绵羊肺炎支原体（Mycoplasma ovipneumoniae，MO）是引发羊传染性胸膜肺炎的主要致病菌。细胞外囊泡（Extracellular vesicles，EVs）是由细胞主动分泌、膜包裹的纳米级大小的囊泡，其既可增强宿主的抗感染免疫、亦可介导病原体的免疫逃逸。前期研究中，项目组已分离到了MO感染的小鼠巨噬细胞RAW264.7分泌的EVs，但该EVs在MO感染过程中对宿主细胞具有怎样的调节作用？EVs中哪些组分参与了免疫调节？其又是通过哪些途径实现了对宿主细胞的免疫调节？上述科学问题均有待解决。因此，本项目拟以超速离心技术大量提取MO感染的RAW264.7 EVs，将其作用于未感染的巨噬细胞，明确该EVs对巨噬细胞的免疫调节效应；利用蛋白质组学技术筛选EVs介导的候选“免疫调节蛋白”；探究候选“免疫调节蛋白”所介导的免疫调节机制。通过本研究，期望从新的角度完善MO的致病机制理论。

Mycoplasma ovipneumoniae (MO) is the main pathogen causing pleuropneumonia in sheep. Extracellular vesicles (EVs) are nano-sized vesicles that are secreted by cells and encapsulated by membrane, which can enhance anti-infection immunity and mediate immune evasion. Previous studies in our team found that MO-infected RAW264.7 also secreted EVs, but what funtion does the EVs have in the process of infecting host cells with MO? What components of EVs are involved in immune regulation? What mechanism does it achieve immune regulation of host cells? The above scientific questions have not been resolved yet. Therefore, this project will extract EVs from MO-infected RAW264.7 by ultracentrifugation; After interacting with host immune cells, researching whether EVs participate in host immune regulation; Using proteomics technology to screen EVs-mediated "immunomodulation proteins"; Exploring the immune regulation mechanisms mediated by EVs and their "immunomodulation proteins". Through this study, it is expected to perfect the pathogenesis theory of MO in a new perspective.