Pathogenicity of chicken anaemia agent in bursectomised chickens.

Bursectomised (Bx) chickens, but not intact chickens, developed anaemia when inoculated with chicken anaemia agent (CAA) at 2 weeks of age. No antibodies against CAA were produced in the Bx chickens and CAA was persistently recovered from them. In contrast, CAA disappeared from the intact chickens with the development of high titres of antibody. It was strongly suggested that the pathogenicity of CAA was dependent on the production of humoral antibody against CAA in infected chickens. Histopathologically, no inclusion bodies suggestive of parvovirus infection were observed in the tissues of affected chickens.