Lymphoreticular tumour in pen-raised pheasants associated with a reticuloendotheliosis like virus infection.

An outbreak of a lymphoproliferative disease in pheasants is described. Nodular or diffuse tumours were found on the head and in various internal organs. The lesions consisted of undifferentiated lymphoreticular cells. A typical C-type virus, similar to reticuloendotheliosis virus was isolated in tissue culture. However, this virus particle could not be seen in the tumours. The isolate is antigenically related to the reticuloendotheliosis group of viruses. Typical reticuloendotheliosis was induced by tumour and spleen cells from a field case in both young pheasants and chickens. Antibodies to the reticuloendotheliosis virus group were demonstrated in serum samples from naturally diseased and experimentally infected birds. The virus could be re-isolated from experimentally infected birds in tissue culture. Serological and virological evidence indicate that Marek's disease virus and avian leukosis viruses of subgroup A, B, C and D were not involved in the induction of the lymphoproliferative disease in pheasants.