Fertilization-related sperm antigens and their immunocontraceptive potentials

Vaccine(s) for contraception will provide an attractive alternative to cont raception. There has been a renewed interest in defining fertilization-rela ted sperm antigens that can be used for the development of a contraceptive vaccine. The sperm-zona pellucida (ZP) recognition and binding constitutes the most important event in the fertilization process, and the molecules in volved at this site are attractive candidates for immunocontraception. Exte nsive research indicates that there are four sperm surface proteins that bi nd to oocyte ZP3 in humans and they belong to the four molecular regions of 95, 63, 51, and 14-18 kDa, respectively. Our laboratory is actively engage d in cloning and sequencing of cDNAs encoding for these sperm proteins and investigating the applications of recombinant (r) proteins in immunocontrac eption and infertility. Presently, the cDNAs encoding for the 14-18-kDa pro teins, designated the NZ-1 and NZ-2, respectively, and the 51-kDa protein, designated fertilization antigen, have been cloned and sequenced. Active im munization with the rFA-1 antigen caused a reversible block/inhibition in f ertility of female mice by raising a sperm/testis-specific immune response. FA-1 antigen is also involved in human immunoinfertility, and a recent cli nical trial indicates that it will have a clinical application in the treat ment of immunoinfertile men. The long-term goal is to employ various recomb inant fertilization antigens and/or their bioeffective peptide epitopes in a single formulation, to generate an anti-sperm vaccine that will be strong ly immunogenic and highly efficacious for regulation of fertility.