A comparison of the pathogenicity of four avian reoviruses in chickens.

Four avian reoviruses were orally inoculated into 1-day-old chickens to determine pathogenicity, virus persistence in the intestinal tract, and effects on body weight gains. Avian reoviruses Reo-25 and W3-492 belonged to two separate serotypes, and viruses TC 897 and W3-410 were antigenically related to W3-492. Isolate W3-492, which was highly pathogenic, was very rarely recovered from cloacal swabs collected 2 weeks postinoculation, but inoculated chickens gained significantly less weight (P less than or equal to 0.001) than uninoculated controls during the 5-week test study. Isolate Reo-25 persisted the longest in the intestinal tract, and isolates TC 897 and W3-410, of intermediate persistence, had no significant effect on body weights. There was no apparent correlation between serotype and pathotype of avian reoviruses.