Institute for Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany.
Vet Microbiol. 2013 Dec 27;167(3-4):584-91. doi: 10.1016/j.vetmic.2013.09.010. Epub 2013 Sep 13.
Suilysin is a pore-forming cholesterol-dependent cytolysin secreted by Streptococcus suis (S. suis), an important swine and zoonotic pathogen. The role of suilysin in S. suis host-cell interaction is still unclear. We found a higher adherence and invasion rate of an unencapsulated sly-positive strain in comparison to its isogenic sly-negative mutant. Electron microscopy revealed that formation of membrane ruffles accompanying invasion of the sly-positive strain was abolished in the sly-negative mutant. Inhibition experiments showed that the actin cytoskeleton was involved in suilysin-mediated effects. Point-mutation of the domain putatively responsible for macropore-formation resulted in abolished hemolytic and cytolysin activity, but had no effect on S. suis host cell association. Concluding, our results indicate that subcytolytic suilysin promotes S. suis association with epithelial cells.
溶血素是由猪链球菌（S. suis）分泌的一种形成孔的胆固醇依赖性细胞毒素，是一种重要的猪和人畜共患病病原体。溶血素在 S. suis 与宿主细胞相互作用中的作用尚不清楚。我们发现，与遗传同源的 sly 阴性突变体相比，未包裹的 sly 阳性菌株的粘附和侵袭率更高。电子显微镜显示，侵袭 sly 阳性菌株时伴随的细胞膜皱襞形成在 sly 阴性突变体中被消除。抑制实验表明，肌动蛋白细胞骨架参与了溶血素介导的作用。推测负责形成大孔的结构域的点突变导致溶血和细胞毒素活性丧失，但对 S. suis 宿主细胞的关联没有影响。综上所述，我们的结果表明，亚细胞毒性溶血素促进了 S. suis 与上皮细胞的关联。
