新疆出血热病毒糖蛋白Gc不同区段抗原DNA疫苗诱导小鼠的免疫应答

Immune responses in mice induced by DNA vaccines containing different glycoprotein C （Gc） gene fragments of Xinjiang hemorrhagic fever virus

目的 构建新疆出血热病毒（Xinjiang hemorrhagic fever virus,XHFV）糖蛋白两个区段抗原的DNA疫苗,并观察其免疫应答效果.方法 分别将XHFV YL04057株糖蛋白Gc上的两个抗原区段GcⅠ（1 229~1 349 aa）和GcⅡ（1 443~1 566 aa）编码的DNA序列插入真核表达载体pVAX1中,构建真核质粒pVAX1-GcⅠ和pVAX1-GcⅡ;经酶切和测序鉴定,质粒免疫小鼠,通过T细胞增殖试验、细胞因子含量测定和ELISA法检测抗体对其诱导的免疫应答效果进行评价.结果 经双酶切鉴定和测序证实重组质粒构建正确;实验组小鼠IgG产生水平与pVAX1对照组相比有明显升高;pVAX1-GcⅠ和pVAX1-GcⅡ免疫组小鼠血清中的抗体效价均高于1：3 200;pVAX1-GcⅡ免疫组的小鼠脾脏T淋巴细胞增殖明显,IFN-γ的表达水平也高达160.27 pg/ml,与对照组相比,差异有统计学意义（P〈0.01）.结论 成功构建XHFV糖蛋白两个区段抗原DNA疫苗,靶抗原在体内可有效表达;各免疫组均激起了较强的体液免疫及细胞免疫应答,pVAX1-GcⅡ实验组免疫原性和免疫效果较好,可将其作为新疆出血热病毒的候选疫苗.

Objective To construct two DNA vaccines based on two glycoprotein antigen segments of Xinjiang hemorrhagic fever virus （XHFV） and to evaluate the immune responses in BALB/c mice following vaccination.Methods Two recombinant expression plasmids pVAX1-GcⅠand pVAX1-Gc Ⅱ were constructed by inserting XHFV YL04057 strain Gc Ⅰ （1 229-1 349 aa） and Gc Ⅱ （1 443-1 566 aa） fragments into the eukaryotic expression vector pVAX1 and then were identify by restriction enzyme digestion and sequencing analysis.The recombinant expression plasmids were transfected into mice by hydrodynamics-based transfection.Immune responses induced in mice were evaluated by testing the proliferation of T cells with MTT,measuring serum antibody level with ELISA and detecting cytokines in the supernatant of spleen cell culture with ELISA kit.Results The recombinant expression plasmids were successfully constructed as indicated by the results of restriction enzyme digestion and sequencing analysis.Expression of Gc Ⅰ and Gc Ⅱ genes in mice liver tissues was detected.Antibody titers in mice immunized with pVAX1-GcⅠor pVAX1-Gc Ⅱ were higher than those in mice immunized with pVAX1.Compared with pVAX1,pVAX1-Gc Ⅱ significantly enhanced the proliferation of splenic T lymphocytes and the expression of IFN-γ （P〈0.01）.Conclusion The constructed two DNA vaccines for XHFV can induce specific humoral and cellular immune responses in mice.pVAX1-Gc Ⅱ is better than pVAX1-GcⅠin immunogenicity and protective efficacy,suggesting that it can be used as a promising candidate for the development of DNA vaccine for XHFV.