[Interests and limits of immunocontraception]

Recent studies from WHO indicated that a large proportion of human contraceptive needs cannot be covered by the already existing means for different reasons (medical, economical, political, and cultural). Therefore, development of new effective methods targeting birth control methods affordable by under-privileged populations turns out to be necessary. Over the last 20 years, a large number of strategies have been used for contraceptive vaccines and thus multiple antigens have been identified as potential targets for immunocontraception. Nowadays, the most acute researches are based on suppression of the secretion and the activity of gonadotropic hormones (GnRH, LH/hCG, FSH) or the targeting of antibodies specific to sperm surface (RSA-1, SP10, SP17, TCLe-1, PH-20) and oocyte antigens (ZP1, ZP2, ZP3). We developed a contraceptive vaccine against FSH receptor. Adult male monkeys (Macaca radiata) were immunized with filamentous phages displaying at their surface N-terminal peptides of the FSH receptor. Long term male contraception has been achieved without any alteration of circulating testosterone levels, sexual behaviour or of any other discernable metabolic changes. Interruption of vaccination resulted in full recovery of sperm production and male fertility. Contraceptive vaccines are aimed to block an essential step in the reproductive process. From this point of view, efforts have to be focused on the challenge to raise is to ally our knowledge on reproductive physiology and protein biochemistry for a better understanding of the target antigen's function.