Evaluation of the potential contraceptive use of hCRISP1 in a non-human primate model

ELLERMAN DA; WEIGEL MUÑOZ M; ERNESTO JI; COHEN DJ; YUDIN A; OVERSTREET J; TOLLNER T; CUASNICÚ PS

New Hampshire, EEUU

Congreso; Gordon Research Conference on Fertilization and activation of development; 2009

Gordon Research Conferences

Evidence from our group indicated that human epididymal protein CRISP1 (hCRISP1), like its rat counterpart, participates in gamete fusion through its binding to complementary sites on the human egg. As a first approach to evaluate the relevance of hCRISP1 for human fertility, immunization studies were carried out in a non-human primate model. Male and female M. fascicularis were immunized with hCRISP1 (coupled to maltose binding protein, MBP), MBP as control, or the monkey homologue of hCRISP1 (mkCRISP1), and their sera collected at different intervals after immunization. Analysis of the immune sera by ELISA revealed that while no anti-hCRISP1 or anti mkCRISP1 antibodies were detected in pre-immune or control sera, a specific immune response that increases as a function of time was detected in animals injected with the human or monkey CRISP1 protein. Characterization of the sera by Western blot indicated that sera from both hCRISP1 and mkCRISP1-immunized animals were capable of specifically recognizing native sperm monkey CRISP1 in sperm extracts. Sperm number, motility and morphology in animals immunized with hCRISP1 were not different from those obtained before immunization, suggesting the lack of detrimental effects of the antibodies on testicular sperm production and epididymal maturation. ELISA assays also indicated the presence of anti-hCRISP1 antibodies in seminal plasma from those animals injected with hCRISP1. Finally, the observation that ejaculated sperm from hCRISP1-immunized animals exhibited a patchy fluorescent pattern in their heads when exposed only to second antibody, confirmed both the access of the anti-hCRISP1 antibodies to sperm within the male tract and their binding to the cells in vivo. These results, together with the already established participation of hCRISP1 in gamete fusion, support both the potential involvement of anti-hCRISP1 antibodies in human immunoinfertility and hCRISP1 as a likely candidate for the development of a human male contraceptive approach.