Polyacrylate-GnRH Peptide Conjugate as an Oral Contraceptive Vaccine Candidate

Contraceptive vaccines are designed to elicit immune responses against major components of animal reproductive systems. These vaccines, which are most commonly administered via injection, typically target gonadotropin-releasing hormone (GnRH). However, the need to restrain animals for treatment limits the field applications of injectable vaccines. Oral administration would broaden vaccine applicability. We explored contraceptive vaccine candidates composed of GnRH peptide hormone, universal T helper PADRE (P), and a poly(methylacrylate) (PMA)-based delivery system. When self-assembled into nanoparticles, PMA-P-GnRH induced the production of high IgG titers after subcutaneous and oral administration in mice. PADRE was then replaced with pig T helper derived from the swine flu virus, and the vaccine was tested in pigs. High levels of systemic antibodies were produced in pigs after both injection and oral administration of the vaccine. In conclusion, we developed a simple peptide–polymer conjugate that shows promise as an effective, adjuvant-free, oral GnRH-based contraceptive vaccine.

Immunocontraceptive potential of a GnRH receptor-based fusion recombinant protein

Background The management of stray dog population has been of utmost importance due to their overpopulation, increase in dog bites incidence, and rabies. Contraceptive vaccines, a non-surgical alternative to spaying and neutering are viewed as a valuable option for the management of dog population. In this study, the contraceptive potential of a recombinant fusion protein containing the three genes GnRH, GnRH receptor, and ZP3 was explored. Results The gene fragment encoding GnRH, GnRHR, and ZP3 along with the antigenic epitopes of canine distemper virus and tetanus toxoid was assembled, synthesized, and cloned into pET28a expression vector. The resulting construct GVAC08 was successfully transformed into BL21DE3 strain of E. coli and confirmed by colony PCR. The recombinant GVAC08 protein was expressed and purified using Ni-NTA and was confirmed to be a 50-KDa protein by SDS PAGE and Western blot. Mice were immunized with the GVAC08 protein using Freund’s complete adjuvant followed by a booster using Freund’s incomplete adjuvant. This induced a high antibody titer against GnRH, GnRH receptor, and ZP3 which was determined by ELISA. Conclusion Mating studies showed that the GVAC08 recombinant protein was able to reduce the litter size in immunized mice showing improved efficacy. However, the vaccine candidate with further improvements will be a viable contraceptive vaccine.

Non-surgical methods of regulation reproductive function and contraception males of domestic animals

The regulation of male reproductive function today is not limited to surgical castration; there are many other methods of controlling reproductive function. Non-surgical methods of controlling male reproductive function can be reversible and not reversible, i.e., reproductive function is preserved or completely suppressed. Castration of males or orchiectomy leads to irreversible sterility of the male, when the male completely loses the ability to reproduce. This operation can also entail some side effects: obesity, underdevelopment of the external genital organs, an increased risk of diabetes or hypothyroidism, problems with frequent urination and behavioral problems. Therefore, methods of non-surgical management of reproductive function and contraception in males are being actively developed. The article presents the latest methods of contraception and the management of the reproductive function of male domestic animals (cats, dogs): clinical application GnRH and agonists GnRH, Non-Peptide GnRH Antagonists, GnRH-Toxin Conjugate, GnRH Vaccines and other immune contraceptive vaccines, chemical sterilants for intratesticular injections, calcium chloride, zinc gluconate, chlorhexidine digluconate, hypertonic saline, sex steroids (progestines), gene silencing, kisspeptin and GnIH, targeting delivery of cytotoxins, single-dose hormonal male and female sterilianr, FSH – receptor ligand cytotoxin conjugates, Sperm Protein Reactive with Antisperm Antibodies (SPRASA) Reversible Inhibition of Sperm under Guidance(RISUG).

Designing a Construct of Chimeric Multi-Epitopes Protein for Contraceptive Vaccine in Mice: An Immunoinformatics and In Silico Study

Background: Contraceptive vaccines (CVs) can be used as a valuable and alternative method for the prevention of gestation in humans and animals. These vaccines can have several targets, such as superficial sperm proteins. Vaccines based on sperm antigens are quite efficacious to create a contraceptive effect. However, multi-epitope vaccines are more effective in stimulating the immune system and producing more antibodies to reduce the infertility rate. Materials and Methods: This study aimed to design and evaluate a chimeric fusion protein containing IZUMO, SACA3, and PH-20 epitopes. IZUMO1, SACA3, and PH-20 were assessed, and appropriate regions were selected using various bioinformatics tools, including IEDB, I-TASSER, ProtParam, Asa-View, and Chimera software. Protein epitopes were selected based on various characters, including specificity, solvent accessibility, their weight and length, antigenic intensity, and topology. Epitopes with high antigenic potential were selected and joined together by linkers. The designed fusion protein was simulated using Molecular Dynamic, GROMACS 5, and Chimera 1.14 software. Results: The results demonstrated that all antigenic plots and availability of epitopes in the new construct remained constant. The spermatic antigens were combined using rigid linkers as a new construct and showed a stable formation with proper solvent accessibility validated by ProSA-web and PROCHECK. Also, comparing the new structure with its original one did not show any structural change. Conclusion: Based on bioinformatics results, the fusion protein that consists of three spermatic antigens has productive potential to stimulate the immune system and capable of producing more antibodies in circulation and reliable infertility.

Role of Antisperm Antibodies in Infertility, Pregnancy, and Potential forContraceptive and Antifertility Vaccine Designs: Research Progress and Pioneering Vision

Sperm of humans, non-human primates, and other mammalian subjects is considered to be antigenic. The effect of changes in autoimmunity on reproductive cells such as spermatozoa and oocytes play a critical but indistinct role in fertility. Antisperm antibodies (ASAs) are invariably present in both females and males. However, the degree of ASA occurrence may vary according to individual and gender. Although the extent of infertility due to ASAs alone is yet to be determined, it has been found in almost 9–12% of patients who are infertile due to different causes. Postcoital presence of spermatozoa in the reproductive tract of women is not a contributory factor in ASA generation. However, ASA generation may be induced by trauma to the vaginal mucosa, or by anal or oral sex resulting in the deposition of sperm inside the digestive tract. It is strongly believed that, in humans and other species, at least some antibodies may bind to sperm antigens, causing infertility. This form of infertility is termed as immunological infertility, which may be accompanied by impairment of fertility, even in individuals with normozoospermia. Researchers target ASAs for two major reasons: (i) to elucidate the association between ASAs and infertility, the reason ASAs causes infertility, and the mechanism underlying ASA-mediated infertility; and (ii) to assess the potential of ASAs as a contraceptive in humans in case ASAs influences infertility. Therefore, this review explores the potential application of ASAs in the development of anti-spermatozoa vaccines for contraceptive purposes. The usefulness of ASAs for diagnosing obstructive azoospermia, salpingitis, and oligoasthenoteratozoospermia has been reviewed extensively. Important patents pertaining to potential candidates for spermatozoa-derived vaccines that may be utilized as contraceptives are discussed in depth. Antifertility vaccines, as well as treatments for ASA-related infertility, are also highlighted. This review will address many unresolved issues regarding mechanisms involving ASAs in the diagnosis, as well as prognoses, of male infertility. More documented scientific reports are cited to support the mechanisms underlying the potential role of ASA in infertility. The usefulness of sperm antigens or ASAs (recombinant) in human and wild or captive animal contraceptive vaccines has been revealed through research but is yet to be validated via clinical testing.

Contraceptive Vaccines and Pregnancy Prevention

According to WHO, 80 million pregnancies each year are unintended and 45 million undergo abortion. There remains a continuing need for effective long-term contraceptives with minimal side effects. Contraceptive Vaccines (CV) thus provides an attractive solution due to its periodic intake, high specificity, reversibility and minimal side effects. This review aims to evaluate the potential of contraceptive vaccines for pregnancy prevention based on journal articles obtained from PubMed, Elsevier Clinical Key and Google Scholar. CV works by using the body’s own immune system to target molecules which take part in the reproduction process but do not confer other pleiotropic effects other than infertility. Three main mechanisms of CV are currently studied, namely by affecting gamete production, gamete function and gamete differentiation (hCG). Of all these, hCG vaccines are of great interest as they are formed by early embryos, not the pregnant female hence providing the least side effects when inhibited. They are the first CV to pass Phase I and II trials successfully and found to remain effective as long as antibody titres stay above 50 ng/mL. Those vaccinated can also easily undergo pregnancy when titres go below 35 ng/mL. Normal reproductive functions also remain following vaccination. An immunological approach to contraception remains an innovative idea and has been proven effective in both experimental and clinical trials. If ongoing trials remain successful, CV will mark another progress in the field of mass contraception and its implementation would hopefully reduce the current prevalence of unintended pregnancies.

Contraceptive efficacy of priming and boosting doses of controlled-release PZP in wild horses

Context At some sites, wild horse populations have been effectively and non-invasively regulated using remote darting with porcine zona pellucida (PZP) immunocontraceptive vaccines. However, this model has not been widely applied to wild horse herds in western USA, many of which are difficult to access because they roam large areas and are wary of people. Single-treatment, multi-year contraceptive vaccines would significantly broaden the scope for successful contraceptive management. Aims The aims of the present field studies were to (1) test the contraceptive effectiveness and longevity of primers incorporating PZP–adjuvant emulsions plus PZP and adjuvant in controlled-release pellets (‘PZP-22’); and (2) compare the contraceptive effectiveness and duration of PZP–adjuvant emulsion-only boosters with those of PZP-22 boosters when administered by hand or remote darting to PZP-22-primed mares. Methods Wild horses in herd management areas in Colorado and Utah, USA, were rounded up in 2008 and in Utah again in 2012. Previously untreated females received a single hand-injection of PZP–emulsion plus controlled-release PZP pellets (‘PZP-22’ vaccine) and were then released. In Autumn 2010, 50 Colorado females treated in 2008 were booster-darted with either the PZP-22 vaccine or the PZP emulsion alone. In Utah, 57 previously treated females rounded up in 2012 received hand-injections of either the PZP emulsion–pellet vaccine or the PZP emulsion alone. Maternity was established through field observation of nursing and other close associations. Key results Effectiveness of initial controlled-release PZP treatments over 2 years was low relative to previous trials. However, boosters delivered by dart or by hand to PZP-22-primed mares yielded high levels of contraceptive effectiveness for 3 years, with no consistent difference between simple PZP-emulsion boosters and boosters incorporating controlled-release pellets. Conclusions Priming mares with PZP-22 extends the efficacy of a subsequent PZP booster to at least 3 consecutive years. Implications Regulation of wild horse populations may be achieved with existing contraceptive agents by developing models and management plans that account for the increased longevity of repeated contraceptive treatments.