日本血吸虫Mr26000GSTDNA疫苗和重组蛋白疫苗联合免疫的保护作用研究

Protective Efficacy of Co-immunization with Sj26 DNA and Recombinant Protein Vaccine Against Schistosoma japonicum in Mice

目的观察日本血吸虫Mr26000谷胱甘肽S-转移酶(Sj26)DNA疫苗和重组蛋白(rSj26GST)疫苗联合免疫对小鼠的保护作用。方法将Sj26基因克隆入含有增强型绿色荧光蛋白的真核表达载体pEGFP-N3,构建重组质粒pEGFP-Sj26,并转染幼仓鼠肾细胞(BHK),用荧光显微镜和蛋白质印迹法(Western blotting)检测蛋白的表达。联合免疫组BALB/c小鼠分别在第0、2周用pEGFP-Sj26免疫2次,第4周再用rSj26GST加强免疫1次;而单独免疫的pEGFP-Sj26组及rSj26GST组,与上组同步各自免疫3次。末次免疫后2周进行感染攻击,45d后剖杀,计数成虫及肝内虫卵。同时设PBS对照组。结果pEGFP-Sj26在BHK中能有效表达。联合免疫组的减虫率为50·8%,显著高于pEGFP-Sj26(28·0%)和rSj26GST组(25·5%)(P值均<0·01)。联合免疫组以及pEGFP-Sj26、rSj26GST组减卵率分别为32·7%、20·6%、33·0%;联合免疫组及rSj26GST组,肝组织中每条雌虫平均产卵数显著低于PBS对照组(P值均<0·01)。结论联合免疫组的保护作用优于pEGFP-Sj26和rSj26GST单独免疫组。

Objective To study the protective efficacy of co-immunization with Schistosoma japonicum glutathione Stransferase （Sj26） DNA and recombinant Sj26 protein （rSj26 GST） vaccine against Schistosoma japonicum in BALB/c mice. Methods The Sj26 gene was cloned into eukaryotic expression vector pEGFP-N3 with enhanced green fluorescence protein. The recombinant plasmid pEGFP-Sj26 was transfected into baby hamster kidney （BHK） ceils, fluorescent microscope and Western blotting were employed to identify the expressed products. Each mouse in co-immunization group was primed with plasmid pEGFP-Sj26, boosted 2 weeks later and immunized with rSj26 GST 4 weeks later. While each mouse in pEGFP-Sj26 group and rSj26 GST group was primed and boosted with pEGFP-Sj26 or rSj26 GST independently. Two weeks after last immunization, each mouse was challenged with 40 ± 1 cercariae of S.japonicum Chinese strain. At the 45th day post-infection, mice were sacrificed and the worms were perfused from portal vein and the number of worms and eggs in liver tissue were counted. Results In BHK cells transfected with the recombinant plasmid pEGFP-Sj26, the expression of Sj26-EGFP fusion protein was confirmed by fluorescent microcopy and Western blotting. The worm reduction rate in co-immunized group was 50. 8%, significantly higher than that in pEGFP-Sj26 group （28.0%, P 〈 0.01） and rSj26 GST group （25.5%, P 〈 0. 01）. Liver egg reduction rate in coimmunized group, pEGFP-Sj26 group and rSj26 GST group were 32.7%, 20. 6% and 33.0% respectively. The number of eggs per female in liver of co-immunized mice and rSj26 GST group were significantly higher than that in control group （P 〈0. 01）. Conclusion Compared to the immunization with pEGFP-Sj26 or rSj26 GST alone, the co-immunization with pEGFP-Sj26 and rSj26 GST can enhance protective efficacy in BALB/c mice.