Frequency and significance of hepatitis B virus surface gene variant circulating among ‘antiHBc only’ individuals in Eastern India

Abstract

Background Genetic mutation might account for the presence of hepatitis B virus (HBV) DNA among antiHBc only individuals. The aim of the study was to assess the prevalence and significance of surface gene mutations among antiHBc only cases in our population. Methods Three hundred and three antiHBc(+) sera of adults (mean age, 33.7 ± 11.0; range 18–65 years) as well as HBsAg(+)/HBV DNA(+) ( n = 19) controls were included in this study. Surface gene and basal core promoter (BCP)-precore region were amplified and surface gene was analyzed after direct sequencing. Results One hundred and seventy-eight out of 303 (58.8%) was antiHBc only, 39/171 (22.8%) of them was HBV DNA(+). Genotypes A, C, D were found among both HBsAg(+) and antiHBc(+) samples. Single or multiple amino acids substitutions were found in 82% samples, however, G145R vaccine escape mutation was rare. Individuals having substitutions within as well as outside major hydrophilic loop (MHL) region were detected; some of these mutations were in overlapping RT domain of polymerase (Pol) gene. Conclusions The existence of occult HBV infection among antiHBc only individuals could not be explained fully by mutations in the ‘a’ determinant region of surface gene in our population.