RT Journal Article SR Electronic(1) A1 Kidd-Ljunggren, Karin A1 Couroucé, Anne-Marie A1 Öberg, Monica A1 Kidd, Alistair H.YR 1994 T1 Genetic conservation within subtypes in the hepatitis B virus pre-S2 region JF Journal of General Virology, VO 75 IS 6 SP 1485 OP 1490 DO https://doi.org/10.1099/0022-1317-75-6-1485 PB Microbiology Society, SN 1465-2099, AB 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., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-75-6-1485