Reisolation of avian arthrotropic reovirus R2 from chicks infected as embryos

Four groups of specific-pathogen-free (SPF) chicken eggs of 7 days' incubation were inoculated via the yolk sac with a range of 10-fold dilutions of avian reovirus R2. Deaths between days 8 and 18 of incubation increased in number with increased virus dose inoculated, and virus was recovered with high frequency from all groups except those given the lowest dose. For those chicks which hatched, cloacal swabs at day-old failed to demonstrate virus in the chicks given the lowest dose, although those infected with the two higher doses were positive. At 7 days post-hatch, however, virus could be isolated from target tissues e.g. liver, hock joints and rectal contents, of most chicks in all groups, but many samples were not positive until after three cell culture passages. It is considered that this method of experimental infection could conveniently simulate natural egg transmission of avian reoviruses.