HBV-preS2/S-C3d联合基因疫苗诱导的特异性免疫应答及其意义

The antigen-specific immune responses induced by HBV-preS2/S-C3d3 combined DNA vaccine

目的:研究HBV-preS2/S-C3d联合基因疫苗诱导的特异性体液和细胞免疫应答及其意义。方法:CR2结合实验检测C3d融合蛋白的结合特性;分别用TR421、TR421-preS2/S和TR421-preS2/S-C3d3重组质粒免疫小鼠,ELISA法检测特异性抗HBs-IgG的亲合力,3H-TdR掺入法检测其特异性淋巴细胞增殖活性(SI),半定量RT-PCR法检测IL-4、IFN-γ、T-bet和GATA-3基因表达的水平。结果:C3d融合蛋白可有效地结合CR2;TR421-preS2/S-C3d3质粒基因免疫诱导的抗HBs-IgG水平、亲合力以及SI均明显高于TR421-preS2/S组,并且前者诱导的IL-4、IFN-γ、T-bet和GATA-3基因表达水平也均高于后者。结论:C3d通过结合CR2、上调IL-4和转录因子的表达、促进抗体亲合力成熟来增强基因免疫诱导的HBV特异性免疫应答。

Objective：To investigate the antigen-specific humoral and cellular immune responses induced by HBV-preS2/S- C3d3 combined DNA vaccines. Methods：Raji cell binding assay was performed to evaluate the expressed protein. Female BALB/c mice were primed by i. m. gene immunization with different recombinant plasmids three times at three-week interval. The levels and avidity of specific IgG in sera collected at the indicated times from each group were determined by ELISA. Splenocytes from immunized mice were stimulated with hCGβ protein and then harvested to analyze specific lympho-proliferative response by ^3H-Thymidine incorporation assay. The mRNA levels of IL-4, IFN-γ,T-bet and GATA-3 were detected by semi-quantitative RT-PCR. Results： preS2/S-C3d3 fusion proteins could bind CR2 positive Raft cells. The levels and avidity of HBsAg specific IgG,lympho-proliferative response in the mice immunized with TR421-preS2/S-C3d3 were significant higher than those in TR421-preS2/S-immunized mice. The increase of IL-4 ,T-bet and GATA-3 mRNA levels was detected in mice with preS2/S-C3d3-expressing DNA compared with mice with preS2/S-expressing DNA,but the IFN-γ mRNA level decreased. Conclusion：C3d could enhance both humoral and cellular immune responses against HBV following gene immunization by binding CR2, upregulating the expression of IL-4 and accelerating the avidity maturation of anti-HBs IgG.