A comparison of single and repeated oral infection of chicks with two avian reoviruses.

Groups of specific pathogen-free light hybrid chicks were inoculated with one dose or repeated doses on alternate days of avian reovirus strain R2 isolated from tenosynovitis, or strain 49/82, isolated from infectious stunting. Strain 49/82 induced significant reductions in weight gain after infection by either method, as did strain R2 after repeated doses. Neither virus induced clinical signs or gross lesions of stunting or tenosynovitis in the five weeks of observation. Both viruses and methods of infection induced similar microscopic changes of reovirus tenosynovitis in the hock joints. Repeated doses caused a more prolonged persistence of virus in the intestine than a single dose. Cloacal swabbing indicated that strain 49/82 was more persistent in the gut after repeated doses than virus R2. For both strains, the persistence of virus in the liver was short-lived and the proportions of birds with virus in the hock joints were similar after both methods of infection. Repeated inoculations did not exacerbate the joint lesions or heighten the neutralising antibody response. However, for certain studies of reovirus infections, repeated inoculations with the virus may give a more accurate simulation of a natural infection.