Effect of antibodies to sperm-specific recombinant contraceptive vaccinogen (rCV) on murine fertilization: search for an animal model to examine its contraceptive potential

Calcium Channels and Ca2+ Fluctuations in Sperm Physiology

Generating new life in animals by sexual reproduction depends on adequate communication between mature and competent male and female gametes. Ion channels are instrumental in the dialogue between sperm, its environment, and the egg. The ability of sperm to swim to the egg and fertilize it is modulated by ion permeability changes induced by environmental cues and components of the egg outer layer. Ca(2+) is probably the key messenger in this information exchange. It is therefore not surprising that different Ca(2+)-permeable channels are distinctly localized in these tiny specialized cells. New approaches to measure sperm currents, intracellular Ca(2+), membrane potential, and intracellular pH with fluorescent probes, patch-clamp recordings, sequence information, and heterologous expression are revealing how sperm channels participate in fertilization. Certain sperm ion channels are turning out to be unique, making them attractive targets for contraception and for the discovery of novel signaling complexes.

Identification of sperm immunoreactive antigens for immunocontraceptive purposes: a review

Antisperm antibodies (ASA) may be a reason of infertility in some individuals. They may affect pre- as well as post-fertilization stages of the reproductive process. There is ongoing progress in the identification of sperm antigens related to fertilization. The employed methods for this purpose include recombinant DNA technology and the most advanced proteomic analysis. This paper enlists the different approaches undertaken in order to identify and characterize the immunoreactive sperm antigens. We have mainly focused on those, which have been already studied in regard of their immunocontraceptive potential, although it has been impossible to include all published data concerning the topic in a single article. Few novel sperm auto- and isoantigens, discovered recently, have also been reviewed even if their role in fertilization has not been yet established.

Sperm specific proteins-potential candidate molecules for fertility control

The increase in population growth rate warrants the development of additional contraceptive methods that are widely acceptable, free from side effects and less expensive. Immunocontraception, and in particular the targeting of antibodies to gamete-specific antigens implicated in sperm egg binding and fertilization, offers an attractive approach to control fertility. The development of a contraceptive vaccine based on sperm antigen represents a promising approach to contraception. In mammals, fertilization is completed by the direct interaction of sperm and egg, a process mediated primarily by sperm surface proteins. Sperm have proteins that are unique, cell specific, immunogenic and accessible to antibodies. A few of the sperm specific proteins have been isolated and characterized. The antibodies raised against the sperm specific antigens have proved to be extremely effective at reducing sperm-egg interaction in vitro; fertility trials in sub-human primates would eventually prove the effectiveness of the sperm antigens in terms of contraceptive efficacy.