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Background: In chronic hepatitis C patients with an initial virological response (IVR) during antiviral therapy (that is, HCV RNA becomes negative before week 16 of treatment) the significance of reappearing viraemia below the detection limit of PCR is not known. We studied this phenomenon in subsets of patients., Methods: We assessed HCV RNA at weeks 16 and 20 of therapy by PCR and by more sensitive transcription-mediated amplification (TMA) in 23 patients with breakthrough or relapse and in 34 patients with sustained virological response (SVR). All patients participated in a high-dose-interferon induction study for difficult-to-treat patients. Therapy consisted of amantadine hydrochloride and ribavirin, combined with interferon-alpha2b induction during the first 6 weeks and thereafter combined with weekly pegylated interferon-alpha2b., Results: Among the 57 IVR patients, we detected transient or persistent reappearance of low levels of HCV RNA in 10 of the 23 (43%) patients with eventual breakthrough or relapse; but in none of the 34 SVR patients. In 5 of 10 patients reappearing HCV RNA was only detectable by TMA., Conclusion: Reappearance of low levels of HCV RNA in patients with IVR predicts treatment failure.

We evaluated the Roche COBAS TaqMan HCV Test For Use With The High Pure System (TaqMan HPS; Roche Diagnostics), for the extraction, detection and quantitation of hepatitis C virus (HCV) RNA in serum or plasma of HCV-infected individuals. The TaqMan HPS is a real-time PCR assay with a reported linear dynamic range of 3.0x10(1) to 2.0x10(8) HCV RNA IU/ml, and a reported lower limit of detection (LLD) of 10 IU/ml. Calculation of the HCV RNA titre is based upon an external standard curve in the presence of an internal control. Intra-assay and inter-assay variation were small in reference panel members with HCV RNA > or =100 IU/ml. Genotype performance and quantitative correlation between the TaqMan HPS and the bDNA (VERSANT HCV 3.0 assay; Bayer Diagnostics), assessed in 59 patient samples, were good for HCV genotype 1 but poor for genotypes 2, 3 and 4. For genotypes 2, 3 and 4, values obtained from the TaqMan HPS were in general 0.5 log lower than those from the bDNA. Sensitivity was poor in low viral titre samples of genotypes 1, 2, 3 and 4. The LLD (95%) was estimated at 41 HCV RNA IU/ml for genotype 4. The TaqMan HPS underestimates HCV RNA at all levels in plasma and serum from HCV-infected individuals, and the LLD should be reconsidered. This is clinically relevant because underestimation of HCV RNA levels during therapy may lead physicians into making incorrect treatment decisions.