Immunocontraception in male feral swine treated with a recombinant gonadotropin-releasing hormone vaccine
Tyler A. Campbell, PhD; Michelle R. Garcia, PhD; Lowell A. Miller, PhD; Martha A. Ramirez; David B. Long, MS; Jean-Baptiste Marchand, PhD; Fergal Hill, MB, BChir
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Objective: To determine if a recombinant gonadotropin-releasing hormone (GnRH) vaccine is a potential immunocontraceptive agent for juvenile male feral swine.
Materials and methods: At the beginning of the trial (Day 0) we treated animals in Treatment One with a single injection of a sham vaccine containing 1 mL of a buffer-adjuvant emulsion (adjuvant: AdjuVac; National Wildlife Research Center, Fort Collins, Colorado). Treatment Two received 1000 μg of a recombinant GnRH (rGnRH) vaccine (IMX294; Imaxio, Lyon, France). Treatment Three received 500 μg of a rGnRH vaccine. Treatment Four received 1000 μg of a GnRH vaccine (GonaCon; National Wildlife Research Center, Fort Collins, Colorado). On Day 90, Treatment Three received an additional 500-μg boost treatment. All vaccines were emulsified with AdjuVac and injected intramuscularly into the rump. On Day 180, we performed necropsies on swine and compared mass of testes, percent normal seminiferous tubules, numbers of spermatogonia, spermatocytes, and spermatids, serum testosterone levels, and anti-GnRH antibody titers among treatments.
Results: As expected, a single dose of GonaCon vaccine reduced testes mass, serum testosterone, and percent normal tubules, and restricted sperm development at each stage. These reductions in reproductive development were associated with elevated GnRH antibodies. The single injection of rGnRH was not as effective in reducing these reproductive parameters; however, the two-dose injection of rGnRH was as effective as the single injection of GonaCon.
Implication: Further research and development is needed into oral immunocontraceptive vaccines and oral delivery systems.
Keywords: feral, fertility control, gonadotropin-releasing hormone, immunocontraception
Cite as: Campbell TA, Garcia MR, Miller LA, et al. Immunocontraception in male feral swine treated with a recombinant gonadotropin-releasing hormone vaccine. J Swine Health Prod 2010;18(3):118-124.
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