IL-18增强日本血吸虫DNA疫苗Sj23的免疫保护效果

将小鼠IL-18基因和日本血吸虫Sj23膜蛋白基因分别插入pVAX1载体,构建真核表达质粒pVAX/mIL-18和pVAX/Sj23,联合或单独免疫小鼠,以pVAX1空载体作对照,免疫2次,间隔2周,2次免疫后4周攻击日本血吸虫尾蚴.体液和细胞免疫检测结果表明,联合免疫组能诱导小鼠产生较强的抗日本血吸虫成虫可溶性抗原(SWAP)IgG,较高水平的IFN-γ和IL-2.攻虫试验表明,联合免疫小鼠成虫减虫率和肝脏减卵率分别达41.6%和49.4%,明显高于pVAX/Sj23单独免疫组(减虫率和肝脏减卵率分别为26.5%和41.4%).以上试验结果表明,IL-18能明显增强Sj23 DNA疫苗在小鼠体内的免疫应答,并且产生较强的保护作用.

IL-18 augments protective immunity of Sj23 plasmid DNA vaccine against Schistosoma japonicum in mice

Two recombinant plasmids pVAX/Sj23 and pVAX/mIL-18 containing Schistosoma japonicum 23 000 membrane protein (Sj23) and murine IL-18 were evaluated for their ability to induce immune responses and to protect against S. japonicum challenge in mice. All animals vaccinated with pVAX/Sj23 alone or plus pVAX/mIL-18 developed specific anti-SWAP (soluble worm antigen preparation) ELISA antibody and splenocyte proliferation response,and co-injection of pVAX/mIL-18 significantly increased the production of IFN-γ and IL-2 compared with pVAX/Sj23 alone, indicating that IL-18 enhances the Th1-dominant immune response. The challenge experiment showed that worm reduction rates in pVAX/Sj23 group compared with control group (pVAX1) was 26.5% and in the pVAX/Sj23 plus pVAX/mIL-18 group was 41.9% ,and the hepatic egg reduction rates were 42.7 and 49.6%,respectively. These results indicated that co-injection of an IL-18 plasmid with Sj23 DNA vaccine efficiently improves the protective effect against S. japonicum infection.