MURINE INFLUENZA VIRUS ENCEPHALOMYELITIS

Abstract

The direct inoculation of neurotropic NWS strain of the influenza virus into the brains of Swiss albino white mice results in an acute meningoencephalomyelitis. The myelitis is described for the first time. The cerebral lesions are marked by a severe ventriculitis, characterized by a necrotizing ependymitis and a lesser involvement of the choroid plexus. During the first three to four days of the infection, increasingly frequent and prominent paraventricular inflammatory and degenerative lesions are seen in the brain and paracanalicular ones in the spinal cord. There is a gradual decrease in the number and severity of the lesions from the fifth to the seventh days. Intranuclear inclusions and fewer cytoplasmic ones are described for the first time in this experimental condition and are seen in both cerebral and spinal cord lesions. They are present in nerve cells but not in glial or other cells. Segmental demyelination is encountered sparingly and is most notable in the corpus callosum. Astrocytosis is a prominent and early feature of experimental murine influenzal meningoencephalitis and is probably reactive in character.