Pathogenicity of influenza A virus in ependymal organ culture

Ependymal organ culture was used as a model to study the effect of influenza A virus on the ciliated ependyma of the rat. One-square-milli-meter portions of cerebellum from newborn rats were harvested in roller tubes containing Ham's F-12 medium calf serum, and glutamine. Ciliary activity was monitored by stereomicroscopy and, after vigorous ciliary motion was established, tubes were inoculated with 0.1 ml of an inoculum containing 35 plaque-forming units (PFU) of neurotropic influenza A virus (WSN strain). Explants were examined by scanning electron microscopy (SEM) at 2 and 7 days and by transmission electron microscopy (TEM) at 7 days. When compared to noninfected controls, SEM showed that at 2 days the density of microvilli and cilia was decreased in influenza A virus-infected explants. At 7 days, the ependymal cells were nearly denuded of cilia and microvilli, and macrophage like cells were frequently resting upon the ependymal surface. TEM showed numerous viral particles, both budding from the cells surface and located extracellularly near the cell surface.