This research proposal is directed toward understanding the molecular basis of gamete interaction, with particular emphasis on functional characterization of sperm components. As an initial approach, anti-sperm monoclonal antibodies (mAbs) were generated that have been used to: 1) dissect the events of fertilization into individual steps, and 2) identify the sperm components recognized by the fertilization-inhibiting mAbs. At present, we have identified sperm-specific components that participate selectively in the induction of the acrosome reaction and in sperm-egg plasma membrane fusion. Study of these proteins is limited by the very small quantities of pure proteins that can be obtained by conventional techniques. Consequently, I am proposing to harness the techniques of molecular biology to clone the relevant genes and to express the proteins in large amounts so that their properties can be studied in detail. In addition, experiments in progress are aimed at generating new mAb probes directed toward other functional activities of the sperm. Again, it is anticipated that the study of these proteins may require cloning and expression of the relevant genes to obtain sufficient quantities of these proteins for their characterization. One of the ultimate goals of this work is the development of a sperm-targeted contraceptive vaccine. Previous passive immunization experiments indicate that sperm antigens, identified by the mAbs described above, are reasonable candidates in the development of a prototype vaccine. The limited quantities of antigen available reiterate the point that the only effective approach may be to clone the relevant genes. In this case, I envisage inserting the appropriate genes encoding sperm antigens into an immunization vector, such as vaccinia. The identification of genes that encode these functional proteins in mouse sperm will permit analysis of the human genome for the identification of homologous sequences that may eventually be used in developing a relevant human contraceptive vaccine. My primary motivation in requesting this RCDA is to acquire several years of unrestricted time to establish the appropriate molecular biological techniques in my laboratory. This will enable me to clone the genes encoding specific sperm proteins that function in fertilization which will make possible a detailed study of the properties of these proteins, as well as the incorporation of the relevant genes into prototype contraceptive vaccines.