乙型肝炎病毒表面抗原基因点突变对HBsAg抗原性的影响

Antigenic properties of mutant hepatitis B virus surface antigen

目的研究乙型肝炎病毒表面抗原（HBsAg）常见基因点突变对HBsAg抗原性的影响，了解我国目前常用的HBsAg检测试剂对HBVS基因突变株的检测灵敏性，减少漏检，有效控制乙肝病毒（HBV）感染的传播。方法构建HBsAg重组野毒株和重组变异株表达质粒，分别将重组野毒株HBsAg表达质粒pSS1adw2及pSS1adr和重组变异株HBsAg表达质粒pSS1adw2-145Arg、pSS1ad-126Ser和pSS1adr-126Asn转染COS-7细胞，进行瞬时转染。采用市售HBsAg ELISA检测试剂盒对细胞上清进行抗原性检测。结果野毒株HBsAg和两种126位变异株HBsAg具有较好的抗原性；145位点突变后导致HBsAg的抗原性下降。结论推测是由于145位点变异影响了“a”抗原决定簇的空间结构，从而降低了其与抗-HBs的结合能力。

Objective To study the antigenic properties of mutant hepatitis B virus surface antigen, to understand the sensitivity of the commercially available HBsAg assays to the variants and to reduce the undetectability of the variants. Methods Recombinant eukaryntic expression plasmids for HBsAg. The recombinant eukaryntic expression plasmids pSSladr,pSS1adw2,pSS1adw2-145Arg,pSS1adr-126 Ash and pSS1adr-126Ser were transfected into COS-7 cells. HBsAg in the superuatants of transfected cells was detected by using different commercial ELISA kits. Results The absorbance value of pSS1adr-126 Ash and pSS1adr-126Ser plasmids were similar to that of the wild type HBsAg, the absorbance value of pSS1adw2-145Arg plasmids was lower than that of the wild type HBsAg. Conclusion h is estimated that the antigenicity of HBsAg mainly depended on the amino acid sequence of “a” antigen determinant and its conformation, so 145 amino acid substitutions led to the change of conformation and the antigenicity of variant HBsAg was lower than that of the wild type.