血清乙型肝炎表面抗原和表面抗体共阳性慢性HBV感染者病毒S基因变异分析

Surface gene variants of hepatitis B virus of the co-existence of HBsAg and HBsAb in patients with chronic HBV infection

目的探讨乙型肝炎表面抗原（HBsAg）和表面抗体（HBsAb）共阳性患者乙肝病毒．S基因区氨基酸变化特点，了解分子病毒学特征。方法对26例HBsAg和HBsAb共阳性且DNA阳性的慢性HBV感染者（实验组）和随机选取的39例HBsAg阳性HBsAb阴性且DNA阳性慢性HBV感染者（对照组）的HBVDNAS区基因序列进行PCR扩增和测序，并对s区氨基酸序列进行比对分析。结果HBsAg和HBsAb共阳性组s基因区氨基酸突变高于对照组，两者差异具有统计学意义（P〈0．05）；在a决定簇（aa124～147）尤其是第1个茎环结构内（aa124～137）氨基酸突变频率明显高于对照组（5．49％VS1．09％，P〈0．05）。结论HBsAg和HBsAb共阳性患者Js基因a决定簇第1个茎环结构氨基酸变异明显增加，推测与HBsAg和HBsAb共阳性现象的发生可能有相关性。

Objective To analyze the characteristics of S gene varivants of patients with chronic hepatitis B virus infection with coexistence of HBsAg and HBsAb. Methods HBV 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. Results The 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 higher 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）. Conclusion The 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.