Sperm antigenicity shared in five vertebrate classes

The antigens of spermatozoa are of special interest because of their involvement in immunoinfertility and because they are candidate targets for immunocontraception. Conserved sperm epitopes from divergent species may present a suitable source and an animal model for the investigation of the above factors. We compared spermatozoa from six species of vertebrates belonging to five different classes, in order to demonstrate the existence of shared antigens. We used whole fixed male germ cells from trout, frog, turtle, rooster, rabbit and human in the enzyme-linked immunosorbent assay with rabbit polyclonal sperm-specific antisera. After absorption of the antisera with non-gametic (liver powder) and gametic tissue preparations, we established significant cross-reactions among the spermatozoa of all tested species. The antigenic similarities were the strongest between spermatozoa of trout and frog, trout and human, rabbit and turtle, rabbit and rooster. These data demonstrate the existence of highly conserved epitopes in spermatozoa from divergent vertebrate species belonging to different animal classes, in contrast to structures of the female gametes (zona pellucida) for which antigenicity was found to be limited to the animal class. © 2002 Elsevier Science Inc. All rights reserved.