Blue wing disease of chickens: experimental infection with a Swedish isolate of chicken anaemia agent and an avian reovirus.

Isolates of an avian reovirus and chicken anaemia agent (CAA) from a field case of blue wing disease (BWD) in Sweden were inoculated into groups of SPF, one-day-old chicks as follows: Expt 1, an organ suspension from the field case; Expt 2, a selected non-purified reovirus isolate grown in chicken embryo liver cells. Expt 3, a plaque-purified reovirus strain; Expt 4, the CAA isolate from the organ suspension and Expt 5, a combination of reovirus (from Expt 3) and CAA (from Expt 4). The inoculations were given intraperitoneally. In a sixth experiment the isolates were given intramuscularly. The chicks in Expts 1, 2, 5 and 6 became ill after two weeks, and several birds died or were killed when moribund between 13 and 22 days of age. These birds had lesions similar to those found in field cases of BWD, i.e., atrophy of the thymus and the bursa of Fabricius and petechial haemorrhages in the skin. All of them had atrophie bone marrow. The chicks inoculated with the cloned reovirus strain (Expt 3) or CAA alone (Expt 4), did not show any apparent signs of disease. In Expt 4, lesions were found in the thymus, bursa of Fabricius, and bone marrow but to a less severe degree. In Expts 1, 2 and 5 both the reovirus and the CAA were successfully reisolated.