Quantification of hepatitis C virus (HCV) RNA in a multicenter study: implications for management of HCV genotype 1-infected patients.

Assessment of the viral load in hepatitis C virus (HCV) genotype 1-infected patients is critical before, during, and after antiviral therapy. In patients achieving a rapid virological response at week 4 of treatment, the viral load at the baseline is considered a predictive criterion of a sustained virological response 24 weeks after the discontinuation of treatment. A >or=2-log(10) drop in the viral load at week 12 of treatment (early virological response) triggers the continuation of therapy. We organized a multicenter study (MS) for diagnostic laboratories involved in the quantification of HCV RNA. Commercial assays, including two based on real-time reverse transcription-PCR (TaqMan system), and in-house methods, were used by the 61 participants. The overall reproducibility of the commercial quantitative nucleic acid amplification techniques (qNAT) was acceptable. As the intermethod variability among commercial qNAT for HCV RNA was still present, the manufacturers of these test kits should join efforts to harmonize the means of quantification of HCV RNA. This study also shows that caution should be exercised when the baseline viral load is evaluated and when the 2-log(10) reduction after 12 weeks of therapy is interpreted. Finally, this MS confirms the higher sensitivity of the commercial qNAT based on the TaqMan system, making them the elective assays for the monitoring of therapy.

Collaborative study for the calibration of a new Italian HCV RNA reference preparation against the international standard.

We organised a collaborative study to calibrate a new Italian reference preparation for HCV RNA, the ISS 0102 reagent, to be used for plasma pools testing. This preparation will replace the previous one, the ISS 0498 reagent, as we are running short of it. The ISS 0102 reagent was obtained by appropriately diluting an HCV RNA-positive donation. Every participant in the collaborative study received four coded panels, each consisting of 5 semi-logarithmic dilutions of the international standard, 5 semi-logarithmic dilutions of the ISS 0102, and 2 samples of a negative plasma pool. Based on the results provided by the 22 participating laboratories, an HCV RNA concentration of 4500 IU/ml was assigned to the reference material. This preparation is available free of charge to any laboratory upon request.

Overestimation of the hepatitis C virus RNA content of reference preparations by the AMPLICOR HCV monitor test, version 2.0.

An evaluation of the AMPLICOR hepatitis C virus (HCV) monitor test, version 2.0 (Roche Diagnostics), was carried out to investigate whether this test overestimates the HCV RNA content of reference preparations. Satisfactory accuracy was observed when the World Health Organization HCV international standard was included in the assay and a modified formula was used to calculate the viral content.