Differential sensitivity of hepatitis C virus quasispecies to interferon-alpha therapy.

The quasispecies nature of hepatitis C virus was investigated in a patient with chronic hepatitis C virus infection who underwent interferon-alpha therapy. The hepatitis C virus E2/NS1 region was amplified and cloned, and multiple clones were sequenced before and after interferon-alpha therapy. The hepatitis C virus quasispecies can be grouped into three groups by phylogenetic tree analysis. Quasispecies from all the groups were present before interferon-alpha therapy. However, only group 3 remained after interferon-alpha therapy. In addition, only group 3 hepatitis C virus quasispecies were present during the early biochemical relapse. These data indicate that various groups of hepatitis C virus quasispecies may have different sensitivity to interferon-alpha.