Antiviral Resistance Mutations and Genotype-Associated Amino Acid Substitutions in Treatment-Naive Hepatitis B Virus-Infected Individuals from the Indian Subcontinent

Background/Aims: Antiviral resistance is a major challenge to the treatment currently available for hepatitis B virus (HBV). In this study, mutations that may affect the antiviral efficacy in treatment-naive HBV-infected individuals were analyzed. Methods: Ninety-seven treatment-naive HBV-infected individuals were included in this study. HBV reverse transcriptase (rt) domains were sequenced and nucleotide differences were compared to GenBank wild-type sequences. Furthermore, HBV genotypes, subgenotypes and subtypes were determined by analyzing surface gene sequences. Results: An adefovir-related rtI233V mutation was identified in 4 subjects. The rtS213T lamivudine and entecavir refractory mutant was presented in 3 individuals. Altogether, drug-related, atypical and novel HBVrt amino acid substitutions were seen in 73 positions. The HBV genotypes A, C, D and G were depicted in 15, 21, 60 and 1 individuals, respectively. There were 17 HBVrt amino acid substitutions that are associated with certain genotypes of HBV. Mutations in HBVrt corresponded to established surface gene mutations in 9 patients. Conclusion: This data shows that antiviral-resistant HBV strains do exist in treatment-naive individuals in this region. Further studies are essential to characterize the role of HBVrt amino acid substitutions in response to anti-HBV therapy. Copyright (C) 2011 S. Karger AG, Basel