Identification of the Avian Myeloblastosis Virus Genome

Abstract

In addition to neoplasias caused in chickens by helper viruses of the avian myeloblastosis virus (AMV) complex, acute myeloblastic leukemia is induced by a defective leukemogenic component. To identify the leukemogenic viral genome the unintegrated and integrated viral DNA intermediates were chracterized. Linear viral DNA isolated from the cytoplasm of helper virus (MAV-1 or MAV-2) infected chicken embryonic fibroblasts (CEF) has a mass of 5.3 million daltons (md) (Bergmann et al. 1980). The linear MAV-1 and MAV-2 DNAs can be distinguished from one another by cleavage with the restriction endonuclease Hind III, because MAV-1 DNA contains one more Hind III recognition site than does MAV-2. Linear viral DNA isolated from the cytoplasm of CEF infected with standard AMV (AMV-S) which contains the defective leukemogenic component showed a minor molecular species of 4.9 md in addition to the major species of 5.3 md. Eco RI or Hind III digestion of the linear viral DNA from AMV-S-infected CEF generates specific fragments in addition to those unique for MAV-1 or MAV-2 viral DNA (Bergmann et al. 1980). A Hind III digest of AMV-S linear viral DNA also indicates that more than 90% of the AMV-S virus complex is MAV-1 like, while the remainder represents both the leukemogenic and MAV-2-like viruses (Souza et al. 1980).