GonaCon™ is a gonadotropin releasing hormone (GnRH) contraceptive vaccine developed at the USDA National Wildlife Research Center (NWRC) that contains keyhole limpet hemocyanin (KLH) coupled to GnRH. The vaccine is administered intramuscularly in an emulsion with the NWRC adjuvant, AdjuVac™. This first-generation vaccine, developed in 1998, has been very effective in contracepting every species tested. However, because of the high cost of KLH, NWRC has developed a second generation GnRH vaccine, replacing KLH with a less expensive mollusk protein. This second generation GnRH vaccine, called GonaCon-Blue™, is currently being tested in several species and has proven to be as, or more effective than the original GonaCon™. Scientists with the Reproductive Control Methods Project at the NWRC are also testing a recombinant GnRH antigen developed by Dr. Talwar of the Talwar Research Institute, India. The recombinant antigen was produced from plasmid gene expression grown in and extracted from E. coli. The antigen is combined with the NWRC AdjuVac™ to form an emulsion similar to the GonaCon™ preparation. The recombinant vaccine has been shown to be effective as a single or dual injection for contraception of adult female pigs in a short-term study at the Swine Research Facility at Penn State University. Although the long term effectiveness of the recombinant vaccine remains to be established, this small molecule of approximately 14,000 MW is of considerable interest because it may be effective in oral or transcutaneous applications. It could also be scaled-up for large field applications.

The physiological mechanisms controlling ovarian follicular growth and ovulation involve a complex exchange of systemic signals and a localized exchange of molecules between the oocyte and surrounding somatic cells. It has been demonstrated that the oocyte itself plays an essential role in regulating these processes by secreting two key regulatory proteins: bone morphogenetic protein-15 (BMP15) and growth and differentiation factor-9 (GDF9). Natural mutations in their expression and vaccination against these growth factors have been shown to cause sterility in sheep. The aim of this 3-year study was to determine the effect of vaccination against GDF9 and BMP15 on fertility in female white-tailed deer. Does were randomly assigned to two groups (n = 10/group). Each doe received a primary vaccination followed by a booster 47 days later. After the first year, a subset of animals (n = 4-5/group) received an additional booster vaccination. Blood samples were collected at regular intervals to determine antibody titers and progesterone concentrations. Early pregnancy was assessed by ultrasound, and fawning was subsequently monitored. For the BMP15 group, over the 3 years 80%, 100%, and 75% of does fawned with fawning rates of 2.4, 3.5, and 3.3 fawns/doe, respectively. For the GDF9 group, 80%, 25%, and 25% of does fawned with fawning rates of 2.6, 1, and 2 fawns/doe, respectively. The fawning rate of untreated animals in the herd was 1.8 fawns/doe. Although all animals in the BMP15 group had high antibody titers, they were not made infertile, and they became more fecund. Most animals in the GDF9 group had high antibody titers, but fecundity was not affected the first year; however, they were made infertile in Years 2 and 3. Results from this study demonstrate that vaccination against GDF9 has potential to control fertility in deer. Further research will be required to determine the appropriate timing for administering the vaccine and the longevity of effect.