A trypsin-sensitive avian reovirus: isolation and experimental infection of poults and chicks

A reovirus (strain TR1) was isolated from the hock joint of a turkey with arthritis. It was rarely excreted in the faeces of poults after oral or intranasal inoculation and only occasionally following footpad inoculation. The virus did not localise in the hock joints or cause lesions. Cyclophosphamide-induced immunosuppression of poults did not modify the infection. Oral inoculation of chicks with a high dose of strain TR1 resulted in joint localisation, of virus and erosive arthritis. Footpad inoculation caused deaths in 13 of 15 chicks by 8 days pi due to hepatic necrosis. Intranasal inoculation of chicks resulted in a delayed and limited faecal excretion. However, joint lesions were most marked in chicks infected via this route. The infectivity of strain TR1 in chick embryo liver cell monolayers was reduced by almost 3.0 log(10) after treatment with 0.01% trypsin for 30 min, but the infectivity of strain R2 was unaffected. Bile salts had no effect on either virus. This trypsin-sensitive reovirus was much more pathogenic for chicks than for poults. The respiratory route may be important in the dissemination of trypsin-sensitive avian reoviruses such as this.