Jeffrey Lee of the University of Toronto in Canada will engineer single-domain camelid antibodies (nanobodies) to block the interaction between two proteins exclusive to the sperm and egg that mediate their fusion and thereby fertilization, as affordable, non-hormonal contraceptives with fewer side effects. Nanobodies are exquisitely specific binding proteins that make attractive therapeutics because of their additional simplicity, stability, and smaller size compared to antibodies, also lowering the cost of their production. They hypothesize that their small size is well adapted to reach the site of sperm-egg binding and block this interaction. To generate specific nanobodies they will immunize alpacas or llamas with the purified sperm and egg proteins and use phage display and ELISA to isolate antigen-specific nanobodies. These will then be tested for their ability to block sperm-egg fusion using biophysical assays, mating, and IVF models.
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