Patent Grant
7074415
The present invention is related to antigens, epitopes and antibodies directed to these epitopes, more particularly polypeptide antigens of streptococcus pneumoniae pathogen which may be useful for prophylaxis, diagnostic or treatment of streptococcal infection.
S. pneumoniae is an important agent of disease in man especially among infants, the elderly and immunocompromised persons. It is a bacterium frequently isolated from patients with invasive diseases such as bacteraemia/septicaemia, pneumonia, meningitis with high morbidity and mortality throughout the world. Even with appropriate antibiotic therapy, pneumococcal infections still result in many deaths. Although the advent of antimicrobial drugs has reduced the overall mortality from pneumococcal disease, the presence of resistant pneumococcal organisms has become a major problem in the world today. Effective pneumococcal vaccines could have a major impact on the morbidity and mortality associated with S. pneumoniae disease. Such vaccines would also potentially be useful to prevent otitis media in infants and young children.
Efforts to develop a pneumococcal vaccine have generally concentrated on generating immune responses to the pneumococcal capsular polysaccharide. More than 80 pneumococcal capsular serotypes have been identified on the basis of antigenic differences. The currently available pneumococcal vaccine, comprising 23 capsular polysaccharides that most frequently caused disease, has significant shortcomings related primarily to the poor immunogenicity of some capsular polysaccharides, the diversity of the serotypes and the differences in the distribution of serotypes over time, geographic areas and age groups. In particular, the failure of existing vaccines and capsular conjugate vaccines currently in development to protect young children against all serotypes spurres evaluation of other S. pneumoniae components. Although immunogenicity of capsular polysaccharides can be improved, serotype specificity will still represent a major limitation of polysaccharide-based vaccines. The use of a antigenically conserved immunogenic pneumococcal protein antigen, either by itself or in combination with additional components, offers the possibility of a protein-based pneumococcal vaccine.
PCT WO 98/18930 published May 7, 1998 entitled “Streptococcus Pneumoniae antigens and vaccines” describes certain polypeptides which are claimed to be antigenic. However, no biological activity of these polypeptides is reported. Similarly, no sequence conservation is reported, which is a necessary species common vaccine candidate.
PCT WO 00/39299 describes polypeptides and polynucleotides encoding these polypeptides. PCT WO 00/39299 demonstrates that polypeptides designated as BVH-3 and BVH-11 provide protection against fatal experimental infection with pneumococci.
Therefore there remains an unmet need for Streptococcus antigens that may be used as components for the prophylaxis, diagnostic and/or therapy of Streptococcus infection.
An isolated polynucleotide comprising a polynucleotide chosen from;
In other aspects, there are provided novel polypeptides encoded by polynucleotides of the invention, pharmaceutical or vaccine composition, vectors comprising polynucleotides of the invention operably linked to an expression control region, as well as host cells transfected with said vectors and methods of producing polypeptides comprising culturing said host cells under conditions suitable for expression.
It was determined that portions of the BVH-3 and BVH-11 polypeptides were internal. Other portions were not present in important strains such as encapsulated s. pneumonia causing disease strains. It would be advantageous to have a polypeptide that comprises a portion that is not internal. When large portions of a polypeptide are internal, these portions are not exposed on the bacteria. However, these portions can be very immunogenic in a recombinant polypeptide and will not confer protection against infections. It would also be advantageous to have a polypeptide that comprises a portion that is present in most strains.
The present invention is concerned with polypeptides in which undesired portions have been deleted and/or modified in order to obtain a specific immune response.
In accordance with the present invention, there are also provided polypeptides or polynucleotides encoding such polypeptides comprising protective domains.
Surprisingly, when the undesired portion of the polypeptides are deleted or modified, the polypeptides have desired biological properties. This is surprising in view of the fact that some of these portions were described as being epitope bearing portion in the patent application PCT WO 98/18930. In other publications such as PCT WO 00/37105, portions identified as histidine triad and coil coiled regions were said to be of importance. The present inventors have found that variants of the polypeptide BVH-3 and BVH-11 in which certain portions were deleted and/or modified and chimeras of these polypeptides have biological properties and generate a specific immune response.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence as disclosed in the present application, the tables and figures.
In accordance with one aspect of the present invention, there is provided an isolated polynucleotide comprising a polynucleotide chosen from;
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence chosen from table A, B, D, E, G or H or fragments, analogues or derivatives thereof.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 95% identity to a second polypeptide comprising a sequence chosen from table A, B, D, E, G or H or fragments, analogues or derivatives thereof.
According to one aspect, the present invention relates to polypeptides characterised by the amino acid sequence chosen from table A, B, D, E, G or H or fragments, analogues or derivatives thereof.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence chosen from table A, B, D, E, G or H.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 95% identity to a second polypeptide comprising a sequence chosen from table A, B, D, E, G or H.
According to one aspect, the present invention relates to polypeptides characterised by the amino acid sequence chosen from table A, B, D, E, G or H.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence chosen from table B, E or H or fragments, analogues or derivatives thereof.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 95% identity to a second polypeptide comprising a sequence chosen from B, E or H or fragments, analogues or derivatives thereof.
According to one aspect, the present invention relates to polypeptides characterised by the amino acid sequence chosen from table B, E or H or fragments, analogues or derivatives thereof.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 70% identity to a second polypeptide comprising a sequence chosen from table B, E or H.
According to one aspect, the present invention provides an isolated polynucleotide encoding a polypeptide having at least 95% identity to a second polypeptide comprising a sequence chosen from B, E or H.
According to one aspect, the present invention relates to polypeptides characterised by the amino acid sequence chosen from table B, E or H.
In accordance with the present invention, all nucleotides encoding polypeptides and chimeric polypeptides are within the scope of the present invention.
In a further embodiment, the polypeptides or chimeric polypeptides in accordance with the present invention are antigenic.
In a further embodiment, the polypeptides or chimeric polypeptides in accordance with the present invention are immunogenic.
In a further embodiment, the polypeptides or chimeric polypeptides in accordance with the present invention can elicit an immune response in an individual.
In a further embodiment, the present invention also relates to polypeptides which are able to raise antibodies having binding specificity to the polypeptides or chimeric polypeptides of the present invention as defined above.
In one embodiment, the polypeptides of table A (BVH-3) or table D (BVH-11) comprise at least one epitope bearing portion.
In a further embodiment, the fragments of the polypeptides of the present invention will comprise one or more epitope bearing portion identified in Table C and F. The fragment will comprises at least 15 contiguous amino acid of the polypeptide of table C and F. The fragment will comprises at least 20 contiguous amino acid of the polypeptide of table C and F.
In a further embodiment, the epitope bearing portion of the polypeptide of table A(BVH-3) comprises at least one polypeptide listed in Table C.
In a further embodiment, the epitope bearing portion of the polypeptide of table B(BVH-11) comprises at least one polypeptide listed in Table F.
An antibody that “has binding specificity” is an antibody that recognises and binds the selected polypeptide but which does not substantially recognise and bind other molecules in a sample, such as a biological sample. Specific binding can be measured using an ELISA assay in which the selected polypeptide is used as an antigen.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
In accordance with the present invention, “protection” in the biological studies is defined by a significant increase in the survival curve, rate or period. Statistical analysis using the Log rank test to compare survival curves, and Fisher exact test to compare survival rates and numbers of days to death, respectively, might be useful to calculate P values and determine whether the difference between the two groups is statistically significant. P values of 0.05 are regarded as not significant.
As used herein, “fragments”, “derivatives” or “analogues” of the polypeptides of the invention include those polypeptides in which one or more of the amino acid residues are substituted with a conserved or non-conserved amino acid residue (preferably conserved) and which may be natural or unnatural. In one embodiment, derivatives and analogues of polypeptides of the invention will have about 70% identity with those sequences illustrated in the figures or fragments thereof. That is, 70% of the residues are the same. In a further embodiment, polypeptides will have greater than 75% homology. In a further embodiment, polypeptides will have greater than 80% homology. In a further embodiment, polypeptides will have greater than 85% homology. In a further embodiment, polypeptides will have greater than 90% homology. In a further embodiment, polypeptides will have greater than 95% homology. In a further embodiment, polypeptides will have greater than 99% homology. In a further embodiment, derivatives and analogues of polypeptides of the invention will have less than about 20 amino acid residue substitutions, modifications or deletions and more preferably less than 10. Preferred substitutions are those known in the art as conserved i.e. the substituted residues share physical or chemical properties such as hydrophobicity, size, charge or functional groups.
The skilled person will appreciate that analogues or derivatives of the proteins or polypeptides of the invention will also find use in the context of the present invention, i.e. as antigenic/immunogenic material. Thus, for instance proteins or polypeptides which include one or more additions, deletions, substitutions or the like are encompassed by the present invention. In addition, it may be possible to replace one amino acid with another of similar “type”. For instance replacing one hydrophobic amino acid with another hydrophilic amino acid.
One can use a program such as the CLUSTAL program to compare amino acid sequences. This program compares amino acid sequences and finds the optimal alignment by inserting spaces in either sequence as appropriate. It is possible to calculate amino acid identity or similarity (identity plus conservation of amino acid type) for an optimal alignment. A program like BLASTx will align the longest stretch of similar sequences and assign a value to the fit. It is thus possible to obtain a comparison where several regions of similarity are found, each having a different score. Both types of identity analysis are contemplated in the present invention.
In an alternative approach, the analogues or derivatives could be fusion proteins, incorporating moieties which render purification easier, for example by effectively tagging the desired protein or polypeptide, It may be necessary to remove the “tag” or it may be the case that the fusion protein itself retains sufficient antigenicity to be useful.
In an additional aspect of the invention there are provided antigenic/immunogenic fragments of the proteins or polypeptides of the invention, or of analogues or derivatives thereof.
The fragments of the present invention should include one or more such epitopic regions or be sufficiently similar to such regions to retain their antigenic/immunogenic properties. Thus, for fragments according to the present invention the degree of identity is perhaps irrelevant, since they may be 100% identical to a particular part of a protein or polypeptide, analogue or derivative as described herein. The key issue, once again, is that the fragment retains the antigenic/immunogenic properties.
Thus, what is important for analogues, derivatives and fragments is that they possess at least a degree of the antigenicity/immunogenic of the protein or polypeptide from which they are derived.
In accordance with the present invention, polypeptides of the invention include both polypeptides and chimeric polypeptides.
Also included are polypeptides which have fused thereto other compounds which alter the polypeptides biological or pharmacological properties i.e. polyethylene glycol (PEG) to increase half-life; leader or secretory amino acid sequences for ease of purification; prepro- and pro-sequences; and (poly)saccharides.
Furthermore, in those situations where amino acid regions are found to be polymorphic, it may be desirable to vary one or more particular amino acids to more effectively mimic the different epitopes of the different streptococcus strains.
Moreover, the polypeptides of the present invention can be modified by terminal —NH2 acylation (e.g. by acetylation, or thioglycolic acid amidation, terminal carboxy amidation, e.g. with ammonia or methylamine) to provide stability, increased hydrophobicity for linking or binding to a support or other molecule.
Also contemplated are hetero and homo polypeptide multimers of the polypeptide fragments, analogues and derivatives. These polymeric forms include, for example, one or more polypeptides that have been cross-linked with cross-linkers such as avidin/biotin, gluteraldehyde or dimethylsuperimidate. Such polymeric forms also include polypeptides containing two or more tandem or inverted contiguous sequences, produced from multicistronic mRNAs generated by recombinant DNA technology.
Preferably, a fragment, analogue or derivative of a polypeptide of the invention will comprise at least one antigenic region i.e. at least one epitope.
In order to achieve the formation of antigenic polymers (i.e. synthetic multimers), polypeptides may be utilised having bishaloacetyl groups, nitroarylhalides, or the like, where the reagents being specific for thio groups. Therefore, the link between two mercapto groups of the different peptides may be a single bond or may be composed of a linking group of at least two, typically at least four, and not more than 16, but usually not more than about 14 carbon atoms.
In a particular embodiment, polypeptide fragments, analogues and derivatives of the invention do not contain a methionine (Met) starting residue. Preferably, polypeptides will not incorporate a leader or secretory sequence (signal sequence). The signal portion of a polypeptide of the invention may be determined according to established molecular biological techniques. In general, the polypeptide of interest may be isolated from a streptococcus culture and subsequently sequenced to determine the initial residue of the mature protein and therefore the sequence of the mature polypeptide.
According to another aspect, there are provided vaccine compositions comprising one or more streptococcus polypeptides of the invention in admixture with a pharmaceutically acceptable carrier diluent or adjuvant. Suitable adjuvants include oils i.e. Freund's complete or incomplete adjuvant; salts i.e. AlK(SO4)2, AlNa(SO4)2, AlNH4(SO4)2, silica, kaolin, carbon polynucleotides i.e. poly IC and poly AU. Preferred adjuvants include QuilA and Alhydrogel. Vaccines of the invention may be administered parenterally by injection, rapid infusion, nasopharyngeal absorption, dermoabsorption, or bucal or oral. Pharmaceutically acceptable carriers also include tetanus toxoid.
The term vaccine is also meant to include antibodies. In accordance with the present invention, there is also provided the use of one or more antibodies having binding specificity for the polypeptides of the present invention for the treatment or prophylaxis of streptococcus infection and/or diseases and symptoms mediated by streptococcus infection.
Vaccine compositions of the invention are used for the treatment or prophylaxis of streptococcus infection and/or diseases and symptoms mediated by streptococcus infection as described in P. R. Murray (Ed, in chief), E. J. Baron, M. A. Pfaller, F. C. Tenover and R. H. Yolken. Manual of Clinical Microbiology, ASM Press, Washington, D.C. sixth edition, 1995, 1482p which are herein incorporated by reference. In one embodiment, vaccine compositions of the present invention are used for the treatment or prophylaxis of meningitis, otitis media, bacteremia or pneumonia. In one embodiment, vaccine compositions of the invention are used for the treatment or prophylaxis of streptococcus infection and/or diseases and symptoms mediated by streptococcus infection, in particular S. pneumoniae, group A streptococcus (pyogenes), group B streptococcus (GBS or agalactiae), dysgalactiae, uberis, nocardia as well as Staphylococcus aureus. In a further embodiment, the streptococcus infection is S. pneumoniae.
In a particular embodiment, vaccines are administered to those individuals at risk of streptococcus infection such as infants, elderly and immunocompromised individuals.
As used in the present application, the term “individuals” include mammals. In a further embodiment, the mammal is human.
Vaccine compositions are preferably in unit dosage form of about 0.001 to 100 μg/kg (antigen/body weight) and more preferably 0.01 to 10 μg/kg and most preferably 0.1 to 1 μg/kg 1 to 3 times with an interval of about 1 to 6 week intervals between immunizations.
Vaccine compositions are preferably in unit dosage form of about 0.1 μg to 10 mg and more preferably 1 μg to 1 mg and most preferably 10 to 100 μg 1 to 3 times with an interval of about 1 to 6 week intervals between immunizations.
According to another aspect, there are provided polynucleotides encoding polypeptides characterised by the amino acid sequence chosen from table A, B, D, E, G or H or fragments, analogues or derivatives thereof.
According to another aspect, there are provided polynucleotides encoding polypeptides characterised by the amino acid sequence chosen from table B, E or H or fragments, analogues or derivatives thereof.
In one embodiment, polynucleotides are those illustrated in table A, B, D, E, G or H which encodes polypeptides of the invention.
In one embodiment, polynucleotides are those illustrated in table B, E or H which encodes polypeptides of the invention.
It will be appreciated that the polynucleotide sequences illustrated in the figures may be altered with degenerate codons yet still encode the polypeptides of the invention. Accordingly the present invention further provides polynucleotides which hybridise to the polynucleotide sequences herein above described (or the complement sequences thereof) having 50% identity between sequences. In one embodiment, at least 70% identity between sequences. In one embodiment, at least 75% identity between sequences. In one embodiment, at least 80% identity between sequences. In one embodiment, at least 85% identity between sequences. In one embodiment, at least 90% identity between sequences. In a further embodiment, polynucleotides are hybridizable under stringent conditions i.e. having at least 95% identity. In a further embodiment, more than 97% identity.
Suitable stringent conditions for hybridation can be readily determined by one of skilled in the art (see for example Sambrook et al., (1989) Molecular cloning: A Laboratory Manual, 2nd ed, Cold Spring Harbor, N.Y.; Current Protocols in Molecular Biology, (1999) Edited by Ausubel F. M. et al., John Wiley & Sons, Inc., N.Y.).
In a further embodiment, the present invention provides polynucleotides that hybridise under stringent conditions to either
In a further embodiment, the present invention provides polynucleotides that hybridise under stringent conditions to either
In a further embodiment, the present invention provides polynucleotides that hybridise under stringent conditions to either
In a further embodiment, the present invention provides polynucleotides that hybridise under stringent conditions to either
In a further embodiment, polynucleotides are those encoding polypeptides of the invention illustrated in table A, B, D, E, G or H.
As will be readily appreciated by one skilled in the art, polynucleotides include both DNA and RNA.
The present invention also includes polynucleotides complementary to the polynucleotides described in the present application.
In a further aspect, polynucleotides encoding polypeptides of the invention, or fragments, analogues or derivatives thereof, may be used in a DNA immunization method. That is, they can be incorporated into a vector which is replicable and expressible upon injection thereby producing the antigenic polypeptide in vivo. For example polynucleotides may be incorporated into a plasmid vector under the control of the CMV promoter which is functional in eukaryotic cells. Preferably the vector is injected intramuscularly.
According to another aspect, there is provided a process for producing polypeptides of the invention by recombinant techniques by expressing a polynucleotide encoding said polypeptide in a host cell and recovering the expressed polypeptide product. Alternatively, the polypeptides can be produced according to established synthetic chemical techniques i.e. solution phase or solid phase synthesis of oligopeptides which are ligated to produce the full polypeptide (block ligation).
General methods for obtention and evaluation of polynucleotides and polypeptides are described in the following references: Sambrook et al, Molecular Cloning: A Laboratory Manual, 2nd ed, Cold Spring Harbor, N.Y., 1989; Current Protocols in Molecular Biology, Edited by Ausubel F. M. et al., John Wiley and Sons, Inc. New York; PCR Cloning Protocols, from Molecular Cloning to Genetic Engineering, Edited by White B. A., Humana Press, Totowa, N.J., 1997, 490 pages; Protein Purification, Principles and Practices, Scopes R. K., Springer-Verlag, New York, 3rd Edition, 1993, 380 pages; Current Protocols in Immunology, Edited by Coligan J. E. et al., John Wiley & Sons Inc., New York which are herein incorporated by reference.
For recombinant production, host cells are transfected with vectors which encode the polypeptide, and then cultured in a nutrient media modified as appropriate for activating promoters, selecting transformants or amplifying the genes. Suitable vectors are those that are viable and replicable in the chosen host and include chromosomal, non-chromosomal and synthetic DNA sequences e.g. bacterial plasmids, phage DNA, baculovirus, yeast plasmids, vectors derived from combinations of plasmids and phage DNA. The polypeptide sequence may be incorporated in the vector at the appropriate site using restriction enzymes such that it is operably linked to an expression control region comprising a promoter, ribosome binding site (consensus region or Shine-Dalgarno sequence), and optionally an operator (control element). One can select individual components of the expression control region that are appropriate for a given host and vector according to established molecular biology principles (Sambrook et al, Molecular Cloning: A Laboratory Manual, 2nd ed, Cold Spring Harbor, N.Y., 1989; Current Protocols in Molecular Biology, Edited by Ausubel F. M. et al., John Wiley and Sons, Inc. New York incorporated herein by reference). Suitable promoters include but are not limited to LTR or SV40 promoter, E. coli lac, tac or trp promoters and the phage lambda PL promoter. Vectors will preferably incorporate an origin of replication as well as selection markers i.e. ampicilin resistance gene. Suitable bacterial vectors include pET, pQE70, pQE60, pQE-9, pbs, pD10 phagescript, psiX174, pbluescript SK, pbsks, pNH8A, pNH16a, pNH18A, pNH46A, ptrc99a, pKK223-3, pKK233-3, pDR540, pRIT5 and eukaryotic vectors pBlueBacIII, pWLNEO, pSV2CAT, pOG44, pXT1, pSG, pSVK3, pBPV, pMSG and pSVL. Host cells may be bacterial i.e. E. coli, Bacillus subtilis, Streptomyces; fungal i.e. Aspergillus niger, Aspergillus nidulins; yeast i.e. Saccharomyces or eukaryotic i.e. CHO, COS.
Upon expression of the polypeptide in culture, cells are typically harvested by centrifugation then disrupted by physical or chemical means (if the expressed polypeptide is not secreted into the media) and the resulting crude extract retained to isolate the polypeptide of interest. Purification of the polypeptide from culture media or lysate may be achieved by established techniques depending on the properties of the polypeptide i.e. using ammonium sulfate or ethanol precipitation, acid extraction, anion or cation exchange chromatography, phosphocellulose chromatography, hydrophobic interaction chromatography, hydroxylapatite chromatography and lectin chromatography. Final purification may be achieved using HPLC.
The polypeptide may be expressed with or without a leader or secretion sequence. In the former case the leader may be removed using post-translational processing (see U.S. Pat. No. 4,431,739; U.S. Pat. No. 4,425,437; and U.S. Pat. No. 4,338,397 incorporated herein by reference) or be chemically removed subsequent to purifying the expressed polypeptide.
According to a further aspect, the streptococcus polypeptides of the invention may be used in a diagnostic test for streptococcus infection, in particular S. pneumoniae infection. Several diagnostic methods are possible, for example detecting streptococcus organism in a biological sample, the following procedure may be followed:
a) obtaining a biological sample from a patient;
b) incubating an antibody or fragment thereof reactive with a streptococcus polypeptide of the invention with the biological sample to form a mixture; and
c) detecting specifically bound antibody or bound fragment in the mixture which indicates the presence of streptococcus.
Alternatively, a method for the detection of antibody specific to a streptococcus antigen in a biological sample containing or suspected of containing said antibody may be performed as follows:
a) obtaining a biological sample from a patient;
b) incubating one or more streptococcus polypeptides of the invention or fragments thereof with the biological sample to form a mixture; and
c) detecting specifically bound antigen or bound fragment in the mixture which indicates the presence of antibody specific to streptococcus.
One of skill in the art will recognize that this diagnostic test may take several forms, including an immunological test such as an enzyme-linked immunosorbent assay (ELISA), a radioimmunoassay or a latex agglutination assay, essentially to determine whether antibodies specific for the polypeptide are present in an organism.
The DNA sequences encoding polypeptides of the invention may also be used to design DNA probes for use in detecting the presence of streptococcus in a biological sample suspected of containing such bacteria. The detection method of this invention comprises:
a) obtaining the biological sample from a patient;
b) incubating one or more DNA probes having a DNA sequence encoding a polypeptide of the invention or fragments thereof with the biological sample to form a mixture; and
c) detecting specifically bound DNA probe in the mixture which indicates the presence of streptococcus bacteria.
The DNA probes of this invention may also be used for detecting circulating streptococcus i.e. S. pneumoniae nucleic acids in a sample, for example using a polymerase chain reaction, as a method of diagnosing streptococcus infections. The probe may be synthesized using conventional techniques and may be immobilized on a solid phase, or may be labelled with a detectable label. A preferred DNA probe for this application is an oligomer having a sequence complementary to at least about 6 contiguous nucleotides of the streptococcus pneumoniae polypeptides of the invention.
Another diagnostic method for the detection of streptococcus in a patient comprises:
a) labelling an antibody reactive with a polypeptide of the invention or fragment thereof with a detectable label;
b) administering the labelled antibody or labelled fragment to the patient; and
c) detecting specifically bound labelled antibody or labelled fragment in the patient which indicates the presence of streptococcus.
A further aspect of the invention is the use of the streptococcus polypeptides of the invention as immunogens for the production of specific antibodies for the diagnosis and in particular the treatment of streptococcus infection. Suitable antibodies may be determined using appropriate screening methods, for example by measuring the ability of a particular antibody to passively protect against streptococcus infection in a test model. One example of an animal model is the mouse model described in the examples herein. The antibody may be a whole antibody or an antigen-binding fragment thereof and may belong to any immunoglobulin class. The antibody or fragment may be of animal origin, specifically of mammalian origin and more specifically of murine, rat or human origin. It may be a natural antibody or a fragment thereof, or if desired, a recombinant antibody or antibody fragment. The term recombinant antibody or antibody fragment means antibody or antibody fragment which was produced using molecular biology techniques. The antibody or antibody fragments may be polyclonal, or preferably monoclonal. It may be specific for a number of epitopes associated with the streptococcus pneumoniae polypeptides but is preferably specific for one.
A further aspect of the invention is the use of the antibodies directed to the streptococcus polypeptides of the invention for passive immunization. One could use the antibodies described in the present application. Suitable antibodies may be determined using appropriate screening methods, for example by measuring the ability of a particular antibody to passively protect against streptococcus infection in a test model. One example of an animal model is the mouse model described in the examples herein. The antibody may be a whole antibody or an antigen-binding fragment thereof and may belong to any immunoglobulin class. The antibody or fragment may be of animal origin, specifically of mammalian origin and more specifically of murine, rat or human origin. It may be a natural antibody or a fragment thereof, or if desired, a recombinant antibody or antibody fragment. The term recombinant antibody or antibody fragment means antibody or antibody fragment which was produced using molecular biology techniques. The antibody or antibody fragments may be polyclonal, or preferably monoclonal. It may be specific for a number of epitopes associated with the streptococcus pneumoniae polypeptides but is preferably specific for one.
The following are reference tables summarizing the sequences disclosed in the present application:
This example describes the bacterial strains, plasmids, PCR primers, recombinant proteins and hybridoma antibodies used herein.
S. pneumoniae SP64 (serogroup 6) and SP63 (serogroup 9) clinical isolates were provided by the Laboratoire de la Santé Publique du Québec, Sainte-Anne-de-Bellevue; Rx1 strain, a nonencapsulated derivative of the type 2 strain D39 and the type 3 strain WU2 were provided by David E. Briles from University of Alabama, Birmingham and the type 3 clinical isolate P4241 was provided by the Centre de Recherche en Infectiologie du Centre Hospitalier de l'Université Laval, Sainte-Foy. E. coli strains DH5α (Gibco BRL, Gaithesburg, Md.); AD494 (λDE3) (Novagen, Madison, Wis.) and BL21 (λDE3) (Novagen) as well as plasmid superlinker pSL301 vector (Invitrogen, San Diego, Calif.); PCMV-GH vector (gift from Dr. Stephen A. Johnston, Department for Biochemistry, University of Texas, Dallas, Tex.); pET32 and pET21 (Novagen) and pURV22.HIS expression vectors (
Table 1. List of PCR oligonucleotide primers
Molecular biology techniques were performed according to standard methods. See for example, Sambrook, J., Fritsch, E. F., Maniatis, T., “Molecular cloning. A laboratory manual” Vol. 1–2–3 (second edition) Cold Spring Harbour Laboratory Press, 1989, New York, which is herein incorporated by reference. PCR-amplified products were digested with restriction endonucleases and ligated to either linearized plasmid pSL301, pCMV-GH, pET or pURV22.HIS expression vector digested likewise or digested with enzymes that produce compatible cohesive ends. Recombinant pSL301 and recombinant pCMV-GH plasmids were digested with restriction enzymes for the in-frame cloning in pET expression vector. When pET vectors were used, clones were first stabilized in E. coli DH5α before introduction into E. coli BL21(λDE3) or AD494 (λDE3) for expression of full-length or truncated BVH-3, BVH-11 or BVH-11-2 molecules. Each of the resultant plasmid constructs was confirmed by nucleotide sequence analysis. The recombinant proteins were expressed as N-terminal fusions with the thioredoxin and His-tag (pET32 expression system); as C-terminal fusions with an His-tag (pET21 expression system); or as N-terminal fusions with an His-tag (pURV22.HIS expression system). The expressed recombinant proteins were purified from supernatant fractions obtained after centrifugation of sonicated IPTG-(pET systems) or heat-(pURV22.HIS) induced E. coli using a His-Bind metal chelation resin (QIAgen, Chatsworth, Calif.). The gene products generated from S. pneumoniae SP64 are listed in the following Table 2. The gene fragment encoding BVH-3-Sp63 protein (amino acid residues 21 to 840 on SEQ ID NO: 10) was generated from S. pneumoniae SP63 using the PCR-primer sets OCRR479-OCRR480 and the cloning vector pSL301. The recombinant pSL301-BVH-3Sp63 was digested for the in-frame cloning in pET32 vector for the expression of the BVH-3-Sp63 molecule.
Monoclonal antibody (Mab)-secreting hybridomas were obtained by fusions of spleen cells from immunized mice and non-secreting, HGPRT-deficient mouse myeloma SP2/0 cells by the methods of Fazekas De St-Groth and Scheidegger (J Immunol Methods 35 : 1–21, 1980) with modifications (J. Hamel et al. J Med Microbiol 23 : 163–170, 1987). Female BALB/c mice (Charles River, St-Constant, Quebec, Canada) were immunized with either BVH-3M (thioredoxin-His•Tag-BVH-3M fusion protein/pET32 system), BVH-11M (thioredoxin-His•Tag-BVH-11M fusion protein/pET32 system), BVH-11-2M (thioredoxin-His•Tag-BVH-11-2M fusion protein/pET32 system), BVH-11B (thioredoxin-His•Tag-BVH-11B fusion protein/pET32 system), BVH-3M (His•Tag-BVH-3 fusion protein/pURV22.HIS system) or NEW1 (NEW1-His•Tag fusion protein/pET21 system) gene products from S. pneumoniae strain SP64 to generate the Mab series H3-, H11-, H112-, H11B-, H3V-, and HN1-, respectively. Culture supernatants of hybridomas were initially screened by enzyme-linked-immunoassay (ELISA) according to the procedure described by Hamel et al. (Supra) using plates coated with preparations of purified recombinant BVH-3, BVH-11 and/or BVH-11-2 proteins or suspensions of heat-killed S. pneumoniae cells. The Mab-secreting hybridomas selected for further characterization are listed in Table 3 and Table 4 from the following Example 2. The class and subclass of Mab immunoglobulins were determined by ELISA using commercially available reagents (Southern Biotechnology Associates, Birmingham, Ala.).
Furthermore, the cloning and expression of chimeric gene(s) encoding for chimeric polypeptides and the protection observed after vaccination with these chimeric polypeptides are described.
BVH-3 and BVH-11 gene fragments corresponding to the 3′end of the genes were amplified by PCR using pairs of oligonucleotides engineered to amplify gene fragments to be included in the chimeric genes. The primers used had a restriction endonuclease site at the 5′ end, thereby allowing directional in-frame cloning of the amplified product into digested plasmid vectors (Table 1 and Table 2). PCR-amplified products were digested with restriction endonucleases and ligated to linearized plasmid pET21 or pSL301 vector. The resultant plasmid constructs were confirmed by nucleotide sequence analysis. The recombinant pET21 plasmids containing a PCR product were linearized by digestion with restriction enzymes for the in-frame cloning of a second DNA fragment and the generation of a chimeric gene encoding for a chimeric pneumococcal protein molecule. Recombinant pSL301 plasmids containing a PCR product were digested with restriction enzymes for the obtention of the DNA inserts. The resulting insert DNA fragments were purified and inserts corresponding to a given chimeric gene were ligated into pET21 vector for the generation of a chimeric gene. The recombinant chimeric polypeptides listed in Table 2 were as C-terminal fusion with an His-tag. The expressed recombinant proteins were purified from supernatant fractions obtained from centrifugation of sonicated IPTG-induced E. coli cultures using a His-Bind metal chelation resin (QIAgen, Chatsworth, Calif.).
Groups of 8 female BALB/c mice (Charles River) were immunized subcutaneously two times at three-week intervals with 25 μg of either affinity purified His•Tag-fusion protein identifed in presence of 15–20 μg of QuilA adjuvant. Ten to 14 days following the last immunization, the mice were challenged challenged intravenously with 10E5–10E6 CFU of S. pneumoniae type 3 strain WU2. The polypeptides and fragments are capable of eliciting a protective immune response.
This example describes the identification of peptide domains carrying target epitopes using Mabs and recombinant truncated proteins described in example 1.
Hybridomas were tested by ELISA against truncated BVH-3, BVH-11 or BVH-11-2 gene products in order to characterize the epitopes recognized by the Mabs. The truncated gene products were generated from S. pneumoniae SP64 strain except for BVH-3-Sp63 which was generated from S. pneumoniae SP63 strain. As a positive control, the reactivity of each antibody was examined with full-length BVH-3, BVH-11 or BVH-11-2 recombinant proteins. In some cases, the Mab reactivity was evaluated by Western immunoblotting after separation of the gene product by SDS-PAGE and transfer on nitrocellulose paper. The reactivities observed is set forth in the following Table 3 and Table 4.
The deduced locations of the epitopes are summarized in
Mabs H11-7G11 and H3V-15A10 react with epitopes in more than one position on BVH-3. The reactivity of H11-7G11 with BVH-3AD, BVH-3B, BVH-3C, BVH-11A and BVH-11-2M molecules suggests that H11-7G11 epitope might comprised HXXHXH sequence. This sequence is repeated, respectively, 6 and 5 times in BVH-3 and BVH-11/BVH-11-2 protein sequences. The lack of reactivity of Mab H11-7G11 with NEW 10 molecule suggests that the epitope includes the HGDHXH sequence. Multiple-position mapping of H3V-15A10 epitope on BVH-3 is suggested by the reactivity of the Mab with two BVH-3 fragments that do not overlap.
Interestingly, Mabs H3-7G2, H3V-9C6 and H3V-16A7 were not reactive with BVH-3 Sp63 thus allowing the location of their corresponding epitopes on a 177-amino acid fragment comprised between amino acids 244 and 420 on BVH-3 molecule of S. pneumoniae SP64 (
As can be seen from the data in Table 4, the Mabs that are reactive with BVH-11- and/or BVH-11-2 and that do not recognize BVH-3 molecules can be divided into three groups according to their reactivities with BVH-11A and NEW10 recombinant proteins. Some Mabs reacted exclusively with either BVH-11A or NEW10 protein while other Mabs were reactive with both, BVH-11A and NEW10 recombinant proteins.
This example describes the construction of BVH-3 and BVH-11-2 gene libraries for the mapping of epitopes.
BVH-3 and BVH-11-2 gene libraries were constructed using recombinant pCMV-GH and PSL301 plasmid DNA containing respectively, BVH-3 gene sequence spanning nucleotides 1837 to 4909 (SEQ ID NO: 2) or BVH-11-2 gene sequence spanning nucleotides 172 to 2630 (SEQ ID NO: 5) and the Novatope® library construction and screening system (Novagen). The recombinant plasmids containing BVH-3 or BVH-11-2 gene fragment were purified using QIAgen kit (Chatsworth, Calif.) and digested with the restriction enzymes BglII and XbaI respectively. The resulting BglII-XbaI DNA fragments were purified using the QIAquick gel extraction kit from QIAgen and digested with Dnase I for the generation of randomly cleaved DNA. DNA fragments of 50 to 200 bp were purified, treated with T4 DNA polymerase to blunt the target DNA ends and add a single 3′dA residue, and ligated into pSCREEN-T-Vector (Novagen) following the procedures suggested by the manufacturer (Novatope® System, Novagen). The gene libraries of E. coli clones, each of which expressing a small peptide derived from BVH-3 or BVH-11-2 genes were screened by standard colony lift methods using Mabs as immunoprobes. The colony screening was not successful with Mabs producing very high backgrounds on colony lifts. Moreover, in some cases, Mabs failed to detect epitope-expressing-colonies. The lack of reactivity can possibly be explained by the small amount of recombinant proteins produced or the recognition of conformation-dependent epitopes consisting of different protein domains. Sequencing of DNA inserts from positive clones determined the location of the segment that encodes the target epitope. The data are presented in Table 5. The peptides encoded by DNA inserts into the recombinant pSCREEN-T vector can be purified and used as immunogens as described below in Example 6.
The peptide sequences obtained from the screening of BVH-3 and BVH-11-2 gene libraries with the Mabs are in agreement with the Mab ELISA reactivities against the truncated gene products. As expected, the amino acid sequences obtained from H11-7G11 contained the sequence HGDHXH. These findings provide additional evidence for the location of epitopes recognized with the Mabs. Interestingly, although the Mabs H112-10G9, H112-10A2 and H11B-11B8 were reactive against the same peptide sequence (amino acid residues 594 to 679 on BVH-11-2 protein sequence), clones corresponding to the sequence spanning from amino acid residues 658 to 698 were only picked up by Mab H11B-11B8 thus revealing the location of H11B-11B8 epitope between amino acid residues 658 to 679 (SEQ ID NO: 163). Mabs H112-10G9, H112-10A2, and H11B-11B8 are directed against 3 distinct non overlapping epitopes located closely on the peptide sequence corresponding to amino acid residues 594 to 679 (SEQ ID NO: 22).
BVH-3 and BVH-11-2 gene libraries with Mabs
Clone/
Protein
Nucleotide
Amino acid
SEQ ID
Mab
designation
position
position
Amino acid sequence
NO
This example describes the immunization of animals with recombinant proteins for the generation of antibody reactive with BVH-3, BVH-11 and/or BVH-11-2.
NZW rabbits (Charles River Laboratories, St-Constant, Québec, Canada) were immunized subcutaneously at multiple sites with 50 μg or 100 μg of the purified BVH-3M, L-BVH-3AD, NEW1, NEW13, or L-BVH-11 recombinant protein in presence of 80 μg of QuilA adjuvant (Cedarlane Laboratoratories Ltd, Hornby, Canada). The rabbits were boosted two times at three-week intervals with the same antigen and blood samples were collected before each immunization and 6 to 28 days following the last immunization. The sera samples were designated preimmune, post 1st, post 2nd or post 3rd injection. The rabbit immune response to immunization was evaluated by ELISA using recombinant BVH-3M (BVH-3M-His•Tag fusion protein/pET21 system) or BVH-11M (BVH-11M-His•Tag fusion protein/pET21 system) proteins or suspensions of heat-killed S. pneumoniae Rx-1 cells as coating antigens. ELISA titer was defined as the reciprocal of the highest sera dilution at which absorbance A410 value was 0.1 above the background value. Antibodies reactive with BVH-3 and/or BVH-11 epitopes were elicited following immunization in all animals as shown in the following Table 6. Antibody reactive with recombinant or pneumococcal antigens was not present in the preimmune sera. The immune response to immunization was detectable in the sera of each rabbit after a single injection of recombinant antigen. The antibody response following the second injection with either antigen tested was characterized by a strong increase in antibody titer. Interestingly, good titers of antibody reactive with S. pneumoniae cells, with an average titer of 52,000 after the third immunization, were obtained, thus establishing that native pneumococcal epitopes are expressed on the recombinant E. coli gene products. These data support the potential use of BVH-3, BVH-11 and/or BVH-11-2 gene products and the antibody raised to BVH-3, BVH-11 and/or BVH-11-2 gene products as vaccines for the prevention and the treatment of pneumococcal disease, respectively.
S.
pneumoniae
This example describes the protection of animals against fatal experimental pneumococcal infection by administration of antibody raised to BVH-3, BVH-11 or BVH-11-2 gene products.
High-titer Mab preparations were obtained from ascites fluid of mice inoculated intraperitoneally with Mab-secreting hybridoma cells according to the method described by Brodeur et al (J Immunol Methods 71 :265–272, 1984). Sera samples were collected from rabbits immunized with BVH-3M as described in Example 4. The rabbit sera collected after the third immunization and ascites fluid were used for the purification of antibodies by precipitation using 45 to 50% saturated ammonium sulfate. The antibody preparations were dissolved and dialyzed against phosphate-buffered saline (PBS).
CBA/N (xid) mice (National Cancer Institute, Frederick, Mass.) were injected intraperitoneally with either 0.1 ml of purified rabbit antibodies or 0.2 ml of ascites fluid before intravenous challenge with approximately 200 CFU of the type 3 S. pneumoniae strain WU2. Control mice received sterile PBS or antibodies purified from preimmune rabbit sera or sera from rabbits immunized with an unrelated N. meningitidis recombinant protein antigen. One group of mice was challenged with S. pneumoniae before the administration of anti-BVH-3 antibody. Samples of the S. pneumoniae challenge inoculum were plated on chocolate agar plates to determine the number of CFU and verify the challenge dose. The CBA/N mice were chosen because of their high susceptibility to S. pneumoniae infection. The LD50 of WU2 injected intravenously to CBA/N mice is estimated to be ≦10 CFU. Deaths were recorded at 24-h intervals for a period of at least 7 days.
The protection data obtained from mice injected with rabbit anti-BVH-3 antibody are set forth in the following Table 7. Nine out of 10 mice receiving the anti-BVH-3 antibody survived the challenge in contrast to none of 10 mice injected with control antibody or PBS buffer. The observation that antibody raised to the BVH-3-M molecule passively protected even when administered after the challenge demonstrated the ability of anti-BVH-3 antibody to prevent death even from an already established infection.
In an other experiment, 0.1 ml of rabbit antibody prepared from preimmune and immune sera were administered intraperitoneally to CBA/N mice four hours before intranasal challenge with 280 CFU of S. pneumoniae P4241 type 3 strain. As seen in the following Table 8, all immunized mice survived the challenge while none of 9 mice receiving preimmune sera antibody or buffer alone were alive on day 6 post-infection. S. pneumoniae hemocultures on day 11 post-challenge were negative for all surviving mice. Furthermore, 100% protection was observed in mice receiving monoclonal antibodies H112-10G9 or a mixture of H112-10G9 and H11B-7E11 which are directed against BVH-11/BVH-11-2.
Altogether, the results from Table 7 and Table 8 clearly establish that immunization of animals with a BVH-3 gene product such as BVH-3M elicited protective antibodies capable of preventing experimental bacteremia and pneumonia infections.
The protection data obtained for mice injected with ascites fluid are set forth in the following Table 9. Administration of a volume of 0.2 ml of ascites fluid of 0.2 ml of some sets of ascites fluid prevented death from experimental infection. For example, H112-3A4+H112-10G9 and H112-10G2+H112-10D7 sets of 2 Mabs conferred complete protection against experimental infection. These data indicated that antibody targetting BVH-11 and/or BVH-11-2 epitopes gave efficient protection. The Mabs H112-3A4, H112-10G9, H112-10D7, H112-10A2, H112-3E8, H112-10C5, H11B-11B8, H11B-15G2, H11B-1C9, H11B-7E11, H11B-13D5 and H11-10B8 were present in at least one protective pair of Mabs and were said to be protective and reactive against protective epitopes. The locations of protection-conferring epitopes on BVH-11-2 molecules are summarized in Table 10 and
Altogether the data set forth in Table 9 and Table 10 suggest that the protection eliciting BVH-11- and BVH-11-2-epitopes is comprised in the carboxy terminal product containing amino acids 229 to 840 and 227 to 838, on BVH-11 and BVH-11-2 proteins, respectively.
Altogether the data presented in this example substantiate the potential use of antibodies raised to BVH-3, BVH-11 or BVH-11-2 molecules as therapeutic means to prevent, diagnose or treat S. pneumoniae diseases.
This example describes the localization of surface-exposed peptide domains using Mabs described in Example 1.
S. pneumoniae type 3 strain WU2 was grown in Todd Hewitt (TH) broth (Difco Laboratories, Detroit Mich.) enriched with 0.5% Yeast extract (Difco Laboratories) at 37° C. in a 8% CO2 atmosphere to give an OD600 of 0.260 (˜108 CFU/ml). The bacterial suspension was then aliquoted in 1 ml samples and the S. pneumoniae cells were pelletted by centrifugation and resuspended in hybridoma culture supernatants. The bacterial suspensions were then incubated for 2 h at 4° C. Samples were washed twice in blocking buffer [PBS containing 2% bovine serum albumin (BSA)], and then 1 ml of goat fluorescein (FITC)-conjugated anti-mouse IgG+IgM diluted in blocking buffer was added. After an additional incubation of 60 min at room temperature, samples were washed twice in blocking buffer and fixed with 0.25% formaldehyde in PBS buffer for 18–24 h at 4° C. Cells were washed once in PBS buffer and resuspended in 500 μl of PBS buffer. Cells were kept in the dark at 4° C. until analyzed by flow cytometry (Epics® XL; Beckman Coulter, Inc.). Ten thousands (10,000) cells were analyzed per sample and the results were expressed as % Fluorescence and Fluorescence index (FI) values. The % Fluorescence is the number of fluorescein-labelled S. pneumoniae cells divided by 100 and the FI value is the median fluorescence value of pneumococci treated with Mab supernatant divided by the fluorescence value of pneumococci treated with the conjugate alone or with a control unrelated Mab. A FI value of 1 indicated that the Mab has not been detected at the surface of the bacteria whereas a FI value higher than 2 was considered positive when at least 10% of the pneumococcal cells were labelled and indicated that the Mab was reactive with cell-surface exposed epitopes. The following Table 11 summarized the data obtained with the Mabs tested by flow cytometry.
Flow cytometric analysis revealed that the Mabs reactive with BVH-3C and/or BVH-11A molecules did not bind to the cell surface. In contrast, with the exception of Mabs H3V-9C6 and H3V-16A7, the Mabs reactive with NEW 1, NEW 2, NEW 3, NEW 22 or NEW 23 BVH-3 gene products were detected at the surface of pneumococci. These data indicated that the first 225 amino acid residues located at the amino end of BVH-3 are internal. The lack of binding of Mabs H3V-9C6 and H3V-16A7 suggest some portions of the sequence corresponding to the 177-amino acids absent from the BVH-3 molecule of S. pneumoniae SP63 appears not to be accessible to antibodies.
Results from BVH-11- and/or BVH-11-2-reactive Mabs revealed that there is a good correlation between surface-exposure and protection. All Mabs reactive with internal epitopes as determined by the flow cytometry assay were not protective whereas all the protective Mabs described in Example 5 gave a positive signal in flow cytometry. Although an FI value of 9.0 and a % Fluorescence of 81.2 were obtained with Mab H11-7G11, this Mab was not shown to protect. Additional assays can be used to further evaluate whether this Mab and its corresponding epitope might participate in anti-infectious immunity.
S. pneumoniae by flow cytometry analysis
This example describes the immunization of animals with peptide epitopes of BVH-3 and BVH-11-2.
The recombinant pSCREEN-T vector (Novagen, Madison, Wis.) containing DNA fragment (nucleotides 2421 to 2626 on SEQ ID NO: 5) encoding the Mab 3A4-epitope (SEQ ID NO: 24) was transformed by electroporation (Gene Pulser II apparatus, BIO-RAD Labs, Mississauga, Canada) into E. coli Tuner (λDE3) pLysS [BL21 (F′ ompT hsdSB (rB−mB−) gal dcm lacYI pLysS (Cmr)] (Novagen). In this strain, the expression of the fusion protein is controlled by the T7 promoter which is recognized by the T7 RNA polymerase (present on the λDE3 prophage, itself under the control of the lac promoter inducible by isopropyl-β-D-thiogalactopyranoside (IPTG). The pLysS plasmid reduces the basal fusion protein expression level by coding for a T7 lysozyme, which is a natural inhibitor of the T7 RNA polymerase.
The transformants were grown at 37° C. with 250 RPM agitation in LB broth (peptone 10 g/l, yeast extract 5 g/l, NaCl 5 g/l) supplemented with 50 mM glucose, 100 μg/ml carbenicillin and 34 μg/ml chloramphenicol, until the absorbance at 600 nm reached a value of 0,7. The overexpression of T7 gene 10 protein-His•Tag-3A4.1 fusion protein was then induced by the addition of IPTG to a final concentration of 1 mM and further incubation at 25° C. with 250 RPM agitation for 3 hours. Induced cells from a 800-ml culture were pelleted by centrifugation and frozen at −70° C. The fusion protein was purified from the soluble cell fraction by affinity chromatography based on the binding of a six histidine residues sequence (His-Tag) to divalent cations (Ni2+) immobilized on a metal chelation Ni-NTA resin (Qiagen, Mississauga, Canada). Briefly, the pelleted cells were thawed and resuspended in Tris buffered sucrose solution (50 mM Tris, 25% (w/v) sucrose) and frozen at −70° C. for 15 minutes. Cells were incubated 15 minutes on ice in the presence of 2 mg/ml lysozyme before disruption by sonication. The lysate was centrifuged at 12000 RPM for 30 minutes and Nickel charged Ni-NTA resin (QIAgen) was added to the supernatant for an overnight incubation at 4° C., with 100 RPM agitation. After washing the resin with a buffer consisting of 20 mM Tris, 500 mM NaCl, 20 mM imidazole pH 7,9, the fusion 3A4.1 protein was eluted with the same buffer supplemented with 250 mM imidazole. The removal of the salt and imidazole was done by dialysis against PBS at 4° C. The protein concentration was determined with BCA protein assay reagent kit (Perce, Rockford, Ill.) and adjusted to 760 μg/ml.
To evaluate whether immunization with an epitope peptide sequence could confer protection against disease, groups of 6 female CBA/N (xid) mice (National Cancer Institute) are immunized subcutaneously three times at three-week intervals with affinity purified T7gene10 protein-His•Tag-3A4.1 fusion protein or, as control, with QuilA adjuvant alone in PBS. Twelve to fourteen days following the third immunization, the mice are challenged intravenously with S. pneumoniae WU2 strain or intranasally with P4241 strain. Samples of the S. pneumoniae challenge inoculum are plated on chocolate agar plates to determine the number of CFU and to verify the challenge dose. The challenge dose are approximalety 300 CFU. Deaths are recorded daily for a period of 14 days and on day 14 post-challenge, the surviving mice are sacrificed and blood samples tested for the presence of S. pneumoniae organisms. The 3A4.1 protein or other tested protein is said protective when the number of mice surviving the infection or the median number of days to death is significantly greater in the 3A4.1-immunized group compared to the control mock-immunized group.
This example illustrates the improvement of the antibody response to pneumococci using BVH-3 fragments and variants thereof.
The combined results obtained from studies of Mab reactivity with truncated gene products, epitope-expressing colonies and live intact pneumococci presented in examples 2, 3 and 6, allowed to delineate between surface-exposed and internal epitopes. The epitopes detected by Mabs that efficiently bound to pneumococci cells mapped to a region comprised between amino acid residues 223 to 1039 of BVH-3 described in SEQ ID NO 6. The existence of protective epitopes in the BVH-3-carboxyl half was confirmed by demonstrating that mice immunized with NEW1 molecule were protected from fatal infection with P4241 strain.
Gene sequence comparison revealed that in some strains, the region of BVH-3 encoding for amino acids 244 to 420 as described in SEQ ID NO6 is absent thus suggesting the lack of utility of this sequence in vaccine to prevent disease caused by such strains (SEQ ID NO: 9 versus SEQ ID NO: 1). Further BVH-3 fragments or variants thereof were designed in the purpose to develop a universal highly effective vaccine that would target the immune response to ubiquitous surface-exposed protective epitopes. BVH-3 gene fragments designated NEW1 (encoding amino acid residues 472 to 1039 from SEQ ID NO: 6) and NEW40 (encoding amino acid residues 408 to 1039 from SEQ ID NO: 6) were amplified from the S. pneumoniae strain SP64 by PCR using pairs of oligonucleotides engineered for the amplification of the appropriate gene fragment. Each of the primers had a restriction endonuclease site at the 5′end, thereby allowing directional in-frame cloning of the amplified product into the digested plasmid vector. PCR-amplified products were digested with restriction endonucleases and ligated to linearized plasmid pET21 (Novagen) expression vector digested likewise. Oligonucleotide primers HAMJ489 (ccgaattccatatgcaaattgggcaaccgactc; NdeI) and HAMJ279 (cgccaagcttcgctatgaaatcagataaattc; HindIII) were used for the NEW 40 construction. Clones were first stabilized in E. coli DH5α before introduction into E. coli BL21 (λDE3) for expression of the truncated gene products. Variants from NEW1 and NEW40 were generated by mutagenesis using the Quickchange Site-Directed Mutagenesis kit from Stratagene and the oligonucleotides designed to incorporate the appropriate mutation. The presence of 6 histidine tag residues on the C-terminus of the recombinant molecules simplified the purification of the proteins by nickel chromatography. The following tables 12 and 13 describe the sequences of the primers used for the mutagenesis experiments and the variant gene products generated, respectively. Mutagenesis experiments using primer sets 39, 40, 46, 47 or 48 resulted in silent changes and were performed in the purpose of improving the expression of the desired gene or gene fragment since it was observed that during the course of expression, BVH-3 gene and fragments of, shorter secondary translation initiation products were coexpressed.
Primer
Primer
SEQ ID
Primer SEQUENCE
set
identification
No
5′ - - -> 3′
Groups of 7 or 8 female BALB/c mice (Charles River) immunized as described earlier in example 1 were used for protection experiments against intranasal challenge with virulent S. pneumoniae P4241 strain. The mice were observed for 10 to 14 days post-infection. Data from Table 15 clearly indicate that the NEW35A molecule was equivalent to the parental NEW1 in term of protection. Interestingly, high survival rates where obtained for NEW40- and NEW56-immunized groups with 7 and 8 survivors out of 8 animals, respectively. Similarly, NEW25 comprising amino acid residues 233 to 1039 protected 7 out of 8 animals from lethal infection.
Additionally, flow cytometry analyses of the binding capacity of the sera antibodies from the vaccinated animals revealed that NEW40 and NEW56 antibodies labelled live intact pneumococci more efficiently than antibodies raised to BVH-3M (Table 15).
pneumoniae type 3 strain WU2 as measured by flow cytometry.
Cytometry results are expressed as fluorescence index value where the fluorescence index is the median fluorescence value of pneumococci treated with test sera divided by the background fluorescence value of pneumococci treated with the fluorescein conjugate alone. In these flow cytometric assays, all sera were used at a dilution of 1:50 and the sera from mice immunized with BVH-3C fragment or QuilA adjuvant alone gave a value similar to the background value.
Altogether the protection and pneumococci antibody binding data indicate that vaccination using NEW1 or NEW40 molecules and variants thereof, directs the immune response to conserved protective surface-exposed epitopes.
This example describes the cloning and expression of a chimeric deletant BVH-11-2 gene encoding for a chimeric polypeptide corresponding to BVH-11-2 conserved protective surface-exposed epitopes present in most if not all S. pneumoniae strains.
BVH-11-2 gene fragments corresponding to 4 gene regions, were amplified by PCR using pairs of oligonucleotides engineered to amplify fragments originating from SEQ ID NO: 5 spanning nucleotides 1662 to 1742, 1806 to 2153, 2193 to 2414 and 2484 to 2627 from S. pneumoniae strain Sp64 BVH-11-2 gene.
The primers used, HAMJ490-491, HAMJ492-HAMJ493, HAMJ494-HAMJ495, HAMJ496-HAMJ354 had a restriction endonuclease site at the 5′ end, thereby allowing directional in-frame cloning of the amplified product into the digested pET21b(+) plasmid vector (Table 16). PCR-amplified products were digested with restriction endonucleases and ligated to linearized plasmid pSL301 vector digested likewise except for the PCR-amplified fragment obtained with the primer pair HAMJ490-HAMJ491. The HAMJ490-HAMJ491 PCR-amplified product was purified from agarose gel using a QIAquick gel extraction kit from QIAgen (Chatsworth, Calif.) and ligated into pGEM-T plasmid vector without any prior restriction endonuclease digestion. The resultant plasmid constructs were confirmed by nucleotide sequence analysis. The recombinant plasmids containing each of the four were digested with restriction endonucleases corresponding with the 5′ end of each primer pair used for the PCR-amplification. The fragments were purified from agarose gel like described earlier and were all ligated to linearized plasmid pET21b (+) digested with the restriction enzymes NdeI and HindIII for the in-frame cloning of the four different regions of the BVH11-2 gene. Clones were first stabilized in E. coli DH5α before introduction into E. coli BL21 (λDE3) for expression of a chimeric pneumococcal protein molecule.
The resulting NEW43 gene sequence (SEQ ID No 257) is described in
The deduced amino acid sequence of NEW43 protein (SEQ ID No 258) is described in
SEQ ID
Nucleotide
Restriction
Primer
NO
Sequence 5′ - 3′
position
sites
NEW43-derived molecules designated VP43S and NEW86 were generated from gene amplification and cloning experiments using PCR primers described in Tables 16 and 18 and pET21 expression plasmid vector. Variants from NEW43 were generated by mutagenesis using the Quickchange Site-Directed Mutagenesis kit from Stratagene and the oligonucleotides designed to incorporate the appropriate mutation. The presence of 6 histidine tag residues on the C-terminus of the recombinant molecules simplified the purification of the proteins by nickel chromatography. The following tables 19 and 20 describe the sequences of the primers used for the mutagenesis experiments the NEW43 variant gene products generated, respectively.
SEQ
Primer
Primer
ID
Primer SEQUENCE
set
identification
NO
5′ - - -> 3′
S. pneumoniae SP64
Groups of 7 or 8 female BALB/c mice (Charles River) immunized as described earlier in example 1 were used for protection experiments against intranasal challenge with virulent S. pneumoniae P4241 strain. Data from Table 21 clearly indicate that NEW 19, NEW43 and variants thereof provided protection against experimental pneumonia.
This example describes the cloning and expression of chimeric genes encoding for a chimeric protein corresponding to the carboxy-terminal region of BVH-3 or variants thereof in fusion, at either the carboxyl end or the amino end, to NEW43 or variants thereof.
The chimeric genes comprising a BVH-3 truncate variant gene and a NEW43 or NEW43 variant gene have been designed following the procedure described in example 1. The polypeptides encoded by these chimeric genes are listed in the table 22. Briefly, gene fragments to be included in a chimeric gene were amplified by PCR using pairs of oligonucleotides engineered so that the primers had a restriction endonuclease site at the 5′ end, thereby allowing directional in-frame cloning of the amplified product into digested plasmid vectors (Table 23 and Table 24). PCR-amplified products were digested with restriction endonucleases and ligated to linearized plasmid pSL301 vector. The resultant plasmid construct were confirmed by nucleotide sequence analysis. The recombinant pSL301 plasmids containing a PCR product were redigested with the same endonuclease restriction enzyme for the obtention of the DNA inserts. The resulting insert DNA fragments were purified and inserts corresponding to a given chimeric gene were ligated into pURV22-NdeI vector for the generation of a chimeric gene. The expressed recombinant proteins were purified from supernatant fractions obtained from centrifugation of sonicated heat-induced E. coli cultures using multiple chromatographic purification steps.
This application claims the benefit of U.S. provisional application 60/212,683 filed Jun. 20, 2000 which is herein incorporated by reference.
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| 6800744 | Doucette-Stamm et al. | Oct 2004 | B1 |
| 20030232976 | Hamel et al. | Dec 2003 | A1 |
| 20040081662 | Hermand et al. | Apr 2004 | A1 |
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| WO9818930 | May 1998 | WO |
| WO 9818930 | May 1998 | WO |
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| 20030077293 A1 | Apr 2003 | US |
| Number | Date | Country | |
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| 60212683 | Jun 2000 | US |
