Prospects for Sperm Immunocontraceptive Vaccines

Abstract

The global population growth rate represents one of the greatest threats to mankind to day . Most of today's population is concentrated in the developing countries and if left unchecked, may lead to deleterious consequences.Contraception is one of the ways of controlling population growth , however, contraceptive methods used today are not available to many individuals due to sociological , financial, or educational limitations. Immunocontraception may provide alternative to the current contraceptive methods due to its reversibility and the fact that most of the developing countries where populationgrowth is highest , have service infrastructure for delivery of disease vaccines into which contraceptive vaccines could be incorporated.Immunizations against sperm components are feasible since antibodies can be raised against unique antigens on spermatozoa and interfere with fertilization process . However, whole sperm cannot be used for immunization as it shares some somatic epitopes that may have harmful effects .Therefore, a unique sperm specific and acceptable immunogen must be found which has no harmful effects .A number of sperm specific proteins with immunocontraceptive potential have been identified , however only a small number (Sp-10, Sp-17, FA-1, PH-20 and LDH-C4) have been extensively characterized . This article evaluates the current status of these and other sperm targeted molecules that have been proposed as candidates for immunocontraceptive vaccine. Choice of non-human primate animal models for contraceptive vaccine development is also highlighted. It further discusses the problems encountered in the development of these molecules to full contraceptive agents.