CONVERGING ANTIGENIC STRUCTURE OF A RECOMBINANT VIRAL PEPTIDE DISPLAYED ON DIFFERENT FRAMEWORKS OF CARRIER PROTEINS

A peptide reproducing the G-H loop amino acid sequence of foot-and-mou th disease virus VP1 protein was fused to the solvent-exposed C-termin us of the bacteriophage P22 tailspike protein [Carbonell and Villaverd e (1996) Gene, in press], a homotrimeric polypeptide with a strong bet a-helical structure. This fusion does not interfere with the biologica l activities of the phage tail, The antigenic profile of the complex a ntigenic site A within the G-H loop has been determined by competitive ELISA with a panel of monoclonal antibodies directed against differen t overlapping B-cell epitopes, The antigenic data have been compared w ith those obtained with a set of 12 chimeric beta-galactosidases displ aying the G-H loop on different exposed regions, A high coincidence ha s been evidenced between the antigenicity of the viral peptide fused t o the phage protein and that of some peptides inserted in an exposed l oop of the activating interface of beta-galactosidase, This indicates that completely different structural frameworks of carrier proteins ca n provide similar constraints that allow the recombinant peptide to su ccessfully mimic the antigenicity, and probably conformational feature s, of the natural peptide on the virion surface.