Hepatitis B virus with a proposed genotype I was found in Sichuan Province, China.

To date, eight hepatitis B virus (HBV) genotypes, A-H, have been designated, and two additional genotypes, I and J, have also been proposed. A serological survey targeting children in difficult-to-reach vaccination areas was carried out in remote counties of Sichuan Province, China. HBV genotypes and serotypes were also determined from HBsAg-positive serum samples by direct sequencing. Phylogenetic analysis showed two strains isolated from the Yi ethnic children clustered with the proposed genotype I. The pairwise genome genetic distance was 7.5% between genotypes I and C, and ranged from 8.4% to 15.2% between genotype I and other genotypes, except genotype C. Grouping Scan analyses of the two strains revealed apparent recombination events between an unknown genotype and genotype C. Two out of four HBV strains isolated from the Yi ethnic children were confirmed to be genotype I, suggesting widespread circulation and common infection with genotype I HBV in the local Yi population. High prevalence of HBsAg and low hepatitis B vaccination coverage indicated that additional efforts are needed to control HBV infection in those areas.