Experimental parainfluenza type 1 virus-induced encephalopathy in adult mice. Pathogenesis of chronic degenerative changes in the CNS.

The pathogenicity of the 6/94 strain of parainfluenza type 1 virus, originally isolated from multiple sclerosis brain, was studied in adult mouse brains. Intracerebral inoculation of the virus caused mononuclear cell infiltration in the form of perivascular cuffing and a diffuse exudation into the parenchymal tissue, preferentially in cerebral white matter, that resulted in marked degeneration over a 90-day observation period. Immunofluorescent staining revealed viral antigen in the ependymal lining cells only during the first seven days after infection. No correlation was found between the severity of the brain lesions and the level of circulating antiviral antibody, preexisting or newly produced.