EFFECTIVE VACCINATION OF CATTLE USING THE VIRION G-PROTEIN OF BOVINE EPHEMERAL FEVER VIRUS AS AN ANTIGEN

In a series of experiments, the envelope glycoprotein (G protein) of b ovine ephemeral fever virus (BEFV) induced immunity against challenge with virulent virus. Protection correlated with the level of specific serum antibodies to G protein measured by a blocking ELISA test and wi th the level of neutralizing antibody. The optimum vaccination regimen consisted of two injections given 21 days apart at a dose rate of 0.3 2 mu g per cow of purified G protein emulsified in the adjuvant Quil A . This schedule conferred immunity for the duration of the preliminary experiment (46 days). Immunity to severe disease, but not to infectio n, remained for at least 12 months after vaccination, although BEFV co uld not be reisolated from vaccinated cattle following challenge. Unva ccinated cattle used as controls exhibited typical signs of clinical e phemeral fever and BEFV was recovered from all control animals followi ng challenge.