avian leukaemia virus

Group of C-type RNA tumour viruses (Oncovirinae) that cause various leukaemias and other tumours in birds. The acute leukaemia viruses, that are replication-defective and require helper viruses, include avian erythroblastosis (AEV), myeloblastosis (AMV) and myelocytomatosis viruses. AEV carries two transforming genes, v-erbA and v-erbB; the cellular homologue of the latter is the structural gene for the epidermal growth factor receptor. AMV carries v-myb and causes a myeloid leukaemia; avian myelocytomatosis virus carries v-myc. The avian lymphatic leukaemia viruses (ALV) are also Retroviridae but are replication-competent and induce neoplasia only after several months; they often occur in conjunction with replication-defective leukaemia viruses.