Enhancement of antigonadotropin response to the beta-subunit of ovine luteinizing hormone by carrier conjugation and combination with the beta-subunit of human chorionic gonadotropin.

Previous studies have demonstrated the control of fertility in monkeys on immunization with the beta subunit of ovine luteinizing hormone (beta-oLH) along with Freund's complete adjuvant (CFA). An eventual birth control vaccine would demand immunization without CFA. Beta-oLH linked to tetanus toxoid (TT) adsorbed on alum-induced antibody response in bonnet monkeys with detoxified sodium phthalyl derivative of Salmonella enteritidis lipopolysaccharide added only in the first injection. The antibodies reacted with both LH and human chorionic gonadotropin (hCG). A higher immune response was obtained with the use of a conjugate of beta-oLH and beta-hCG linked to a common carrier (TT) or with a mixture of beta-hCG/TT and beta-oLH/TT. In both cases, the antibodies were of high affinity with Ka ranging from 5 X 10(9) to 6 X 10(10) M-1. The antibodies were devoid of reactivity with human thyroid-stimulating hormone and human follicle-stimulating hormone. Monkeys with titers above 120 ng/ml hCG binding capacity (greater than 60 ng/ml in most cases) were protected from becoming pregnant during repeated mating with males of proven fertility in ovulatory cycles.