MUC1抗原的表位预测及模拟位的筛选

目的预测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抗原的模拟位.方法联合运用多种方法对MUC1的二级结构和表面特性,如理化性质、亲水性、可塑性、溶剂可及性及免疫原性等方面进行分析,预测MUC1的抗原表位.利用纯化获得的BC2抗体筛选噬菌体随机7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存在有多个潜在的抗原表位位点,可能的蛋白质抗原表位区域:1-10,24-54,65-77,84-91,108-134,140-156,159-174,179-196,199-210,220-233,237-265,270-299,316-337,351-362,369-396,411-420,445-502.经3轮筛选,获得了30个阳性克隆,DNA序列分析并推导出氨基酸序列:TAPDLRP、SAPDLRP、AAPDSRP及LAPDFRP 4个噬菌体展示肽克隆抑制率均在50%以上.结论应用多参数预测MUC1抗原的B细胞表位,为进一步研究MUC1结构和功能、选择表达新型MUC1分子奠定了基础.所得序列TAPDLRP、SAPDLRP、AAPDSRP及LAPDFRP模拟MUC1抗原表位.

Prediction of the epitope and screening of mimic epitope for MUC1

Objective To predict the B cell epitope for MUC1 antigene and screen the mimic epitope of MUC1 from random phage display peptide library.Methods In order to predict the B cell epitope for MUC1 antigene,the secondary structure and surface properts of MUC1 such as physics and chemical characters,hydrophilicity,antigenicity and so on was analyged with various methods. The purified BC2 Ab was used to screen in phage random 7 peptide library. The positive clones were identified by sandwich ELISA,competitive inhibiton assay.Results Many distinct antigenic epitopes in MUC1 were identified by computation:1-10,24-54,65-77,84-91,108-134,140-156,159-174,179-196,199-210,220-233,237-265, 270-299, 316-337, 351-362, 369-396,411-420,445-502. 30 positive clones were acquired after 3 rounds of screening. Amino acid sequences deduced from DNA sequences showed four different sequences: TAPDLRP,SAPDLRP,AAPDSRPand LAPDFRP. 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 the control.Conclusions 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 TAPDLRP,SAPDLRP,AAPDSRPand LAPDFRP are the mimotopes which could mimic the epitope of MUC1.