Pseudorabies Virus EP0 Protein Counteracts an Interferon-Induced Antiviral State in a Species-Specific Manner

ABSTRACT Pseudorabies virus (PRV), an alphaherpesvirus related to herpes simplex virus type 1 and varicella-zoster virus, infects a broad host range of mammals. A striking characteristic of PRV infection is the different symptoms and outcomes of infection in natural and nonnatural hosts. Adult pigs, the natural hosts of PRV, survive infection with only mild respiratory symptoms, while nonnatural hosts, including rodents and cattle, invariably die after exhibiting neurological symptoms. Here, we show that the PRV EP0 protein is necessary to overcome an interferon-mediated antiviral response in primary cells from the natural host of PRV but is not necessary in nonnatural-host cells.