Identification of mimotope peptides which bind to the mycotoxin deoxynivalenol-specific monoclonal antibody

Monoclonal antibody 6F5 (mAb 6F5), which recognizes the mycotoxin deoxyniva lenol (DON) (vomitoxin), was used to select for peptides that mimic the myc otoxin by employing a library of filamentous phages that have random 7-mer peptides on their surfaces. Two phage clones selected from the random pepti de phage-displayed library coded for the amino acid sequences SWGPFPF and S WGPLPF. These clones were designated DONPEP.2 and DONPEP.12, respectively. The results of a competitive enzyme-linked immunosorbent assay (ELISA) sugg ested that the two phage displayed peptides bound to mAb 6F5 specifically a t the DON binding site. The amino acid sequence of DONPEP.2 plus a structur ally flexible linker at the C terminus (SWGPF-PFGGGSC) was synthesized and tested to determine its ability to bind to mAb 6F5. This synthetic peptide (designated peptide C430) and DON competed with each other for mAb 6F5 bind ing. When translationally fused with bacterial alkaline phosphatase, DONPEP .2 bound specifically to mAb 6F5, while the fusion protein retained alkalin e phosphatase activity. The potential of using DONPEP.2 as an immunochemica l reagent in a DON immunoassay was evaluated with a DON-spiked wheat extrac t. When peptide C430 was conjugated to bovine serum albumin, it elicited an tibody specific to peptide C430 but not to DON in both mice and rabbits. In an in vitro translation system containing rabbit reticulocyte lysate, synt hetic peptide C430 did not inhibit protein synthesis but did show antagonis m toward DON-induced protein synthesis inhibition. These data suggest that the peptides selected in this study bind to mAb 6F5 and that peptide C430 b inds to ribosomes at the same sites as DON.