genotyping and mutation pattern in the overlapping mhr region of hbv isolates in southern khorasan, eastern iran

objectives the present study aimed to evaluate the genotypes and prevalence of mutations in a segment of s and rt gene in hbv isolates in southern khorasan, iran. methods this was a population-based study comprising 5,235 randomized samples for hbv screening. a nested-polymerase chain reaction (pcr) test was followed by direct sequencing, and the sequences blast with present sequences of ncbi database for genotyping. alignment and phylogenic analysis was performed using mega-6 software, and mutation pattern of this segment was finally surveyed in bioedit software. results the mean age was 39.07 ± 14.04 years, with 52.2% female and 47.8% male. all isolates belonged to hbv genotype d, sub-genotype d1. the most amino acid substitutions of surface protein were q129h (34.42%) and a168v (8.2%), other escape mutants observed in this study were p127l/t, s117g, t125m, s143l, d144e and e164d. in the rt gene, q149k was the most frequently identified amino acid substitution (9.83%), followed by l122f (8.19%), n118d/t (6.55%), l157m (4.91%), and h124y (3.27%). conclusions this finding represents an ongoing dominancy of hbv genotype d in eastern iran, corresponding to other parts of iran. there were a lot of variations in the s gene leading to an escape mutation, some of which affected the corresponding area of the rt region. background hepatitis b virus, with 8 known distinct genotypes, is one of the most serious health problems which results to liver injuries. the surface gene of hepatitis b virus completely overlaps with the polymerase gene. mutations in the rt gene result in changes in the overlapping hepatitis b surface antigen.