Analysis of the complete genome of hepatitis B virus subgenotype C2 isolate NHB17965 from a HBV infected patient

Hepatitis B Virus: From Diagnosis to Treatment

Hepatitis B infection is still a global concern progressing as acute-chronic hepatitis, severe liver failure, and death. The infection is most widely transmitted from the infected mother to a child, with infected blood and body fluids. Pregnant women, adolescents, and all adults at high risk of chronic infection are recommended to be screened for hepatitis B infection. The initial analysis includes serological tests that allow differentiation of acute and chronic hepatitis. Molecular assays performed provide detection and quantification of viral DNA, genotyping, drug resistance, and precore/core mutation analysis to confirm infection and monitor disease progression in chronic hepatitis B patients. All patients with chronic hepatitis B should be treated with antiviral medications and regularly monitored for efficient treatment. The current treatment is based on nucleos(t)ide analogs and pegylated interferons that save lives by decreasing liver cancer death, liver transplant, slow or reverse the progression of liver disease as well as the virus infectivity.

PreS1 Mutations Alter the Large HBsAg Antigenicity of a Hepatitis B Virus Strain Isolated in Bangladesh

Mutations in the hepatitis B virus (HBV) genome can potentially lead to vaccination failure, diagnostic escape, and disease progression. However, there are no reports on viral gene expression and large hepatitis B surface antigen (HBsAg) antigenicity alterations due to mutations in HBV isolated from a Bangladeshi population. Here, we sequenced the full genome of the HBV isolated from a clinically infected patient in Bangladesh. The open reading frames (ORFs) (P, S, C, and X) of the isolated HBV strain were successfully amplified and cloned into a mammalian expression vector. The HBV isolate was identified as genotype C (sub-genotype C2), serotype adr, and evolutionarily related to strains isolated in Indonesia, Malaysia, and China. Clinically significant mutations, such as preS1 C2964A, reverse transcriptase domain I91L, and small HBsAg N3S, were identified. The viral P, S, C, and X genes were expressed in HEK-293T and HepG2 cells by transient transfection with a native subcellular distribution pattern analyzed by immunofluorescence assay. Western blotting of large HBsAg using preS1 antibody showed no staining, and preS1 ELISA showed a significant reduction in reactivity due to amino acid mutations. This mutated preS1 sequence has been identified in several Asian countries. To our knowledge, this is the first report investigating changes in large HBsAg antigenicity due to preS1 mutations.

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.