avian leukosis

avian leukosis n any of a group of diseases (as lymphoid leukosis) of poultry that are caused by strains of a retrovirus (species Avian leukosis virus of the genus Alpharetrovirus), that involve disturbed blood formation, and that are distinguished individually by special manifestations (as paralysis, tumor formation, leukemia, and eye damage) called also avian leukosis complex

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a group of viral diseases of chickens, transmitted by related oncoviruses and characterized by proliferation of immature erythroid, myeloid, or lymphoid cells. Leukemic forms include erythroblastosis and myeloblastosis and, rarely, lymphoblastic leukemia. Solid tumors in visceral organs are seen in cases of lymphoid leukosis, erythroblastosis, and myelocytomatosis. Some of the causative viruses induce related neoplasms such as sarcomas, hemangiomas, nephroblastomas, hepatocarcinomas, and osteopetrosis gallinarum, which are now classified as belonging to the leukosis sarcoma group. See also avian lymphomatosis and visceral lymphomatosis, under lymphomatosis.