Biological and biochemical comparison of bovid herpesvirus-4 strains

Bovid herpesvirus-4 (BHV-4) isolates V.Test and LVR140, isolated from genital disease, respectively, in bull and in cow, and the reference strains Movar 33/63 and DN599 were compared by several methods: cross-serological relationship studied by indirect immunofluorescence; kinetics of intracellular and extracellular viral production; comparison of the mean plaque size; restriction analysis of viral DNA with restriction enzymes EcoRI, BamHI and HindIII. BHV-4 strains were serologically identical and the kinetics of viral production were very similar. Comparison of the mean plaque size allowed classification into 3 classes (Class I, Movar33/63; Class II, LVR140; Class III, V.Test and DN599) and restriction analysis of viral DNA revealed clear differences between the electrophoretic patterns of the four BHV-4 strains. The differentiation between BHV-4 strains can therefore be achieved by a biological method (mean plaque size) and by restriction analysis. The two genital isolates are easily differentiated by the two methods.