幽门螺杆菌黏附素A抗原H-2~d(I-A)限制性免疫优势Th表位的筛选与鉴定

目的鉴定幽门螺杆菌(Helicobacter pylori,H.pylori)黏附素A抗原(HpaA)H-2d限制性免疫优势Th表位,为H.pylori表位疫苗的研究提供候选表位。方法采用体外扩增的HpaA抗原特异性T细胞和步移重叠合成肽筛选鉴定HpaA抗原的免疫优势Th表位,再利用抗体阻断实验对其H-2d限制性进行分析。结果 18mer氨基酸肽段筛选发现肽段H154-171、H184-201、H190-207、H202-219和H220-237能够激发HpaA特异性CD4+T细胞产生γ-干扰素。其中H154-171激发的应答最强。13mer氨基酸短肽鉴定结果显示:仅H158-170能刺激产生强于18mer氨基酸短肽H154-171的应答反应。同时,抗体阻断试验结果表明:抗H-2d(I-A)抗体能有效阻断该表位激发的应答。结论 H154-171、H184-201、H190-207、H202-219和H220-237是HpaA的小鼠H-2d限制性Th表位,其中H154-171为免疫优势表位肽,该表位的核心氨基酸序列为H158-170,并存在H-2d(I-A)限制性。该研究将为H.pylori表位疫苗研究提供了可能的候选分子。

Identification and characterization of H-2~d(I-A) restricted immunodominant Th epitopes from HpaA of Helicobacter pylori

With the aim of design epitope-based vaccine against Helicobacter pylori(H.pylori),we identified and characterized H-2d restricted immunodominant Th epitopes from HpaA of H.pylori in this study.Immunodominant Th epitope of HpaA was identified by using in vitro expanded HpaA-specific T cells and overlapping synthetic peptides.And then,the H-2d subtype restriction of the epitope was analyzed by antibody blocking test.Mapping of 18 mer overlapping peptides showed that H154-171,H184-201,H190-207,H202-219 and H220-237 could stimulate HpaA-specific T cells to produce IFN-γ,and the response stimulated by H154-171 was the strongest.Mapping of 13 mer overlapping peptides showed that only H158-170 could stimulate an equivalent HpaA-specific T cell response with H154-171.Antibody blocking test showed that epitope H158-170 was restricted by H-2d(I-A).H154-171,H184-201,H190-207,H202-219 and H220-237 were H-2d restricted epitopes of HpaA,of which H154-171 was the immunodominant one,its core sequence was H158-170 and its restriction molecule was H-2d(I-A).All the result indicated that the epitope could be used for epitope-based vaccine design.