Intra-genotypic Recombination and Polymorphisms of Hepatitis B Virus Genome Circulating in Bangladesh

Purpose: Severe liver diseases including cirrhosis are now frequently detected among the Hepatitis B virus (HBV) infected patients. Rapid genetic evolution of HBV with insertions, deletions or frameshift events promotes infection severity. Herein, the purpose of this study is to determine the alterations of the genomic pattern of HBV causing liver cirrhosis. Methods & Materials: From 92 HBV-positive plasma samples, whole-genome of three samples, specifically one sample each for cirrhotic, chronic liver disease (CLD) and usual chronic (no detectable liver disease) patients confirmed by ultrasonography and fibroscan were sequenced and analyzed for potential mutations. Recombination analysis of the sequenced strain was performed using NCBI Genotyping tool and RDP4 software package. Results: The whole-genomes of HBV from CLD, cirrhotic and normal chronic patients share a common potential substitution at 210 amino acid (AA) position in the surface (S) protein. Whole-genome of cirrhotic patient comprises mutations T118V, A128V, S207N, I208T and S210R in the S protein and N53D, Y54H, H126R, S219A in the polymerase (P) protein. However, mutations S53L, I126T, S210N and H9Y, N13H, I91L, I269L, V278I were observed in other two patients in the S and P proteins respectively. On the other hand, a vaccine escape mutation, A128V and a frame shift deletion of three amino acids in the S protein were observed in the strain isolated from the cirrhotic patient, which may have implications to cause liver cirrhosis. Moreover, recombination analysis of the sequences denotes that the HBV genome of cirrhotic patients composed of a recombination of three genotypes D, C and E. Of which, genotype E was not documented before in Bangladesh. This unusual tri-genotypic recombinant event is the first report in the world and might promote the severity of the liver abnormalities. Moreover, there is a stop codon at 28 position in the HBV Core protein in the recombinant strain. Conclusion: The reports of this study emphasize that the genomic alterations of the HBV strains could be highly responsible for evolution of the strain that might boost the severity of the hepatitis B infection. Such evolved and recombinant HBV strains may cause dangerous public health problems in future.