新型幽门螺杆菌多肽纳米疫苗的构建及其免疫保护效应的实验研究

Helicobacter pylori (H. pylori) is the major causative factor of gastritis, peptic ulcers, also closely related to the occurrence of gastric cancer and mucosa-associated lymphoid tissue lymphoma (MALT). Great efforts have been made to develop H. pylori vaccine worldwide, but those candidate vaccines were still with limited in protective effect. We identified an immunodominant CD4+ T cell epitope, HpaA88-100, restricted to HLA-DRB1*1501 in our previous study. The CD4+ T cell responsing specific to HpaA88-100 reduced the risk of gastric disease in H. pylori infected subjects. However, the peptides used as vaccine are susceptible to enzymatic hydrolysis resulting in low bioavailability, and the immunogenicity is poor too. Therefore, how to improve the stability and immunogenicity of peptide vaccines is the key to the success of the vaccine. In recent years, increasing attention is paid to nanotechnology in clinical. Nano adjuvant could enhance the immunogenicity of the antigen. The research group's pre-prepared nanoemulsion has good stability. This study perform the novel nanotechnology (using PLGA prepared nanoparticles, and its surface modified with CS, wrapping the epitope) to prepare the Hp novel nano polypeptide vaccine, in order to improve its immunogenicity and duration in vivo,enhance the immune protective effect of the vaccine. This study will provide a theoretical basis for clinical applications of Hp multiple-peptide nano vaccine.

幽门螺杆菌(Hp)是胃炎?胃溃疡等胃部疾病的主要致病因素,与胃癌?MALT等疾病的发生密切相关?全球已经广泛开展HP疫苗研究,但是这些疫苗的免疫保护效果都十分有限?本课题前期筛选得到一个Hp保护性抗原HpaA来源的HLADRB1*1501限制性CD4+T细胞免疫优势表位HpaA88-100,并证实该表位诱发的特异性CD4+T细胞能降低Hp感染者患胃部疾病的风险?但多肽疫苗免疫原性弱，易被酶解致使免疫保护效应低下。因此如何提高多肽疫苗的稳定性和免疫原性是疫苗能否成功的关键。近年来纳米技术日益得到重视，纳米佐剂可以增强抗原的免疫原性。课题组前期制备的纳米乳佐剂具有较好的稳定性。本课题拟运用新型纳米技术(使用PLGA制备纳米粒,并用CS对其表面进行修饰,包裹该表位多肽)制备Hp新型纳米多肽疫苗,以提高疫苗的免疫原性和作用时间，增强疫苗的保护效应?本课题将为Hp多肽纳米疫苗的临床应用提供理论依据。

幽门螺杆菌(Hp)是胃炎､胃溃疡等胃部疾病的主要致病因素,与胃癌､MALT等疾病的发生密切相关｡本课题前期筛选得到一个Hp保护性抗原HpaA来源的HLADRB1*1501限制性CD4+T细胞免疫优势表位HpaA88-100,并证实该表位诱发的特异性CD4+T细胞能降低Hp感染者患胃部疾病的风险｡但多肽疫苗免疫原性弱。本课题拟运用新型纳米技术(使用PLGA制备纳米粒,并用CS对其表面进行修饰,包裹该表位多肽)制备Hp新型纳米多肽疫苗,以提高疫苗的免疫原性和作用时间，增强疫苗的保护效应｡因PLGA纳米颗粒的鉴定花费的时间太多，效果都无法令人满意，因此制备了纳米乳多肽疫苗，制备完成，无毒稳定。由于本课题HLA-DRB1*1501转基因小鼠制备失败，无法做纳米乳多肽疫苗的体内保护性评价工作。因此本课题组对人和小鼠MHC限制性HpaA的免疫优势表位进行筛选。研究发现非HLA-DRB1*1501 HP感染人群中，HpaA142-159作为免疫优势表位出现频率最高，HpaA142-159受HLA-DRB1*0901限制，其特异性CD4+T细胞在HLA-DRB1*0901个体中处于免疫优势地位，能被抗原递呈细胞自然加工递呈，且在不同HP菌株蛋白序列中高度保守，可用于HP表位疫苗的设计。上述研究结果发表在《Oncotarget》杂志（影响因子为5.008）。此外，筛选得到了小鼠的H-2d(I-A)限制性HpaA免疫优势表位HpaA154-171，体外实验证实用肽联合CpG免疫能引起强烈的CD4+T细胞应答，通过减少小鼠胃HP的定植量，保护其免受HP的感染。课题组将进一步对该表位的纳米化进行研究，尝试制备PLGA纳米疫苗并在普通的小鼠中评价其免疫保护效果。本课题培养博士生1名，硕士生2名。课题其他相关研究论文正在撰写中，希望能发表SCI论文1篇，中文文章1篇。