Sequences in the gag-pol-5'env region of avian leukosis viruses confer the ability to induce osteopetrosis.

DNA sequences encoding the genomes of three subgroup E avian leukosis viruses have been molecularly cloned. Virus recovered from one of these cloned DNAs (pRAV-0) caused no osteopetrosis while virus recovered from the second (lambda NY203) caused late onset osteopetrosis and virus recovered from the third (lambda NTRE-2) caused intermediate onset osteopetrosis. Restriction endonuclease fragments of the cloned viral DNAs were used to construct recombinant viruses that could be used to test for the role of gag-pol-5'env and 3'env-LTR sequences in the induction of osteopetrosis. The results of the pathogenicity tests indicate that gag-pol-5'env sequences confer the ability to induce osteopetrosis while 3'env-LTR sequences influence the time of onset and the severity of osteopetrosis.