日本血吸虫抱雌沟蛋白DNA疫苗的研究

为构建含日本血吸虫抱雌沟蛋白(SjGCP)完整ORF的核酸疫苗,评估该核酸疫苗在小鼠体内诱导抗血吸虫感染的免疫保护效果及其保护机制,将编码日本血吸虫大陆株抱雌沟蛋白基因ORF片段克隆到真核表达载体pVAX1中,用重组质粒pVAX1-SjGCP三次肌肉注射BALB/c小鼠,攻击感染血吸虫尾蚴,攻击感染后第42天剖杀小鼠冲虫,计算减虫率及肝和粪便的减卵率,评估其免疫保护效果。用流式细胞术(FCM)检测第3次免疫后小鼠淋巴细胞亚群CD4+、CD8+占总淋巴细胞的百分比及细胞因子IL-4、IFN-γ表达水平,探讨核酸疫苗的免疫机制。结果显示,小鼠经pVAX1-SjGCP质粒免疫后诱导了31.9%的减虫率,以及47.85%、68.04%的肝减卵率和粪便减卵率,与PBS组差异显著;pVAX1-SjGCP免疫组淋巴细胞亚群CD4+、CD8+百分比增加,细胞因子IFN-γ及特异性IgG水平提高,与pVAX1组差异显著。结果表明,血吸虫抱雌沟蛋白基因DNA疫苗能够诱导宿主细胞免疫和体液免疫应答,产生Th1/Th2型混合的细胞免疫反应,具有一定的抗血吸虫感染的免疫保护效果。

Studies on DNA vaccine encoding the full length of gynecophoral canal protein of Schistosoma japonicum

To evaluate the protective efficiency and analyze immune response mechanism induced by vaccinating mice with the DNA vaccine of gynecophoral canal protein of Schistosoma japonicum(SjGCP),the full length cDNA fragement of SjGCP was cloned into the eukaryotic expression vector pVAX1,with the recombinant eukaryotic expression plasmid pVAX1-SjGCP constructed.The purified recombinant plasmid pVAX1-SjGCP was applied to inject BALB/c mice intramuscularly for three times at the interval of two weeks.All the mice were challenged with 40±2 cercariae of S.japonicum after the third vaccination and sacrificed for perfusion on day 42 post-challenge.The worm burden reduction rate as well as egg reduction rate in liver and feces were evaluated.One week after last injection,the percentage of CD4+ and CD8+ lymphocyte subsets and the intracellular cytokines IL-4 and IFN-γ as well as the specific total IgG were detected to investigate the immunologic mechanism induced by the vaccination of DNA vaccine.In result,31.9% worm reduction and 47.85% and 68.04% of liver and feces egg reduction were obtained,respectively.The percentage of CD4+,and CD8+ lymphocytes and levels of IFN-γ cytokine and specific IgG antibody were significantly increased in mice vaccinated with pVAX1-SjGCP compared with those in pVAX1 injected control.In conclusion,the nucleic acid vaccine of Gynecophoral canal protein of S.japonicum could induce the responses of mixed Th1/Th2 cellular immunity and humoral immunity in animal against S.japonicum infection.