ABSTRACT
ObjectiveTo analyze the characteristics of S gene varivants of patients with chronic hepatitis B virus infection with coexistence of HBsAg and HBsAb.MethodsHBV DNA S gene regions were amplified and sequenced in 26 HBsAg-positive/HBsAb-positive patients (test group) and the newly diagnosed 39 HBsAg-positive/HBsAb-negative patients (control group).The sequencing results and amino acid variants of this region were analyzed.ResultsThe amino acid variants were significantly more frequent in test group than in control group among the complete S gene region (P＜0.05).In addition,a significantly bigher amino acid variants arose in patients group versus control group in HBsAg major hydrophilic region (MHR),especially the first loop area of a-determinant (6.69％ vs 0.89％,P＜0.05).ConclusionThe coexistence of HBsAg and HBsAb in patients with chronic HBV infected might be related to the emergence of S gene variants in and around HBsAg a-determinant especially in the first loop area.