A conventionally attenuated glycoprotein E-negative strain of bovine herpesvirus type 1 is an efficacious and safe vaccine.

We examined the vaccine properties of a conventionally attenuated bovine herpesvirus type 1 (BHV-1) mutant strain A. This strain has a deletion that encompasses the glycoprotein E gene and may therefore be used as a marker vaccine. We compared strain A with a commercial live BHV-1 vaccine B. Calves were intranasally vaccinated with strain A or with vaccine B. Strain A was virtually avirulent for young calves. After challenge, vaccinated calves were protected against disease and virus shedding was considerably reduced. After dexamethasone treatment, strain A was not recovered, whereas vaccine B and challenge virus were. We conclude that strain A is suitable for inclusion in a vaccine and has the potential advantage of being used as a marker vaccine.