Abstract
Hamster tracheal organ culture was employed as a model for the study of the pathogenesis of human parainfluenza type 3 virus infection. It clearly supported replication of the virus over a 2-week period of time. Infected tracheal explants were examined with light, electron, and immunofluorescence microscopy. They exhibited specific cytopathologic alterations including nuclear swelling and chromatin margination, multinucleated syncytia and binucleated epithelial cells, and fibroblasts and chondrocytes. Focal destruction and denudation of the respiratory epithelium occurred in later stages of infection. Virus was detected in close association with cilia and was observed budding off the unit membrane of epithelial cells.