Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving nucleic acid
Reexamination Certificate
2001-04-02
2004-11-16
Horlick, Kenneth R. (Department: 1637)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving nucleic acid
C536S024200, C536S024310, C536S024330, C536S023100, C536S025320, C536S026600
Reexamination Certificate
active
06818399
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to separable compositions, methods, and kits for use in multiplexed assay detection of the interaction between ligands and target antiligands.
BACKGROUND OF THE INVENTION
The need to determine many analytes or nucleic acid sequences (for example multiple pathogens or multiple genes or multiple genetic variants) in blood or other biological fluids has become increasingly apparent in many branches of medicine. Most multi-analyte assays, such as assays that detect multiple nucleic acid sequences, involve multiple steps, have poor sensitivity, a limited dynamic range (typically on the order of 2 to 100-fold differences and some require sophisticated instrumentation. Some of the known classical methods for multianalyte assays include the following:
a. The use of two different radioisotope labels to distinguish two different analytes.
b. The use of two or more different fluorescent labels to distinguish two or more analytes.
c. The use of lanthanide chelates where both lifetime and wavelength are used to distinguish two or more analytes.
d. The use of fluorescent and chemiluminescent labels to distinguish two or more analytes.
e. The use of two different enzymes to distinguish two or more analytes.
f. The use of enzyme and acridinium esters to distinguish two or more analytes.
g. Spatial resolution of different analytes, for example on arrays, to identify and quantify multiple analytes.
h. The use of acridinium ester labels where lifetime or dioxetanone formation is used to quantify two different viral targets.
As the human genome is elucidated, there will be numerous opportunities for performing assays to determine the presence of specific sequences, distinguishing between alleles in homozygotes and heterozygotes, determining the presence of mutations, evaluating cellular expression patterns, etc. In many of these cases one will wish to determine in a single reaction, a number of different characteristics of the same sample. In many assays, there will be an interest in determining the presence of specific sequences, whether genomic, synthetic, or cDNA. These sequences may be associated particularly with genes, regulatory sequences, repeats, multimeric regions, expression patterns, and the like. There will also be an interest in determining the presence of one or more pathogens, their antibiotic resistance genes, genetic subtype and the like. The need to identify and quantify a large number of bases or sequences, potentially distributed over centimorgans of DNA, offers a major challenge. Any method should be accurate, reasonably economical in limiting the amount of reagents required and provide for a highly multiplexed assay, which allows for differentiation and quantitation of multiple genes, and/or snp determination, and/or gene expression at the RNA or protein level.
The need to study differential expression of multiple genes to determine toxicologically relevant outcomes or the need to screen transfused blood for viral contaminants with high sensitivity is clearly evident. Finally, while nucleic acid sequences provide extreme diversity for situations that may be of biological or other interest, there are other types of compounds, such as proteins in proteomics that may also offer opportunities for multiplexed determinations.
There is and will continue to be comparisons of the sequences of different individuals. It is believed that there will be about one polymorphism per 1,000 bases, so that one may anticipate that there will be an extensive number of differences between individuals. By single nucleotide polymorphism (SNPs) is intended that there will be a prevalent nucleotide at the site, with one or more of the remaining bases being present in a substantially smaller percent of the population. While other genetic markers are available, the large number of SNPs and their extensive distribution in the chromosomes make SNPs an attractive target. Also, by determining a plurality of SNPs associated with a specific phenotype, one may use the SNP pattern as an indication of the phenotype, rather than requiring a determination of the genes associated with the phenotype. For the most part, the SNPs will be in non-coding regions, primarily between genes, but will also be present in exons and introns. In addition, the great proportion of the SNPs will not affect the phenotype of the individual, but will clearly affect the genotype. The SNPs have a number of properties of interest. Since the SNPs will be inherited, individual SNPs and/or SNP patterns may be related to genetic defects, such as deletions, insertions and mutations, involving one or more bases in genes. Rather than isolating and sequencing the target gene, it will be sufficient to identify the SNPs involved. In addition, the SNPs may also be used in forensic medicine to identify individuals.
Thus an assay for the differentiation and quantitation of multiple genes, and/or snp determination, and/or gene expression at the RNA or protein level, that has higher sensitivity, a large dynamic range (10
3
to 10
4
-fold differences in target levels), a greater degree of multiplexing, and fewer and more stable reagents would increase the simplicity and reliability of multianalyte assays, and reduce their costs.
BRIEF DESCRIPTION OF THE RELATED ART
Holland (
Proc. Natl. Acad. Sci. USA
(1991) 88:7276) discloses that the exonuclease activity of the themostable enzyme
Thermus aquaticus
DNA polymerase in PCR amplification to generate specific detectable signal concomitantly with amplification.
The TaqMan® assay is discussed by Lee in
Nucleic Acid Research
(1993) 21:16 3761).
White (Trends Biotechnology (1996) 14(12): 478-483) discusses the problems of multiplexing in the TaqMan assay.
Marino,
Electrophoresis
(1996) 17:1499 describes low-stringency-sequence specific PCR (LSSP-PCR). A PCR amplified sequence is subjected to single primer amplification under conditions of low stringency to produce a range of different length amplicons. Different patterns are obtained when there are differences in sequence. The patterns are unique to an individual and of possible value for identity testing.
Single strand conformational polymorphism (SSCP) yields similar results. In this method the PCR amplified DNA is denatured and sequence dependent conformations of the single strands are detected by their differing rates of migration during gel electrophoresis. As with LSSP-PCR above, different patterns are obtained that signal differences in sequence. However, neither LSSP-PCR nor SSCP gives specific sequence information and both depend on the questionable assumption that any base that is changed in a sequence will give rise to a conformational change that can be detected. Pastinen,
Clin. Chem
. (1996) 42:1391 amplifies the target DNA and immobilizes the amplicons. Multiple primers are then allowed to hybridize to sites 3′ and contiguous to a SNP (single nucleotide polymorphism) site of interest. Each primer has a different size that serves as a code. The hybridized primers are extended by one base using a fluorescently labeled dideoxynucleoside triphosphate. The size of each of the fluorescent products that is produced, determined by gel electrophoresis, indicates the sequence and, thus, the location of the SNP. The identity of the base at the SNP site is defined by the triphosphate that is used. A similar approach is taken by Haff,
Nucleic Acids Res
. (1997) 25:3749 except that the sizing is carried out by mass spectrometry and thus avoids the need for a label. However, both methods have the serious limitation that screening for a large number of sites will require large, very pure primers that can have troublesome secondary structures and be very expensive to synthesize.
Hacia,
Nat. Genet
. (1996) 14:441 uses a high-density array of oligonucleotides. Labeled DNA samples were allowed to bind to 96,600 20-base oligonucleotides and the binding patterns produced from different individuals were compared. The method is attractive in that SNPs can be directly identified, but the cost of the arr
Salimi-Moosavi Hossein
Singh Sharat
Xiao Vivian
Aclara Biosciences, Inc.
Horlick Kenneth R.
Macevicz Stephen C.
Tung Joyce
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