Acute encephalopathy induced in cats with a stealth virus isolated from a patient with chronic fatigue syndrome.

A simian cytomegalovirus-related stealth virus, isolated from a patient with the chronic fatigue syndrome, induced an acute neurological illness when inoculated into cats. Histological examination of brain tissue showed foci of cells with cytoplasmic vacuolization and an absence of any inflammatory reaction. Electron microscopy confirmed the presence of herpes-like viral particles and viral-like products in the brain of an inoculated animal. These findings support the role of stealth viruses in the pathogenesis of human neurological diseases and provide an animal model to evaluate potential antiviral therapy.