Monoclonal antibody to human fertilization antigen-1 (FA-1) inhibits bovine fertilization in vitro: application in immunocontraception.
A monoclonal antibody (mAb) to the human sperm plasma membrane protein, fertilization antigen-1 (FA-1), was tested for its reactivity with bovine spermatozoa and its effects on bovine fertilization in vitro. Western blot analysis revealed that the FA-1 mAb reacted with proteins of similar molecular mass (53 +/- 2 kDa) in human and bovine sodium deoxycholate (DOC)-solubilized sperm extracts. Indirect immunofluorescence, using epifluorescence microscopy and laser scanning confocal microscopy, revealed that the FA-1 antigen is present in the post-acrosomal region of bovine spermatozoa, which is similar to human FA-1 localization. In bovine in vitro fertilization (IVF) trials, using oocytes obtained from slaughterhouse ovaries, addition of 20, 40, or 80 micrograms/ml of FA-1 mAb to the IVF medium resulted in a linear decrease in the fertilization rate from 86.3% in the controls to 54.6%, 21.6%, and 1.8% in the respective experimental groups (p < 0.01). There was no inhibitory effect (p > 0.10) of the FA-1 mAb on percent sperm motility or other motility characteristics tested, suggesting that human FA-1 mAb inhibits bovine sperm cell function at some point after capacitation. In conclusion, the evolutionarily conserved antigen FA-1 has a molecular identity in bovine sperm similar to that in human sperm, and mAb to human sperm FA-1 inhibits fertilization of bovine oocytes. These results indicate that FA-1 is a promising candidate for the development of a contraceptive vaccine. The research also suggests that bovine species could be used as a model for investigating the use of FA-1 as an immunovaccine in ruminants.
Coonrod
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SA
Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station 77843.
Westhusin
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ME
Naz
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RK
D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D000941:Antigens / Q000032:analysis / Q000276:immunology*; D015153:Blotting, Western; D002417:Cattle; D003269:Contraception, Immunologic; D005260:Female; D005306:Fertilization / Q000187:drug effects*; D005307:Fertilization in Vitro; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D008970:Molecular Weight; D013081:Sperm Motility / Q000187:drug effects; D013094:Spermatozoa / Q000276:immunology
D000911:Antibodies, Monoclonal; D000941:Antigens; C054151:fertilization antigen