LOW DETECTION RATE AND MATERNAL PROVENANCE OF HEPATITIS-B VIRUS S-GENE MUTANTS IN CASES OF FAILED POSTNATAL IMMUNOPROPHYLAXIS IN ENGLAND AND WALES

Hepatitis B virus (HBV) infection occurred despite full passive-active immunoprophylaxis in 20 of 321 infants born to mothers seropositive f or hepatitis B e antigen. In 2 (12%) of 17 infected infants, mother-in fant DNA sequence mismatches were found in a segment of the HBV S gene coding for antigenic determinants of the HBV surface antigen (HBsAg) amplified from sera by polymerase chain reaction (PCR), Point substitu tions occurred in codons 120, 134, and 144 of the HBsAg polypeptide in the variant sequence of 1 infant and in codon 126 in the other; all w ere missense mutations. Mutant sequences could not be recovered from m aternal sera by PCR cloning but were selectively generated using an am plification refractory mutation system, The frequency of potential vac cine escape mutants is therefore low, and these preexist maternally as minor variants.