Monoclonal antibodies to intra-acrosomal proteins inhibit gamete binding in vitro

The sperm-zona pellucida-binding assay in vitro was used as a functional te st for zona pellucida-binding ability of boar spermatozoa after co-incubati on with monoclonal antibodies against intra-acrosomal proteins. The effect of monoclonal antibodies ACR.2 against boar acrosin (55, 53, 45 and 38 kDa) , and Hs-8 against boar intra-acrosomal protein (230, 110, 88, 60, 48 kDa) on boar spermatozoa-porcine oocyte binding was examined. The sperm-zona pel lucida-binding was reduced when medium was supplemented with monoclonal ant ibodies during sperm-oocyte co-incubation, but not when capacitated spermat ozoa were pretreated with monoclonal antibodies before incubation with oocy tes. Our results show that the monoclonal antibodies (ACR.2, Hs-8) against intra-acrosomal proteins reduce the secondary sperm-zona pellucida-binding with statistically significant difference. This suggests the role of these proteins in the early phases of fertilization (C) 2001 by Elsevier Science Inc.