Immunocontraceptive potential of major antigenic determinants of chicken riboflavin carrier protein in the female rat.

Earlier investigations have demonstrated that antibodies generated against the N-terminal (10-17) and C-terminal (200-207) ends of chicken riboflavin carrier protein (RCP; 219 AA), but not towards the internal region (172-179), curtail pregnancy establishment in rodents and sub-human primates. In those studies, epitope peptides conjugated to diphtheria toxoid were used as immunogens. In the present study, linkage of these sequences to extraneous carriers was avoided to rule out the possibility of carrier-mediated suppression of hapten-specific antibody production in long-term immune response. The ability of these three free peptides to function as minivaccines was examined and the functional importance of these sequences in pregnancy establishment in rodents were evaluated. The results obtained reveal that the peptides YGC (residues 3-24) and HAC (residues 200-219) serve as immunocontraceptive vaccines.