Development of a quantitative PCR assay for monitoring HCV viraemia levels in patients with chronic hepatitis C.

The need to improve the efficacy of anti-viral agents directed against the hepatitis C virus (HCV) has prompted the development of quantitative tests to monitor viraemia levels in relation to therapy. In this respect, we have produced a non-competitive, quantitative PCR assay (Amplicor HCV Monitor) which is based on the single, combined, reverse transcription and amplification of the 5' non-coding region of HCV RNA as well as of an internal standard which serves to assess the overall efficiency of the system. The dynamic range of the assay and its precision allows for an accurate quantification between 1000 and 1,000,000 copies of the viral genome per ml. The results of the first clinical evaluation of the test indicated that determination of viraemia may have predictive value when assessed prior to treatment, as patients with less than 50,000 HCV RNA copies per ml tend to show a long-term response to interferon-alpha (IFN-alpha) treatment. Moreover, a decrease of more than 1.5-2 logarithms occurring at 1 month post-initiation of therapy predicts response in a more timely and accurate fashion than ALT measurement. This may help in a better selection of patients to treat, therapy approaches and schedules and in the optimization of the cost-benefit balance.