Cellular pathology of calves experimentally infected with bovine herpes mammillitis virus

The cellular pathology of calves experimentally infected with bovine herpes mammillitis virus by inoculation is described and correlated with clinical, cultural and histological observations in the same animals. Widespread intranuclear virus replication was observed 4 days after inoculation in localized or disseminated cutaneous lesions. The production and release of complete virus particles, the degree of epidermal and sebaceous tissue damage and the febrile response appeared to be at a maximum 8 days after inoculation. Coagulative scab material was observed to contain large numbers of apparently mature virus particles 10 days after inoculation and infective BHM virus could still be isolated from such material removed from lesions 7 days later. The fine structure of the agent and its mode of replication resembled those of the virus of herpes zoster infection in man. Numerous cytoplasmic inclusions were noted adjacent to infected nuclei in electron micrographs of epidermal cell syncytia 6 days after inoculation. It is suggested that these were formed from dyskeratotic material after the breakdown of desmosomal junctions and appeared in a similar manner to the structures observed in some acantholytic processes in man.