禽源肺表面活性蛋白A（cSP-A）是来源于鸡肺上皮细胞分泌的一种亲水性、膜表面糖蛋白, 具有抗病原微生物的天然免疫功能。禽致病性大肠杆菌（APEC）是引起家禽呼吸道感染的主要病原菌，而有关cSP-A抗APEC感染的研究尚未见报道。为探讨cSP-A肺部靶向抗APEC感染的作用机制，首先，拟通过构建噬菌体纳米抗体文库，筛选抗cSP-A纳米抗体；继而，利用cSP-A纳米抗体，通过活体荧光成像技术确定cSP-A作用于鸡呼吸系统的靶点；然后，构建cSP-A单独缺失不同功能区的稳定细胞株，观察各细胞株与APEC的粘附情况，分析抗APEC的cSP-A结构域；最后，通过建立APEC感染鸡巨噬细胞系模型和雏鸡APEC肺感染模型，分别从细胞水平和活体水平探明cSP-A通过抑制TLR4-NF-κB信号途径抗APEC的作用机制，为靶向抗APEC感染提供新思路。

Chicken surfactant protein A (cSP-A) is a hydrophobic and membrane surface glycoprotein believed to play an important role in innate immunity against microorganism infection. Avian pathogenic Escherichia coli (APEC) is a main pathogenic bacteria causing respiratory infection. However, no one article that study cSP-A against APEC infection. In order to study the mechanism of cSP-A targeting against APEC infection, firstly, the anti-cSP-A nanobodies will be screened by using the solid-phase method of phage antibody library. Secondly, the target sites of cSP-A in the respiratory tract of chicken will be observered by animal living imaging technique. Thirdly, in order to confirm the functional domains of cSP-A recognizing APEC, the cell lines that deletion of different functional regions or motif were constructed to observe the adhesion between the cell lines and APEC. By establishing models of macrophage cell line and SPF chickens infected with APEC, the mechanism of cSP-A exerting its anti-APEC effect through inhibiting the activity of NF-κB in the TLR4-NF-κB signaling pathway will be explored.This research will provide a new perspective for the lung-targeting against APEC infection.