Molecular epidemiology and genetic characterization of hepatitis B virus in two major provinces of Pakistan.

Hepatitis B virus (HBV) infection is a major public health issue and is responsible for considerable morbidity and mortality globally. In Pakistan, the prevalence of chronic HBV infection varies from 2% to 4%, with an estimated exposure rate of approximately 34%. The major objective of this study was to determine the prevalence of HBV genotypes and the pattern of escape mutations in the HBV S gene in two major provinces of Pakistan: Punjab and Khyber Pakhtunkhwa. A total of 146 serum/plasma samples collected from hepatitis B patients were sequenced by the Sanger method. Phylogenetic analysis indicated the intermixed circulation of closely related strains of HBV genotype D and subgenotypes HBV/D1, HBV/D2, and HBV/A2 in both provinces, and various escape mutations (Y100C, P120S/T, G119R, C121S/Y, R122K, T126I, A128V, Q129H/R, G130R, T131N/I, M133T/I, Y134N, C137W, S143L, and D144E) were identified. These findings provide important insights into the current prevalence of HBV genotypes in Pakistan and will help in the establishment of more-efficient disease interventions and patient management strategies.