M细胞靶向性细菌样颗粒黏膜投递系统BLPs-peSAM辅助幽门螺旋杆菌多价表位疫苗的免疫效果及机制研究

口服疫苗需要一种有效避免胃酸降解、促进胃肠道M细胞摄取抗原的黏膜投递系统。前期设计了二种可靶向M细胞的乳酸菌表面展示系统：重组乳酸菌系统LL-plSAM和细菌样颗粒系统BLPs-peSAM。已证实以LL-plSAM辅助Hp多价表位疫苗，制备重组乳酸菌疫苗，具有良好的M细胞靶向性，但重组乳酸菌分泌表达能力欠佳、表面展示密度较低，且含抗性质粒。理论上，BLPs-peSAM的抗原表面展示能力更强，安全性更高，本项目拟进一步研究其黏膜投递效果和佐剂分子机制：1）在LL-plSAM基础上，构建BLPs-peSAM，通过免疫荧光染色、全细胞ELISA等技术研究其抗原表面展示和M细胞靶向性。2）以BLPs-peSAM辅助Hp多价表位疫苗，制备细菌样颗粒疫苗，研究其防治Hp感染的效果，并阐明BLPs-peSAM的佐剂分子机制。此项目为我国研制出具有自主知识产权的乳酸菌黏膜投递系统奠定理论依据和实验基础。

Oral vaccines require a delivery system that effectively avoids antigen degradation in gastric acid and promotes antigen uptake in M cells. Two M cell-targeting surface display system of lactic acid bacteria, Recombinant lactobacillus mucosal delivery system LL-plSAM and Bacteria-like particles mucosal delivery system BLPs-peSAM (Dead lactic acid bacteria), were designed in previous studies. Our experimental results confirmed that the recombinant lactobacillus vaccine, which were prepared by using LL-plSAM to assist H. pylori multivalent epitope vaccine, have good M cell-targeting property. However, recombinant lactic acid bacteria have poor capacity of secretory expression, low surface display density, and contain resistant plasmids. Theoretically, compared to LL-plSAM, the BLPs-peSAM system has stronger surface display ability, better mucosal delivery efficiency and higher security. This project prepares to further study the immune effects and adjuvant molecular mechanism of BLPs-peSAM. Firstly, the BLPs-peSAM system will be constructed on the basis of LL-plSAM, and the antigen surface display and M cell-targeting property of BLPs-peSAM will be explored by immunofluorescence staining, whole cell ELSIA and other techniques. Secondly, the bacterial-like particle vaccines will be prepared by using the BLPs-peSAM system to assist H. pylori multivalent epitope vaccine, and its control efficiency against H. pylori infection and the adjuvant molecular mechanism of the BLPs-peSAM system will be further explored. This project is aiming to provide theoretical and experimental basis for the development of lactic acid bacteria mucosal delivery system with independent intellectual property rights in China.