Different susceptibilities of genetic variants of hepatitis C virus (HCV) to interferon (IFN).

Genetic variants of HCV may have different degrees of resistance to IFN and may therefore influence the outcome of IFN therapy. However, selection of HCV variants by IFN has not been investigated in detail. In this paper, heteroduplex analysis was used to monitor major changes of HCV populations in 4 chronically infected patients under IFN therapy. We found that a major variant of the HCV 5' non-coding region (5' NCR) emerged in a responder. In other patients although no new variant of the 5' NCR was identified, significant changes occurred within the core and E1 region of the HCV genome. Disappearance and emergence of HCV variants may reflect their different susceptibilities to IFN. Our results indicate that responses of HCV populations to IFN are complex and need to be characterized by analysis of multiple HCV genome regions.