NLRC4炎性体途径的激活对减毒沙门菌免疫效力的影响分析

沙门菌是一类重要的兼性胞内致病菌，吞噬细胞是其主要的宿主细胞。沙门菌能够逃逸吞噬细胞的杀伤，并在细胞内长期存活，这给畜禽和人类健康带来了严重危害。目前，在减毒沙门菌疫苗研究中，如何抑制减毒菌的胞内存活仍是阻碍其应用的难点之一。据报道，细胞内模式识别受体NLRC4能够识别细胞质中的微生物成分，诱导宿主细胞的程序性死亡，并产生Th1类免疫应答，在防御胞内菌感染中起重要作用。因此，若将该机制应用到减毒沙门菌疫苗的设计中，则能抑制减毒菌的胞内存活。但是，该机制的引入对减毒菌免疫效力的影响尚不清楚。据此，本项目拟构建融合表达SspH2蛋白N端（能被沙门菌III型分泌系统2识别并分泌）和EscI蛋白C端（能激活NLRC4炎性体）的重组减毒沙门菌，分析NLRC4炎性体的激活对减毒沙门菌毒力、体内存活能力和免疫效力的影响，探索NLRC4炎性体通路在减毒沙门菌疫苗研制中的应用前景。

Salmonella is a kind of facultative intracellular pathogenic bacteria. Phagocytes are their major host cells. Salmonella can escape the clearance of phagocytes after infection and survive for a long time in host cells. It is a serious harm to the health of the animal and human. Nowadays, in the development of attenuated Salmonella vaccine, how to inhibit its survival in host cells is still difficult. As reported, the pattern recognition receptor NLRC4 can detect the intracellular microorganism components related with pathopoiesis, and then induce the pyroptosis of host cells and the production of Th1-type immune responses. This mechanism is benefit for the defence against intracellular bacteria. So, if this mechanism can be used in the development of attenuated Salmonella vaccine, the intracellular survival of attenuated Salmonella will be inhibited. But, its influence on the immune responses against attenuated Salmonella is still unclear. Based on these analysis, in this project, we will construct a recombinant attenuated Salmonella fusion expressing N-termianl of SspH2 (can be detected by type III secretion system 2) and C-termianl of EscI (can activate NLRC4 inflammasome) to analyse its virulence, survival in host cells and immunological effect. From the above assay, we can explore the application prospect of NLRC4 inflammasome pathway in the defence against attenuated Salmonella infection.