Abstract：
Outer membrane vesicles (OMVs) are membranous structures frequently observed in Gram-negative bacteria that contain bioactive substances. These vesicles are rich in bacterial antigens that can activate the host\'s immune system, making them a promising candidate vaccine to prevent and manage bacterial infections. The aim of this study was to assess the immunogenicity and protective efficacy of OMVs derived from Salmonella enterica serovar Typhimurium and S. Choleraesuis, while also focusing on enhancing OMV production. Initial experiments showed that OMVs from wild-type strains did not provide complete protection against homologous Salmonella challenge, possible due to the presence of flagella in the purified OMVs samples, which may elicit an unnecessary immune response. To address this, flagellin-deficient mutants of S. Typhimurium and S. Choleraesuis were constructed, designated rSC0196 and rSC0199, respectively. These mutants exhibited reduced cell motility and their OMVs were found to be flagellin-free. Immunization with non-flagellin OMVs derived from rSC0196 induced robust antibody responses and improved survival rates in mice, as compared to the OMVs derived from the wild-type UK-1. In order to enhance OMV production, deletions of ompA or tolR were introduced into rSC0196. The deletion of tolR not only increase the yield of OMVs, but also conferred complete protection against homologous S. Typhimurium challenge in mice. Collectively, these findings indicate that the flagellin-deficient OMVs with a tolR mutation have the potential to serve as a versatile vaccine platform, capable of inducing broad-spectrum protection against significant pathogens.
摘要：
外膜囊泡(OMV)是在革兰氏阴性细菌中经常观察到的膜结构,其含有生物活性物质。这些囊泡富含细菌抗原，可以激活宿主的免疫系统，使它们成为预防和管理细菌感染的有希望的候选疫苗。这项研究的目的是评估来自鼠伤寒沙门氏菌和霍乱沙门氏菌的OMV的免疫原性和保护功效，同时还专注于提高OMV产量。初步实验表明，来自野生型菌株的OMV不能提供针对同源沙门氏菌攻击的完全保护，可能是由于纯化的OMV样品中存在鞭毛，这可能会引发不必要的免疫反应。为了解决这个问题，构建了鼠伤寒沙门氏菌和霍乱沙门氏菌的鞭毛蛋白缺陷突变体，分别指定为rSC0196和rSC0199。这些突变体表现出降低的细胞运动性,并且发现它们的OMV是无鞭毛蛋白的。来自rSC0196的非鞭毛蛋白OMV的免疫诱导了强烈的抗体反应并提高了小鼠的存活率，与源自野生型UK-1的OMV相比。为了提高OMV产量，将ompA或tolR的缺失引入rSC0196。删除tolR不仅增加了OMV的产量，但也赋予了对小鼠同源鼠伤寒沙门氏菌攻击的完全保护。总的来说，这些发现表明，具有tolR突变的鞭毛蛋白缺陷型OMV具有作为通用疫苗平台的潜力，能够诱导针对显著病原体的广谱保护。
