禽致病性大肠杆菌（APEC）通过呼吸道途径感染，是严重危害养禽业健康发展的重要病原菌。新近研究发现VI型分泌系统-2（T6SS-2）使APEC的致病性更加复杂，但T6SS-2效应蛋白Hcp对鸡气管黏膜上皮细胞的致病作用及机理尚不清楚。本项目利用实验室APEC分离株（AE17），研究T6SS-2效应蛋白Hcp的致病作用。拟通过Red同源重组的方法构建Hcp缺失株并对其进行生物学特性评价；利用鸡气管黏膜上皮原代细胞和雏鸡气管感染模型，研究效应蛋白Hcp在气管黏膜上皮细胞致病中的作用；进一步采用iTRAQ磷酸化修饰定量技术确定T6SS-2效应蛋白Hcp引起差异表达的磷酸化蛋白，揭示APEC T6SS-2效应蛋白Hcp致病作用，为探寻以T6SS-2为主要靶点的宿主抗感染提供切实的应用基础，进一步为防治APEC感染提供新思路。

An ordinary way of avian pathogenic Escherichia coli (APEC) infection is through the respiratory tract. Avian pathogenic Escherichia coli (APEC) is important pathogen that cause serious losses to sound development of the poultry industry. Recent study showed the type VI secretion system-2 (T6SS-2) make the pathogenicity of APEC more complex, while the pathogenicity and mechanism of T6SS-2 effector protein on chicken tracheal epithelium cell is unclear. To research the pathogenic mechanism of Hcp in the APEC isolated strain named AE17, which is isolated in our group, we construct APEC-Hcp mutant strain with red recombination system and evaluate its biological characteristics. The chicken tracheal epithelium cell and chick model infected through trachea are used to observe pathogenic mechanism of Hcp in tracheal epithelium cell. Furthermore, iTRAQ phosphorylation technique is used to verify phosphoprotein effected by Hcp. All the studies are to reveal the pathogenicity of APEC-T6SS-2 effector protein Hcp, and provide not only more effective application foundation for anti-infection through T6SS-2 as the main target, but also provide a new perspective for the prevention and treatment of APEC.