弧菌多表位疫苗的构建及其交叉免疫保护效应研究

Vibrio is one of the main pathogens in marine aquaculture. The development of vibrio vaccine is valuable to the healthy and sustainable development of aquaculture. In recent years, a variety of vaccine candidate with good immune protection have been found. Because of the diversity of pathogens and their complicated serotypes, there is no real sense of the broad spectrum of Vibrio vaccine. In our previous study, we found that the outer membrane proteins OmpK, OmpU and LamB are the common antigens among Vibrio species, which have good cross-immunoprotection. They can be used as a versatile vaccine candidate of Vibrio species. Interestingly, several highly conserved epitopes were found in these vaccine candidates, and its immune response range was complementary, which the immune response covered the typical pathogenic bacteria in aquaculture animals. The result suggests that these outer membrane proteins could be used as a candidate for the design of multi-epitope vaccine. Therefore, bioinformatics, molecular biology, immunology and other technologies will be performed to develop a multi-epitope vaccine for the prevention of Vibriosis. Frist, epitopes will de identified from the vaccine candidate. Then, multi-epitope vaccine will be constructed by the complementary dominant epitopes. Finally, the cross-immunoprotective effect of the multi-epitope vaccine will be investigated.

弧菌是海水养殖动物的主要病原之一。弧菌疫苗的研制对水产养殖业的健康持续发展具有重要意义。尽管近年来已发现多种具有良好免疫保护作用的亚单位疫苗候选，但由于弧菌种类多，血清型复杂，目前尚未出现有效的弧菌广谱疫苗。本课题组前期研究发现，外膜蛋白OmpK、OmpU和LamB为弧菌的共同抗原，具有良好的交叉免疫保护性，可以作为弧菌广谱疫苗的候选抗原。有趣的是，三个候选抗原中存在多个高度保守的抗原表位，且其免疫反应谱具有互补作用，其反应范围覆盖了水产养殖动物中典型病原弧菌，可利用三种候选抗原优势表位的互补作用进行弧菌广谱疫苗的设计。为此，本项目拟借鉴表位疫苗的研究思路，利用生物信息学、分子生物学、免疫学等多种技术手段，对候选抗原中的优势抗原表位进行鉴定，在此基础上利用优势表位的互补作用构建具有免疫保护作用的多表位疫苗，并对其在免疫应答过程中的交叉免疫保护效应进行探究，为弧菌广谱疫苗的应用研究奠定基础。

本项目以三种具有交叉免疫保护作用的外膜蛋白——OmpK、OmpU 和LamB为研究对象，通过抗原表位预测技术结合免疫学手段，对候选抗原中的优势抗原表位进行鉴定，利用优势抗原表位的互补作用，构建具有免疫保护作用的多表位疫苗，并对其免疫保护作用进行评价。1）确定了4个在弧菌中保守的优势B细胞抗原表位（K1、K2、B1和B3）；2）发现了两个隐性抗原表位（K7和U2）；3）设计和构建了两种多表位疫苗（EVK-10和EVK-20）；4）获得了多表位疫苗EVK-10的表达产物；5）证实了抗原表位K7可作为多表位疫苗设计的有效靶标。上述成果为弧菌多表位疫苗的设计、构建，以及免疫保护机制的研究提供了科学依据。