HBe antigen loss during lamivudine therapy is not caused by mutations in precore and core promoter genes in patients with chronic hepatitis B

HBe antigen (HBeAg) loss or seroconversion can occur during lamivudine therapy. The purpose of this study was to analyze nucleotide sequences in precore and core promoter regions, and examine the influence of mutations in these regions on the disappearance of HBeAg during lamivudine therapy. Serial serum samples were obtained from 51 patients (HBeAg loss in 26 patients) at commencement of therapy (baseline) and after 1 year of lamivudine therapy. Serum samples were amplified with PCR and nucleotide sequences of HBV were analyzed. At baseline, a precore stop codon mutation (A1896) was identified in 8 of 26 HBeAg loss patients and in 8 of 25 HBeAg non-loss patients. At 1 year, precore mutation was observed in 4 of 14 patients analyzed who showed HBeAg loss. At 1 year, however, a precore mutation was observed also in 3 of 9 analyzed patients who showed no HBeAg loss. Core promoter mutations were noted in 21 of 26 HBeAg loss patients and in 20 of 25 HBeAg non-loss patients. At 1 year, core promoter mutations were noted in 11 of 14 HBeAg loss patients and in 8 of 9 HBeAg non-loss patients. Our data suggested that during lamivudine therapy, core promoter and precore mutations do not influence HBeAg loss or seroconversion but may reduce the viral level upon HBeAg loss or seroconversion.