Characterization of a novel hepatitis B virus subgenotype B10 among chronic hepatitis B patients in Yunnan, China.

Diversity and complexity of Hepatitis B Virus (HBV) may be related to clinical outcome, disease prognosis, and response to antiviral treatment in infected patients. HBV has been classified into ten genotypes (A-I) and over 50 subgenotypes. However, there are still some variants of HBV that need to be classified. Here, we investigated genotypic profiles of HBV among 150 patients with chronic hepatitis B in Yunnan, China, and characterized a novel HBV subgenotype B10. Multiple subgenotypes were identified in 146 subjects with successful sequencing for the S gene, including genotype B2 (48.6%, 71/146), C1 (34.2%, 50/146), B4 (8.9%, 13/146), C2 (0.7%, 1/146), C5 (0.7%, 1/146) and an unclassified group (6.8%,10/146). To characterize the unclassified group, seven HBV complete genomes were successfully amplified and analyzed. The seven strains constituted a potentially novel B subgenotype that we designated as B10 based on the characteristics of a monophyletic cluster, > 4% genetic distances, no significant evidence of recombination, and no epidemiologic link among individuals. Moreover, Bayesian analyses showed that HBV B10 originated around the B·C 1.80 thousand years old, suggesting a much ancient HBV strain. This findings highlighted the importance of continual monitoring of genetic diversity of HBV strains in Yunnan, China.