Hepatitis B virus genotypes and subgenotypes in Xishuangbanna, China

Abstract

Objective To investigate the distribution of hepatitis B virus (HBV) genotypes and subgenotypes in Xishuangbanna, Yunnan Province, China. Methods Study subjects were selected from people of Han nationality and two ethnic minorities (Dai and Hani) from May 2012 to April 2013, which are the two largest ethnic groups in Xishuangbanna. Nest-PCR and gene sequencing were performed to obtain the full genome sequence of HBV, and HBV genotypes and subgenotypes were analyzed by phylogenetic tree construction and genetic distance calculation. Results Tree analysis of the full genome sequence of HBV detected three HBV genotypes in this areas: 139 (76.0%) cases of genotype B, among which 105 (57.4%) were subgenotype B2 and 34 (18.6%) were subgenotype quasi B3; 41 (22.4%) cases of genotype C, among which 33 (18.0%) were subgenotype C1 (18.0%), 4 (2.2%) were subgenotype C2, and 4 (2.2%) were subgenotype C5 (2.2%); and 3 (1.6%) cases of genotype I. Comparative analysis of HBV genotype and subgenotype distribution in the three populations revealed that the HBV genotype distribution in Hani people was significantly different from that in other two ethnic groups (Hani vs Han: χ2 = 8.416, P = 0.006; Hani vs Dai: χ2 = 15.636, P<0.001); the prevalence of genotype B was significantly higher in Hani people than in the other two groups, but genotype I was not detected in Hani people. The distribution of HBV subgenotypes in the three populations was significantly different as well (Han vs Dai: χ2 = 33.598, P< 0.001; Han vs Hani: χ2 = 22.102, P< 0.001; Hani vs Dai: χ2 = 16.129, P = 0.001). Subgenotype quasi B3 existed only in Dai and Hani minority populations but not in Han nationality. The prevalence of subgenotype C1 in Dai people was higher than that in the other two ethnic groups, and subgenotype C5 was detected only in Dai people. The subgenotypes of genotype C in Hani population were all subgenotype C1. Conclusion The distribution of HBV genotypes and subgenotypes in this area is complicated and has unique characteristics among different ethnic groups. Key words: Hepatitis B virus; Genotype; Subgenotype