Efficacy of immunization of high-risk infants against hepatitis B virus evaluated by polymerase chain reaction

Abstract

The polymerase chain reaction (PCR) is a rapid and very sensitive method to detect viral genomes. In the present study, the efficacy of immunization against hepatitis B virus (HBV) of high-risk infants was evaluated by PCR. Twenty-nine infants born to 24 HBeAg-positive carrier mothers were given hepatitis B immune globulin (HBIG) at birth and thereafter received repeated inoculations of plasma-derived vaccine or HBIG, or both, within 1 year. Serum samples at 1 year following immunization were stored at -40 degrees C for later analysis using PCR to detect HBV-DNA. When HBV genomes were detected in infants, the DNA sequences in the S gene of HBV were determined. Of 29 infants, 2 were positive for HBV-DNA at the 1 year following immunization; one had the HBV containing only the wild-type sequence in the S gene and became negative for HBV-DNA during the follow-up period. In contrast, another had the HBV, which contained nucleotide substitutions that altered the expression of the common group-specific determinant "a" of the S gene and resulted in clinical hepatitis with viral persistence. PCR analysis suggests that immunization against HBV prevents effectively high-risk infants from mother-to-child transmission. Even then, however, it is possible that amino acid substitutions in the "a" determinant of the S gene are associated with failure of conventional immunization against HBV.