Circulating genotypes of hepatitis B virus in Arunachal Pradesh.

BACKGROUND & OBJECTIVE There is a paucity of information on distribution of hepatitis B genotypes from northeastern part of India. Arunachal Pradesh, one of the northeastern State of India bordering Bhutan, China and Myanmar, reported abnormally high numbers of hepatitis B surface antigen (HBsAg) positive cases in one of its districts during January-June 2005. We conducted this study in the subsequent months (August-December 2005) to know the prevalent genotypes by a rapid and specific method based on type-specific primers in Upper Dibang valley of Arunachal Pradesh. METHODS A total of 438 randomly selected individual were screened for HBsAg positivity. Of the 93 HBsAg positive individuals, 36 HBsAg and HBV DNA positive samples were processed for HBV genotyping using type-specific primer based nested PCR (TSP-PCR). Representative samples were retested with RFLP-PCR based genotyping and nucleotide sequencing. RESULTS Of the 36 samples, 29 (80.1%) could be genotyped by the TSP-PCR based method used. The predominant genotype was genotype A (41.6%) followed by genotypes C (27.8%) and D (11.1%). Seven isolates (19.9%) could not be genotyped by this method. INTERPRETATION & CONCLUSION The presence of genotype C in this part of the country needs attention as genotype C takes a more aggressive disease course. Also, detection of genotype C in this isolated community bordering Tibet suggests viral gene flow from Tibet or other South-east Asian countries where genotype C of HBV is predominant.