Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Reexamination Certificate
2001-01-26
2003-06-24
Housel, James (Department: 1648)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
C536S024330, C536S024320, C536S023100, C536S023720, C536S023740, C536S023740, C435S005000, C435S007950, C435S008000, C435S091330
Reexamination Certificate
active
06583279
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to materials and methods for detection of Hepatitis B viral nucleic acids, in particular to probes and primers for detection of Hepatitis B in hybridization and amplification assays.
BACKGROUND OF THE INVENTION
Hepatitis B virus (HBV) is a partially double-stranded DNA virus which uses a unique replication mechanism incorporating an intermediate reverse transcription step. It is a major causative agent of chronic hepatitis and has been implicated in liver cirrhosis and hepatocellular carcinoma. Accurate identification and quantitation of HBV DNA is important not only for detecting HBV infection but also for monitoring the efficacy of antiviral treatments. A simple assay for HBV DNA using branched-DNA (bDNA) probes has been used for quantitation but was found to be insufficiently sensitive to monitor serum virus levels in patients undergoing antiviral treatment. More recently, HBV DNA has been detected and quantitated in more sensitive PCR assays, using both the Amplicor™ HBV Monitor test and the TaqMan™ technology for real-time detection.
The present invention provides probes and primers for detection of HBV nucleic acids which may provide a more rapid and sensitive means for detecting HBV than immunological and culture-based methods. Further the probes and primers of the invention may allow more reliable detection of naturally occurring variants of HBV, as they are based on an analysis of conserved regions of the HBV DNA polymerase gene.
SUMMARY OF THE INVENTION
The present invention provides primers and probes derived from the HBV DNA polymerase gene which are predicted to facilitate detection and/or quantification of all presently known genotypes of HBV (A-F). That is, a single amplification primer pair according to the invention should efficiently amplify all known genotypes of HBV, which may then be detected in a single detection step using the detector probes and primers of the invention.
DETAILED DESCRIPTION OF THE INVENTION
The primers, hybridization probes and detector primers of the present invention are complementary to regions of the HBV DNA polymerase gene. Design of the disclosed primers and probes was based on relatively conserved regions in an alignment of multiple HBV DNA polymerase gene sequences. One goal was to develop probes and primers which, in spite of heterogeneity in the gene sequence, would be expected to for provide amplification, detection and/or quantitation of all presently known HBV genotypes with approximately equal efficiency. In some cases this was accomplished by overlapping the hybridization site of the 5′ ends of certain of the detector probes with the hybridization site of the 3′ end an amplification primer. This approach took advantage of short stretches of relative sequence conservation in the primer hybridization region and avoided much of the sequence heterogeneity evident in the intervening region between the two amplification primers. This technique also allowed use of a smaller target sequence, which would be expected to improve amplification efficiency.
As used herein, an amplification primer is an oligonucleotide for amplification of a target sequence by extension of the oligonucleotide after hybridization to the target sequence or by ligation of multiple oligonucleotides which are adjacent when hybridized to the target sequence. At least a portion of the amplification primer hybridizes to the target. This portion is referred to as the target binding sequence and it determines the target-specificity of the primer. In addition to the target binding sequence, certain amplification methods require specialized non-target binding sequences in the amplification primer. These specialized sequences are necessary for the amplification reaction to proceed and typically serve to append the specialized sequence to the target. For example the amplification primers used in Strand Displacement Amplification (SDA) include a restriction endonuclease recognition site 5′ to the target binding sequence (U.S. Pat. No. 5,455,166 and U.S. Pat. No. 5,270,184). Nucleic Acid Sequence Based Amplification (NASBA) Self Sustaining Sequence Replication (3SR) and transcription based amplification primers require an RNA polymerase promoter linked to the target binding sequence of the primer. Linking such specialized sequences to a target binding sequence for use in a selected amplification reaction is routine in the art. In contrast, amplification methods such as PCR which do not require specialized sequences at the ends of the target, generally employ amplification primers consisting of only target binding sequence.
As used herein, the terms “primer” and “probe” refer to the function of the oligonucleotide. A primer is typically extended by polymerase or ligation following hybridization to the target but a probe typically is not. A hybridized oligonucleotide may function as a probe if it is used to capture or detect a target sequence, and the same oligonucleotide may function as a primer when it is employed as a target binding sequence in an amplification primer. It will therefore be appreciated that any of the target binding sequences disclosed herein for amplification, detection or quantitation of HBV may be used either as hybridization probes or as target binding sequences in primers for detection or amplification, optionally linked to a specialized sequence required by the selected amplification reaction or to facilitate detection.
Based on the alignment of multiple HBV DNA polymerase gene sequences, the following amplification primers were designed for testing in SDA reactions. Target binding sequences are underlined. The remaining 5′ portion of the sequence comprises the restriction endonuclease recognition site (RERS) that is required for the SDA reaction to proceed plus a generic non-target-specific tail sequence. It will be readily apparent that the target binding sequences may be used alone to amplify the target in reactions which do not require specialized sequences or structures (e.g., PCR) and that other specialized sequences required by amplification reactions other than SDA (e.g., an RNA polymerase promoter) may be substituted for the RERS-containing sequence shown below. “R” and “L” in the primer name indicates “right” and “left” primers, respectively, when the oligonucleotides are used in amplification reactions:
AMPLIFICATICN PRIMERS
HBV1AL1
CGATTCCGCTCCAGACTTCTCGGG
CCCCTGCTCGTGTTA
SEQ ID NO:1
HBV1AL2
CGATTCCGCTCCAGACTTCTCGGG
CCCCTGCTCGTGTT
SEQ ID NO:2
HBV1AL3
CGATTCCGCTCCAGACTTCTCGGG
ACCCCTGCTCGTGTT
SEQ ID NO:3
HBV1AR1
ACCGCATCGAATGCATGTCTCGGG
GGTATTGTGAGGATT
SEQ ID NO:4
HBV1AR2
ACCGCATCGAATGCATGTCTCGGG
TGAGGATTATTGTCAAC
SEQ ID NO:5
HBV1AR3
ACCGCATCGAATGCATGTCTCGGG
TATTGTGAGGATT
SEQ ID NO:6
The following detector primers were also designed for detection of amplification products produced using the amplification primers. They hybridize to the target sequence downstream of or overlapping an amplification primers so that they are displaced during the amplification reaction. The detector primer hybridization site may or may not overlap the hybridization site of the amplification primer. An advantage of this detection method is that the target sequence can be detected and/or quantified as the amplification reaction is occurring, i.e., in “real-time” rather than at an endpoint. The target binding sequences of the primers are underlined. The remaining portion of the sequence forms a hairpin structure which is typically labeled to facilitate detection of amplification products, for example as described in U.S. Pat. No. 5,928,869. It will be readily apparent that the target sequence may be used alone for detection (typically linked to a detectable label) and that other detectable sequences and labels may be substituted for the hairpin as is known in the art (e.g., G-quartets, linear sequences for specific probe hybridization, or restriction sites). See, for example, U.S. Pat. No. 5,547,861; U.S. Pat. No. 5,928,869; U.S. Pat. No. 5,593,867; U.S. Pat. No. 5,550,025; U.S. Pat.
Berger Dolores M.
Fort Thomas L.
Hellyer Tobin J.
Nussbaumer William A.
Becton Dickinson and Company
Housel James
Kiang Allan M.
Li Bao Qun
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