Sequence diversity and variability in the putative envelope proteins including hypervariable regions of hepatitis C virus

Hepatitis C virus (HCV) genomes show sequence diversities among virus isolates. In particular, the putative envelope region encoding gp35 and gp70 shows on extensive sequence diversity in the whole viral genome. We identified two hypervariable regions [HVR1 (27 amino acids) and HVR2 (7 amino acids)] in the N-terminal region of gp70 of the HCV-II genotype. In the HCV-I genotype, extensive diversity of amino acid sequence in HVR1 is also observed in the same region (21 amino acids), but such diversity in HVR2 is not clearly observed like HCV-II genotype. In addition, the alteration of amino acids in HVR1 was also observed in patients with chronic hepatitis. It is suggested mutation in HVR1 is involved in the mechanism of persistent HCV infection.