Phage-displayed peptides as biosensor reagents.

This study investigated the potential to utilize phage-displayed peptides as reagents in sensor applications. A library of random 12-mers displayed on phage was panned against staphylococcal enterotoxin B (SEB), a causative agent of food poisoning. Nine SEB binding phage clones were isolated, all of which share the consensus sequence Trp His Lys at their amino terminus. Binding of several of these phage was shown to be inhibited when they were assayed in a competitive enzyme-linked immunosorbent assay (ELISA) format with synthesized peptide corresponding to the peptide-encoding region of one of the clones. Whole phage were labeled with the dye Cy5, and incorporated into fluoroimmunoassays. Labeled phage were able to detect SEB down to a concentration of 1.4 ng/well in a fluorescence-based immunoassay. When incorporated into an automated fluorescence-based sensing assay, Cy5-labeled phage bound to probes coated with SEB generated a robust signal of about 10,000 pA, vs a signal of 1,000 pA using a control fiber coated with streptavidin. These results demonstrate the potential for development of phage-based sensor reagents.