CONTRACEPTIVE POTENTIAL OF PORCINE ZONA-PELLUCIDA IN CATS

The contraceptive potential of solubilized porcine zona pellucida (spZ P) was studied in 2 groups of cats after active immunization using sli ghtly different protocols. Cats from Group 1 (n=3) were immunized with a total of 300 8g spZP divided in 4 sc multisite injections (each of 37.5 8g) given at 10 day intervals followed by a booster 150 days afte r the initial immunization. Cats from Group 2 (n=5) were immunized wit h a total of 400 8g spZP divided in 4 im injections (each of 50 8g) gi ven at 2 wk intervals followed by a booster 92 days after initial immu nization. Immunogen was emulsified in Complete Freund Adjuvant for the first dose and in Incomplete Freund Adjuvant for the following 3 dose s. The respective controls were immunized in the same manner using onl y adjuvant and PBS. Immunofluorescence studies showed intense fluoresc ence on the zona pellucida (ZP) of the oocytes isolated from immunized cats, as well as on the ZP of porcine and cat oocytes preincubated in immune sera. Sera from cats immunized with spZP inhibited in vitro bi nding was demonstrated in oocytes isolated from immunized group 1 cats . In vivo fertility data in Group2 cats revealed that only 1 of 5 cats became pregnant, the one with the lowest anti-spZP titer. The results from the experiments reported above, suggest that in this preliminary study spZP can elicit antibodies with contraceptive potential in acti vely immunized female cats.