Observations on the virus of infectious bovine rhinotracheitis, and its affinity with the Herpesvirus group

Abstract Infectious bovine rhinotracheitis virus is readily propagated by serial passage in cultures of calf kidney or rabbit spleen cells, producing a herpes-like cytopathic effect. It is ether sensitive; but cross neutralization tests show it to be immunologically distinct from herpes simplex. A local tissue reaction was caused by virus inoculation into the skin or testis of rabbits; this was not transmissible in series. Electron microscopy of infected tissue cultures reveals intranuclear virus-like particles, each with one membrane and a diameter of about 115 mμ; larger particles, measuring about 150 mμ and with two membranes, occur in the cytoplasm and at the cell surfaces. It is suggested (1) that the virus is a bovine member of the Herpesvirus group; (2) that viruses giving rise to nuclear inclusions of Cowdry's type A may constitute a natural taxonomic group.