Hepatitis C virus detection by single-round PCR specific for the terminal 3' noncoding region.

A single-round PCR method with primers specific for the 3' noncoding region (NCR) of hepatitis C virus (HCV) has been developed. Using a double RNAzol-B extraction, a high-temperature reverse-transcription step with SuperScript II reverse transcriptase, and a 40-cycle two-temperature PCR with a TaqStart antibody hot-start procedure, we were able to detect a 92-nucleotide fragment of the recently discovered 98-nucleotide highly conserved sequence at the 3' terminus of the HCV genome. Direct sequencing of the PCR products confirmed the specificity of the PCR and demonstrated conservation in this region. Only one nucleotide change in 14 specimens was found. End point dilution titration of sera with known viral RNA titers showed the sensitivity of the single-round 3' NCR PCR to be comparable to those of the established nested 5' NCR assays (fewer than 25 HCV genome equivalents). To evaluate specificity and sensitivity, a panel of 116 serum samples characterized by nested 5'-end PCR, genotyping, and quantitative assays was tested. A high degree of concordance (96%) between the 3' NCR and 5' NCR PCR results was found. The sequence conservation at the 3' end of the HCV genome among common genotypes and the savings in time, labor, and reagents from a single-round PCR make this assay a useful addition to the detection systems available to identify and monitor HCV infection.