MOLECULAR EPIDEMIOLOGY OF HEPATITIS-B VIRUS IN CENTRAL-AMERICA REFLECTED IN THE GENETIC-VARIABILITY OF THE SMALL S-GENE

The S genes of 31 Central American hepatitis B virus (HBV) strains bel onging to genotypes A, C, D, and F (4, 1, 4, and 22 strains, respectiv ely) were compared with 104 published S genes. According to the deduce d S gene product, 21 genotype F strains encoded adw4, while 1 encoded ayw4. Three clusters were revealed within genotype F, which correlated with substitutions at residue 45. In a cluster of 18 Central American and 1 Alaskan strain, all had Thr(45). One cluster included 2 Central American strains and 6 strains from South America and Europe, which h ad Leu(45). Two Nicaraguan strains differed by five substitutions, inc luding a Pro(45) in the S gene product from other F strains. In conclu sion, the dominating HBV genotype was F, which might be the reason for a low prevalence of HBV in the area, despite high prevalence of hepat itis A. These infections otherwise vary in parallel and are considered to reflect socioeconomic conditions.