Current status of a unique vaccine preventing pregnancy.

The ability of a vaccine linking beta hCG to a carrier to generate antibodies against hCG, its reversibility and safety was established by Phase I clinical trials conducted in India, Finland, Sweden, Chile and Brazil. Employing a hetero-species dimer (beta hCG-αoLH) linked to tetanus toxoid further improved the immunogenicity of the vaccine. Phase II clinical trials showed that anti-hCG titres above 50 ng/ml prevented pregnancy of sexually active fertile women without derangement of ovulation and menstrual regularity. On decline of antibodies, women conceived again to give birth to normal progeny. A genetically engineered vaccine consisting of beta hCG linked to B subunit of heat labile enterotoxin of E. coli has been made. It is expressed as DNA as well as protein. Priming with DNA followed by protein version of the vaccine generates very high titres against hCG in mice. Extensive toxicology studies in 2 species of rodents, and marmosets have shown complete safety of the vaccine. The vaccine is cleared for Clinical trials by the National Review committee on Genetic Manipulation and Drugs Controller General of India.