Hepatitis C virus (HCV) genotype distribution in German isolates: studies on the sequence variability in the E2 and NS5 region.

We report on molecular characterization of hepatitis C virus (HCV) isolates in intravenous drug abusers, as compared to non-drug using patients with posttransfusion hepatitis or sporadic hepatitis of unknown origin. Virus typing was performed by RFLP analysis of PCR products in the 5' NCR. Subtyping was done by hybridization with subtype specific probes or by sequencing in the NS4 and NS5 region, respectively. HCV subtype 1b was found most commonly among all the isolates. However, the subtype 3a had a high prevalence (about 46%) in the group of drug addicts. In these subtype 3a isolates the N-terminal part of the E2 protein was highly variable. This confirms the presence of a hypervariable region (HVR1) in this envelope protein found in all hepatitis C viruses. Each subtype 3a isolate examined had a characteristic unique hypervariable region in the E2 protein. It is noteworthy that there are four amino acids in this region which were highly conserved between all HCV sequences published. It can be assumed that such conserved amino acids are significant for structure and function of this viral protein. In our HCV subtype 3a isolates the NS5 sequences were highly conserved.