Rabies encephalitis: immunohistochemical investigations.

Three cases of human rabies encephalitis were studied immunohistochemically using a specific antiserum to rabies ribonucleoprotein (RNP) and the peroxidase-antiperoxidase method. In this way, RNP could be specifically demonstrated in all cerebral regions and the spinal cord with a predilection for virus attack on the diencephalon and the brain stem according to the clinical course of the disease, and possibly reflecting the phenomenon of pathoclisis. Virus antigen was mainly present in the nerve cell bodies and processes, and in glial cells, especially in the interfascicular oligodendroglia, which seems to be a route of rabies virus infection in the later course of this fatal disease. Immunohistochemically, virus antigen was not limited to the Negri bodies: it was also traceable in the cytoplasm. Altogether, many more virus infected cells were established by immunostaining than were to be expected by the presence of Negri bodies in hematoxylin-eosin stained sections.