HUMAN SYNTHETIC PEPTIDE VACCINE FOR CONTRACEPTION TARGETING SPERM

Abstract

A vaccine targeting sperm is an interesting approach to contraception. The acceptability of a sperm antigen for contraceptive vaccine development is contingent upon its sperm-specificity, surface expression for antibody binding, and involvement in fertilization. Sperm-zona pellucida (ZP) binding is a pivotal step and constitutes an attractive site for immunointerception. Using phage display technology, we have identified a novel dodecamer peptide sequence, designated as YLP₁₂, that is present on sperm, and is involved in ZP binding and sperm capacitation/acrosome reaction in man/mouse. Extensive search in the human and mouse genome sequence databases did not indicate a complete identity with the YLP₁₂nucleotide sequence. It is peptide mimetic with sperm receptor carbohydrate mimicking action that is involved in oocyte binding. The sperm-specific YLP₁₂sequence is also involved in involuntary immunoinfertility in men, indicating its autoantigenicity, sperm-specificity, and involvement in fertility/infertility in humans. Vaccination of female animals with synthetic YLP₁₂peptide causes a long-term reversible contraception by raising a sperm-specific immune response. The contraceptive effect could also be completely reversed voluntarily at any time by immunoneutralization of antibodies using intravaginal administration of the peptide. Thus, the novel synthetic YLP₁₂peptide is an attractive candidate for contraceptive vaccine development, and diagnosis and treatment of immunoinfertility in humans.

• human sperm
• antisperm antibodies
• immunocontraception
• sperm antigens
• acrosome reaction