Patent Application
20110263448
The present invention relates to a specific set of genes useful for determining the efficacy of a treatment against multiple sclerosis (MS).
This application incorporates by reference the attached sequence listing in both paper and electronic copy in .txt format, created Sep. 12, 2008. Applicant further certifies that the content contained in the paper and electronic copies are identical.
Many disease states are characterized by differences in the expression levels of various genes either through changes in the copy number of the genetic DNA or through changes in levels of transcription of particular genes (e.g., through control of initiation, provision of RNA precursors, RNA processing, etc.).
Multiple sclerosis (MS) is a chronic neurological and inflammatory disease of the central nervous system (CNS). In people affected by MS, patches of damage called plaques or lesions appear in seemingly random areas of the CNS white matter. At the site of a lesion, a nerve insulating material, myelin, is lost in a process known as demyelination. Inflammation, demyelination, oligodendrocyte death, membrane damage and axonal death all contribute to the symptoms of MS. An unpredictable disease of the central nervous system, MS can range from relatively benign to somewhat disabling, to devastating, as communication between the brain and other parts of the body is disrupted. Many investigators believe MS to be an autoimmune disease, whereby the immune system destroys the nerve-insulating myelin. Such assaults may be linked to a yet unknown environmental trigger, such as a virus, diet, or allergy.
A physician may diagnose MS in some patients soon after the onset of the illness. In others, however, doctors may not be able to readily identify the cause of the symptoms, leading to years of uncertainty and multiple diagnoses punctuated by baffling symptoms that mysteriously wax and wane. The vast majority of patients are mildly affected, but in the worst cases, MS can render a person unable to write, speak, or walk. MS is a disease with a natural tendency to remit spontaneously, for which there is no universally effective treatment. No single laboratory test is yet available to prove or rule out MS, nor does a cure exist. Additionally, no laboratory test exists that identifies treatment-responsive and non-responsive patients. Therefore, there is a great need in the art for improved diagnostic tests for MS, as well as therapeutic targets for the development of new strategies to treat MS.
Compounds which are used as therapeutics to treat MS, such as interferon beta (e.g. Betaseron), presumably reverse some or all of these gene expression changes. The expression change of at least some of these genes may, therefore, be used as a method to monitor, or even predict, the efficacy of such therapeutics. As a result, some or all of these gene expression changes may be considered to be, and may be utilized as, a biomarker fingerprint. By extension, the gene products may also be used as biomarkers. Besides being used to monitor or predict the efficacy of a therapeutic, biomarkers may also be used to identify patients who are predicted to respond positively to therapeutic administration and those that might revert to non-responsive status.
The present invention relates to differentially expressed genes and the use of these differentially expressed genes for the prediction and prognosis of multiple sclerosis as well as the use of these differentially expressed genes to monitor, evaluate or analyze the efficacy of a treatment for multiple sclerosis. Specifically, this invention relates to an array useful for evaluating efficacy of multiple sclerosis treatment comprising probes specific for these differentially expressed genes.
Thus, the present invention provides for an array useful for evaluating efficacy of a treatment for multiple sclerosis (MS) in a subject comprising a plurality of probes specific to one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, whereby efficacy is evaluated by a change in gene expression of said dysregulated or counter-regulated genes subsequent to said treatment when compared to gene expression prior to said treatment. The present invention also provides a method of using the array for evaluating efficacy of a treatment for MS.
Additionally, the present invention provides for a method for evaluating efficacy of a treatment for multiple sclerosis comprising: (a) determining the level of expression of one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, in a first biological sample taken from the patient prior to treatment with an anti-MS agent; (b) determining the level of expression of the dysregulated gene and counter-regulated gene in at least a second biological sample taken from the patient subsequent to the initial treatment with the anti-MS agent; and (c) comparing the level of expression of the dysregulated and counter-regulated gene in the second biological sample with the level of expression of the dysregulated and counter-regulated gene in the first biological sample; wherein a change in the level of expression of the dysregulated or counter-regulated gene in the second biological sample compared to the level of expression of the dysregulated or counter-regulated gene in the first biological sample indicates the effectiveness of the treatment.
Further, the present invention provides a method for identifying a compound useful for the treatment of multiple sclerosis comprising: (a) analyzing the level of expression of one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, in a cell or tissue sample prior to treatment with a compound; (b) analyzing the level of expression of the dysregulated and counter-regulated genes in a cell or tissue sample subsequent to treatment with the compound; wherein a variation in the expression level of the dysregulated and counter-regulated genes is indicative of drug efficacy.
The present invention also provides a method for detecting neutralizing antibodies in patient response to introduction of interferonβ-1B comprising: (a) determining the level of expression of one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, in a first biological sample taken from the patient prior to treatment with an anti-MS agent; (b) determining the level of expression of the dysregulated gene and counter-regulated gene in at least a second biological sample taken from the patient subsequent to the initial treatment with the anti-MS agent; and (c) comparing the level of expression of the dysregulated and counter-regulated gene in the second biological sample with the level of expression of the dysregulated and counter-regulated gene in the first biological sample; whereby it can be determined whether the neutralizing antibody activity has reduced interferonβ-1B efficacy or had no effect on drug efficacy.
The present invention also provides for a gene expression fingerprint comprising an expression profile for a specific set of genes which are differentially expressed upon introduction of interferonβ-1B, wherein the fingerprint is useful for correlation to measureable clinical response of a patient such as MRI, relapse rate, disease progression, and disability scores (EDSS).
It is to be understood that this invention is not limited to the particular methodology, protocols, cell lines, animal species or genera, constructs, and reagents described and as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention which will be limited only by the appended claims.
It must be noted that as used herein and in the appended claims, the singular forms “a,” “and,” and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a gene” is a reference to one or more genes and includes equivalents thereof known to those skilled in the art, and so forth.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this invention belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the invention, the preferred methods, devices and materials are now described.
All publications and patents mentioned herein are hereby incorporated herein by reference for the purpose of describing and disclosing, for example, the constructs and methodologies that are described in the publications which might be used in connection with the presently described invention. The publications discussed above and throughout the text are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention.
Interferon beta (IFNβ) induces a broad range of responses that have been classified as anti-viral, anti-proliferative, or immunomodulatory. This functional multiplicity contributes to the challenge in understanding the mechanism of action responsible for its efficacy in MS. Two basic approaches are currently used to measure IFNβ bioactivity in-vitro - the viral protection assay (CPE assay) and a recently introduced assay that monitors the expression of a single antiviral gene, MxA, induced by both type I (IFNγ) and type II (IFNβ) interferons. By their nature, neither of these antiviral based assays can claim to provide a direct correlation to the anti-proliferative or immunomodulatory activities of IFNβ. Thus, provided is a novel approach to measure IFNβ bioactivity in vitro that provides this direct correlation.
This approach utilizes a unique fingerprint of genes, termed the “IFN Response In clinical Samples” (IRIS) genes, which were specifically selected within the disease setting based on their involvement in the regulation of biologies known to be associated with MS and disease progression. An array was developed utilizing the IRIS genes to measure the effectiveness of a treatment (e.g. IFN response) in MS patients.
Based on different gene expression patterns observed in peripheral blood mononuclear cells (PBMC) between healthy individuals, relapse remitting multiple sclerosis (RRMS) patients naive to treatment, and those treated with IFNβ-1B (e.g. Betaseron), a clinically-relevant set of MS-associated genes was identified. Shown in
Shown in
Provided in Table 1 are standard IFN inducible genes commonly used to measure IFNβ activity.
Provided in Table 2 are genes identified in MS patients to be counter-regulated upon treatment with IFNβ-1B (i.e. Betaseron). These genes, which are differentially expressed between healthy individuals and MS patients, revert back to “healthy” levels upon IFNβ-1B treatment. By healthy, it is intended to mean that levels are similar to individuals without MS.
Provided in Table 3 are genes identified in MS patients to be dysregulated upon treatment with IFNβ-1B (i.e. Betaseron). By dysergulated, it is intended to mean that the genes are differentially expressed between healthy individuals and MS patients. These genes revert back to “healthy” levels upon IFNβ-1B treatment.
The genes found in Table 3 were selected by a gap ratio analysis. This analysis calculates the gap ratio of the minimum expression level of the treated set (4 hrs post Betaseron injection) to the maximum value of the control (untreated or time zero). A set of IFNβ responsive genes determined to produce a gap ratio greater than or equal to 2 for any of the probe sets were compiled. From this, a set of genes, previously described to have a diversity of functions associated with immune regulation, immune response modulation (TH1 vs TH2) and IFN signaling were then selected as IRIS genes.
The present invention also provides for a gene expression fingerprint comprising an expression profile for a specific set of genes which are differentially expressed upon introduction of interferonβ-1B, wherein the fingerprint is useful for correlation to measureable clinical response of a patient such as MRI, relapse rate, disease progression, and disability scores (EDSS).
In some embodiments, the specific set of genes for the gene expression fingerprint include all those shown in
The IRIS genes can be measured directly using any state of the art gene profiling method including RT-PCR or by array, such as gene oligonucleotide arrays or RT-PCR formatted microfluidic cards. Because the fingerprint of IRIS genes includes only a select number of genes, in some embodiments, a low density array can also be used. To create an array, probes which selectively hybridize to the IRIS genes are placed onto an array for gene expression analysis. This array is useful for evaluating efficacy of a treatment for MS in a subject.
In some embodiments, a method to evaluate the efficacy of a treatment for MS in a subject using the array is also provided. Provided in
Thus, the present invention provides for an array useful for evaluating efficacy of a treatment for multiple sclerosis (MS) in a subject comprising a plurality of probes specific to one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, whereby efficacy is evaluated by a change in gene expression of said dysregulated or counter-regulated genes subsequent to said treatment when compared to gene expression prior to said treatment.
In some embodiments, the one or more dysregulated genes are selected from those listed in Table 3. In some embodiments, the one or more counter-regulated genes is selected from those listed in Table 2.
In some embodiments, the array also includes some house keeping genes or assay control genes or markers to ensure the assay is functioning properly and for normalization purposes. These assay control markers include endogenous genes and cell lineage genes. Examples of endogenous genes include but are not limited to GAPDH (NM—002046) and HPRT1 (NM—000194). Examples of cells lineage genes include but are not limited to CD3e (NM—000733), CD14 (NM—000591), CD19 (NM—001770), ITGAX (NM—000887), NCAM (NM—181351), and CD16 (NM—000560).
In some embodiments, the IRIS genes are formatted onto an array, such as a microfluidic TaqMan assay plate, along with house keeping genes to quantitate gene expression levels in cells. In some embodiments, the IRIS genes are formatted onto a microarray.
The present invention also provides for a method for evaluating efficacy of a treatment for multiple sclerosis comprising: (a) determining the level of expression of one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, in a first biological sample taken from the patient prior to treatment with an anti-MS agent; (b) determining the level of expression of the dysregulated gene and counter-regulated gene in at least a second biological sample taken from the patient subsequent to the initial treatment with the anti-MS agent; and (c) comparing the level of expression of the dysregulated and counter-regulated gene in the second biological sample with the level of expression of the dysregulated and counter-regulated gene in the first biological sample; wherein a change in the level of expression of the dysregulated or counter-regulated gene in the second biological sample compared to the level of expression of the dysregulated or counter-regulated gene in the first biological sample indicates the effectiveness of the treatment.
In some embodiments, the change in the level of expression of the dysregulated and counter-regulated genes creates a pattern that correlates to measureable clinical response such as MRI, relapse rate, disease progression, and disability scores (EDSS), wherein the pattern is determined using statistical methods. These statistical measurements include, but are not limited to, group comparison T-tests, random forest classifications, and conditional inference tree modeling.
In some embodiments, the one or more dysregulated genes are selected from those listed in Table 3. In some embodiments, the one or more counter-regulated genes are selected from those listed in Table 2. In some embodiments, the biological sample is from blood, urine, bone marrow, or biopsy sample.
Also provided, is a method for identifying a compound useful for the treatment of multiple sclerosis comprising: (a) analyzing the level of expression of one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, in a cell or tissue sample prior to treatment with a compound; (b) analyzing the level of expression of the dysregulated and counter-regulated genes in a cell or tissue sample subsequent to treatment with the compound; wherein a variation in the expression level of the dysregulated and counter-regulated genes is indicative of drug efficacy.
The IRIS array is also useful for detecting neutralizing antibodies in patient response to introduction of interferonβ-1B. Thus, provided is a method for detecting neutralizing antibodies in patient response to introduction of interferonβ-1B comprising: (a) determining the level of expression of one or more dysregulated genes and one or more counter-regulated genes, wherein said dysregulated and counter-regulated genes display a response to introduction of interferonβ-1B, in a first biological sample taken from the patient prior to treatment with an anti-MS agent; (b) determining the level of expression of the dysregulated gene and counter-regulated gene in at least a second biological sample taken from the patient subsequent to the initial treatment with the anti-MS agent; and (c) comparing the level of expression of the dysregulated and counter-regulated gene in the second biological sample with the level of expression of the dysregulated and counter-regulated gene in the first biological sample; whereby it can be determined whether the neutralizing antibody activity has reduced interferonβ-1B efficacy or had no effect on drug efficacy.
RRMS patient sera were assayed for inhibition of IFNβ-induced gene expression in normal PBMC and neutralizing titers were calculated using the Kawade formula described in
Effects of patient NAbs and the WHO anti-IFNβ standard against IFNβ-1B and IFNβ-1A are also presented. (See
Thus, the present invention helps to clarify the effects of NAbs on specific biologies related to IFNβ treatment in RRMS and to implement the IRIS approach in predicting response to MS treatment.
In accordance with the present invention, methods are provided for the assaying of gene expression in patients suffering from MS. As discussed above, the principal applications of this assay are to: (a) identify patients whose gene expression profile correlates with clinical response to IFNβ treatment, (b) identify patients whose gene expression profile reflects a refractory response to treatment, (c) identify patients whose neutralizing antibody status, as measured by the current viral inhibition assay, correlates with the absence of clinical response to treatment and (d) identify patients whose neutralizing antibody status has no impact on IFNβ efficacy. In each of these assays, the expression of a particular set of genes, set forth in the preceding sections, will be measured. The following is a discussion of various aspects of these methods.
There are a variety of ways by which one can assess gene expression. These methods either look at protein or at mRNA levels. Methods looking at mRNAs all fundamentally rely, at a basic level, on nucleic acid hybridization. Hybridization is defined as the ability of a nucleic acid to selectively form duplex molecules with complementary stretches of DNAs and/or RNAs. Depending on the application envisioned, one would employ varying conditions of hybridization to achieve varying degrees of selectivity of the probe or primers for the target sequence.
Typically, a probe or primer of between 13 and 100 nucleotides, preferably between 17 and 100 nucleotides in length up to 1-2 kilobases or more in length will allow the formation of a duplex molecule that is both stable and selective. Molecules having complementary sequences over contiguous stretches greater than 20 bases in length are generally preferred, to increase stability and selectivity of the hybrid molecules obtained. One will generally prefer to design nucleic acid molecules for hybridization having one or more complementary sequences of 20 to 30 nucleotides, or even longer where desired. Such fragments may be readily prepared, for example, by directly synthesizing the fragment by chemical means or by introducing selected sequences into recombinant vectors for recombinant production.
For applications requiring high selectivity, one will typically desire to employ relatively high stringency conditions to form the hybrids. For example, relatively low salt and/or high temperature conditions, such as provided by about 0.02 M to about 0.10 M NaCl at temperatures of about 5 ° C. to about 70° C. Such high stringency conditions tolerate little, if any, mismatch between the probe or primers and the template or target strand and would be particularly suitable for isolating specific genes or for detecting specific mRNA transcripts. It is generally appreciated that conditions can be rendered more stringent by the addition of increasing amounts of formamide.
For certain applications, for example, lower stringency conditions may be used. Under these conditions, hybridization may occur even though the sequences of the hybridizing strands are not perfectly complementary, but are mismatched at one or more positions. Conditions may be rendered less stringent by increasing salt concentration and/or decreasing temperature. For example, a medium stringency condition could be provided by about 0.1 to 0.25 M NaCl at temperatures of about 37 ° C. to about 55° C., while a low stringency condition could be provided by about 0.15 M to about 0.9 M salt, at temperatures ranging from about 20° C. to about 55° C. Hybridization conditions can be readily manipulated depending on the desired results.
In other embodiments, hybridization may be achieved under conditions of, for example, 50 mM Tris-HCl (pH 8.3), 75 mM KCl, 3 mM MgCl2 , 1.0 mM dithiothreitol, at temperatures between approximately 20° C. to about 37° C. Other hybridization conditions utilized could include approximately 10 mM Tris-HCl (pH 8.3), 50 mM KCl, 1.5 mM MgCl2, at temperatures ranging from approximately 40° C. to about 72° C.
In certain embodiments, it will be advantageous to employ nucleic acids of defined sequences of the present invention in combination with an appropriate means, such as a label, for determining hybridization. A wide variety of appropriate indicator means are known in the art, including fluorescent, radioactive, enzymatic or other ligands, such as avidin/biotin, which are capable of being detected. In some embodiments, one may desire to employ a fluorescent label or an enzyme tag such as urease, alkaline phosphatase or peroxidase, instead of radioactive or other environmentally undesirable reagents. In the case of enzyme tags, colorimetric indicator substrates are known that can be employed to provide a detection means that is visibly or spectrophotometrically detectable, to identify specific hybridization with complementary nucleic acid containing samples.
In general, it is envisioned that the probes or primers described herein will be useful as reagents in solution hybridization, as in PCR, for detection of expression of corresponding genes, as well as in embodiments employing a solid phase. In embodiments involving a solid phase, the test DNA (or RNA) is adsorbed or otherwise affixed to a selected matrix or surface. This fixed, single-stranded nucleic acid is then subjected to hybridization with selected probes under desired conditions. The conditions selected will depend on the particular circumstances (depending, for example, on the G+C content, type of target nucleic acid, source of nucleic acid, size of hybridization probe, etc.). Optimization of hybridization conditions for the particular application of interest is well known to those of skill in the art. After washing of the hybridized molecules to remove non-specifically bound probe molecules, hybridization is detected, and/or quantified, by determining the amount of bound label. Representative solid phase hybridization methods are disclosed in U.S. Pat. Nos. 5,843,663, 5,900,481 and 5,919,626. Other methods of hybridization that may be used in the practice of the present invention are disclosed in U.S. Pat. Nos. 5,849,481, 5,849,486 and 5,851,772. The relevant portions of these and other references identified in this section of the Specification are incorporated herein by reference.
Since many nucleic acids, especially mRNAs, are in low abundance, nucleic acid amplification greatly enhances the ability to assess expression. The general concept is that nucleic acids can be amplified using paired primers flanking the region of interest. The term “primer,” as used herein, is meant to encompass any nucleic acid that is capable of priming the synthesis of a nascent nucleic acid in a template-dependent process. Typically, primers are oligonucleotides from ten to twenty and/or thirty base pairs in length, but longer sequences can be employed. Primers may be provided in double-stranded and/or single-stranded form, although the single-stranded form is preferred.
Pairs of primers designed to selectively hybridize to nucleic acids corresponding to selected genes are contacted with the template nucleic acid under conditions that permit selective hybridization. Depending upon the desired application, high stringency hybridization conditions may be selected that will only allow hybridization to sequences that are completely complementary to the primers. In other embodiments, hybridization may occur under reduced stringency to allow for amplification of nucleic acids containing one or more mismatches with the primer sequences. Once hybridized, the template-primer complex is contacted with one or more enzymes that facilitate template-dependent nucleic acid synthesis. Multiple rounds of amplification, also referred to as “cycles,” are conducted until a sufficient amount of amplification product is produced.
The amplification product may be detected or quantified. In certain applications, the detection may be performed by visual means. Alternatively, the detection may involve indirect identification of the product via chemilluminescence, radioactive scintigraphy of incorporated radiolabel or fluorescent label or even via a system using electrical and/or thermal impulse signals.
A number of template dependent processes are available to amplify the oligonucleotide sequences present in a given template sample. One of the best known amplification methods is the polymerase chain reaction (referred to as PCR) which is described in detail in U.S. Pat. Nos. 4,683,195, 4,683,202 and 4,800,159, and in Innis et al., 1988, each of which is incorporated herein by reference in their entirety.
A reverse transcriptase PCR (RT-PCR) amplification procedure may be performed to quantify the amount of mRNA amplified. Methods of reverse transcribing RNA into cDNA are well known (see Sambrook et al., 1989; hereby incorporated by reference). Alternative methods for reverse transcription utilize thermostable DNA polymerases. These methods are described in WO 90/07641, hereby incorporated by reference. Polymerase chain reaction methodologies are well known in the art. Representative methods of RT-PCR are described in U.S. Pat. No. 5,882,864, hereby incorporated by reference.
Whereas standard PCR usually uses one pair of primers to amplify a specific sequence, multiplex-PCR (MPCR) uses multiple pairs of primers to amplify many sequences simultaneously (Chamberlan et al., 1990; hereby incorporated by reference). The presence of many PCR primers in a single tube could cause many problems, such as the increased formation of misprimed PCR products and “primer dimers”, the amplification discrimination of longer DNA fragment and so on. Normally, MPCR buffers contain a Taq Polymerase additive, which decreases the competition among amplicons and the amplification discrimination of longer DNA fragment during MPCR. MPCR products can further be hybridized with gene-specific probe for verification. Theoretically, one should be able to use as many as primers as necessary. However, due to side effects (primer dimers, misprimed PCR products, etc.) caused during MPCR, there is a limit (less than 20) to the number of primers that can be used in a MPCR reaction. See also European Application No. 0 364 255 and Mueller and Wold (1989) ; hereby incorporated by reference.
Another method for amplification is ligase chain reaction (“LCR”), disclosed in European Application No. 320 308, incorporated herein by reference in its entirety. U.S. Pat. No. 4,883,750, hereby incorporated by reference, describes a method similar to LCR for binding probe pairs to a target sequence. A method based on PCR and oligonucleotide ligase assay (OLA), disclosed in U.S. Pat. No. 5,912,148, hereby incorporated by reference, may also be used.
Alternative methods for amplification of target nucleic acid sequences that may be used in the practice of the present invention are disclosed in U.S. Pat. Nos. 5,843,650, 5,846,709, 5,846,783, 5,849,546, 5,849,497, 5,849,547, 5,858,652, 5,866,366, 5,916,776, 5,922,574, 5,928,905, 5,928,906, 5,932,451, 5,935,825, 5,939,291 and 5,942,391, GB Application No. 2 202 328, and in PCT Application No. PCT/US89/01025, each of which is incorporated herein by reference in its entirety.
Qbeta Replicase, described in PCT Application No. PCT/US87/00880, may also be used as an amplification method in the present invention. In this method, a replicative sequence of RNA that has a region complementary to that of a target is added to a sample in the presence of an RNA polymerase. The polymerase will copy the replicative sequence which may then be detected.
An isothermal amplification method, in which restriction endonucleases and ligases are used to achieve the amplification of target molecules that contain nucleotide 5′-[.alpha.-thio]-triphosphates in one strand of a restriction site may also be useful in the amplification of nucleic acids in the present invention (Walker et al., 1992). Strand Displacement Amplification (SDA), disclosed in U.S. Pat. No. 5,916,779, is another method of carrying out isothermal amplification of nucleic acids which involves multiple rounds of strand displacement and synthesis, i.e., nick translation.
Other nucleic acid amplification procedures include transcription-based amplification systems (TAS), including nucleic acid sequence based amplification (NASBA) and 3SR (Kwoh et al., 1989; Gingeras et al., PCT Application WO 88/10315, incorporated herein by reference in their entirety). European Application No. 329 822 disclose a nucleic acid amplification process involving cyclically synthesizing single-stranded RNA (“ssRNA”), ssDNA, and double-stranded DNA (dsDNA), which may be used in accordance with the present invention.
PCT Application WO 89/06700 (incorporated herein by reference in its entirety) discloses a nucleic acid sequence amplification scheme based on the hybridization of a promoter region/primer sequence to a target single-stranded DNA (“ssDNA”) followed by transcription of many RNA copies of the sequence. This scheme is not cyclic, i.e., new templates are not produced from the resultant RNA transcripts. Other amplification methods include “race” and “one-sided PCR” (Frohiman, 1990; Ohara et al., 1989).
Following any amplification, it may be desirable to separate the amplification product from the template and/or the excess primer. In one embodiment, amplification products are separated by agarose, agarose-acrylamide or polyacrylamide gel electrophoresis using standard methods (Sambrook et al., 1989). Separated amplification products may be cut out and eluted from the gel for further manipulation. Using low melting point agarose gels, the separated band may be removed by heating the gel, followed by extraction of the nucleic acid.
Separation of nucleic acids may also be effected by chromatographic techniques known in art. There are many kinds of chromatography which may be used in the practice of the present invention, including adsorption, partition, ion-exchange, hydroxylapatite, molecular sieve, reverse-phase, column, paper, thin-layer, and gas chromatography as well as HPLC.
In certain embodiments, the amplification products are visualized. A typical visualization method involves staining of a gel with ethidium bromide and visualization of bands under UV light. Alternatively, if the amplification products are integrally labeled with radio- or fluorometrically-labeled nucleotides, the separated amplification products can be exposed to x-ray film or visualized under the appropriate excitatory spectra.
In one embodiment, following separation of amplification products, a labeled nucleic acid probe is brought into contact with the amplified marker sequence. The probe preferably is conjugated to a chromophore but may be radiolabeled. In another embodiment, the probe is conjugated to a binding partner, such as an antibody or biotin, or another binding partner carrying a detectable moiety.
In particular embodiments, detection is by Southern blotting and hybridization with a labeled probe. The techniques involved in Southern blotting are well known to those of skill in the art (see Sambrook et al., 1989). One example of the foregoing is described in U.S. Pat. No. 5,279,721, incorporated by reference herein, which discloses an apparatus and method for the automated electrophoresis and transfer of nucleic acids. The apparatus permits electrophoresis and blotting without external manipulation of the gel and is ideally suited to carrying out methods according to the present invention.
Other methods of nucleic acid detection that may be used in the practice of the instant invention are disclosed in U.S. Pat. Nos. 5,840,873, 5,843,640, 5,843,651, 5,846,708, 5,846,717, 5,846,726, 5,846,729, 5,849,487, 5,853,990, 5,853,992, 5,853,993, 5,856,092, 5,861,244, 5,863,732, 5,863,753, 5,866,331, 5,905,024, 5,910,407, 5,912,124, 5,912,145, 5,919,630, 5,925,517, 5,928,862, 5,928,869, 5,929,227, 5,932,413 and 5,935,791, each of which is incorporated herein by reference.
Microarrays comprise a plurality of polymeric molecules spatially distributed over, and stably associated with, the surface of a substantially planar substrate, e.g., biochips. Microarrays of polynucleotides have been developed and find use in a variety of applications, such as screening and DNA sequencing. One area in particular in which microarrays find use is in gene expression analysis.
In gene expression analysis with microarrays, an array of “probe” oligonucleotides is contacted with a nucleic acid sample of interest, i.e., target, such as polyA mRNA or total RNA from a particular tissue type. Contact is carried out under hybridization conditions and unbound nucleic acid is then removed. The resultant pattern of hybridized nucleic acid provides information regarding the genetic profile of the sample tested. Methodologies of gene expression analysis on microarrays are capable of providing both qualitative and quantitative information.
A variety of different arrays which may be used are known in the art. The probe molecules of the arrays which are capable of sequence specific hybridization with target nucleic acid may be polynucleotides or hybridizing analogues or mimetics thereof, including: nucleic acids in which the phosphodiester linkage has been replaced with a substitute linkage, such as phophorothioate, methylimino, methylphosphonate, phosphoramidate, guanidine and the like; nucleic acids in which the ribose subunit has been substituted, e.g., hexose phosphodiester; peptide nucleic acids; and the like. The length of the probes will generally range from 10 to 1000 nucleotides (nts), where in some embodiments the probes will be oligonucleotides and usually range from 15 to 150 nts and more usually from 15 to 100 nts in length, and in other embodiments the probes will be longer, usually ranging in length from 150 to 1000 nts, where the polynucleotide probes may be single- or double-stranded, usually single-stranded, and may be PCR fragments amplified from cDNA.
The probe molecules on the surface of the substrates will correspond to selected genes being analyzed and be positioned on the array at a known location so that positive hybridization events may be correlated to expression of a particular gene in the physiological source from which the target nucleic acid sample is derived. The substrates with which the probe molecules are stably associated may be fabricated from a variety of materials, including plastics, ceramics, metals, gels, membranes, glasses, and the like. The arrays may be produced according to any convenient methodology, such as preforming the probes and then stably associating them with the surface of the support or growing the probes directly on the support. A number of different array configurations and methods for their production are known to those of skill in the art and disclosed in U.S. Pat. Nos. 5,445,934, 5,532,128, 5,556,752, 5,242,974, 5,384,261, 5,405,783, 5,412,087, 5,424,186, 5,429,807, 5,436,327, 5,472,672, 5,527,681, 5,529,756, 5,545,531, 5,554,501,5,561,071, 5,571,639, 5,593,839, 5,599,695, 5,624,711, 5,658,734, 5,700,637, and 6,004,755.
Following hybridization, where non-hybridized labeled nucleic acid is capable of emitting a signal during the detection step, a washing step is employed where unhybridized labeled nucleic acid is removed from the support surface, generating a pattern of hybridized nucleic acid on the substrate surface. A variety of wash solutions and protocols for their use are known to those of skill in the art and may be used.
Where the label on the target nucleic acid is not directly detectable, one then contacts the array, now comprising bound target, with the other member(s) of the signal producing system that is being employed. For example, where the label on the target is biotin, one then contacts the array with streptavidin-fluorescer conjugate under conditions sufficient for binding between the specific binding member pairs to occur. Following contact, any unbound members of the signal producing system will then be removed, e.g., by washing. The specific wash conditions employed will necessarily depend on the specific nature of the signal producing system that is employed, and will be known to those of skill in the art familiar with the particular signal producing system employed.
The resultant hybridization pattern(s) of labeled nucleic acids may be visualized or detected in a variety of ways, with the particular manner of detection being chosen based on the particular label of the nucleic acid, where representative detection means include scintillation counting, autoradiography, fluorescence measurement, calorimetric measurement, light emission measurement and the like.
Prior to detection or visualization, where one desires to reduce the potential for a mismatch hybridization event to generate a false positive signal on the pattern, the array of hybridized target/probe complexes may be treated with an endonuclease under conditions sufficient such that the endonuclease degrades single stranded, but not double stranded DNA. A variety of different endonucleases are known and may be used, where such nucleases include: mung bean nuclease, S1 nuclease, and the like. Where such treatment is employed in an assay in which the target nucleic acids are not labeled with a directly detectable label, e.g., in an assay with biotinylated target nucleic acids, the endonuclease treatment will generally be performed prior to contact of the array with the other member(s) of the signal producing system, e.g., fluorescent-streptavidin conjugate. Endonuclease treatment, as described above, ensures that only end-labeled target/probe complexes having a substantially complete hybridization at the 3′ end of the probe are detected in the hybridization pattern.
Following hybridization and any washing step(s) and/or subsequent treatments, as described above, the resultant hybridization pattern is detected. In detecting or visualizing the hybridization pattern, the intensity or signal value of the label will be not only be detected but quantified, by which is meant that the signal from each spot of the hybridization will be measured and compared to a unit value corresponding the signal emitted by known number of end-labeled target nucleic acids to obtain a count or absolute value of the copy number of each end-labeled target that is hybridized to a particular spot on the array in the hybridization pattern.
In another aspect of the invention, one may employ a protein-based diagnostic approach. The most common form of protein identification is by the use of antibodies. As used herein, the term “antibody” is intended to refer broadly to any immunologic binding agent such as IgG, IgM, IgA, IgD and IgE. Generally, IgG and/or IgM are preferred because they are the most common antibodies in the physiological situation and because they are most easily made in a laboratory setting. The term “antibody” also refers to any antibody-like molecule that has an antigen binding region, and includes antibody fragments such as Fab′, Fab, F(ab′).sub.2, single domain antibodies (DABs), Fv, scFv (single chain Fv), and the like. The techniques for preparing and using various antibody-based constructs and fragments are well known in the art. Means for preparing and characterizing antibodies, both polyclonal and monoclonal, are also well known in the art (See, e.g., Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988; incorporated herein by reference).
In accordance with the present invention, immunodetection methods are provided. Some immunodetection methods include enzyme linked immunosorbent assay (ELISA), radioimmunoassay (RIA), immunoradiometric assay, fluoroimmunoassay, chemiluminescent assay, bioluminescent assay, and Western blot to mention a few. The steps of various useful immunodetection methods have been described in the scientific literature, such as, e.g., Doolittle and Ben-Zeev 0, 1999; Gulbis and Galand, 1993; De Jager et al., 1993; and Nakamura et al., 1987, each incorporated herein by reference.
In general, the immunobinding methods include obtaining a sample suspected of containing a relevant polypeptide, and contacting the sample with a first antibody under conditions effective to allow the formation of immunocomplexes. In terms of antigen detection, the biological sample analyzed may be any sample that is suspected of containing an antigen, such as, for example, a tissue section or specimen, a homogenized tissue extract, a cell, or even a biological fluid.
Contacting the chosen biological sample with the antibody under effective conditions and for a period of time sufficient to allow the formation of immune complexes (primary immune complexes) is generally a matter of simply adding the antibody composition to the sample and incubating the mixture for a period of time long enough for the antibodies to form immune complexes with, i.e., to bind to, any antigens present. After this time, the sample-antibody composition, such as a tissue section, ELISA plate, dot blot or western blot, will generally be washed to remove any non-specifically bound antibody species, allowing only those antibodies specifically bound within the primary immune complexes to be detected.
In general, the detection of immunocomplex formation is well known in the art and may be achieved through the application of numerous approaches. These methods are generally based upon the detection of a label or marker, such as any of those radioactive, fluorescent, biological and enzymatic tags. U.S. patents concerning the use of such labels include U.S. Pat. Nos. 3,817,837; 3,850,752; 3,939,350; 3,996,345; 4,277,437; 4,275,149 and 4,366,241, each incorporated herein by reference. Of course, one may find additional advantages through the use of a secondary binding ligand such as a second antibody and/or a biotin/avidin ligand binding arrangement, as is known in the art.
The antibody employed in the detection may itself be linked to a detectable label, wherein one would then simply detect this label, thereby allowing the amount of the primary immune complexes in the composition to be determined. Alternatively, the first antibody that becomes bound within the primary immune complexes may be detected by means of a second binding ligand that has binding affinity for the antibody. In these cases, the second binding ligand may be linked to a detectable label. The second binding ligand is itself often an antibody, which may thus be termed a “secondary” antibody. The primary immune complexes are contacted with the labeled, secondary binding ligand, or antibody, under effective conditions and for a period of time sufficient to allow the formation of secondary immune complexes. The secondary immune complexes are then generally washed to remove any non-specifically bound labeled secondary antibodies or ligands, and the remaining label in the secondary immune complexes is then detected.
Further methods include the detection of primary immune complexes by a two step approach. A second binding ligand, such as an antibody, that has binding affinity for the antibody is used to form secondary immune complexes, as described above. After washing, the secondary immune complexes are contacted with a third binding ligand or antibody that has binding affinity for the second antibody, again under effective conditions and for a period of time sufficient to allow the formation of immune complexes (tertiary immune complexes). The third ligand or antibody is linked to a detectable label, allowing detection of the tertiary immune complexes thus formed. This system may provide for signal amplification if this is desired.
One method of immunodetection designed by Charles Cantor uses two different antibodies. A first step biotinylated, monoclonal or polyclonal antibody is used to detect the target antigen(s), and a second step antibody is then used to detect the biotin attached to the complexed biotin. In that method the sample to be tested is first incubated in a solution containing the first step antibody. If the target antigen is present, some of the antibody binds to the antigen to form a biotinylated antibody/antigen complex. The antibody/antigen complex is then amplified by incubation in successive solutions of streptavidin (or avidin), biotinylated DNA, and/or complementary biotinylated DNA, with each step adding additional biotin sites to the antibody/antigen complex. The amplification steps are repeated until a suitable level of amplification is achieved, at which point the sample is incubated in a solution containing the second step antibody against biotin. This second step antibody is labeled, as for example with an enzyme that can be used to detect the presence of the antibody/antigen complex by histoenzymology using a chromogen substrate. With suitable amplification, a conjugate can be produced which is macroscopically visible.
Another known method of immunodetection takes advantage of the immuno-PCR (Polymerase Chain Reaction) methodology. The PCR method is similar to the Cantor method up to the incubation with biotinylated DNA, however, instead of using multiple rounds of streptavidin and biotinylated DNA incubation, the DNA/biotin/streptavidin/antibody complex is washed out with a low pH or high salt buffer that releases the antibody. The resulting wash solution is then used to carry out a PCR reaction with suitable primers with appropriate controls. At least in theory, the enormous amplification capability and specificity of PCR can be utilized to detect a single antigen molecule.
As detailed above, immunoassays are in essence binding assays. Certain immunoassays are the various types of enzyme linked immunosorbent assays (ELISAs) and radioimmunoassays (RIA) known in the art. However, it will be readily appreciated that detection is not limited to such techniques, and Western blotting, dot blotting, FACS analyses, and the like may also be used.
In one exemplary ELISA, the antibodies of the invention are immobilized onto a selected surface exhibiting protein affinity, such as a well in a polystyrene microtiter plate. Then, a test composition suspected of containing the antigen, such as a clinical sample, is added to the wells. After binding and washing to remove non-specifically bound immune complexes, the bound antigen may be detected. Detection is generally achieved by the addition of another antibody that is linked to a detectable label. This type of ELISA is a simple “sandwich ELISA”. Detection may also be achieved by the addition of a second antibody, followed by the addition of a third antibody that has binding affinity for the second antibody, with the third antibody being linked to a detectable label.
In another exemplary ELISA, the samples suspected of containing the antigen are immobilized onto the well surface and then contacted with the anti-ORF message and anti-ORF translated product antibodies of the invention. After binding and washing to remove nonspecifically bound immune complexes, the bound anti-ORF message and anti-ORF translated product antibodies are detected. Where the initial anti-ORF message and anti-ORF translated product antibodies are linked to a detectable label, the immune complexes may be detected directly. Again, the immune complexes may be detected using a second antibody that has binding affinity for the first anti-ORF message and anti-ORF translated product antibody, with the second antibody being linked to a detectable label.
Another ELISA in which the antigens are immobilized, involves the use of antibody competition in the detection. In this ELISA, labeled antibodies against an antigen are added to the wells, allowed to bind, and detected by means of their label. The amount of an antigen in an unknown sample is then determined by mixing the sample with the labeled antibodies against the antigen during incubation with coated wells. The presence of an antigen in the sample acts to reduce the amount of antibody against the antigen available for binding to the well and thus reduces the ultimate signal. This is also appropriate for detecting antibodies against an antigen in an unknown sample, where the unlabeled antibodies bind to the antigen-coated wells and also reduces the amount of antigen available to bind the labeled antibodies. “Under conditions effective to allow immune complex (antigen/antibody) formation” means that the conditions preferably include diluting the antigens and/or antibodies with solutions such as BSA, bovine globulin (BGG) or phosphate buffered saline (PBS)/Tween. These added agents also tend to assist in the reduction of nonspecific background. The “suitable” conditions also mean that the incubation is at a temperature or for a period of time sufficient to allow effective binding. Incubation steps are typically from about 1 to 2 to 4 hours or so, at temperatures preferably on the order of 25° C. to 27° C., or may be overnight at about 4° C. or so.
The antibodies of the present invention may also be used in conjunction with both fresh-frozen and/or formalin-fixed, paraffin-embedded tissue blocks prepared for study by immunohistochemistry (IHC). The method of preparing tissue blocks from these particulate specimens has been successfully used in previous IHC studies of various prognostic factors, and/or is well known to those of skill in the art (Brown et al., 1990; Abbondanzo et al., 1999; Allred et al., 1990).
Also contemplated in the present invention is the use of immunohistochemistry. This approach uses antibodies to detect and quantify antigens in intact tissue samples. Generally, frozen-sections are prepared by rehydrating frozen “pulverized” tissue at room temperature in phosphate buffered saline (PBS) in small plastic capsules; pelleting the particles by centrifugation; resuspending them in a viscous embedding medium (OCT); inverting the capsule and pelleting again by centrifugation; snap-freezing in −70° C. isopentane; cutting the plastic capsule and removing the frozen cylinder of tissue; securing the tissue cylinder on a cryostat microtome chuck; and cutting 25-50 serial sections.
Permanent-sections may be prepared by a similar method involving rehydration of the 50 mg sample in a plastic microfuge tube; pelleting; resuspending in 10% formalin for 4 hours fixation; washing/pelleting; resuspending in warm 2.5% agar; pelleting; cooling in ice water to harden the agar; removing the tissue/agar block from the tube; infiltrating and/or embedding the block in paraffin; and cutting up to 50 serial permanent sections.
It will be apparent to those skilled in the art that the examples and embodiments described herein are by way of illustration and not of limitation, and that other examples may be used without departing from the spirit and scope of the present invention, as set forth in the claims.
The relative gene expression is measured with a sequence detection system (eg. ABI Prism 7900 HT) using the application software designed for that detection unit (eg. SDS2.1). The expression level for each IRIS gene is calculated by the comparative CT method using the equation 2-δδCT where δδCT equals the normalized signal level in sample “A” (eg IFNβ stimulated) relative to the normalized signal level in a calibrator sample (eg. non-stimulated control). Samples can be normalized using the GAPDH or the HPRT1 housekeeping gene. Alternatively samples can be normalized using cell lineage markers for T cells (CD3), B cells (CD19), monocytes (CD14), dendritic cells (ITGAX), neutrophils (NCAM) or NK cells (CD16) when looking at the response in patient PBMC samples. For NAb analysis, IRIS gene expression is compared between samples containing a concentration of patient serum with 10 LU/mL IFNβ and the calibrator sample with 10 LU/mL IFNβ alone and the TRU neutralization titer will be calculated using the Kawade method as described. (See
Using IRIS gene expression analysis described above, we find that the extent of neutralization of IFNβ induction appears to be unique for each IRIS gene analyzed. For example the standard IFNβ response gene MxA gene was very sensitive to neutralization while other IRIS genes required higher sera concentrations for neutralization. (See
All publications and patents mentioned in the above specification are incorporated herein by reference. Various modifications and variations of the described methods of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the above-described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are intended to be encompassed by the following claims.
This application claims priority to U.S. Provisional Application Ser. No. 61/097,227 filed Sep. 16, 2008, the entirety of which is hereby incorporated by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2009/057196 | 9/16/2009 | WO | 00 | 3/16/2011 |
| Number | Date | Country | |
|---|---|---|---|
| 61097227 | Sep 2008 | US |
