Hepatitis B Virus Genome Analysis in Patients of Hepatocellular Carcinoma and Asymptomatic Carriers from Northern, Southern and North East India

Abstract

The present study was designed to analyse the whole genome and mutational profile of hepatitis B virus (HBV) isolates in hepatocellular carcinoma (HCC) and asymptomatic carriers from three regions of India. Seventy-five HBV-related HCC and 15 HBV-related asymptomatic carriers were included in the study. HBV DNA was amplified by six sets of walking primers. Amplicons were sequenced commercially, submitted to GenBank translated into amino acid and aligned using BioEdit v7.0.9. Mutations membering 60, 15, 23 and 1 were observed in PC/C, X, P and S genes respectively. Mutations like 10I → L were significantly associated with HCC cases from North East India (NEI) [(P = 0.01; OR = 5.63) versus South India (SI)] and [(P < 0.01; OR=16.63) versus North India (NI)]. Mutations like 41S → T (P < 0.001; OR = 19.01), 92V → G (P < 0.001; OR = 19.01), 96N → T (P < 0.001; OR = 19.01) and 164Q → P (P = 0.0279; OR = 3.085) were significantly associated with HCC cases from NI [vs SI]. Widely reported 28 W → stop mutation was found in a few HCC cases. Also, 132 → stop [(P = 0.004486; OR = 5.479 versus SI) and [(P = 0.004486; OR = 5.479) versus NEI] was interesting. 267I → N and 268D → T were exclusive to HCC from NEI, while 270S → F was exclusive to HCC from NI. Reported drug mutants (80L → I, 236N → T, 169I → T and 181A → V) were observed. The PC/C region was most prone to mutation followed by P, X and S regions. Maximum variation in HBV genome was observed in HCC cases from NI and least in asymptomatic HBV carriers. Novel mutations in surface (132 stop), poly-merase (frameshift mutation at 178), core (10I → L, 41S → T, 92V → G, 96N → T and 164Q → P) and X (33P → S) genes need further studies.