恶性疟原虫感染的红细胞膜表面蛋白1模拟肽的筛选及鉴定

Screening and Preliminary Identification of Mimetic Peptides of Plasmodium falciparum,Infected Erythrocyte Membrane Surface Protein 1

目的筛选恶性疟原虫感染的红细胞膜表面蛋白1(PfEMP-1)的噬菌体表位模拟肽。方法细胞间粘附分子ICAM-1模拟12肽(KLYLIAEGSVAA)能模拟ICAM-1分子与疟原虫感染红细胞结合的功能,以展示该短肽的噬菌体为靶,采用差减筛选法(subtraction method)对噬菌体环7肽库进行3轮筛选,通过ELISA、竞争抑制试验鉴定获得的噬菌体短肽与ICAM-1之间的结合特性。对阳性克隆进行DNA及氨基酸序列分析并与PfEMP-1氨基酸序列进行同源性比较。结果ELISA筛选22个克隆有3个为阳性克隆,氨基酸序列分析显示2个克隆的展示的短肽序列为C-ITAVPVR-C,另1为C-DIMGGYN-C。同源性分析未发现2短肽序列与野生型MC株恶性疟原虫PfEMP-1的氨基酸序列有同源性。但竞争抑制试验显示3个阳性克隆均可与15.2单抗间互相竞争抑制与ICAM-1分子的结合。结论获得2种PfEMP-1噬菌体构象表位模拟肽,两短肽能与ICAM-1分子特异性结合。

Objective To screen and identify mimetic peptides of Plasmodium falciparum-infected erythrocyte membrane surface protein 1 in order to explore anti-adhesive agent against cerebral malaria. Methods Phage-borne peptide KLYLIAEGSVAA was used as panning targets to select target binders in a disulfide-constrained heptapeptides library. Three rounds of biopanning were carried out and then ELISA and competitive ELISA were used to evaluate the binding character between phage-borne peptides and ICAM-1. The insert DNA sequences of positive clones were determined and their amino acid sequences were deduced. Results After three-round panning, 22 clones were randomly chosen from the third panning and analyzed. Three clones showed positive interaction with ICAM-1, and two of them possessed the amino acid sequence C-ITAVPVR-C, the other one was C-DIMGGYN-C. These peptides specifically inhibited the binding of 15.2 antibody to ICAM-1 detected by competitive ELISA. Conclusion Two kinds of mimetic peptides of PfEMP-1 have been obtained, which can bind with ICAM-1 specifically.