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Genetic conservation within subtypes in the hepatitis B virus pre-S2 region

1994; Microbiology Society; Volume: 75; Issue: 6 Linguagem: Inglês

10.1099/0022-1317-75-6-1485

1465-2099

Karin Kidd‐Ljunggren, Anne Couroucé, Mats Öberg, Alistair H. Kidd,

Hepatitis Viruses Studies and Epidemiology

The antigenic determinants for the main hepatitis B vims (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 phylogen- etically different strains.