MOLECULAR EPIDEMIOLOGY OF HEPATITIS-B VIRUS-VACCINE VARIANTS IN SINGAPORE

Perinatal infection with variants of hepatitis B virus occurs despite combined immunoprophylaxis with hepatitis B immunoglobulin and current ly licensed plasma-derived and recombinant yeast hepatitis B vaccines, Several variants have been detected during a large study of infants b orn to carrier mothers in Singapore. The most frequent variant was a v irus in which a single amino acid substitution Gly to Arg occurred at amino acid position 145 of the outer protein coat of the virus. Simila r mutations have been described in Italy, Japan, the USA and a number of other countries. The emergence of antibody escape mutants is a caus e for concern for the detection of virus and possibly for future immun ization programmes.