Molecular characterization of hepatitis B virus reveals circulation of multiple subgenotypes of genotype D with clinically important mutations in central India

Purpose: Hepatitis B virus (HBV) is one of the leading causes of morbidity and mortality across the globe. The pathogenesis, clinical outcomes, disease progression and response to antiviral treatment of HBV depend on infecting genotypes and mutations across HBV genome. There is a lack of such information from central India. The present study was planned to identify genotype/subgenotype and epidemiologically important mutation in HBV circulating in the area.

Methods: Samples positive for HBsAg by ELISA from 2012 to 2016 were included and analysed in this retrospective study. The amplification of partial S gene (n = 25) and full genome (n = 10) was carried out to determine the genotype/subgenotype and genome wide mutations of HBV. The sequencing data was analysed using bioinformatics tools.

Results: All 25 sequences belonged to genotype D; subgenotypes D1, D2, D3 and D5 with dominance of D1 were detected in the study subjects. Mutational profiling revealed the presence of nucleotide substitutions in promoter/regulatory/precore region associated with liver disease progressions. The amino acid (aa) changes associated with vaccine escape, immune escape, antiviral resistance and progression to liver cirrhosis (LC) or hepatocellular carcinoma (HCC) were detected.

Conclusions: This maiden molecular study on HBV from central India indicates that the genotype D with subgenotypes D1, D2, D3 and D5 harbouring mutations of clinical and epidemiological importance are in circulation. This study will serve as a baseline for future. Studies with larger sample size may aid in identifying the circulation of more genotypes.