Molecular evolution and genomics of hepatitis B virus subgenotype C2 strain predominant in the chronic patients in Bangladesh.

Evolution of hepatitis B virus (HBV) is a mystery and caused mainly by genomic mutations as well as recombination. Viral evolution may be responsible for increasing disease severity and render resistance to the existing treatment processes. HBV/C2 strain is associated with chronicity, which may progress to the liver cirrhosis and hepatocellular carcinoma. Furthermore, HBV/C2 strain is highly prevalent in the chronic hepatitis B patients in Bangladesh. Hence, the molecular evolution of that strain and its disease pattern need to be uncovered. Herein, the purpose of this study is to determine the potential mutations of HBV complete genome sequences isolated in Bangladesh and the molecular evolution of HBV/C2 strain. Mutation analysis of the total 57 complete genome sequences of HBV in Bangladesh revealed that 42.11%, 12.28%, 7.02% and 3.51% of the strains were vaccine resistant, HBsAg detection escape, HBV immunoglobulin escape, multi-drug resistant respectively. Furthermore, of the vaccine resistant strains, 16.67% were observed resistant to both vaccine, HBsAg detection and immunoglobulin escape. Bayesian skyline analysis with 462 HBV/C2 strains from 2000 to 2017 revealed the evolution of the strain was in nineteenth century with two rapid sharp increases in the genetic diversity at the end of the twentieth century and then a sudden decrease in the early twenty-first century as observed in C and X gene analysis. This study may help researchers and clinicians to get a better knowledge about the emergence and evolution of HBV/C2 strain that may help to find a proper treatment strategy against hepatitis B.