Development of a
vaccine(s) based on sperm
antigens represents a promising approach to
contraception. The utility of an
antigen in
immunocontraception is contingent upon sperm/testis-specificity and its involvement in the fertilization process. Since, the sperm-zona pellucida (ZP) recognition and binding constitutes the most important event in the fertilization process, molecules involved at this site are attractive candidates for
immunocontraception. Using hybridoma technology, subtractive hybridization, and differential display technology, our laboratory has delineated several sperm
antigens. These
antigens have testis-specific expression and have a role in the fertilization process. The cDNAs encoding for the
antigens have been cloned and sequenced. Among these, the
fertilization antigen (FA-1) is particularly interesting, because it is involved in immuno-
infertility in humans. Using the phage
peptide display technique, a novel dodecamer sequence of a approximately 72+/-5 kD
antigen, designated as YLP(12), that is testis-specific and involved in human sperm-ZP recognition/binding, was identified. A synthetic 12-mer
peptide was generated based on this sequence. In the hemizona assay,
YLP(12) peptide and its monovalent Fab'
antibodies specifically and significantly inhibited human sperm-ZP binding. Furthermore, the presence of specific
antibodies reactive with
YLP(12) peptide, were identified in the serum and seminal plasma of immuno-infertile men. Thus, FA-1 and YLP(12) are promising target
antigens for the development of
contraceptive vaccines as well as for specific diagnosis and treatment of
male infertility.