Inhibition of in vitro fertilization by a monoclonal antibody reacting with the zona pellucida of the oviductal egg but not with that of the ovarian egg of the golden hamster

A glycoprotein designated ZP-0 is secreted from the epithelial cells of the oviduct and is bound to the zonae pellucidae (ZPe) of the oviductal eggs. We have previously established a monoclonal antibody reacting with ZP-0, termed AZPO-8. In the present study, we have examined the effect of AZPO-8 on in vitro fertilization in the hamster. Treatment of the oviductal eggs with AZPO-8 at concentrations of more than 100 μg/ml resulted in: (1) the formation of "zona precipitation" on the outer region of the ZP; (2) inhibition of sperm binding to ZP; (3) the acquisition of resistance to protease treatment. Fertilization was inhibited by AZPO-8 in a dose-dependent manner. These results indicate that a monoclonal antibody (MoAb) to an additional component of ZP derived from the oviduct shows an inhibitory effect on fertilization in vitro.