Primate response to immunization with a homologous zona pellucida peptide

Development of a contraceptive vaccine using zona pellucida (ZP) antigens has been hampered by the observation that the immune response to the antigens results in altered ovarian function and depletion of the follicular pool of oocytes. The amino acid sequences of many ZP proteins have been determined in the past decade allowing study of fully synthetic peptide immunogens based on these ZP sequences. Such immunogens permit a precisely targeted response. The non-human primate is the best model for predicting how women may respond to ZP peptide vaccines. Cynomolgus macaques (Macaca fascicularis) have been immunized with synthetic peptides comprising a human ZP3 epitope and a macaque homologue of the same epitope. In both studies, immune response to the peptides was initiated, and infertility was accompanied by normal ovarian function.