Zona Pellucida Composition: Species Cross Reactivity and Contraceptive Potential of Antiserum to a Purified Pig Zona Antigen (PPZA)

Abstract

Antiserum produced against a M_r 60,000 component (PPZA, purified pig zona antigen) isolated from porcine zonae was examined in respect to its species cross reactivity and contraceptive potential. Antiserum to PPZA produced precipitation layers of varying intensities on the zonae of all species tested. The degree of cross reactivity of anti-PPZA serum for zonae from various species, estimated by precipitation and immunofluorescent titrations, was in the order of human≥squirrel monkey>rabbit>rat>mouse. Percentages of ¹²⁵I-labeled solubilized zonae from these species precipitated by a l:5000 dilution of the antiserum were 49, 27, 18, 18, and 0, respectively, for the pig, squirrel monkey, human, rabbit, and mouse. Pretreatment of intact zonae from human and squirrel monkey with PPZA antibody resulted in the in vitro inhibition of homologous sperm adherence to such treated zonae, thus demonstrating the contraceptive potential of PPZA antiserum in these two species. Similar treatments using the rabbit and mouse systems did not show any observable inhibition of homologous sperm adherence.