Necessity of adjuvants for inducing effective antibody response to zona pellucida antigens

Rhesus monkeys evoked a vigorous antibody response to a single heteroimmunization dose of zona pellucida antigens, when these were administered along with complete Freund's adjuvant. The antisera recognized all the three major porcine zona glycoprotein families and the animals were rendered amenorrheic after such immunization. Monkeys immunized with zona without adjuvant, however, failed to show any anti-zona antibody response and had normal menstrual cycles. Zona pellucida glycoproteins are thus not effective immunogens unless administered along with a powerful adjuvant.