Published online by Cambridge University Press: 14 May 2001
To determine whether sperm membrane components, rSMP-B and YWK-II, aresuitable candidates as immunocontraceptives in humans, antifertilityactivities of the antibodies to the peptide fragments, rSMP-229 andrSMP-230 of rSMP-B and YAL-198 of YWK-II, were examined. In a previousreport, anti-rSMP-230 antibody was shown to immobilise human sperm andto block human fertilisation, and the antigen (rSMP-230) to interactwith antisperm antibodies found in sera of infertile women. Antibodyto the second synthetic peptide, rSMP-229, corresponding to a differentsegment of rSMP-B, mimicked the biological activities of the anti-rSMP-230antibody. Anti-YAL-198 antibody significantly, although weakly, inhibitedhuman fertilisation. In the murine model, the anti-rSMP-B antibodies blockedin vitro fertilisation of mouse eggs but had no influence on embryogrowth. Anti-YAL-198 antibody, however, arrested the growth of zygotes. Inconclusion, rSMP-B, a human sperm protein, is a promising candidate in thedevelopment of an immunocontraceptive for human application. A secondsperm protein, YWK-II, is effective as an antifertility immunogen inexperimental animals.