Immunization of male mice with B-cell epitopes in transmembrane domains of CatSper1 inhibits fertility

Capsule:
Two B-cell epitopes in transmembrane domains of CatSper1 show immunocontraceptive potential in male mice, and induce high titer of specific antibody, which impairs sperm function and causes sperm agglutination.

Authors:
Honggang Li, Ph.D., Xiaofang Ding, Ph.D., Cuicui Guo, B.A., Huangtao Guan, B.A., Chengliang Xiong, M.D.
Volume 97, Issue 2 , Pages 445-452, February 2012

Objective:
To evaluate the contraceptive ability of two B-cell epitopes in CatSper1.

Design:
In vivo study with mice.

Setting:
University laboratory animal service center.

Animal(s):
BALB/c mice.

Intervention(s):
Two predicted B-cell epitopes in the extracellular part of transmembrane domains and pore region of CatSper1 were synthesized to immunize male mice.

Main Outcome Measure(s):
Fertility, epididymal sperm function, and the presence of specific antibody in immunized males were investigated.

Result(s):
Significant reduction of fertility was observed in mating trial with no evident systemic illness or abnormal mating behavior. Epididymal sperm of epitope-immunized males exhibited impaired ability to fertilize eggs in vitro, and showed sperm agglutination in some animals, while presenting no changes in sperm viability or progressive motility. High titer of antibodies was induced in the sera, and the antibodies’ specificity was confirmed. The binding of the antibodies to epididymal sperm of epitope-immunized males was observed.

Conclusion(s):
CatSper members could be the effective and viable targets for immunocontraception. These two epitopes in CatSper1 share high identity between mouse and human and may be effective for fertility regulation in humans.

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