Real-time monitoring of HCV-RNA by single tube assay kit and potential importance for predicting virological sustained response in patients with chronic hepatitis C

In an attempt to predict virological sustained responders among patients with chronic hepatitis C after interferon therapy, HCV-RNA in serum was measured by a one tube RT-PCR assay kit using the RNA corresponding to 5 μL serum (standard assay) or 300 μL serum (enhanced-sensitivity assay). Dilution analysis revealed that sensitivity of the ‘enhanced-sensitivity assay’ increased by 10–100-fold when compared with a ‘standard assay'. Using these assays, prospective study of interferon therapy on 38 HCV-RNA seropositive cases with chronic hepatitis (total amount 702 MU; duration of treatment 5–6 months) was performed. At the end of treatment, six were still positive and 32 became negative by the ‘standard assay', whereas an additional eight cases became positive (total 14 cases positive; the remaining 24 cases negative) by the ‘enhanced-sensitivity assay'. Hepatitis C viral RNA state at the end of treatment remained the same 6 months later in 23 cases (61%) by a ‘standard assay’ and in 31 (82%) by the ‘enhanced-sensitivity assay'. Of importance was that all patients (14 cases) demonstrating HCV-RNA in serum at the end of therapy, even by the ‘enhanced-sensitivity assay', did not show the disappearance of HCV-RNA in serum despite the long follow up. From these results, in order to improve our treatment efficacy, we should try to modify our treatment protocol to the extent that at least HCV-RNA becomes undetectable. That can be only feasible during treatment by real-time monitoring of HCV-RNA.