Porcine zonae pellucidae immunization of tammar wallabies (Macropus eugenii): fertility and immune responses

This study looked at the feasibility of targeting the zona pellucida for a contraceptive vaccine as a possible alternative method of control for overabundant macropods. Tammar wallabies, as a model for other macropods, were immunized with porcine zonae pellucidae (PZP) and were found to achieve significant concentrations of antibody to PZP in sera and reproductive tract fluids. Wallabies immunized with PZP exhibited lower ovarian weight with reduced numbers of antral follicles when compared with control animals. Wallabies were placed in a natural mating trial followed by an artificial insemination trial. None of the PZP-immunized wallabies produced offspring in the natural mating trial compared with 67% of control animals. To further assess fertility, a sub-sample of the wallabies were superovulated and artificially inseminated. This resulted in all control wallabies producing fertilized ova and all PZP-immunized wallabies failing to ovulate. These results suggest that immunocontraception based on targeting antigens of the zona pellucida may be an effective strategy for fertility reduction in macropods.