A comparison of the pathogenicity of three strains of bovid herpesvirus 2 in calves.

The isolates of Bovid herpesvirus 2 share common morphological, physical and antigenic features, but differences in their pathogenicity for cattle have been found among the strains. In order to investigate this aspect in more detail a comparative study was made of the skin lesions produced in calves by three strains of the virus: Allerton BA, bovine mammilitis and 69/1L0. The results show that Allerton BA was less pathogenic for calves than the other two strains used in the experiment. This conclusion is supported by the observations that very few inclusion bodies were found in the lesions produced by Alerton BA, and the maximum titre of virus in the lesions was lower than the titres obtained with bovine mammillitis and 69/1L0. Moreover the thickness and diameter of the lesions with Allerton BA were less than those with the other strains. It is speculated that Allerton BA strain, which originated from a buffalo, might behave similarly to bovine mammillitis and 69/1LO following serial passages in cattle.