Ability of linear and cyclic peptides of neutralization antigenic site 1 of poliovirus type 1 to induce virus cross-reactive and neutralizing antibodies.

Eight peptides encompassing neutralization antigenic site 1 of poliovirus type 1 (residues 93-103 of VP1) were synthesized in linear or cyclized form and used to immunize rabbits. The resulting anti-peptide antibodies were tested for their ability to react with linear peptide 95-104, with infectious virus D-particles and heated C-particles and for their capacity to neutralize poliovirus infectivity. A good correlation was observed between the ability of different peptide antisera to immunoprecipitate D-particles and neutralize virus infectivity. The peptides that induced a neutralizing antibody response in the highest number of immunized animals contained flanking residues 104-115 in addition to the 93-103 residues of the epitope. However, a high neutralizing antibody titre was also obtained in two of ten animals immunized with peptide 93-104 cyclized via an amide bond between Asp93 and Lys103. It seems, therefore, that, at least in rabbits, the T-cell epitope recently identified in residues 103-115 of VP1 need not be present in the peptide immunogen in order to obtain poliovirus-specific neutralizing antibodies.