Early pathogenesis of experimental reovirus infection in chickens.

One-day-old specific-pathogen-free, light hybrid chickens were infected orally with an avian arthrotropic reovirus and examined at intervals from 2 h until 12 days after infection. Entry, primary replication and spread of virus were studied by infectivity assay, immunohistochemical study and electron microscopy in a wide range of tissues. These showed viral entry and primary replication in the epithelium of intestine and bursa of Fabricius within 12 h after oral infection. These were followed by a rapid and pantropic distribution of virus which reached most tissues within 24 to 48 h after infection.