基于抗原表位预测的MUC1模拟肽表位筛选

Screening of mimic epitope for MUC1 based on prediction of the antigenic epitope

目的:预测粘蛋白1(Mucin1,MUC1)抗原的B细胞表位,从噬菌体随机多肽文库筛选及鉴定MUC1抗原的模拟表位。方法:对MUC1的二级结构及免疫原性进行分析,预测MUC1的抗原表位。利用纯化获得的Ma695抗体筛选噬菌体随机12肽库,夹心ELISA分析噬菌体克隆,测定阳性克隆DNA序列,竞争性抑制实验鉴定阳性噬菌体克隆。结果:MUC1存在有17个潜在的抗原表位区域。经3轮筛选,获得了14个阳性克隆,DNA序列分析并推导出其氨基酸序列:KHYDPFHHRMPQ,QADTARSVALAG,VPSKPDLHVRSI及MTPIHYWNHNRV;4个噬菌体展示肽克隆抑制率均在50%以上。结论:预测MUC1抗原B细胞表位,为进一步研究MUC1结构和功能奠定了基础。所得序列KHYDPFHHRMPQ,QADTARSVALAG,VPSKPDLHVRSI及MTPIHYWNHNRV能模拟MUC1抗原表位。

Objective：To predict the B cell epitope for MUC1 antigene and screen the mimic epitope of MUC1 from random phage dispay peptide library. Methods：In order to predict the B cell epitope for MUC1 antigen,the secondary structure and antigenicity was analysed with various methods. The purified Ma695 Ab was used to screen in phage random 12 peptide library. The positive clones were identified by sandwich ELISA and competitive inhibiton assay. Results：17 distinct antigenic epitope regions in MUC1 were identified by computation. 14 positive clones were acquired after 3 rounds of screening. Amino acid sequences deduced from DNA sequences showed four different sequences：KHYDPFHHRMPQ,QADTARSVALAG,VPSKPDLHVRSI and MTPIHYWNHNRV. The inhibitory assay showed that the 4 mimic epitope peptides displaying on the phage surface could effectively inhibit the combination of antibody with antigen and the inhibitory rates of each mimic epitope were 50% higher than that in the controls. Conclusion： Prediction of the B cell epitope for MUC1 can provide a basic clues for studies on structure and function of MUC1. The results indicated that KHYDPFHHRMPQ,QADTARSVALAG,VPSKPDLHVRSI and MTPIHYWNHNRV are the mimotopes which could mimic the epitope of MUC1.