Abstract

BASULTO BAKER, Roberto et al. Effects of Two GnRH-based Recombinant Vaccine Candidates on Pig Fertility. Rev. prod. anim. [online]. 2018, vol.30, n.3, pp. 48-56. ISSN 2224-7920.

This paper describes for the first time the generation of the K88ab-GnRH hybrid fimbriae, the fusion of N. meningitidis P64k protein (P64k-GnRH), and its evaluation as vaccine candidates to control fertility in mammals. Twenty hybrid male pigs were randomly distributed in four groups: placebos and immunized with K88ab-GnRH, P64k-GnRH and a GnRH analogue (GnRHm1), linked to a tetanus toxoid (TT) T-helper epitope (positive control), respectively. The pigs were immunized at 9-10 weeks of age, using a two-dose scheme, and were sacrificed sixteen weeks later. K88ab-GnRH, P64k-GnRH, and GnRHm1-TT induced higher, similar, and lower testosterone levels in the serum, compared to the placebo, respectively. In the K88ab-GnRH group, the pigs underwent a reduction in testicle size and weight (P 0.01), and the weight of epididymes compared to the placebo; none of them was able to ejaculate. In the P64k-GnRH group, the pigs had a reduction in testicle weight (P 0.05), and only one of them was able to ejaculate. The testicles of the pigs immunized with K88ab-GnRH and P64k-GnRH showed structural and functional damage; spermatogenesis was also affected. The accessory sexual glands of the P64k-GnRH group were normal, in contrast to K88ab-GnRH, where interstitial fibrosis was observed. The damage caused by K88ab-GnRH and P64k-GnRH in the target organs evaluated were in all cases lower than the affectations caused by the GnRHm1-TT peptide.

Keywords : GnRH; K88ab; P64k; immunocastration; carrier protein.

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