猪链球菌2型荚膜唾液酸对细菌毒力和宿主炎症反应的影响

摘要

[ Objective] We clarified the pathogenic influence of the absence of Streptococcus suis type 2 capsular saliva acid on BLAB/c mice. [ Methods] The virulence of the experimental strains were compared; the distribution of strains in vivo was determined by quantitative plating. Histopathological analysis was used to qualitatively compare the different pathogenicity of wild strain and knockout strains. ELISA was used to test the levels of cytokine in whole blood cells for the stimulation of strains. [ Results ] The virulence of mutant strains was significantly reduced, and when the genes were restored, toxicity levels were recovered to that of the wild type strain. The distribution in blood and in the brain between wild strain and knock out strains has significant difference, and Streptococcus suis type 2 strains can cause different degrees of brain damage. During the in vitro test, the mutant strains can stimulate the whole blood cells to secrete higher levels of MCP-1 and IL-6. [Conclusion] Capsular saliva acid affects bacterial virulence and host cell inflammation response. As an important virulence factor of Streptococcus suis type 2, it can damage the blood brain barrier and cause meningitis.%[目的]阐明猪链球菌2型荚膜唾液酸是否影响细菌毒力以及宿主对其炎症反应应答,为研究猪链球菌2型的致病机制奠定基础.[方法]比较实验菌株对BLAB/c小鼠模型的致病性；通过涂板计数的方法检测实验菌株在小鼠体内的分布；观察小鼠脑组织病理改变,分析实验菌株感染小鼠后中枢神经系统的病变差异；从小鼠体外全血细胞水平,运用ELISA法检测实验菌株感染后细胞炎性因子的分泌水平.[结果]荚膜唾液酸合成基因neuB缺失突变株△neuB相比野生株05ZYH33株,对小鼠毒力显著降低,回复突变株c△neuB毒力回复至野生株水平；野生株和突变株在血液及脑组织中分布具有显著差异,均可致BLAB/c小鼠脑组织不同程度的损伤；与野生株组相比较,细菌/细胞相互作用不同时间点后,突变株组体外刺激小鼠全血细胞分泌MCP-1、IL-6的水平显著提高；[结论]荚膜唾液酸影响细菌的毒力及宿主细胞对其的炎症反应应答,它是猪链球菌2型穿透血脑屏障导致脑膜炎的重要毒力因子.