Comparison of HCV RNA assays for the detection and quantification of hepatitis C virus RNA levels in serum of patients with chronic hepatitis C treated with interferon

Detection and quantification of hepatitis C virus (HCV) RNA levels by using the standardized qualitative AmplicorTM HCV and quantitative Amplicor HCV MonitorTM assays (Roche Molecular Systems) were evaluated in 48 patients with chronic hepatitis C treated with interferon. Results were compared with an in‐house reverse transcription and polymerase chain reaction (RT‐PCR) assay and the branched DNA (bDNA) assay (QuantiplexTM, version 1.0, Chiron Diagnostics). Concordance of the qualitative results with the AmplicorTM HCV and in‐house RT‐PCR assays occurred in 82% of the samples. All but one of the discrepant specimens were found positive by the AmplicorTM HCV assay and negative by the in‐house RT‐PCR. Among the samples with HCV RNA levels measurable with the Amplicor HCV MonitorTM assay, 22% had HCV RNA titers below the detection limit of the QuantiplexTM assay. A statistically significant correlation was found between the 2 quantitative assays, although lower titers were obtained with the Amplicor HCV MonitorTM assay. More important, a good correlation was observed in the evolution of viremia as measured by the 2 assays during interferon therapy. During follow‐up of interferon treatments, with the Amplicor HCV MonitorTM assay, persisting viremia was still detected in 27% of the patients who normalised alanine aminotransferase (ALT), emphasizing the bioclinical relevance of the assay. Pretreatment serum HCV RNA levels above 105 copies/ml were found more frequently in nonresponders than in responders (76% vs. 44%; P < 0.05). Given their great sensitivity and the significant correlations, the AmplicorTM HCV qualitative and quantitative assays appear useful fo the diagnosis and management of hepatitis C infection, and especially for monitoring of therapy. J. Med. Virol. 52:105–112, 1997. © 1997 Wiley‐Liss, Inc.