NITRIC-OXIDE SYNTHASE TYPE-II EXPRESSION BY DIFFERENT CELL-TYPES IN MHV-JHM ENCEPHALITIS SUGGESTS DISTINCT ROLES FOR NITRIC-OXIDE IN ACUTE VERSUS PERSISTENT VIRUS-INFECTION

Intranasal inoculation with mouse hepatitis virus strain JHM (MHV-JHM) results in acute meningoencephalitis. We found NOS II mRNA expression in brains of acutely infected animals on days 5 through 7 after infec tion. In situ hybridization and immunohistochemistry demonstrated NOS II message and protein in infiltrating macrophages. Persistent infecti on with MHV-JHM results in chronic demyelinating encephalomyelitis. NO S II mRNA was detected in persistently infected spinal cords. In situ hybridization and immunohistochemistry showed expression of NOS II in astrocytes in and around demyelinated lesions. These results suggest t he role of NO release in acute versus persistent infection with this v irus, and its contribution to the resulting pathology, may be differen t.