse serum) was added for additional blocking. This solution helps to prevent non-specific binding in the assay well. The plates were incubated for about 30 minutes and then washed with dH2O. Subsequently, 100 μL/well of a 224 nM solution of each peptide was added to the assay wells for a brief incubation, after which the plates were washed with dH2O (sera samples were tested for reactivity to individual peptides, rather than a mixture of all three). Next, 100 μL/well horse radish peroxidase labeled streptavidin (Jackson ImmunoResearch) diluted to 200 ng/mL in blocking solution was added, allowed to incubate for about 30 minutes and then the plates washed; o-phenylenediamine substrate (OPD) was used as the chromagen to generate signal, and the reaction was quenched using 1 N sulfuric acid. Signal was read at a wavelength of 492 nm.
Screening of mouse sera for relative affinity.
Relative affinity testing was completed for each sera sample—peptide combination for which a strong signal was seen in the previous assay. To determine the relative affinity of each serum sample for the individual core peptides, samples were tested for reactivity to limiting concentrations of each biotin labeled peptide. The assay format was identical to that described above, except that instead of preparing serial dilutions of mouse sera test samples, each sample was prepared at a single dilution, in blocking solution. Additionally, the individual peptides were tested at varying concentrations, beginning with a 500 nM solution in blocking solution followed by ten log 2 dilutions, also in blocking solution. Binding curves were generate and used to determine relative affinity for each sera sample. Based on these results, RBF/DnJ mice # 306 and 315 were chosen for B cell fusion.
Mouse splenocyte fusion.
On the day of fusion, the mice were euthanized and their splenocytes were harvested and placed into Iscoves Modified Dulbeccos Medium (IMDM) supplemented with Pen Strep (Invitrogen Corporation). A cell fusion was performed as described by Kohler and Milstein (Nature 1975; 256:495-7). Each mouse spleen was placed into a petri dish containing IMDM. The splenocytes were perfused out of each spleen using a syringe containing IMDM and a cell scraper. All splenocytes from mouse # 306 and 315 were isolated and pooled in a 50 ml centrifuge tube, then counted using a hemocytometer with trypan blue dye exclusion to determine viability. Approximately 8.0×108 total cells at 89% viability were recovered from these spleens. Approximately 7.6×106 cells/ml were estimated to be B-cells based on their physical appearance under the microscope. Approximately 5 mL of this cell suspension was used for a first fusion experiment (fusion 208A), and the remaining cells were processed using magnetic activated cell sorting (MACS) and a Pan B-cell isolation kit (Miltenyi Biotech) to enrich the cell population for B-cells and deplete other cell types. Approximately 6.7×108 total cells were incubated with the Pan B-cell biotin labeled antibody cocktail followed by the anti-biotin micobeads per manufacturer's instructions. The cell suspension/microbead mixture was washed by centrifugation and passed over a Miltenyi Biotech LS column contained within a magnetic field. B-cells flow freely through the column and other cell types are retained in the column. The columns were washed 3 times with PBS containing 2% FBS to wash out all B-cells. The B-cell suspension was centrifuged and the pellet was resuspended in IMDM, and then counted using a hemocytometer. Approximately 1.4×108 B-cells were recovered from the enrichment procedure. Approximately 7.0×10′ B-cells from that suspension were used for a second fusion experiment (fusion 208B) and the remaining B-cells were cryopreserved for later usage.
The unenriched splenocytes from the spleens (˜-3.8×107B-cells for fusion 208A) and the enriched B-cell pool (˜7.0×107B-cells for fusion 208B) were washed by centrifugation in separate tubes and the cell pellets were re-suspended in IMDM. These splenocytes were mixed with an equal number of NS/0 myeloma cells and centrifuged into a pellet. The fusion was accomplished by exposing the splenocytes and NS/0 cells to 50% Polyethylene glycol (PEG) (American Type Culture Collection—Molecular Weight 1300-1600) in HSFM. One mL of the PEG solution was added to each cell pellet over 30 seconds, followed by one additional minute of incubation. The PEG and cell pellet was diluted by slowly adding 30 mL of IMDM over 30 seconds. The fused cells were then removed from suspension by centrifugation and decanting the supernatant. The cell pellet from each fusion (208A and 208B) was re-suspended into ˜250 mL of IMDM supplemented with ˜10% FBS (Hyclone Laboratories), HAT (Hypoxanthine, Aminopterin, Thymidine) (Sigma Laboratories), HT Supplement (Invitrogen Corporation), BM Condimed H1 (Roche Applied Science), Cholesterol and L-Glutamine (Invitrogen Corporation) in order to select for hybridomas. The fused cells were seeded into T162 culture flasks containing the HAT medium and cultured in bulk for approximately 48 hours at 37 ° C. with 5% CO2. Following 48 hours of HAT selection, the bulk culture was centrifuged and the pellet was re-suspended into semi-solid tissue culture medium. The semi-solid tissue culture medium consisted of a 50% mixture of 2X IMDM (Invitrogen) with Clone Matrix (Molecular Devices) supplemented with 10% FBS, HT Supplement, Penn/Strep, L-Glutamine, and anti-mouse IgG-FITC Clone Detect (Molecular Devices). The semi-solid culture plates were allowed to incubate for 7-10 days before colony selection on the ClonepixFL (Molecular Devices). A colony grown in the semi-solid medium was considered a clone because the single cell initiating it had not been allowed to move and mix with other cells during growth, but all cell lines of interest will be subcloned at a later date to ensure clonality. An immunoprecipitation reaction occurs between the antibody being produced by the colony and the goat anti-mouse IgG Fc-FITC that fluoresces. The brighter the fluorescence signal observed, the more antibody being produced. Colonies were analyzed for fluorescence on the ClonepixFL and the ones with the brightest fluorescent signal were selected for automated transfer to 96 well tissue culture plates containing IMDM supplemented with 10% FBS, HT supplement, cholesterol, L-Glutamine, and Pen Strep. The 96 well tissue culture plates were allowed to grow for 3 to 7 days at 37 ° C. prior to supernatant screening for antibody production.
Hybridoma screening and selection using peptides.
Cell supernatant samples were analyzed for anti-HCV antibodies by EIA. Sheep anti-mouse IgG Fc (Jackson Immunoresearch) was coated on 96 well micro-titer EIA plates at 1 μg/mL. After the capture reagent had been coated on the solid phase, remaining solution was removed and the plates were blocked using 3% BSA in PBS. The wells were washed with distilled water and cell supernatants were added to the blocked plates and allowed to incubate at room temperature for at least one hour. The anti-mouse IgG Fc captures the anti-HCV mouse antibody from the supernatant. Following the incubation, the plates were washed using distilled water. A 3% normal mouse serum in BSA block solution was added to all wells and incubated at room temperature for 30 minutes to block any unbound sheep anti-mouse IgG Fc capture sites coated on the plate. The wells were washed with distilled water and a mixture of the biotinylated HCV peptides described in Example 2 (i.e. corresponding to amino acids 134-154, 141-161, and 151-171 of HCV-1), each at 100 ng/mL, was added and incubated for 30 minutes at room temperature. Following this incubation, the biotinylated antigens were washed from the plates using distilled water and streptavidin-HRPO (Jackson Immunoresearch) diluted to approximately 200 ng/mL was added to the plates and allowed to incubate for 30 minutes. The plates were washed with distilled water and o-phenylenediamine substrate was used as the chromagen to generate signal. Plates were read at 492 nm and the results were analyzed. Wells were considered positive if they had an EIA signal at least 3 times greater than background. Positive wells were expanded to 24 well plates in IMDM supplemented with 10% FBS, HT supplement, cholesterol, and L-Glutamine.
Following 5-14 days of growth, the 24 well cultures were evaluated by EIA in the same manner as previously described, except the supernatant samples were titrated against each of the biotinylated HCV core peptides individually and BSA to identify clones that might bind nonspecifically to the peptides or the blocking protein. The 24 well cultures generating signal at least 5 times greater than the average BSA background value of 0.08 OD units with at least one of the screening peptides were considered positive and selected for further evaluation. Values are listed in Table 1.
Cloning and expression of recombinant HCV Corel-169.
The nucleotide sequence encoding amino acids 1-169 of HCV-1 was codon optimized for E. coli expression and cloned into a modified pET32a vector wherein the sequence encoding a thioredoxin fusion protein was eliminated and replaced with Methionine (M). In addition, a carboxy-terminal hexahistidine tag (SEQ ID NO:580) was included immediately after codon 169 of HCV core to facilitate purification via immobilized metal affinity chromatography (IMAC). E. coli BL21(DE3) cells were transformed with purified plasmid DNA and a clone harboring the plasmid pET-HCVCore1-169 identified. The protein expressed therefrom was designated as HCV Corel-169.
Protein expression was achieved by culturing the pET-HCVCore1-169-transformed E. coli BL21(DE3) cells in terrific broth (TB) medium. Cells were grown in a fermentor to an OD600nm of 10 and then induced with 1 mM IPTG and grown at 37° C. for approximately three hours until an OD600nm of approximately 20 was obtained. Cells were harvested by centrifugation and lysed by sonication in 25 mM Tris-HCl buffer (pH 7.4) containing 150 mM NaCl, 1 mM DTT, 5 mM MgCl2, lysozyme and benzonase. The lysate was clarified by centrifugation and the insoluble fraction was dissolved in 25 mM Tris-HCl buffer (pH 7.4) containing 150 mM NaCl, 6 M urea, 1.0% n-dodecyl-ß-D-maltoside, 1 mM DTT, and 5 mM MgCl2. The dissolved lysate was again clarified by centrifugation and the soluble fraction was loaded onto a HisTrap Fast Flow column (GE Healthcare). The column was then washed with 25 column volumes of 25 mM Tris-HCl buffer (pH 7.4) containing 150 mM NaCl, 1 mM DTT, 5 mM MgCl2, 6 M urea, 0.1% n-dodecyl-B-D-maltoside, and 10 mM imidazole. Elution was done using the same buffer and a linear gradient of imidazole (0-500 mM). Eluted fractions containing the desired protein of interest (determined by SDS-PAGE) were pooled and dialyzed against 25 mM Tris-HCl buffer (pH 7.4) containing 150 mM NaCl, 1 mM DTT, 5 mM MgCl2, with and without 6 M urea and 0.1% n-dodecyl-ß-D-maltoside.
Hybridoma screening using core antigen.
The 24 well cultures were then evaluated by EIA for their ability bind HCV core1-169 (as described in Example 6) coated directly onto microtiter plates (solid phase assay). HCV core1-169 was coated onto 96 well micro-titer EIA plates at 1 μg/mL. After the capture reagent had been coated on the solid phase, the solution was removed and the plates were blocked using 3% BSA in PBS. The wells were washed with distilled water and 5 fold serial dilutions of the cell culture supernatants were added and allowed to incubate at room temperature for at least one hour. The plates were washed with distilled water and a HRP labeled goat anti-mouse IgG FC antibody diluted at approximately 200 ng/ml in BSA block solution was added to the plates and allowed to incubate for 30 minutes at room temperature. The plates were washed with distilled water and o-phenylenediamine substrate was used as the chromagen to generate signal. Plates were read at 492 nm and the results were analyzed.
Antibodies with BSA background reactivity greater than or equal to the core 1-169 reactivity value were considered negative and not used in calculating the average BSA background value. For the remainder of antibodies to be considered positive for core 1-169, they had to have an EIA signal of, at least, 0.50 OD units, or at least 5 times greater than the average BSA background signal of 0.10 OD units. Values are listed in Table 2.
Hybridoma screening via core antigen capture assay.
The cell lines that were identified as positive at the 24 well stage by peptide-based EIA (Example 5) or HCV Corel-169 solid phase immunoassay (Example 7) were expanded for cryopreservation, followed by generation of high-density spent-cell supernatant. The high density exhausted supernatant from fusion 208A and 208B cell lines were tested for their ability to detect HCV Corel-169 captured from solution by a monoclonal antibody (14-153-229, U.S. Pat. No. 7,858,752) directed against an epitope within the nucleic acid binding domain of HCV Core (e.g. amino acids 1-125), also known as Domain 1. An anti-domain 1 monoclonal antibody was coated on the solid phase of 96 well micro-titer EIA plates at 1μg/mL. After the capture reagent had been coated on the solid phase, it was removed and the plates were blocked for 30 minutes at room temperature using a 5× PBS buffer containing 2% fish gelatin, 0.5% Tween20, and 0.1% n-Dodecyl-N,N-Dimethylamine-N-Oxide (Affymetrix). The plates were washed with distilled water and a 50 ng/ml solution of Corel-169 antigen diluted in the fish gelatin/detergent solution was added to all wells and allowed to incubate for at least 30 minutes at room temperature. The wells were washed with distilled water and cell supernatants were titrated down the blocked plates and allowed to incubate at room temperature for at least 30 minutes at room temperature. The plates were washed with distilled water and a HRP labeled goat anti-mouse IgG FC antibody diluted to approximately 200 ng/ml in BSA block solution was added to the plates and allowed to incubate for 30 minutes at room temperature. The plates were washed with distilled water and o-phenylenediamine substrate was used as the chromagen to generate signal. Plates were read at 492 nm and the results were analyzed. Antibodies were considered positive for Corel-169 if they had EIA signal of, at least, 0.50 OD units, or at least 5 times greater than the average BSA background signal of 0.10 OD units. Values are listed in Table 3.
Determination of anti-HCV Core Antibody binding kinetics.
The affinities/kinetics of the anti-HCV core peptide 134-171 monoclonal antibodies were determined using a Biacore 4000 instrument (GE Healthcare Bio-Sciences AB, Uppsala, Sweden). First, after pre-treating a CM5 Series S biosensor chip (GE Healthcare) with duplicate injections of 100 mM HCl, 50 mM NaOH, and 0.1% SDS, a rabbit anti-mouse IgG Capture Biosensor was created by amine-coupling rabbit anti-mouse IgG antibody (GE Healthcare, Piscataway, NJ) on Spots 1, 2, 4, and 5 in all four flow cells of the biosensor chip via EDC/NHS/ethanolamine chemistry provided in an Amine Coupling Kit (GE Healthcare). Clarified anti-HCV Core antibody exhausted hybridoma supernatants and HCV Core peptide were diluted into a filtered buffer composed of 10× HBS-EP+buffer (GE Healthcare; hereinafter “running buffer”) diluted 10-fold into distilled H2O, supplemented with 0.1% BSA and 0.1% CM-Dextran, and 0.2 μm filtered. Each HCV Core antibody supernatant was diluted 1:1 with running buffer and 0.2 μm filtered again. A 53 amino acid custom peptide (ALRZ-9 peptide, Anaspec, Fremont, Calif.) was chemically synthesized to contain HCV Core residues 134-171 and a carboxy-terminal tetanus toxoid (TT) immunogenic T-cell epitope peptide (Eur. J. Immunol. (1989), 19:2237-2242) with the terminal amino and carboxy groups acetylated and amidated, respectively. The lyophilized HCV core 134-171-tetanus toxoid synthetic peptide immunogen was diluted in distilled water to a stock concentration of 0.7 or 1 mg/mL and further diluted into running buffer to concentrations of either 0.457 to 3,000 nM or 0.412 to 2,700 nM, both using a 3-fold dilution series. All antigen solutions were 0.2 μm filtered prior to use.
The HCV Core 134-171-TT peptide procedure was as follows: 10 μL of HCV Core antibody was separately injected over Spots 1 and 5 in all four flow cells at 10 μL/minute. After all the spots contained captured antibody, the flow rate was increased to 30 μL/minute and the biosensor was equilibrated at this new flow rate for 2 minutes; then, a 3 minute injection (90 μL) of HCV Core peptide followed by 4 minutes of running buffer. All biosensor surfaces were regenerated with one 30 μL injection of 10 mM glycine, pH 1.7 (GE Healthcare), at a flow rate of 10 μL/minute. All concentrations were tested in duplicate. The binding kinetics (association and dissociation) were monitored via sensorgrams during antigen injection followed by running buffer. The sensorgrams were double-referenced and fit to a 1:1 binding model using Biacore 4000 Evaluation software (GE Healthcare Bio-Sciences AB) to determine association and dissociation rates, as well as overall KD. Kinetic and affinity values are listed in Table 4. If values are not present, then either binding kinetics could not be determined or the antibody did not interact with the HCV Core 134-171-TT peptide in this assay.
BIACore Antibody Binding Pair Analysis with Nucleic Acid Binding Domain mAbs
The ability of the anti-HCV core peptide 134-171 monoclonal antibodies to form antibody binding pairs with anti-HCV Core C11-3, C11-7, C11-9, and C11-14 (U.S. Pat. No. 6,727,092; Morota, et al, J. Virol. Meth., 2009, 157:8-14) antibodies and recombinant HCV Corel-169 antigen was determined using a Biacore 4000 instrument (GE Healthcare Bio-Sciences AB). First, after pre-treating a CM5 Series S biosensor chip (GE Healthcare) with duplicate injections of 100 mM HCl, 50 mM NaOH, and 0.1% SDS, a rabbit anti-mouse IgG Capture Biosensor was created by amine-coupling rabbit anti-mouse IgG antibody (GE Healthcare, Piscataway, N.J.) on Spots 1, 2, 4, and 5 in all four flow cells of the biosensor chip via EDC/NHS/ethanolamine chemistry provided in an Amine Coupling Kit (GE Healthcare).
Clarified anti-HCV Core (peptide aa 134-171) antibody exhausted hybridoma supernatants, recombinant HCV Corel-169 antigen, 3 different purified mouse monoclonal IgG representing isotypes IgG1, IgG2a, and IgG2b non-reactive to HCV Core used as blocking reagents, and anti-HCV Core C11-3, C11-7, C11-9, and C11-14 mAbs were diluted into a filtered running buffer (hereinafter “running buffer”) composed of 10× PBS buffer (GE Healthcare) diluted 5-fold into distilled H2O, supplemented with 3 mM EDTA, 0.1% BSA, 0.1% CM-Dextran, 0.1% n-Dodecyl-N,N-Dimethylamine-N-Oxide, an extra 500 mM NaCl, and 0.2 μm filtered. Each HCV Core antibody supernatant was diluted 1:1, the recombinant HCV Corel-169 antigen was diluted to 500 nM per the calculated dimer molecular weight (39,453 Da), the anti-HCV Core C11-3, C11-7, C11-9, and C11-14 purified monoclonal antibodies were individually diluted to 20 μg/mL, and the 3 mouse IgG blocking reagents were all diluted as a pool with each isotype having a concentration of at least 100 μg/mL in running buffer. All dilutions were 0.2 μm filtered prior to use.
The HCV Core antibody-antigen-antibody sandwich procedure was as follows. 20 μL of the HCV Core C11 antibodies were injected over Spots 1 and 5 in all four flow cells at 10 μL/minute: C11-3 in flow cell 1, C11-7 in flow cell 2, C11-9 in flow cell 3, and c11-14 in flow cell 4. The flow rate was increased to 30 μL/minute and the remaining available anti-mouse IgG binding sites on the biosensor were blocked with the mouse IgG1, IgG2a, and IgG2b isotype pool by injecting 60 μL over Spots 1 and 2 and then 60 μL over Spots 4 and 5 in all flow cells. 60 μL of HCV Corel-169 antigen was injected over Spot 1 and then another 60 μL over Spot 5 in all flow cells. 60 μL of one HCV Core antibody diluted supernatant was inject over Spots 1 and 2 over all flow cells and another diluted supernatant over Spots 4 and 5 in all flow cells. The flow rate was decreased 10 μL/minute and all biosensor surfaces were regenerated with one 30 injection of 10 mM glycine, pH 1.7 (GE Healthcare).
Using the Biacore 4000 Evaluation Epitope Mapping software module (GE Healthcare Bio-Sciences AB), the binding response for each C11 antibody, antigen, and HCV Core antibody supernatant was determined after each injection and used to calculate an expected response reference value using the dimeric antigen and antibody (150,000 Da) molecular weights. An expected percent binding value was determined using individual samples versus the reference value. Any expected percent binding values that were greater than 5.0 were considered positive for the ability to form an antibody sandwich with the recombinant HCV Corel-169 antigen. Expected percent values are listed in Table 5.
Immunoglobulin purification and labeling.
Anti-HCV core hybridomas were expanded in Hybridoma Serum Free Medium (Invitrogen Corporation) supplemented with L-glutamine and 10% Ultra Low IgG FBS (Invitrogen Corporation) and seeded into roller bottles at approximately 0.5×10E5 cells/mL. The cultures were incubated at 37° C. while rotating at approximately 1 revolution per minute for 10-14 days, or until a terminal end culture was obtained. The terminal roller bottle supernatant was harvested and clarified with a 0.45 micron filter. The clarified supernatant was diluted with an equal volume of 1.5 M glycine, 3M NaCl buffer, pH 8.9, then loaded onto a pre-equilibrated 5 ml Protein A column using the AKTA automated purification system (Amersham/Pharmacia/GE). The column was then washed with approximately 5 column volumes of binding buffer and when a stable baseline is achieved, the mAb was eluted with 0.1 M sodium citrate buffer, pH 2.8. The IgG was then transferred to a desalting column and exchanges into PBS, pH 7.2-7.4, and then further dialyzed in PBS pH 7.2-7.4, using 10,000 molecular weight cut-off dialysis membrane (Pierce Chemical). Selected antibodies were biotinylated by using Sulfo-NHS-LC-Biotin (Pierce) at a 20-fold molar excess and incubated for 30 minutes at room temperature. Unbound biotin was removed through dialysis in PBS pH 7.2-7.4. All biotinylated monoclonals were tested by EIA to confirm successful labeling.
HCV core antigen capture assays.
Purified anti-HCV core134-171 monoclonal antibodies were evaluated for their ability to form binding pairs with themselves and two other domain 1 monoclonal antibodies using HCV core1-169 recombinant antigen in an EIA format. Anti-HCV Domain 1 monoclonal antibodies, C11-7 and C11-9, and anti-HCV core134-171 monoclonals were coated onto microtiter plates at approximately 1000 ng/ml and allowed to incubate overnight at 2-8 degrees C. After the capture reagent had been coated on the solid phase, the plates were blocked using a 5× PBS buffer containing 2% fish gelatin, 0.5 Tween 20, and 0.1% n-dodecyl-N,N-dimethylamine-N-oxide. The wells were washed with distilled water and purified core 1-169 antigen was added to the blocked plates in serial dilutions from 50 to 0.78 ng/ml diluted in fish gelatin block, and then allowed to incubate at room temperature for approximately 30 minutes. The wells were washed with distilled water and biotin labeled anti-HCV core monoclonals were added to the plates at concentrations ranging from 100 to 5000 ng/ml, and then incubated for 30 minutes at room temperature. The plates were washed with distilled water and streptavidin-HRPO diluted to approximately 200 ng/mL was added to the plates and allowed to incubate for 30 minutes at room temperature. The plates were washed with distilled water and o-phenylenediamine substrate was used as the chromagen to generate signal and the optical density at 492 nm was measured.
Table 6 summarizes the assay signal (OD492 nm) for each antibody pair combination using 25 ng/ml of corel-169 antigen, which indicates whether or not each binding pair is capable of forming a sandwich. An OD492 value of at least 3× greater than the value generated by a negative control (NC) monoclonal antibody as a capture or conjugate reagent are considered positive for core antigen detection.
Sequences of anti-Core 134-171 variable domains.
A subset of the anti-HCV core 134-171 hybridomas were selected for determination of variable heavy (VH) and variable light (VL) chain nucleotide and deduced amino acid sequences. Total RNA was extracted from the hybridoma cells using Trizol (Invitrogen) or Tri-Reagent (Sigma) according to the manufacturer's recommendations. The heavy chain and light chain cDNA was generated from the extracted total RNA using Superscript III (Life Technologies) and oligo dT primers following standard protocols. The 5′ RACE (rapid amplification of cDNA ends) protocol was used to amplify the variable heavy and light chain cDNA sequences using a dC anchor primer (5′-AAGCAGTGGTATCAACGCAGAGTACCCCCCCCCCCCCCCCC-3′; SEQ ID NO:581) and a generic primer specific to the constant region of the mouse heavy or light chain (Novogen). Amplicons were cloned into a commercially available vector (pCR2.1-TOPO cloning kit, Invitrogen) per the manufacturer's directions and transformed into TOP10 E. coli. At least eight colonies were selected for PCR amplification of cloned variable domain sequences using M13 forward and reverse primers. Amplicons were treated with ExoSap (Affymetrix) prior to sequencing using M13 forward primer and BigDye Terminator v3.1 cycle sequencing kit (Applied Biosystems, Foster City, Calif.). Sequences were obtained using ABI3130x1 automated sequencer and assembled and analyzed using Vector NTI software (Invitrogen).
Deduced amino acid sequences were aligned using ClustalW (Higgins et al., Nucleic Acids Res. 22:4673-4680, 1994) as implemented in the MEGA5 software package (Tamura et al., Molecular Biology and Evolution 28: 2731-2739, 2011). MEGA5 software was used to determine groupings or clusters of related heavy chain amino acid sequences from the alignments and phylogenetic tree construction using the Neighbor Joining method with complete deletion of sequence gaps in the alignment. Tree topology, and hence clusters or groups therein, was examined for reliability by using a bootstrap test from 1000 replicates. As a general rule, if the bootstrap value for a given interior branch is 95% or higher, then the topology at that branch is considered “correct” (Nei and Kumar, Molecular Evolution and Phylogenetics, 2000; Oxford University Press, New York). Analysis of heavy chain variable domain sequences from 52 anti-HCV core 134-171 monoclonals revealed the existence of 4 main groups with bootstrap values >95%. Antibodies comprising three of these groups exhibited specificity for binding to one of each of the peptides used for screening, i.e. Group B with peptide 1 (134-154), Group A with peptide 2 (141-161), and Group C with peptide 3 (151-171).
Epitope mapping of C11-3 (Abt-4)
Purified HCV core monoclonal antibody C11-3 (aka Abt-4) samples were analyzed for reactivity to overlapping HCV core antigen peptides by EIA. Biotin-(SGSG)-15 mer HCV core-amide peptides were synthesized that overlapped by two amino acids and encompassed the entire length of HCV core protein amino acids 1-191 (Mimotopes). Each of the 89 synthesized peptides was coated in an individual micro-titer well as indicated on the peptide plate key as shown in Table 7. The coated plate was kept dry in a sealed foil pouch and stored at <10 degrees C. until ready for use. The peptide coated plate for the test C11-3 antibody was blocked using 3% BSA in PBS with 0.5% Tween 20. The blocked plate were washed with distilled water and a 2 ug/mL solution of purified C11-3 antibody, diluted in BSA block solution, was added to each peptide coated well of the blocked plate and allowed to incubate at room temperature for at least one hour. Following incubation the plate was washed with distilled water. A 200 ng/mL solution of peroxidase labeled F(ab′)2 fragment goat anti-mouse IgG Fc fragment specific (Jackson Immunoresearch) in BSA block solution was added to all wells and incubated at room temperature for 30 minutes. The plate was washed with distilled water and o-phenylenediamine substrate was used as the chromagen to generate signal. The plate was read at 492 nm and the results (shown in Tables 8 and 9) were analyzed. Wells were considered positive if they had an EIA signal at least 3 times greater than background. The C11-3 (ABT-4) mAb reacts with peptide numbers 48-53.
Sequences of the C11-3/Abt-4 reactive HCV core peptides are aligned in Table 10 below. The reactive peptides span from HCV core amino acids 95 to 117. The minimal overlap of the reactive peptide is highlighted in gray, and represents amino acids 103-109 of HCV core.
The present application is a continuation of copending U.S. application Ser. No. 16/422,211, filed May 24, 2019, which is a divisional of U.S. application Ser. No. 15/189,638, filed Jun. 22, 2016, now U.S. Pat. No. 10,345,311, issued Jul. 9, 2019, which is a continuation-in-part of U.S. application Ser. No. 15/079,013, filed Mar. 23, 2016, now U.S. Pat. No. 10,197,573, issued on Feb. 5, 2019, which is a divisional of U.S. application Ser. No. 14/138,991, filed Dec. 23, 2013, now U.S. Pat. No. 9,371,374, issued Jun. 21, 2016, which claims the benefit of U.S. Provisional Application No. 61/783,529, filed Mar. 14, 2013, each of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61783529 | Mar 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15189638 | Jun 2016 | US |
| Child | 16422211 | US | |
| Parent | 14138991 | Dec 2013 | US |
| Child | 15079013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16422211 | May 2019 | US |
| Child | 17231782 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15079013 | Mar 2016 | US |
| Child | 15189638 | US |
