Substitution of the CD81 Binding Site and β-Sandwich Area in E2 of HCV in Cambodia.

The high genetic variability of hepatitis C virus (HCV) is the main obstacle to developing a vaccine. E2 has attracted attention for vaccine development because targeting this protein could potentially overcome issues related to the genetic diversity of HCV. In this study, we analyzed HCV genes in the general population of Cambodia and investigated the E2 locus as a candidate for vaccine development. HCV sero-epidemiological surveys were conducted between the period 2010 and 2014, with an HCV RNA–positive rate of 1.3% (11/868). Follow-up blood samples were collected from four anti-HCV– and HCV RNA– positive patients (genotype 1b: 2 cases, 6e: 1 case, 6r: 1 case) after 4.12 years. Analysis of HCV full-length nucleotide sequences in paired specimens revealed that the mutation rates of HCV genotypes 1b and 6e/6r were 1.61–2.03 × 10−3 and 2.52–2.74 × 10−3 substitutions/site/year, respectively. Non-synonymous substitutions were detected in HVR1, the front layer of the CD81 binding site, and the β-sandwich, but not in the N-terminal region or adjacent to the CD81 binding site. Therefore, we conclude that the CD81 binding site is a promising locus for HCV vaccine development.