Immunocontraception of the feral horse: Comparison of PZP and PZP-KLH vaccine formulations

Porcine zona pellucida (PZP) and PZP-keyhole limpet hemocyanin conjugate (PZP-KLH) antigens were studied for inclusion in immunocontraceptive vaccine protocols in horses and mice. Captive feral mares were randomly assigned to the following treatment groups: KLH in FCA/PBS in FIA/PBS in FIA, PZP in FCA/PZP in FIA/PZP in FIA, PZP-KLH in FCA/PZP-KLH in FIA/PZP in FIA, PZP-KLH in FIA/PZP in FIA/PZP in FIA, or PZP-KLH in FIA/PZP-KLH in FIA/PZP in FIA. All mares immunized with PZP and/or PZP-KLH exhibited anti-PZP IgG antibody titers significantly higher than KLH negative controls. No immunization protocol tested interfered with ovulatory cycles in mares as determined by fecal ovarian hormone analysis. Treatment groups immunized with PZP in FCA/PZP in FIA/PZP in FIA and PZP-KLH in FIA/PZP in FIA/PZP in FIA had significantly reduced pregnancy rates compared to KLH negative controls. Inhibition of fertility correlated with high anti-PZP IgG antibody titers, particularly with high percentages of IgGa and IgG(T). Delayed-type hypersensitivity skin test results and anti-KLH IgG antibody titers were not associated with pregnancy status.; Mice were randomly assigned to the following treatment groups: PBS in FCA/PBS in FIA/PBS in FIA, KLH in FCA/KLH in FIA/KLH in FIA, PZP in FCA/PZP in FIA/PZP in FIA, PZP in FCA/PZP-KLH in FIA/PZP in FIA, PZP-KLH in FCA/PZP KLH in FIA/PZP in FIA, or PZP-KLH in FCA/PZP in FIA/PZP in FIA. All mice immunized with PZP and/or PZP-KLH exhibited anti-PZP IgG antibody titers significantly higher than PBS and KLH negative controls. No immunization protocol tested interfered with ovulatory cycles in mice as determined by vaginal epithelial cytology. All PZP and PZP-KLH immunization protocols significantly inhibited fertility compared to fertility rates in the PBS and KLH negative control groups. Inhibition of fertility was associated with high anti-PZP IgG antibody titers, particularly with high percentages of IgG1 and IgG3. Histological examination of ovaries revealed significantly higher percentages of primary/secondary follicles and corpora lutea/corpora albicans and significantly lower percentages of empty follicles in ovaries of non-pregnant mice, although pre-antral and antral follicles were not significantly different from pregnant mice. Anti-KLH IgG antibody titers were not significantly correlated with pregnancy status.