Abstract：Purpose: To obtain mimicking epitopes of mAbs against infectious bursal disease virus (IBDV) VP2 using phage display technique, so as to offer basis for further study of their immuno-protection against infectious bursal disease (IBD). Methods: The 12-mer phage random peptide library was screened with four purified mAbs against IBDV-VP2（1B5、5D1、2H11 and I-4-4-3 ) and 40 clones were obtained, among which, 32 positive clones were identified by ELISA.We chosen 20 positive clones for DNA sequence analysis and four ascendant 12-peptides were determined as different epitopes of IBDV-VP2. The four ascendant 12-peptides shared no more than three continuous amino acid residues similar with the sequences of IBDV-VP2 registered in GenBank, and their conjunction with mAbs against IBDV-VP2 can be inhibited by VP2 protein,which indicated that the epitopes were conformation-dependent. When the four mimicking epitopes were expressed tandem, protein r4EPIS was obtained. The results from SDS-PAGE analysis showed that the proportion of r4EPIS was 20% of the total bacterial proteins and the molecular weight was 30 kDa. The r4EPIS showed specificity and reactionogenicity by use of immunoblotting test with polyclonal antibodies. Conclusion: Four conformation-dependent mimic epitopes of mAbs against IBDV-VP2 were obtained by phage display technique.
