A FRIEND-VIRUS MUTANT ENCODES A SMALL GLYCOPROTEIN THAT CAUSES ERYTHROLEUKEMIA

The Pvu Delta mutant of Friend spleen focus-forming virus encodes the smallest env glycoprotein (apparent M(r), 41,000) known to activate er ythropoietin receptors. In vivo, Pvu Delta causes erythroblastosis and the development of erythroleukemia. We isolated two leukemic cell lin es that contain Pvu Delta; both synthesize hemoglobin in response to d imethyl sulfoxide. The Pvu Delta env gene contains a 204-base deletion in the ecotropic-specific region, suggesting that this domain of the glycoprotein is not essential for viral pathogenesis.