Immunofluorescence staining for the diagnosis of herpes encephalitis.

Direct immunofluorescence staining for herpes simplex virus was applied to cryostat sections of 43 specimens removed at brain biopsy. Herpes antigen was found in 10 specimens and virus was isolated from them. Antigen was found in one specimen from which virus was not isolated. Two specimens from which virus was isolated gave equivocal fluorescence. Thirty specimens gave no fluorescence or live virus. Immunofluorescence provided a diagnosis in three hr compared with 24-42 hr for virus isolation. Indirect immunofluorescence staining was applied to sections of brain removed at necropsy and fixed in formalin. Herpes antigen was found in sections of six of the 12 brains examined.