Experimental reovirus infection in chickens: observations on early viraemia and virus distribution in bone marrow, liver and enteric tissues.

The nature of viraemia and tissue distribution of reovirus were studied in the early phase after oral infection of 1-day-old specific-pathogen-free (SPF) White Leghorn chicks with the R2 strain of avian reovirus. A range of tissues collected up to 3 weeks after infection was titrated for their viral content. Virus was present in the plasma, erythrocyte and mononuclear fractions of the blood within 30 hours post-inoculation (p.i.) and was widely distributed in tissues, including the bone marrow by 3 to 5 days p.i. A greater part of the viraemia was associated with plasma, virus in the blood mononuclear fraction being detected only occasionally. There was more infectious virus in the duodenum than the liver and the highest virus titres were found in cloacal swabs taken 1 to 5 days p.i. It was also evident that virus reached the liver within a very short time after infection (<6 hours p.i.) although the source of this early hepatic virus was considered to be residual inoculum absorbed directly into the portal blood. Viraemic virus titres could not be correlated either with duodenal or hepatic virus titre alone.