The development of a contraceptive vaccine by purification of antigens from gametes.

There are several ways to make immunological contraceptive vaccines. We are trying to purify gamete antigens from human seminal plasma and porcine zona pellucida (ZP) by using several monoclonal antibodies (Mabs) for this purpose. A human seminal antigen relevant to sperm immobilization with corresponding antibody was purified by immunoaffinity chromatography-bound Mab 1C4. This antigen was common to human milk protein but is different from lactoferrin. It was termed "ferrisplan" and was secreted mainly from the epithelial cells of seminal vesicle and adhered to the midpiece and postnuclear cap region of spermatozoa. Another Mab 2C6 reacted only to the SP component but not to other organ extract including human milk protein. The corresponding antigen to Mab 2C6 is aimed to purify by using high performance liquid chromatography and immunoaffinity chromatography-bound Mab 2C6. Several Mabs to porcine ZP antigens common to human ZP did not block human in vitro fertilization unless the second antibody (anti-mouse gamma-globulin) was used. It is speculated that porcine ZP will not contain the antigenic component that relates to sperm receptor of human ZP. Therefore, an antigenic molecule located close to sperm receptor of human ZP must be purified from the porcine ZP by using immunoaffinity chromatography-bound Mab and other biochemical methods, expecting production of a corresponding antibody that blocks the fertilization in humans.