Effect of varying dosages and adjuvants on antibody response in squirrel monkeys (Saimiri sciureus) immunized with the porcine zona pellucida Mr = 55,000 glycoprotein (ZP3).

Using the porcine zona pellucida Mr = 55,000 (ZP3) glycoprotein as immunogen, the effect of varying ZP3 dosages (50 micrograms, 25 micrograms, 5 micrograms) or adjuvants (200 micrograms ZP3 with either Freund's, A1[OH]3, or a muramyl dipeptide analog [MDP] on antibody response was evaluated in female squirrel monkeys. Although the dosage range investigated did result in dose-dependent titration profiles, antisera from all dosage groups demonstrated in vitro contraceptive potential. MDP was as effective an adjuvant as Freund's in eliciting high titers of antibodies demonstrating contraceptive potential. A1(OH)3 was not an effective adjuvant in this system. Fertility data, utilizing those monkeys in the dosage study, suggested that an RIA titer greater than 40% binding was necessary to prevent pregnancy. We conclude that in the squirrel monkey system, a 50 micrograms dosage of ZP3 should be adequate for inhibiting fertility and that MDP would serve as a satisfactory alternative adjuvant for Freund's.