迟缓爱德华氏菌（Edwardsiella tarda）是一种鱼类致病菌，可以感染多种海水和淡水鱼类，给养殖业造成了巨大的经济损失。研究表明，迟缓爱德华氏菌是典型的胞内寄生菌，能够逃避宿主的各种免疫防御，在宿主血清和吞噬细胞内存活并繁殖。因此，免疫逃逸被认为是迟缓爱德华氏菌至关重要的致病机制，也是该菌相关疾病免疫防控的一个重大障碍。然而，尽管迟缓爱德华氏菌免疫逃逸现象在科学界是一种共识，但是其中蕴含的分子机制却完全不清楚。基于此，本申请项目拟系统筛选迟缓爱德华氏菌的抗血清杀伤因子和抗免疫细胞杀伤因子，对关键因子进行功能解析，阐明这些因子的作用方式和表达调控，从而揭示迟缓爱德华氏菌的免疫逃逸机制。同时，在理论研究的基础上，项目还将探索免疫逃逸因子在迟缓爱德华氏菌病防御中的应用潜能。本项目研究结果将不但促进我们对鱼类胞内寄生菌致病机理的深入了解，而且也为相关疫病的免疫防控提供靶点和理论指导。

Edwardsiella tarda is an important fish pathogen and can infect many species of marine and freshwater fish, thus causing heavy economic losses to aquaculture industries. Studies have indicated that E. tarda is a typical intracellular pathogen that evades the immune defense of the host and survives in host serum and phagocytes. Hence, immune evasion is an important virulence mechanism of E. tarda and a barrier to prevention of edwardsiellosis. However, the molecular basis of this phenomenon is unknown. Based on these observations, we in this study plan to identify E. tarda factors that are involved in anti-serum and anti-phagocyte immunity and, through analyzing the function, expression, and regulation patterns of these factors, explore the mechanism of immune evasion. In addition, we also plan to investigate the applicability of immune evasion-related factors in the control of edwardsiellosis. Taken together, our study will add insights to the infection mechanism of E. tarda and provide targets and theoretical guidance for disease control.