细胞免疫和体液免疫构成了昆虫先天免疫系统的两个主要分支。前期研究显示某些C型凝集素（CTL）能够作为调理素增强各种细胞免疫反应，如吞噬、集结和包囊，但是对于其增强细胞免疫的作用机理并不清楚。项目组前期已经报道过家蚕基因组所编码的所有C型凝集素的类型和特征，在此基础上，本项目拟以其中4个分泌型CTL（CTL-S2/S3、IML-1/3）为研究对象，构建缺失突变体和定点突变体，通过荧光定位、流式细胞和蛋白印迹分析它们分别与血细胞和细菌的结合，以及对吞噬和包囊的影响，明确序列中参与介导细胞免疫的功能区域和关键位点；通过免疫共沉淀、far-Western和RNAi分析CTL与整合素β亚基成员间的互作关系；通过pull-down联合质谱和糖基化位点分析鉴定CTL的未知膜蛋白受体。本项目有助于揭示C型凝集素参与介导细胞免疫反应的机理，为调控昆虫的免疫系统以达到保护或防治的目的提供理论依据和应用基础。

Cellular immunity and humoral immunity constitute two major branches of the insect innate immune system. Previous studies have shown that some C-type lectins (CTLs) can function as opsonins to enhance various cellular immunity responses, such as phagocytosis, nodulation and encapsulation, but the mechanism by which CTLs enhance cellular immunity is unclear. Our group has reported the classification and features of all CTLs encoded by the Bombyx mori genome. On this basis, this project plans to choose four secreted CTLs (CTL-S2/S3, IML-1/3) as objects of the study. We plan to construct deletion mutants and site-directed mutants to analyze their binding to hemocytes and bacteria, respectively. We will also analyze their effects on phagocytosis and encapsulation by fluorescence localization, flow cytometry and western blotting, to identify the functional domains and key residues that mediate cellular immunity. The interaction between CTLs and integrin β subunit family members will be analyzed by co-immunoprecipitation, far-Western and RNAi. The unknown membrane receptors will be identified by pull-down assay, mass spectrometry and glycosylation assays. This project will help us to uncover the mechanism by which CTLs mediate cellular immunity. And it will provide theoretical and practical foundations for regulating the immune system of insects for purposes of protection or control.