Vaccines for fertility regulation of wild and domestic species

The application of fertility control technologies for the management of animal populations is still a relatively new concept and remains to be proven on a large scale. While there have been demonstrations of its utility using crude antigenic preparations of porcine zona pellucida, refined, cheap and easily delivered vaccines are still in the early phases of development, especially those required for remote delivery to free-ranging wild animal populations. The relative slow emergence of such technologies for practical application clearly reflects the complexity of the science and the requirement for a multidisciplinary research approach when attempting to develop such technologies for wild animal management. In many cases, one of the areas where further information is required is the immunobiology of such target species. Effective immunocontraceptive vaccines will also be critically dependent upon the design of the delivery systems. These will be unique to each species under study. A major challenge for free-ranging species will be to ensure that the vaccine can induce a long-lasting immune response to a high percentage of the target population, thus reducing the frequency and, hence, the cost of vaccine application. Many of the delivery systems being considered will utilise recombinant organisms. Hence, considerations on the use of such organisms needs to take into account the political, ethical and safety constraints prior to any environmental release. Also of prime importance is the issue of species specificity. In some instances, this will be a major challenge and careful thought will need to be given to ensure that specificity can be built into the vaccine at several levels. These might include the target antigen or epitopes, the microbial or other delivery vector, and, where applicable, the bait matrix and any target-specific attractive properties it may require. If these caveats can be satisfied and the public is able to accept the use of such vaccines, the potential for their application to manage animal populations and their impact is most certainly assured.