Evaluation of the Efficacy of Immunocastration Vaccine Composed of Gonadotrophin‐releasing Hormone Conjugated with Salmonella typhimurium Flagellin in Rats

Abstract

Immunocastration is an alternative method to replace surgical castration that is commonly performed in domestic and pet animals. In this study, a new immunocastration vaccine was developed, and its efficacy was evaluated in male rats. Six tandem copies of gonadotrophin-releasing hormone (GnRH) peptide were genetically fused to Salmonella typhimurium flagellin fljB (STF2) that is a ligand of toll-like receptor 5 (TLR5). The recombinant STF2-GnRH protein expressed in Escherichia coli was used as the immunocastration vaccine. Sixteen male rats were equally assigned to four groups. Excluding the control rats, three groups were immunized with 100, 200 and 400 μg of the STF2-GnRH vaccine, respectively. All of the immunized rats developed significantly higher titres of antibodies to GnRH than the control rats. The size and weight of both testes and epididymides from the immunized rats were significantly smaller than those of the control rats. Testicular tissues in the immunized rats demonstrated atrophy of seminiferous tubules and decreased numbers of both spermatogonia and spermatocytes. These data indicate that the newly developed STF2-GnRH vaccine has a potent immunogenicity to GnRH and efficiently suppresses the development of testes in rats.

Immunocontraceptive Effects in Male Rats Vaccinated with Gonadotropin-Releasing Hormone-I and -II Protein Complex

“…ab8491; Abcam, UK) and anti-flagellin polyclonal antibodies (cat no. ab93713, Abcam), as previously described [13][14][15][16].…”

ZNF185‐derived peptide induces fertility suppression in mice

“…Additionally, there were no obvious pathologic changes in the histology of the testis or epididymis between the peptide group and the PBS group. Previous studies have reported an apparent decrease in testis and epididymal weights, as well as obvious pathologic changes in the seminiferous tubules, of immunization animals . However, other studies have shown no pathological changes in the testis and epididymis .…”

“…Previous studies have reported an apparent decrease in testis and epididymal weights, as well as obvious pathologic changes in the seminiferous tubules, of immunization animals. 3,[27][28][29] However, other studies have shown no pathological changes in the testis and epididymis. 1,15,16,30 Our study was consistent with the latter.…”

Design, synthesis, and evaluation of anti-LHRH vaccine candidates based on a lipopeptide delivery system

“…Similar immune responses were found when using polysine dendrimers or carbohydrate (glucose) as a branching core in vaccine construct [90]. Song et al carried out a study using a recombinant protein expressing LHRH with a heatshock protein to immunise BALB/c mice which led to reduced follicular development in their reproductive organs [94]. This recombinant vaccine construct also showed an inhibitory effect on mammary tumour cells [94].…”

“…Song et al carried out a study using a recombinant protein expressing LHRH with a heatshock protein to immunise BALB/c mice which led to reduced follicular development in their reproductive organs [94]. This recombinant vaccine construct also showed an inhibitory effect on mammary tumour cells [94]. Immunisation of ICR male and female mice with a genetic vaccine encoding LHRH with five T helper epitopes in one sequence, effectively reduced testosterone to 75% lower than the baseline and impaired testicular function in male mice and suppressed folliculogenesis in female mice, thus inhibiting fertility in both mouse groups [100].…”