title: Genetic conservation within subtypes in the hepatitis B virus pre-S2 region.
abstract: The antigenic determinants for the main hepatitis B virus (HBV) subtypes adw, adr, ayw and ayr lie in the S (surface) polypeptide. Two amino acid residues in particular, encoded by the S gene at codon positions 122 and 160, have been postulated to determine the different antigenic subtypes. In contrast, the 165 nucleotide pre-S2 gene encodes an immunodominant region common to all subtypes that can give rise to neutralizing antibodies. We have characterized the pre-S2 gene sequences of 29 HBV strains of the three main subtypes, adw, ayw and adr. Seven base positions showed variation that was entirely subtype-specific, with six of these variations leading to subtype-specific amino acid differences. This finding affords the possibility of using pre-S2 sequences for genetic subtyping. Two ayw strains from unrelated patients infected in the Middle East had identical pre-S2 sequences with a block of 12 nucleotides deleted. A geographical correlation with subtype observed from serological results was also apparent from phylogenetic analysis of DNA identities within the pre-S2 region. The results support the concept that the main HBV subtypes truly represent families of phylogenetically different strains.
authors.affiliation: Department of Infectious Disease, University Hospital of Lund, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Kidd-Ljunggren
authors.forename: A M
authors.initials: AM
authors.lastname: Couroucé
authors.forename: M
authors.initials: M
authors.lastname: Oberg
authors.forename: A H
authors.initials: AH
authors.lastname: Kidd
mesh_terms: D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D006514:Hepatitis B Surface Antigens / Q000235:genetics*; D006515:Hepatitis B virus / Q000145:classification / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011498:Protein Precursors / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
chemical_list: D017931:DNA Primers; D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors; C050807:presurface protein 2, hepatitis B surface antigen