Mark P. Bradley

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.

Cloning, sequencing, and characterization of LDH-C4 from a fox testis cDNA library.

A full‐length cDNA encoding the sperm‐specific enzyme lactate dehydrogenase‐C4 was isolated from a fox testis cDNA expression library and sequenced. The deduced translated protein sequence was shown to be 86% identical to that of human LDH‐C4. In the fox testis, mRNA encoding LDH‐C4 was first detected in pachytene spermatocytes. The LDH‐C4 protein monomer was identified in Western blots of sperm membrane extracts as having a molecular weight of approximately 35,000, consistent with the monomeric size of this subunit previously identified in sperm from other species. The LDH‐C4 protein is localized on the sperm plasma membrane overlying the principal piece of the tail. Based on the available sequence data, we were able to identify an epitope within the N‐terminal region of the LDH‐C4 amino‐acid sequence which when administered to female foxes is antigenic and produces antibodies capable of recognizing the native protein.

Applications of Fertility Regulation for the Management of Wild and Domestic Species

Publisher Summary This chapter discusses the applications of fertility regulation for the management of wild and domestic species. Effective and humane management of wild and domestic animal populations is becoming a major issue. This problem can be viewed from two completely different perspectives: (1) The problem of controlling desirable animals in their native environments and (2) the problem of controlling in foreign environments introduced exotic animals. An understanding of the induction, modulation, and duration of reproductive tract immune responses is important for the successful development of immuno-contraceptive vaccines. The precise reproductive tract target site will depend extensively on the vaccine antigens employed for this process. Preliminary modeling studies indicate that fertility control may have a role in the management of fox rabies by reducing the numbers of foxes in a particular region and thus, reducing the transmission rate of the disease. Effective application of a vaccine for fertility control requires that a high level of immunity be achieved among individuals exposed to the vaccine. The application of fertility control technologies for the management of animal populations is still a relatively new concept. Although 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 and testing, especially those required for remote delivery to free-ranging wild animal populations. The relatively slow emergence of such technologies for practical application clearly reflects the complexity of the problem and highlights the requirement for a multidisciplinary research approach when attempting to develop such technologies for wild animal management.