RNA dependent DNA polymerase activity of RNA tumor viruses. V. Rous sarcoma virus single stranded RNA DNA covalent hybrids in infected chicken embryo fibroblast cells

RNA DNA covalent hybrids containing viral RNA were isolated from nuclear fractions of Rous sarcoma virus infected chicken embryo fibroblast cells shortly after virus infection. The formation of covalent hybrid structures depends upon a functional reverse transcriptase in vivo, since its appearance in cells is temperature dependent when infected with Rous sarcoma virus mutant LA335, which contains a temperature sensitive reverse transcriptase.