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The IUP Journal of Genetics & Evolution
Immunocontraception A Possibility from Sperm Antigens and Their Genetic Basis: A Review
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There is an ongoing research in the identification of sperm antigens related to fertilization because the Antisperm Antibodies (ASA) may be a reason of infertility in some individuals which may affect the pre- as well as post-fertilization stages of the reproductive process. This phenomenon is being exploited to develop a vaccine that is immunocontraceptive for effective prevention of fertilization leading to unwanted pregnancy, which offers an attractive approach to the growing global problem of overpopulation. Genetic mechanisms in the determination of antigens, thereby eliciting immune response leading to prevention of fertilization and development, are understood thoroughly, helping in the construction of cDNA library and production of recombinant vaccines.

 
 
 

The present size of the world population is approximately 6.5 billion, and unless we take measures to reduce the growth rate in the near future, it may reach 7-9 billion, as per the predictions made (United Nations, Population Prospects: 1998 edition). The rate of population growth comes down to 2% per year, indicating a decreasing trend, according to the current status. However, the average number of births is very much greater than deaths (i.e., 9-100 million more births than deaths ), especially contributed by birth rate in developing countries (Potts, 1990; Bongaarts, 1992; and 1996), the reason being advances in medicare and improved living standards. It is understood that fertility factor plays an important role in population growth rather than mortality component. A direct necessity arises out of such population phenomenon to arrest growth, for which several contraceptives have to be tried. It is estimated that approximately 500 million couples worldwide have no access to contraception (Diczfalusy, 1999).

In addition to improved availability and access to contraceptive services, the development of novel methods of contraception, which are safer, easy and comfortable, is required to solve global population problem to a greater extent.

One of the challenging approaches would be to provide a safe and reliable method of birth control by a contraceptive vaccine which effectively prevents the fertilization process. Some attempts are being made in this direction considering gamete-specific antigens. Sperm antigens are the potential candidates of immunocontraceptive vaccine which effectively causes prevention of fertilization between an egg and sperm.

This paper emphasizes the genetic diversity and identification of antibodies produced in response to sperm antigens.

Antibody Diversity of Sperm Antigens

There are many antigens existing on the sperm surface, such as Fertilization Antigens (FA-1, FA-2) that can recognize zonapellucida, Sperm Protein (SP), Cleavage Signal Antigen (CS), PH -20, A36 Antigen, Mouse Sperm Antigens (MSA-63, MSA-11) NZ-1, NZ-2 and many other known antigens, which elicit an immense diversity of antibodies with their variable expression.

 
 
 

Genetics & Evolution Journal, CEL-I Endonuclease, Heterozygous Mutants, Homozygous Mutants, Biological Processes, Plant Mutants, Solanum Lycopersicon, Microcentrifuge Tubes, Homozygous Plants, Plant Genes, Cross Pollination, Heteroduplex Formation.