Application of MT3 in the Development and Immunogenicity Evaluation of GnRH Vaccines

Research on immune castration vaccines is of great significance for animal management. In this study, five copies of GnRH were linked to two MT3s by a flexible linker, GGGGS, to construct a recombinant plasmid, pET30a-GnRH5-MT3, which was expressed and purified using E. coli BL21(DE3) cells. The recombinant protein was best expressed under the induction conditions of 25 with 0.25 mM IPTG, with a purity of up to 80% after purification. It was mixed with the external adjuvant ISA 206 and immunized mice by subcutaneous injection. Serum levels of GnRH-specific Antibody, T, FSH and LH were detected by ELISA, and testicular tissue morphology was observed by HE staining. The results showed that GnRH5-MT3 recombinant protein combined with external adjuvant could efficiently induce GnRH-specific antibody production in male mice (P < 0.01-0.001) and significantly reduce the Serum LH, FSH and T concentrations (P < 0.01-0.001). The immunized mice had sparse cells in the seminiferous tubules of the testis, significantly reduced cells at various developmental stages, and almost no mature spermatozoa. This study provides experimental basis for further application of the vaccine in animal immune castration.