PEDV保护性抗原树突细胞靶向融合肽诱导黏膜免疫的分子机制

猪流行性腹泻病毒（PEDV）具有肠道黏膜感染和免疫特点，探索以肠道黏膜免疫的口服疫苗对防治本病具有科学意义，但口服疫苗黏膜免疫应答水平低，保护性差，存在一定缺陷。如何提高黏膜疫苗免疫功效是需要攻克的科学难题。本研究的前期工作将PEDV保护性抗原与树突细胞（DCs）靶向肽融合表达于猪乳酸杆菌表面，以此口服免疫小鼠和猪，从功能上证明靶向疫苗具有提高免疫应答水平。在本项研究中，进一步探讨其免疫的分子机制。以表达PEDV保护性抗原靶向与非靶向融合肽乳酸菌为材料，体外培养肠道DCs，不同抗原肽刺激DCs后，测定DCs对抗原吞噬、处理加工、呈递等关键环节的免疫分子、免疫细胞数量和表型变化以及免疫细胞对乳酸菌载体免疫耐受的分子基础，分析并揭示免疫分子和免疫细胞相互协调、相互制约的免疫网络关系，为充分挖掘黏膜免疫资源，精确设计黏膜疫苗提供理论依据，为猪流行性腹泻和其他相关黏膜感染疾病免疫预防提供新思路。

Porcine epidemic diarrhea virus (PEDV) is infected through the small intestional mucosal routes, so the mucosal immunity is important for the control of the disease. Vaccines with improved efficacy are needed to effectively control PEDV infections. It is a common fact that oral vaccines have low mucosal immune response and poor immune protection, and it is also an important scientific issue to improve the immune efficacy of mucosal vaccine. We previously reported the preparation of recombinant lactobacillus expressing PEDV immunological protective antigen with dendritic cells (DCs) targeting peptides, and oral immunization with mice and pigs could significantly enhance the immune response level. In this study, recombinant Lactobacillus strains expressing PEDV immunoprotective antigen targeting and non-targeting fusion peptide were used for the materials for the immunogen, and DCs were co-cultured with different antigen peptides expressed the surfaces of the Lactobacillus. After DCs were stimulated with different antigen peptides, the morphology of dendritic cells phagocytizing antigen is observed and the phenotypic characteristics are determined, After antigen processing and presentation to lymphocyte, immune molecules in the surfaces of the immunocyte and the cytokines associated with macrophages or T and B lymphocytes were detected , the number and phenotype of immune cells determined. After immunization of pigs with different antigen peptide lactobacillus, the types of antibody producing cells, the subclasses of antibodies and the level of antibody production were detected, meanwhile, the immune tolerance is explored for the immune system to Lactobacillus vector. After all the information about the immune network relationship between immune molecules and immune cells are collected and analyzed , It provides us for fully excavating mucosal immune resources and accurately designing mucosal vaccines, and also provides a new idea for preventing porcine epidemic diarrhea and other related mucosal diseases.