Molecular Characterization of Sperm Antigens with In Vivo Developed Antisperm Antibodies in Variably Inseminated Cross Bred-Heifers/Cows

Molecular characterization of sperm proteins and their immunoreactions to sera from subfertile/infertile animals may give deeper insight to the immunological reason of infertility. The purpose of this study was to characterize antigenic sperm proteins by reacting with blood serum and cervical mucus of variably inseminated heifers/cows using immunoblotting and immunofluorescence techniques. Immunoblot analysis of sperm proteins with blood serum/CM of variably inseminated cows/heifers revealed around 23 polypeptides in cattle sperm, but all proteins did not react with blood serum and cervical mucus of all tested animals. Number of sperm polypeptides that reacted with blood serum of non-inseminated, 1-3, 4-6 and >6 times inseminated heifers/cows were in the range of 11-14, 8-13, 3-14 and 5-13 respectively. Correspondingly cervical mucus of 1-3, 4-6 and >6 times inseminated heifers/cows also recognized about 2-7, 2-13 and 2-12 sperm polypeptides respectively. Immunofluorescence of sperm smears with blood serum and cervical mucus of variably inseminated heifer/cows indicated the presence of antisperm antibodies (ASA) mainly against acrosome surface, post –acrosome and principal piece surface proteins. There was not any difference in range of number of polypeptides detected with blood serum in regard to number of insemination. But range of number of polypeptides detected was higher with cervical mucus of >3 times inseminated animals, which indicated increase in ASA against antigenic sperm proteins in cervical mucus with increase in number of inseminations. It was concluded that ASA are produced in blood serum and cervical mucus of cows/heifers against sperm proteins, irrespective of number of inseminations. In future further characterization of sperm proteins and their homogeneity with bacterial proteins is needed to understand the mechanism of ASA mediated fertility impairment and to develop treatment protocol on the basis of purified antigens.