Experimental pneumovirus infections: 1. Hydrocephalus of mice due to infection with pneumonia virus of mice (PVM).

The effects of the intracerebral inoculation of pneumonia virus of mice (PVM) into neonatal mice were investigated by light microscopy, immunofluorescence, and viral isolation. Viral inclusions and virus-specific antigens, as demonstrated by immunofluorescence, were maximal on the 6th day after inoculation, revealing general infection of ependyma and very limited infection of the leptomeninges and the choroid plexus. Hydrocephalus occurred on Day 21 in 80% of inoculated mice. This report describes the sequence of pathologic events leading to hydrocephalus and supports recent studies indicating that stenosis of the aqueduct is a secondary phenomenon not causally related to the pathogenesis of hydrocephalus. Hydrocephalus was shown to be significantly related to the affected ependyma of the ventricular system. These observations, together with other recent findings, suggest that ependymal cells could play a strategic role in the flow of the cerebrospinal fluid.