BREAKTHROUGH INFECTIONS AND IDENTIFICATION OF A VIRAL VARIANT IN GAMBIAN CHILDREN IMMUNIZED WITH HEPATITIS-B VACCINE

Hepatitis B (HB) breakthrough infections, identified by the presence o f HB core (c) antibody, were found in 32 of 358 Gambian children vacci nated with plasma-derived HB vaccine. Over 2 years, 15 of these childr en lost their HBc antibodies. These children had significantly higher HB surface antibody levels before infection than those who retained HB c antibodies. One child, who responded well to the vaccine, had HB vir al DNA detected in the presence of HBs antibodies. The S gene sequence of this DNA showed nucleotide changes that resulted in an amino acid substitution at residue 141 (lysine to glutamic acid) of the surface a ntigen. This finding suggests the child was infected with a variant vi rus that was not neutralized by antibodies resulting from HB vaccinati on.