• Journal of Microbiology and Biotechnology
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• v.29 no.4
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• pp.658-664
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• 2019

Immunocontraception has been suggested as an optimal alternative to surgical contraception in animal species. Many immunocontraceptive vaccines have been designed to artificially produce antibodies against gonadotropin-releasing hormone-I (GnRH-I) which remove GnRH-I from the vaccinated animals. A deficiency of GnRH-I thereafter leads to a lack of gonadotropins, resulting in immunocontraception. In this study, we initially developed three immunocontraceptive vaccines composed of GnRH-I, GnRH-II, and a GnRH-I and -II (GnRH-I+II) complex, conjugated to the external domain of Salmonella Typhimurium flagellin. As the GnRH-I+II vaccine induced significantly (p < 0.01) higher levels of anti-GnRH-I antibodies than the other two vaccines, we further evaluated its immunocontraceptive effects in male rats. Mean testis weight in rats (n = 6) inoculated twice with the GnRH-I+II vaccine at 2-week intervals was significantly (p < 0.01) lower than in negative control rats at 10 weeks of age. Among the six vaccinated rats, two were non-responders whose testes were not significantly reduced when compared to those of negative control rats. Significantly smaller testis weight (p < 0.001), higher anti-GnRH-I antibody levels (p < 0.001), and lower testosterone levels (p < 0.001) were seen in the remaining four responders compared to the negative control rats at the end of the experiments. Furthermore, seminiferous tubule atrophy and spermatogenesis arrest were found in the testis tissues of responders. Therefore, the newly developed GnRH-I+II vaccine efficiently induced immunocontraception in male rats. This vaccine can potentially also be applied for birth control in other animal species.

• Korean Journal of Veterinary Research
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• v.57 no.3
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• pp.155-158
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• 2017

Surgical castration performed to reduce male-associated problems results in pain and microbial infections in male animals. Therefore, immunocontraception, which is mediated by the animal's own antibodies against reproductive hormones, has been recommended as an alternative to surgical castration when considering the animal's welfare. In this study, a new immunocontraceptive vaccine composed of six tandem copies of gonadotropin-releasing hormone (GnRH) fused to rat granulocyte-macrophage colony-stimulating factor (GM-CSF) was developed, and its efficacy was evaluated in male rats. Three different doses (10, 50, and $100{\mu}g$) of recombinant GM-CSF-GnRH protein were injected three times at intervals of two weeks into male rats. The rats vaccinated with three doses of GM-CSF-GnRH produced a significantly higher level of antibodies against GnRH than that in the negative control rats. Severe atrophy of gonads was observed in rats vaccinated with three doses of GM-CSF-GnRH but not in the negative control rats. The results reveal that the new GnRH vaccine conjugated with rat GM-CSF induces efficient immunocontraception in male rats. This formulation of the immunocontraceptive vaccine would be applicable to both domestic and pet male animals.