Streptococcus equi subspecies equi is a pathogenic bacterium that causes strangles, a highly contagious respiratory infection in horses and other equines. The limitations of current vaccines against S. equi infection warrants the development of an affordable, safe, and effective vaccine. Because gram-positive extracellular vesicles (EVs) transport various immunogenic antigens, they are attractive vaccine candidates. Here, we purified the EVs of S. equi ATCC 39506 and evaluated them as a vaccine candidate against S. equi infection in mice. As an initial step, comparative proteomic analysis was performed to characterize the functional features of the EVs. Reverse vaccinology and knowledge-based annotations were then used to screen potential vaccine candidates (PVCs) for S. equi ATCC 39506. Finally, 32 PVCs were found to be enriched in the EV fraction, suggesting the usefulness of this fraction as a vaccine. Importantly, a significantly higher survival rate after S. equi infection was detected in mice immunized with S. equi-derived EVs via the intraperitoneal route than in mice immunized with heat-killed bacteria. Of note, immunoprecipitation-mass spectrometry results validated various immunogenic antigens within the EV proteome. In conclusion, our results suggest that S. equi-derived EVs can serve as a vaccine candidate against S. equi infection.

马链球菌亚种球菌是病原菌引起扼杀，马和其它马科动物具有高度传染性的呼吸道感染。目前疫苗针对的局限性马链球菌感染权证价格合理，安全，有效的疫苗的开发。由于革兰氏阳性细胞外囊泡 (EV) 运输各种免疫原性抗原，因此它们是有吸引力的候选疫苗。在这里，我们纯化的电动汽车马链球菌ATCC 39506和评估它们作为对疫苗候选人马链球菌小鼠感染。作为第一步，进行了比较蛋白质组学分析以表征 EV 的功能特征。然后使用反向疫苗学和基于知识的注释来筛选马链球菌 ATCC 39506 的潜在候选疫苗 (PVC) 。最后，发现 32 PVCs 富含 EV 部分，表明该部分作为疫苗的有用性。重要的是，后显著较高的存活率马链球菌与免疫的小鼠中检测到感染马链球菌通过比在具有热杀死的细菌免疫的小鼠腹膜内途径衍生电动汽车。值得注意的是，免疫沉淀质谱结果验证了 EV 蛋白质组中的各种免疫原性抗原。总之，我们的结果表明马链球菌衍生的 EV 可作为针对马链球菌感染的候选疫苗。