Induction of infertility in female rats after active immunization with 24 kD antigens from rat testes

A unique polyvalent antiserum against whole washed human sperm was used previously to identify groups of antigens on spermatozoa. The antiserum, designated as Antiserum I, recognized a 40 kD antigen in human sperm extracts. Antiserum I caused agglutination of human sperm and prevented interaction of mouse sperm and oocytes. This serum also recognized a band of 24 kD in rat testicular cytosol. In the present study this group of 24 kD proteins was used as an antigen preparation to actively immunize female rats. Immunization was carried out with two different adjuvants: nor-muramyl dipeptide and SPLPS (a thyalated derivative of lipopolysaccharide). Both groups of animals showed significant antibody titres as detected by indirect immunofluorescence and by sperm agglutination tests. In both groups over 80% of the animals remained infertile, compared to 13% of the controls. It is concluded that a group of antigens in rat testes recognized by Antiserum I offer promise as candidates for a contraceptive vaccine.