title: HBV core sequence: definition of genotype-specific variability and correlation with geographical origin.
abstract: There are eight genotypes and nine subtypes of HBV. Small differences in geographical origin are associated with sequence changes in the surface gene. Here, we compared core gene sequences from different genotypes and geographical regions. Specific combinations of 24 amino acid substitutions at nine residues allowed allocation of a sequence to a subtype. Six of these nine residues were located in different T cell epitopes depending on HBV geographical area and/or genotype. Thirty-seven nucleotide changes were associated uniquely with specific genotypes and subtypes. Unique amino acid and nucleotide variants were found in a majority of sequences from specific countries as well as within subtype ayw2 and adr. Specific nucleotide motifs were defined for Korean, Indian, Chinese, Italian and Pacific region isolates. Finally, we observed amino acid motifs that were common to either South-east Asian or Western populations, irrespective of subtype. We believe that HBV strains spread within constrained ethnic groups, result in selection pressures that define sequence variability within each subtype. It suggests that particular T cell epitopes are specific for geographical regions, and thus ethnic groups; this may affect the design of immunomodulatory therapies.
authors.affiliation: Division of Virology, Institute of Biomedical and Life Science, University of Glasgow, Glasgow, UK.
authors.forename: S M
authors.initials: SM
authors.lastname: Jazayeri
authors.forename: M
authors.initials: M
authors.lastname: Jazayeri
authors.forename: A A
authors.initials: AA
authors.lastname: Basuni
authors.forename: N
authors.initials: N
authors.lastname: Sran
authors.forename: R
authors.initials: R
authors.lastname: Gish
authors.forename: G
authors.initials: G
authors.lastname: Cooksley
authors.forename: S
authors.initials: S
authors.lastname: Locarnini
authors.forename: W F
authors.initials: WF
authors.lastname: Carman
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001210:Asia, Southeastern; D001483:Base Sequence; D005060:Europe; D014644:Genetic Variation; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology* / Q000821:virology; D006512:Hepatitis B Core Antigens / Q000737:chemistry* / Q000235:genetics*; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics; D006801:Humans; D007194:India; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D006512:Hepatitis B Core Antigens; D006514:Hepatitis B Surface Antigens