Precore stop codon mutant in chronic hepatitis B virus infection in children: its relation to hepatitis B e seroconversion and maternal hepatitis B surface antigen

Background/Aims: The aims of this study were to investigate the significance of the precore stop codon mutant in the natural course of hepatitis B virus infection in children, and the influence of maternal transmission. Methods: Sequential sera from 80 hepatitis B virus carrier children both before and after e seroconversion during long-term follow-up were studied using the polymerase chain reaction-amplification created restriction site method. Direct sequencing of the precore region was performed in 89 sera from 32 of the 80 children. Results: The precore stop codon mutant coexisting with wild strain was found in 10% of children initially, and later in 25% of children before e seroconversion. After e seroconversion, wild type was still present in 75% and mutant in 39% of children at the end of follow-up. The mutant alone was present in 15% of anti-HBe positive children without concomitant aminotransferase elevation. Children with earlier emergence of this mutant tended to have higher peak aminotransferase levels. This mutant emerged less frequently in children of hepatitis B virus carrier mothers (37.5%) than in those of non-carrier mothers (65%) (p<0.05). Conclusions: These observations suggest that this mutant is selected by host immune pressure, but is not an initiator in the loss of immune tolerance during childhood chronic hepatitis B virus infection.