PILOT PROJECT: A THEORETICAL FRAMEWORK FOR THE CONTROL OF FERTILITY IN A POPULATION SAMPLE OF RED DEER FROM EL MONTE DE EL PARDO (SPAIN).

Context. The present study aims to promote fertility control as a non-lethal means of managing wild animal populations, specifically red deer (Cervus elaphus) in a region of Spain. The control of fertility in cervids through the use of long-acting contraceptives or other sterilization approaches has been advocated as a reasonable tool in the face of the challenges posed by overpopulation, especially in areas close to urban spaces. Among the contraceptive methods known to date, immunocontraception appears to be the most effective and favorable methodology with respect to the welfare of the animals.Aims: This action plan proposes the use of a single dose injectable immunocontraceptive vaccine (GonaConTM Immunocontraceptive Vaccine) in red deer that inhabit Monte de El Pardo, accompanied by a follow-up study to determine: (1) determine the effectiveness of the GonaConTM vaccine over 3 years in the prevention of pregnancy, (2) determine the possible secondary effects (contraindications), (3) identify any weaknesses and drawbacks of the treatment and (4) propose improvements and future perspectives. As far as we know, it would be the first to establish theoretical bases for the first use of this vaccine in wild red deer in Spain.Methods: The vaccine will be injected into a total of 200 wild female reed deer of reproductive age in Monte de El Pardo. The control group will consist of 50 females who will not be vaccinated but will be evaluated in the same way. The treated individuals in the study will be marked and identified, and follow-up will be carried out for a period of 3 years. The effectiveness of GonaConTM will be quantified by measuring physiological and ethological parameters (behavioral observations). These data will be compared with the results of the control group.Key results. We expect to achieve an average inhibition of reproductive production of more than 80% over the three year period, and it is hoped that in the first year the effectiveness will reach 90-100%, without notable detrimental effects on the physiology or behavior of the individuals in relation to the control group. Similarly, no significant differences are expected between the results from the non-reproductive behavior of the treated deer and that of the control group, in individuals between the start of vaccination and 12 months later (Quy et al. 2014), in the subsequent sampling throughout the 3 years of the study. It is expected that the deer treated with GonaConTM will exhibit a secretion response of sufficient anti-GnRH antibodies to achieve an inhibition in their reproductive behavior and physiology and, therefore, in their fertility (of at least 80% average effectiveness over the 3 years).Implications. The development of this method of population control is essential in urban and suburban areas, where lethal control, by poisoning or capture compromises animal welfare, in addition to the potential risk for the human population. It is expected that stability in the number of deer present in Monte de El Pardo will reduce potential threats that derive directly from collisions with vehicles and transmission of diseases. We suggest that a greater effort to develop less invasive and non-lethal population control modalities is justifiable.

Inactivated Rabies Virus-Vectored Immunocontraceptive Vaccine in a Thermo-Responsive Hydrogel Induces High and Persistent Antibodies against Rabies, but Insufficient Antibodies against Gonadotropin-Releasing Hormone for Contraception

Rabies is preventable through vaccination, but the need to mount annual canine vaccination campaigns presents major challenges in rabies control and prevention. The development of a rabies vaccine that ensures lifelong immunity and animal population management in one dose could be extremely advantageous. A nonsurgical alternative to spay/neuter is a high priority for animal welfare, but irreversible infertility in one dose has not been achieved. Towards this goal, we developed a rabies virus-vectored immunocontraceptive vaccine ERA-2GnRH, which protected against rabies virus challenge and induced >80% infertility in mice after three doses in a live, liquid-vaccine formulation (Wu et al., 2014). To improve safety and use, we formulated an inactivated vaccine in a thermo-responsive chitosan hydrogel for one-dose delivery and studied the immune responses in mice. The hydrogel did not cause any injection site reactions, and the killed ERA-2GnRH vaccine induced high and persistent rabies virus neutralizing antibodies (rVNA) in mice. The rVNA in the hydrogel group reached an average of 327.40 IU/mL, more than 200 times higher than the liquid vaccine alone. The Gonadotropin-releasing hormone (GnRH) antibodies were also present and lasted longer in the hydrogel group, but did not prevent fertility in mice, reflecting a possible threshold level of GnRH antibodies for contraception. In conclusion, the hydrogel facilitated a high and long-lasting immunity, and ERA-2GnRH is a promising dual vaccine candidate. Future studies will focus on rabies protection in target species and improving the anti-GnRH response.

Efficacy of dart-delivered PZP-22 immunocontraceptive vaccine in wild horses (Equus caballus) in baited traps in New Mexico, USA

Context Federally protected wild horses on public lands are undergoing population growth that overwhelms the historical management strategy of removal and adoption. Porcine zona pellucida (PZP) has been used as an injectable immunocontraceptive vaccine to induce reversible infertility in free-roaming horses. PZP vaccination during February and March, which is the optimal time for administering current vaccines, is not possible for the herd on Jarita Mesa Wild Horse Territory (JM WHT), New Mexico, due to severe weather, terrain and subject wariness. AimsThe first goal was to assess bait trapping and remote darting as a minimally disruptive alternative to helicopter gathers for treatment. The second goal was to quantify the efficacy over 2 years following spring treatment with a single injection of PZP-22 (a combination of PZP-adjuvant emulsion and controlled-release pellets) by remote dart delivery. Methods Bait trapping and dart delivery of PZP-22 was carried out on JM WHT from 4 April to 16 June 2012. The herd was observed in the summers of 2011, 2013 and 2014 to determine the foaling status of the study mares. Outcome (foal or no foal) as a function of treatment was analysed using Fisher’s exact test. Key resultsThere were 157 individuals, including 66 females >1 year old, documented in 2011. In 2012, 26 females (including three yearlings) identified by colour and markings were bait trapped and darted with PZP-22. The proportion of treated females foaling was lower than that of untreated females in 2013 and 2014, but the difference was only significant in 2013. Of the treated mares observed in 2013, the two that foaled were the last two treated in 2012. Untreated mares >4 years old were significantly more likely to foal than younger mares. Conclusions Bait trapping at JM WHT permitted successful delivery of PZP-22 in a previously inaccessible herd. Dart administration of PZP-22 in April–June induced at least 1 year of measurable infertility. Implications This is the first demonstration of the efficacy of an initial treatment of PZP-22 delivered by dart instead of hand injection. Considerations for PZP-22 treatment include seasonal timing of treatments and age of treated mares. Treatments need to take place early enough to allow antibody titers to build to contraceptive levels before the breeding season.