Long-Term Efficacy and Reproductive Behavior Associated with GonaCon Use in White-Tailed Deer (Odocoileus virginianus)

GonaCon is a single-shot immunocontraceptive vaccine that targets the reproductive hormone gonadotropin releasing hormone (GnRH). The GnRH peptide used in the vaccine is secreted by the hypothalamus of the brain and is specifically known as luteinizing hormone releasing hormone. This peptide stimulates the synthesis and secretion of luteinizing hormone and follicle stimulating hormone by the anterior pituitary gland. These hormones in turn stimulate hormone and gamete production by the ovary. In earlier studies with deer, we showed that antibodies produced in response to a single shot of GonaCon inactivated endogenous GnRH and greatly reduced fertility, reproductive steroids, and associated behaviors for at least 2 years. In the present study, we report on contraceptive efficacy and behavioral observations up to 6 years after female white-tailed deer were given a single shot of one of several formulations of GonaCon. We compared the standard GonaCon made by conjugating the GNRH peptide to keyhole limpet hemocyanin (GonaCon-KLH) to one with the GnRH peptide conjugated to a blue mollusk protein (GonaCon-Blue) and to a 2-shot regimen with GonaCon-KLH. All GonaCon preparations were made into an emulsion with AdjuVac and administered to 5 mature female deer per treatment. The results showed that the GonaCon-Blue preparation significantly out-performed the other single-shot vaccines, as well as the 2-shot regimen of GonaCon-KLH, with efficacy of 80-100% for each of the 5 years in the study. Interestingly, expression of estrous behavior was minimal in Years 1-2 following treatment for all groups, but expression of estrus increased in later years of the study, even though does remained infertile. This expression of estrus and fertility was reversed with follicle stimulating hormone releasing hormone (FSH-RH) peptide conjugated to a mollusk protein and mixed as an emulsion with AdjuVac. This suggests that does possess an FSH-RH peptide, secreted by the hypothalamus, which modulates follicle development and resulting estrogen production and reproductive behavior.