Selection of phage-display peptides that bind to cucumber mosaic virus coat protein

Several discrete peptides that bind specifically to the coat protein of cuc umber mosaic virus (CMV) were isolated from a diverse phage library display ing random nonapeptides on the major coat protein VIII. Enrichment was show n by polyclonal phage enzyme linked immunosorbent assay (ELISA) after three rounds of selection. Sequencing of the genes encoding 10 of these peptides revealed an absence of any conserved motifs, although nine of them contain ed a high proportion of proline residues. Some of the selected peptides wer e displayed at the N-terminus of thioredoxin and expressed in the cytoplasm of Escherichia coli. Both the phage-displayed and thioredoxin-fusion versi ons of the peptides could detect purified CMV and CMV present in crude leaf extracts from infected plants. By dot blot analysis, a thioredoxin-peptide fusion could readily detect as little as 5 ng of CMV. The peptides did not bind to other plant viruses. These peptides have been shown to be specific and highly sensitive tools in the detection of CMV and, as well as their d iagnostic potential, they could form the basis for a novel disease resistan ce strategy. (C) 1999 Elsevier Science B.V. All rights reserved.