幽门螺杆菌脂多糖核心十一糖的全合成及其免疫活性研究

Helicobacter pylori is a stomach pathogen that infects the large global population and accounts for high attributable risk on gastric cancer. Although antimicrobial therapies for H. pylori infection have been widely applied, antibiotic resistance and high rate of reinfection in patients have become problematic. Therefore, development of vaccine for human against H. pylori infection has been an extremely urgent task. Significantly, the structurally unique and conserved core oligosaccharide of H. pylori lipopolysaccharide (LPS) has been identified as a potential antigen for the glycan-based vaccine. This study aims to explore the detailed relationship of the core oligosaccharide structures of H. pylori LPS and their immunological activity. First, a core oligosaccharides library including different length and modified functional groups of saccharide chains will be constructed with well-defined structures. Then, the immunological properties of these oligosaccharides will be determined and analyzed after immunization by carbohydrate microarray. Saturation-Transfer Difference (STD)-NMR will be applied to analyze antigen-antibody interactions to further optimize antigen structures. This study will elucidate the relationship of structure and immunogenicity of H. pylori core undecasaccharide fragments, which can support future development of H. pylori vaccine.

幽门螺杆菌作为一种人类消化道致病菌，感染人群高，与胃癌发生的关系密切。传统的抗生素治疗虽可降低病原菌感染率，但不断提高的耐药性和重复感染率使得疫苗开发迫在眉睫，而目前没有上市的幽门螺杆菌疫苗。幽门螺杆菌细胞表面脂多糖核心十一糖具有高度的结构特异性和保守性，其天然提取物具有显著的免疫原性，是潜在的免疫靶点。本课题拟以幽门螺杆菌脂多糖核心十一糖为免疫靶点，通过化学合成法制备外核心八糖、内核心三糖和核心十一糖，以及综合糖链结构、糖链长度和修饰基团三方面设计与合成结构明确均一的核心寡糖片段，并构建成库用于寡糖抗原和免疫原性的系统分析；结合糖芯片和饱和转移差谱核磁共振技术（STD-NMR），通过血清筛查和免疫学实验，明确幽门螺杆菌脂多糖核心寡糖的重要免疫表位，并从分子水平上阐明寡糖结构与免疫原性的关系，从而为幽门螺杆菌的糖缀合疫苗开发以及免疫治疗研究奠定理论基础。

幽门螺杆菌作为一种人类消化道致病菌，感染人群高，与胃癌发生的关系密切。传统的抗生素治疗虽可降低病原菌感染率，但不断提高的耐药性和重复感染率使得疫苗开发迫在眉睫，而目前没有上市的幽门螺杆菌疫苗。幽门螺杆菌脂多糖核心十一糖具有高度结构特异性和保守性，且具有显著的免疫活性，是潜在的免疫靶点。本研究项目发展了糖链序贯化和模块化组装策略，整合糖芯片、多糖提取、动物免疫和单克隆抗体制备等技术构建了完整的糖疫苗生物活性研究平台。明确了立体位阻对幽门螺杆菌脂多糖核心十一糖组装的影响，通过序贯化组装[2 + (1 + (3 + (1 + (1 + 3))))]完成了核心十一糖的首次化学合成，从单糖组成、糖链长度和修饰基团三方面出发制备了糖链片段库；利用糖芯片技术开展了幽门螺杆菌脂多糖核心寡糖的抗原性分析，明确了α-1,6-葡聚三糖和磷酸基团是这一重要致病菌糖链的关键抗原表位。进一步完成了其它4种致病菌糖链抗原的高效合成和免疫活性研究。上述研究成果将为幽门螺杆菌等致病菌糖疫苗的创制奠定基础。