Inactivated bovine herpesvirus 1 marker vaccines are more efficacious in reducing virus excretion after reactivation than a live marker vaccine.

A comparative study was carried out to evaluate the efficacy of three bovine herpesvirus 1 (BHV1) marker vaccines to reduce the reexcretion of virus after reactivation of latent BHV1. A live gE-negative vaccine, an inactivated gE-negative vaccine and an experimental gD-subunit vaccine were tested in three identical experiments in which cattle, latently infected with BHV1, were vaccinated twice before they were treated with high doses of dexamethasone. Virus excretion after dexamethasone treatment was compared with that in BHV1-infected, unvaccinated cattle which served as controls. All cattle, controls and vaccinees, excreted virus. However, the inactivated vaccines reduced virus excretion more efficiently than did the live vaccine.