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.