口蹄疫（FMD）的爆发给畜牧业带来严重危害。接种疫苗未能提供足够的免疫保护力。因此，研究FMD疫苗佐剂以提高其免疫原性具有重要意义。清热解毒法是中兽医治疗FMD的重要手段。前期研究发现，口服清热解毒中药马齿苋的活性成分多糖（POL-P3b）能提高机体免疫力、降低体内毒素。本项目拟对POL-P3b扶正祛邪特点，结合前期研究，针对免疫应答的主要启动者树突状细胞（DC），综合应用流式细胞术、ELISA、免疫组化、qRT-PCR、Western blot 和ChIP等方法，阐释POL-P3b的FMD疫苗佐剂作用及增强FMD疫苗免疫应答的机制。由于口服大分子多糖佐剂体内消化吸收机制仍然存在许多现有理论未能解释的瓶颈问题，本研究进一步通过高效液相色谱法（HPLC）、多糖荧光标记和荧光共振能量转移（FRET）等技术，体内外实验揭示小肠细胞摄取POL-P3b的机制，为研究口服多糖佐剂体内吸收提供理论依据。

The outbreak of foot-and-mouth disease (FMD) has led to serious damage to animal husbandry. Vaccination failed to provide enough immune protection. Therefore, it is great significance to study FMD vaccine adjuvants for enhancing the immunogenicity. Heat-clearing and detoxifying method is an important means of Chinese Veterinary Medicine for FMD. The preliminary study has found that oral administration of polysaccharide (POL-P3b) extracted from Portulaca oleracea L., a kind of heat-clearing and detoxifying Chinese medicine, could improve the body’s immune function and reduce the toxin in vivo. According to the Fuzheng Quxie characteristics of POL-P3b, and combined with previous research, this project intends to elucidate the activities of POL-P3b as FMD vaccine adjuvants and the mechanism of enhanced immune response. This research is mainly to dendritic cells (DC), which is the important starter in the immune response. The techniques and methods, involving in flow cytometry, ELISA, immunohistochemistry, qRT-PCR, western blot and chromatin immunoprecipitation assay (ChIP), will be used to confirm that POL-P3b had activities of regulating the immune function. The digestion and absorption mechanism in vivo for macromolecular polysaccharide adjuvants still exists many the bottleneck problem of existing theory fails to explain. This study further to reveal the absorption mechanism of POL-P3b on small intestinal cells in vivo and in vitro by high performance liquid chromatography (HPLC) , fluorescent labeled polysaccharide and fluorescence resonance energy transfer（FRET）techniques. These data will provide theoretical basis for the absorption study of oral polysaccharides adjuvants in the body.