An Immunofluorescent and Histopathological Study of Respiratory Syncytial (RS) Virus Encephalitis in Suckling Mice. ∗ †

Abstract

Summary

The susceptibility of suckling mice of different ages to the neuropathic strain of respiratory syncytial (RS) virus was examined periodically during serial intra-cerebral passage (s) of the virus in newborn mice. By passing the virus serially in mouse brain, beginning with the one-day-old mouse and gradually increasing the age, it became possible to grow the RS virus in 7- and 9-day-old mice. The pathogenesis of the encephalitis produced by neuropathic strain of the RS virus, in intracerebrally inoculated suckling mice, was studied by means of immunofluores-cent and histopathologic techniques. The histological changes were correlated with im-munofluorescen.ee and infectivity titrations. The clinical evidence of encephalitis in the infected mice was found to be associated with extensive necrosis and liquefaction of the brain. This mouse brain adapted strain of RS virus was found to be strictly neuropathic, in that it produced lesions only in the nervous system of the intracerebrally inoculated suckling mice and failed to produce either infection or lesions in any of the extracerebral tissues which were examined.