中文摘要：

为探明猪链球菌2型（SS2）感染的致病机制，利用荧光定量PCR方法，分析不同SS2菌株对3D4／21猪肺泡巨噬细胞各炎症相关细胞因子mRNA体外转录水平的影响。结果显示强毒菌株ZY05719刺激细胞因子转录水平高于其impdh缺失株ZY05719（Aimpdh）和无毒菌株HA0609及低毒菌株CS100322-1。ZY05719诱导多个细胞因子mRNA过度转录，包括IL-18、IL-8和IL-12等。除IL-10外，HA0609诱导其他细胞因子mRNA上调转录；而CS100322-1刺激后，绝大部分细胞因子mRNA处于稳定状态。不同毒力SS2菌株影响细胞因子mRNA转录，且这种影响具有时间上的依赖性。SS2具有调节炎性细胞因子转录的能力，其结果介导炎症反应及白细胞趋集于感染部位，这可能是SS2引起脑膜炎炎症特征的机制之一。

英文摘要：

To study the pathogenesis of Streptococcus suis serotype 2 （SS2） infection, fluorogenic quantitative PCR was used to detect mRNA transcriptional level of inflammation-associated cytokines of porcine alveolar macrophages 3134/21 stimulated by SS2. The transcriptional level of cytokine, induced by high virulent strain ZY05719, was higher than that induced by impdh-deficient mutant ZY05719 （Aimpdh）, HA0609 （avirulent SS2 strain） and CS100322-1 （low virulent SS2 strain）. When IL-18, IL-8 and IL-12 were over-transcripted when induced by ZY05719. All of tested cytokines were upregulated when induced by HA0609, except IL-10. However, the cytokines induced by CS100322-1 stayed stable. Different virulent strains of SS2 seemed to influence the mRNA transcriptional level of cytokines, which was time-dependent. SS2 was capable of regulating important inflammation-associated cytokines resulting in mediating inflammatory reaction and an increased leucocyte recruitment into the sites of infection, which might provide a possible explanation for some of inflammatory features of meningitis caused by SS2.