Objective: To screen phage particles capable of mimicking ochratoxin A and establish immunoassay for ochratoxin A with it.
Methods: An anti-ochratoxin A monoclonal antibody was used as ligand. Biopanning was done to screen the mimicking epitope 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, the inserted amino sequences were deduced by DNA sequencing.
Results: After four rounds of panning, 11 positive clones can bind to the antibody, and the binding can be blocked the free ochratoxin A. The common amino sequence of the mimicking epitope is IRPMVXX. A competitive ELISA immunoassay was established with clone P2, the linear range of the inhibition curves is between 200 pg/ml and 8000 pg/ml, the detecting limitation is 150 pg/ml.
Conclusion: The phage display technique can be successfully applied to screen the mimicking epitope of ochratoxin A. The acquired phages may be used as the surrogate of the toxin to establish the immunoassay.