title: Antiviral resistance mutations and genotype-associated amino acid substitutions in treatment-naïve hepatitis B virus-infected individuals from the Indian subcontinent.
abstract: OBJECTIVE
  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-naïve HBV-infected individuals were analyzed.
  
  
  METHODS
  Ninety-seven treatment-naïve 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.
  
  
  CONCLUSIONS
  This data shows that antiviral-resistant HBV strains do exist in treatment-naïve individuals in this region. Further studies are essential to characterize the role of HBVrt amino acid substitutions in response to anti-HBV therapy.
authors.affiliation: Department of Clinical Virology, Christian Medical College, Vellore, India.
authors.forename: A M
authors.initials: AM
authors.lastname: Ismail
authors.forename: P
authors.initials: P
authors.lastname: Samuel
authors.forename: C E
authors.initials: CE
authors.lastname: Eapen
authors.forename: R
authors.initials: R
authors.lastname: Kannangai
authors.forename: P
authors.initials: P
authors.lastname: Abraham
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D024882:Drug Resistance, Viral; D005260:Female; D006509:Hepatitis B / Q000821:virology*; D006515:Hepatitis B virus / Q000235:genetics* / Q000302:isolation & purification; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D012194:RNA-Directed DNA Polymerase / Q000235:genetics*; D017422:Sequence Analysis, DNA; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D012194:RNA-Directed DNA Polymerase