Zhang Yanyan, Ding Dandan, Liu Manli, Yang Xiaopei, Zong Bingbing, Wang Xiangru, Chen Huanchun, Bei Weicheng, Tan Chen
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, Hubei, China; Key Laboratory of Development of Veterinary Diagnostic Products of Ministry of Agriculture, Huazhong Agricultural University, Wuhan 430070, Hubei, China.
Center of Bio-Pesticide Engineering Research, Hubei Academy of Agricultural Science, Wuhan 430064, Hubei, China.
Microbiol Res. 2016 Apr;185:45-54. doi: 10.1016/j.micres.2016.02.002. Epub 2016 Feb 5.
Streptococcus suis serotype 2 (S. suis 2) is a serious zoonotic pathogen causing septicemia and meningitis in piglets and humans. The capsular polysaccharide (CPS) is an essential virulence factor for S. suis 2 to infect the host. The synthesis of CPS repeating units involves multiple glycosyltransferases. In this study, four genes (cps2E, cps2G, cps2J and cps2L) encoding different glycosyltransferases involved in CPS synthesis were researched in S. suis 2. Four deletion mutants (Δcps2E, Δcps2G, Δcps2J and Δcps2L) with their CPS incomplete and their sialic acid content significantly decreased were constructed in S. suis 2 SC19. All these four mutant strains showed enhanced adhesion to Hep-2 cells and increased sensitivity to phagocytosis. Flow cytometric analysis also revealed that these four mutants were more susceptible to the attack by the complement system. In a mouse model of infection, the mutant strains were rapidly cleared by the immune system, compared with the wild-type strain. In summary, this study characterized four genes (cps2E, cps2G, cps2J and cps2L) involved in CPS synthesis of S. suis 2 SC19 and it revealed that these genes were all crucial for SC19 to invade and survive in the host.
猪链球菌2型（S. suis 2）是一种严重的人畜共患病原体，可导致仔猪和人类发生败血症和脑膜炎。荚膜多糖（CPS）是S. suis 2感染宿主的必需毒力因子。CPS重复单元的合成涉及多种糖基转移酶。在本研究中，对S. suis 2中参与CPS合成的四个编码不同糖基转移酶的基因（cps2E、cps2G、cps2J和cps2L）进行了研究。在S. suis 2 SC19中构建了四个CPS不完整且唾液酸含量显著降低的缺失突变体（Δcps2E、Δcps2G、Δcps2J和Δcps2L）。所有这四个突变菌株对Hep-2细胞的黏附增强，对吞噬作用的敏感性增加。流式细胞术分析还显示，这四个突变体对补体系统的攻击更敏感。在感染小鼠模型中，与野生型菌株相比，突变菌株被免疫系统迅速清除。总之，本研究对S. suis 2 SC19中参与CPS合成的四个基因（cps2E、cps2G、cps2J和cps2L）进行了表征，并揭示这些基因对SC19在宿主体内的侵袭和存活都至关重要。
