REOVIRUS INFECTION IN RAT LUNGS AS A MODEL TO STUDY THE PATHOGENESIS OF VIRAL PNEUMONIA

We undertook the present study to elucidate the pathogenesis of the pa thologic response to reovirus infection in the lungs and further under stand the interactions of reoviruses with pulmonary cells, We found th at reoviruses were capable of causing acute pneumonia in 25- to 28-day -old Sprague-Dawley rats following intratracheal inoculation with the reoviruses type 1 Lang (T1L) and type 3 Dearing (T3D), The onset of th e pneumonia was rapid, marked by type I alveolar epithelial cell degen eration, type II alveolar epithelial cell hyperplasia, and the infiltr ation of leukocytes into the alveolar spaces, More neutrophils were re cruited into the lungs during T3D infection than during T1L infection, and the serotype difference in the neutrophil response was mapped to the S1 gene of reovirus, Viral replication in the lungs was required f or the development of pneumonia due to T1L and T3D infections, and rep lication occurred in type I alveolar epithelial cells, T1L grew to hig her titers in the lungs than did either T3D or type 3 clone 9, and the S1 gene was found to play a role in determining the level of viral re plication, We propose that experimental reovirus infection in the lung s can serve as a model for the pathogenesis of viral pneumonia in whic h pulmonary inflammation results following direct infection of lung ep ithelial cells.