Effect of GonaCon™ vaccine on black-tailed prairie dogs: immune response and health effects.

Management of prairie dogs in the past has included poisoning, fumigants, barriers, and relocation. Because of the diverse attitudes related to prairie dog management, nonlethal methods that allow the existence of prairie dogs but help minimize damage related to population growth need to be developed. GonaCon™ is an immunocontraceptive vaccine that elicits antibodies to native GnRH; this prevents the secretion of reproductive hormones necessary for sperm and oocyte production. Prairie dogs were vaccinated with 0.1, 0.2, or 0.4 mL of the GonaCon™ emulsion intramuscularly in the upper thigh containing 100, 200, or 400 μg GnRH conjugate, respectively. Control animals were vaccinated with 0.4 mL saline emulsion in the upper thigh. Blood samples (≤1 mL) were taken from the femoral vein once pretreatment and at 1, 2, 3, 4, 6, and 15 months post-vaccination. Age (adult or juvenile) did not affect immune response to GonaCon™. Antibody titers were higher in the 200 and 400 μL GonaCon™ groups than in the 100 μL group, and there was no difference between the 200 and 400 μL GonaCon™ groups. No adverse effects of GonaCon™ were noted on weight or blood chemistry parameters during the study. GonaCon™ will likely contracept prairie dogs for ≥1 year in the field using either 200 or 400 μg conjugate. GonaCon™ could be incorporated into management plans to help maintain prairie dog populations while reducing habitat degradation due to overpopulation.