The response of African elephants to a single dose of SpayVac®, a pZP contraceptive vaccine, over a seven-year period

Ursula Berchert

Abstract


As free-ranging African elephant (Loxodonta africana) populations become increasingly confined to smaller ranges, concerns grow about human–elephant conflicts and negative impacts on flora and fauna. Current elephant population management alternatives include translocation, culling, dispersal techniques, surgical sterilization, and contraceptive vaccines. Porcine zona pellucida (pZP) immunocontraception may have the greatest potential to control fertility because it has proven efficacy, and vaccines are easy to handle and safe to administer. SpayVac® (ImmunoVaccine) is a pZP vaccine that has demonstrated single-dose, multi-year contraceptive efficacy in other wildlife species, which would make it practical and economical for field application if it performs similarly in African elephants. Over a 7-year period, we assessed the immune response of African elephants to two SpayVac formulations: non-aqueous (n=3) and aqueous (n=3) emulsions. pZP antibody titers raised by the non-aqueous SpayVac formulation were first detected 4 weeks post-vaccination but did not peak until after 1 year, after which they remained consistently elevated through 7 years. This study demonstrated the ability of a single-dose of non-aqueous SpayVac to elicit an antibody response in African elephants for 7 years. Additional research is needed to determine actual contraceptive efficacy and potential long-term effects on fertility.

Keywords


African elephant, Loxodonta africana, pZP, immunocontraception, SpayVac®

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