HBV/D1: a major HBV subgenotype circulating in Uyghur patients with chronic HBV infection in Xinjiang, China

Each hepatitis B virus (HBV) genotype and subgenotype is associated with a particular geographic distribution, ethnicity, and anthropological history. The present study investigated the genomic characteristics of HBV from Uyghur patients with chronic HBV infection in Xinjiang, China. Among the 53 Uyghur patients enrolled, HBV/D was found to be the dominant strain, with 64.2 % (34/53), 60.4 % (32/53) with HBV/D1 and 3.8 % (2/53) with HBV/D3. In addition to these findings, 3.8 % HBV/B (2/53), 5.7 % HBV/C (3/53), 11.3 % C+D (6/53), 7.5 % B+D (4/53), 3.8 % B+C (2/53) and 3.8 % B+C+D (2/53) were also detected. The full-length genome of seven HBV/D1 isolates and 144 reference sequences retrieved from GenBank were compared and analyzed by biological information methods. These results demonstrate that the D1 isolates from Xinjiang and Central Asia show a close genetic proximity (0.013±0.0007). Furthermore, four unique amino acid substitutions (sp82Asn, sp89His, rt129Leu, rt151Leu) representing background polymorphisms rather than drug resistance mutations or immune escape variants were found in the Uyghur patients of Xinjiang, but these were seldom found in HBV/D1 strains from other regions (0 %-14.3 %). This study indicates that in Xinjiang, unlike HBV-infected Han patients, HBV/D1 is the predominant strain among HBV-infected Uyghur people. Although genetic distance analysis suggests that the HBV/D1 isolates from Xinjiang are closely related to those from Central Asia, unique amino acid substitutions suggest independent evolution of HBV in the Uyghur patients of Xinjiang.