Antigenicity and immunogenicity of P30-derived peptides in experimental models of toxoplasmosis

Abstract P30, also referred to as SAG-1, is now recognized as a major Toxoplasma gondii antigen potentially important for both diagnosis and immunoprophylaxis of toxoplasmosis. By using predictive algorithms, five synthetic peptides (48–67, 82–102, 213–230, 238–256 and 279–285) derived from P30, were investigated for B- and T-cell determinants in mouse and rat experimental models. Antibody recognition appeared more broadly distributed along the P30 sequence, whereas T-cell recognition was mainly targeted on the 238–256 peptide. In the absence of any carrier protein, this peptide induced a B- and T-cell immune response independent of the route of immunization (oral route or subcutaneous injection). This peptide (238–256) induced multiple antibody isotypes. In contrast with the 238–256 peptide, the 48–67 peptide, either free or in the form of a multiple antigenic peptide (MAP) construct or the 279–295 peptide, elicited antibodies associated with a TH2 response. This study reports for the first time the analysis of the antigenic and immunogenic properties of P30-derived peptides and are potentially useful for vaccinal strategies incorporating the P30 Toxoplasma gondii antigen.