猪链球菌2型（SS2）是一种重要的人兽共患病病原，能引起人和猪的感染，主要临床症状是脑膜脑炎。前期研究发现，SS2的丝氨酸激酶stk缺失株侵袭猪脑微血管内皮细胞（pBMEC）血脑屏障模型能力显著减弱，显示丝氨酸/苏氨酸激酶类和磷酸酶系统（STK/STP）在SS2致脑炎中起重要作用，但机制不明。本研究以SS2强毒分离株ZY05719为研究对象，利用转座子诱变技术，以pBMEC血脑屏障模型筛选侵袭血脑屏障减弱的突变体，并鉴定SS2与穿过血脑屏障相关的毒力因子。在此基础上，分析STK、STP对SS2新鉴定的毒力因子、溶血素、烯醇化酶和调节因子CovR的体内、体外磷酸化作用，并在pBMEC血脑屏障模型、SPF小型猪评价毒力因子、调控因子磷酸化对SS2突破血脑屏障的影响。研究结果将解析STK、STP磷酸化修饰影响SS2突破血脑屏障的作用机制，进一步阐明SS2致猪脑膜脑炎的机理。

Streptococcus suis serotype 2(SS2) is one of the important zoonotic pathogens causing serious infections in pigs and human being, and meningitis is the most frequent clinical manifestation.Our previous research demonstrated that the capability of Δstk SS2 to cross the porcine brain microvascular endothelial cells (pBMEC) is weaker than wild type strain, It means serine/threonine kinase and phosphatases (STKs/STPs) in SS2 exert an enormous function on the pathogenicity of meningitis, but the mechanism is unclear. In this proposal, the transposon mutagenesis technology is used to construct the SS2 library of transposon mutants, and the pBMEC is planned to use as the blood brain barrier (BBB)model for SS2,we try to screen the virulent factors of SS2 which are related to cross the pBMEC. After identification of these virulent factor, the analysis on phosphorylation modification of virulent factor and regulator CovR by STKs/STPs will be carried, then the effects of phosphorylation modification of virulent factor and CovR for SS2 to crossing BBB will be evaluated in pBMEC and SPF mini pigs. These results might be helpful to clarify the molecular mechanism of phosphorylation on SS2 crossing BBB, and contribute to the understanding of the pathogenic mechanism of meningitis caused by SS2, and also be useful to developing novel drugs to control swine streptococcosis.