The influenza B virus mouse model of Reye's syndrome: clinical, virologic and morphologic studies of the encephalopathy.

The influenza B virus mouse model of Reye's syndrome was studied to learn more about the encephalopathy in Reye's syndrome. One to 3 days after intravenous influenza B/Lee virus, Balb/c mice became lethargic, seized and lapsed into a fatal coma. Wide-spread cerebral edema without inflammation developed 1-3 days after virus inoculation. Swollen astrocytic foot processes containing increased glial fibrillary acidic protein were located around capillaries. Viral particles were not seen by electron microscopy and complete viral replication did not occur. Immunohistochemical studies demonstrated influenza B viral antigen within many endothelial cells but not within other brain cells. Qualitative (Evans blue dye) and quantitative (percent brain water and technetium -99 pertechnetate) studies of the blood-brain barrier demonstrated abnormalities. This model reproduced many clinical, virologic and pathologic features of the Reye's syndrome encephalopathy. In addition, a non-permissive viral infection of brain endothelial cells occurred which may be important in the pathogenesis of the mouse encephalopathy and may participate in the encephalopathy of Reye's syndrome.