RELATIONSHIPS BETWEEN SEROTYPES AND GENOTYPES OF HEPATITIS-B VIRUS - GENETIC CLASSIFICATION OF HBV BY USE OF SURFACE GENES

Hepatitis B virus (HBV) surface antigen (HBsAg), which is encoded by t he HBV S gene, is conventionally classified into 4 serological subtype s, adw, adr, ayw and ayr. To determine the relationship between the HB sAg seroreactivity and the nucleotide sequence diversity of the HBV S gene, the nucleotide sequences of S genes for HBV isolates reported so far were aligned with each other. The numbers of nucleotide substitut ions were then estimated by the 6-parameter method, and a phylogenetic tree was constructed by the unweighted paired grouping method with ar ithmetic mean (UPGMA) and the neighbor-joining (NJ) method. The phylog enetic trees constructed showed that all isolates were grouped into 4 genotypes (gyw, gdw-1, gdw-2, and gdr), More importantly, the genotype s did not necessarily correspond to the conventional serotypes. In par ticular, serotype 'adw' can be any of genotypes gdw-1, gdw-5 or gdr. T hus, genotyping by S genes gives more accurate information about genet ic variation of HBV.