Evaluation of a DNA Vaccine for Immunocontraceptive Potential Against Zona Pellucida Glycoproteins in Cattle

Abstract

Holstein cows were administered zona pellucida (ZP) DNA vaccine and used to determine the potential of recombinant rabbit ZP glycoproteins (rZP) as immunocontraceptive antigens. Zona pellucida proteins were purified and quantified. Cows were assigned to one of four treatment groups in which plasmids encoding rabbit ZP proteins were administered, i.d., using a gene gun (ZP55, n=2; ZP75, n=2; Hep55, n=2; and Control, n=3). Blood samples were taken before initial vaccination, once weekly for 5 wk and at 148 wk post-immunization. An ELISA was developed to assess anti-ZP titer levels in cow serum and ovarian function in cows was monitored using trans-rectal ultrasonography. Four of the six cows in ZP treatment groups developed antibody titer levels with similar linear responses over time. These cows also experienced reduced ovarian function as indicated by decreases in follicular and luteal activity. Estrous activity was observed in all cows and decreased in ZP treatment cows in comparison to Controls. Further research is needed to determine the relationship between ZP immunocontraception and ovarian function. Still, this study provides a basis for future researchers to use in developing a contraceptive vaccine for cattle.