A subunit vaccine based on glycoprotein E2 of bovine virus diarrhea virus induces fetal protection in sheep against homologous challenge.

The primary aim of a bovine virus diarrhea virus (BVDV) vaccine is to prevent transplacental transmission of virus. E2 genes of three BVDV strains, belonging to antigenic groups IA, IB and II, were expressed in insect cells. Three groups of 12 ewes were immunized twice with one of the E2 proteins. A fourth group served as a control. The ewes were served and the pregnant ewes of each vaccination group were allotted to three different challenge groups. Seven weeks after the second vaccination the ewes were challenged intranasally with one of the three BVDV strains. Three weeks later the fetuses were removed and fetal organs were collected for virus isolation. At the day of challenge all vaccinated ewes had neutralizing antibodies against the homologous BVDV strains. One E2 subunit vaccine prevented fetal infection after homologous challenge.