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.