Vaccines are under development for the control of fertility in males and females. This review discusses developments in anti-fertility vaccines at the National Institute of Immunology, New Delhi, India. A single injection procedure for the sterilization or castration of male animals depending on the site at which the injection is given, has passed through field testing and is expected to be on the market in the near future. Vaccines inducing antibodies against the human chorionic gonadotropin have gone through phase I trials with satisfactory results. A vaccine producing a consistently bioeffective antibody response against gonadotropin-releasing hormone is ready for phase I/II clinical trials in patients of carcinoma of prostate after due experimentation in animals and toxicology studies. Research to identify sperm antigens for incorporation into second generation vaccines is in progress.
PIP: Anti-fertility vaccine research carried out at the National Institute of Immunology in New Delhi, India is summarized. The vaccines react against follicle stimulating hormone (FSH), luteinizing hormone (LH), and gonadotropin releasing hormone (GnRH). Intratesticular injection of Bacillus Calmette-Guerin (BCG) in moderate concentrations causes the degeneration of the blood-testes barrier, which finally leads to reversible azoospermia and it is suited for use in animals. Anti-hCG (anti-human chorionic gonadotropin) vaccines include beta-hCG linked to tetanus toxoid /TT (beta-hCG-TT) the alpha-subunit of ovine LH associated with beta-hCG and linked to TT or cholera toxin chain b (CHB/alpha-oLH, beta-hCG-TT/CHB/, the mixture of hCG and oLH, and 37 amino acid carboxy-terminal peptide (CTP) of beta-hCG linked to diphtheria toxoid (DT). The principle of anti-hCG vaccine is to induce antibodies which can bind to hCG and render it biologically inactive. The beta-subunit of hCG has proven efficacious in controlling fertility, and similarly 36 amino acid CTP was effective in baboons. The beta-hCG- TT vaccine evoked the production of anti-hCG antibodies in 61 of 63 women tested. The mixture of beta-hCG and beta-ovine LH conjugated to TT or CHB /formulation M/ and beta-hCG annealed to alpha-ovine LH and conjugated to TT or to CHB (formulation A/ produced improved) immunogenicity. Immunization with GnRH resulted in decreased testicular size, drop of testosterone levels, and marked atrophy of the prostate. Anti-GnRH vaccine would be tried in patients of carcinoma of the prostate. LDH-C4, a sperm-specific mitochondrial antigen, produced an antibody response in baboons and reduced fertility in the females. Animal fertility control vaccines will be shortly on the market, but the use of recombinant DNA techniques should also accelerate the development of others.