title: Immunohistological studies in viral encephalitis.
abstract: Immunofluorescence (IF) techniques performed on formol-fixed, paraffin-embedded and protease-pretreated sections from autopsy brain for demonstration of rabies and Herpes simplex type 1 (HSV-1) antigens proved to be a simple and effective method to ensure the etiology of some viral encephalitides. In contrast to fresh material, the use of formol-fixed tissues rules out any risk in handling highly infectious material. Another major advantage is the possibility of comparing IF appearance with normal histology of the same section by post-staining with hematoxilineosin (H.E.) or other stains. In 2 animal and one of 2 human rabies cases, neuronal cytoplasmic inclusions were more prominent in IF than in H.E. stains. In 31 cases with a histopathological diagnosis of necrotizing encephalitis, HSV-1 antigen was demonstrated in 17 of 25 acute cases but absent in 6 cases with clinical courses longer than 4 weeks. Specific fluorescence of nuclear inclusions bodies was inconstant and less prominent than that of neuronal cytoplasm and neuronal/glial nuclear membranes. Since HSV-1 positive cells are patchily distributed, limited tissue sampling (e.g. in diagnostic biopsies) may yield false negative results. Paucity of HSV-1-positive cells in the leptomeninges renders CSF immunocytology of limited use for diagnostic purposes.
mesh_terms: D000328:Adult; D000818:Animals; D002540:Cerebral Cortex / Q000276:immunology; D002648:Child; D003670:Deer; D004660:Encephalitis / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D005589:Foxes; D006561:Herpes Simplex / Q000276:immunology*; D006801:Humans; D009336:Necrosis; D011818:Rabies / Q000276:immunology*