Quantitative measurement of serum HCV RNA in patients with chronic hepatitis C: comparison between Amplicor HCV monitor system and branched DNA signal amplification assay.

Quantitative measurement of serum hepatitis C virus (HCV) RNA is important in predicting and monitoring the therapeutic effects of interferon in treating patients with chronic hepatitis C. We compared two commercial available assays, Roche Amplicor HCV Monitor test kits and Chiron branched DNA signal amplification (bDNA) assay, in quantitative measurement of serum HCV RNA in 74 patients with chronic hepatitis C. The serum HCV RNA of each of these patients was qualitatively positive by conventional reverse transcription-nested polymerase chain reaction. Serum HCV RNA was detected positive by the Amplicor test kits in 63 (85%) patients and by the bDNA assay in 58 (78%) patients (P > 0.05). The quantitative results of HCV RNA detected by both assays showed a good linear correlation (r = 0.56, P < 0.001). Amplicor test kits detected 5 patients with low viremia which were below the detection limit of the bDNA assay (2.0 x 10(5) genome equivalents/ml). However, the mean HCV RNA values detected by the Amplicor test kits was 1.26 log lower than that of the bDNA assay. The Amplicor test kits detected only 5 samples (8%) with a HCV RNA value greater than 5 x 10(6) copies/ml, while the bDNA assay detected 23 samples (40%) with a HCV RNA value greater than 5 x 10(6) genome equivalents/ml (P < 0.01). HCV genotype did not affect the positive rate of HCV RNA measurement detected by both assays. However, a significantly higher mean serum HCV RNA value was noted in HCV genotype 1b as compared with the other genotypes. We concluded that the Roche Amplicor HCV Monitor test kits and the Chiron branched DNA signal amplification assay are equally sensitive in the quantitative measurement of serum HCV RNA in patients with chronic hepatitis C and can be reliably used in measuring HCV viremia clinically.