INDUCTION OF NATIVE PROTEIN REACTIVE ANTIBODIES BY IMMUNIZATION WITH PEPTIDES CONTAINING LINEAR B-CELL EPITOPES DEFINED BY ANTIPORCINE ZP3-BETA MONOCLONAL-ANTIBODIES

To identify pertinent target epitopes for contraceptive vaccine develo pment, rabbit polyclonal antibodies were raised against four peptides synthesized from the deduced amino acid (aa) sequence of porcine zona pellucida macromolecule ZP3 beta and coupled to diphtheria toroid (DT) . Synthetic peptides consisted of: P1, 23-37 aa; P2, 164-179 aa with a n additional C-terminal cysteine; P3, 246-263 aa with an extra C-termi nal cysteine; and P4, 310-321 aa residues corresponding to pZP3 beta p recursor protein. Selected sequences were based upon B cell epitopes i dentified previously by monoclonal antibodies. Immune sera reacted wit h their respective peptides and DT in an ELISA, and also recognized po rcine SIZP and pZP3 beta both in ELISA and Western blot and zona pellu cida of porcine oocytes in an indirect immunofluorescence assay. None of the four anti-peptide sera recognized pZP3 alpha in Western blot, e mphasizing the specificity of these antibodies to pZP3 beta. The anti- peptide sera, individually, failed to inhibit in vitro attachment of b oar sperm to antibody treated zona encased porcine oocytes. However, c ombinations of immune sera against peptides such as P1 + P4, P2 + P4 a nd P1 + P2 + P4, did significantly inhibit porcine sperm-oocyte intera ction. These results identify combinations of peptides that could pote ntially be used in the design of an immunocontraceptive vaccine based upon synthetic peptides corresponding to pZP3 beta or its homologues i n other species. (C) 1997 Elsevier Science Ireland Ltd.