Selecting mimotope of ochratoxin A from phage random peptide library and its application

  Objective   To screen phage particles capable of mimicking ochratoxin A and to establish immunoassay for ochratoxin A with it.

  Methods   An anti-ochratoxin A monoclonal antibody was used as ligand.Biopanning was done to screen the mimotope from a phage random 7 peptide library.This library was displayed as a fusion protein with the coat protein Ⅲ of filamentous phage M13.The positive clones were identified by ELISA, and the inserted amino sequences were deduced by DNA sequencing.

  Results   After four rounds of panning, 11 positive clones could bind to the antibody, and the binding could be blocked by free ochratoxin A.The common amino sequence of the mimicking epitope was IRPMVXX.A competitive ELISA immunoassay was established with clone P2;the linear range of the inhibition curves was between 200 pg/ml and 8 000 pg/ml; the detecting limitation was 150 pg/ml.

  Conclusion   The phage display technique could be successfully applied to screen the mimotope of ochratoxin A.The acquired phages might be used as the surrogate of the mycotoxin to establish the immunoassay.