Suppression of the avian sarcoma virus genome in 8-azaquanine-resistant, transformed, hamster cells

The avian sarcoma virus genome (Schmidt-Ruppin strain) in transformed hamster cells resistant to 8-azaquanine [Ha(SR)AG-50] was strongly suppressed. The suppression was genetically stable and could not be overcome by attempts at induction with 5-iodo-2'-deoxyuridine. Fusion of hamster cells, which had suppressed virus genome, with chicken Rous-associated virus (RAV-1)-preinfected cells easily rescued the sarcoma virus. The rescued virus had envelope properties of RAV-1, as determined by viral interference, virus neutralization, and plating on genetically resistant chicken cells. By repeatedly cloning the rescued virus, we determined that virus recombined in the rescue experiment and that the recombinant virus had the envelope properties of helper virus used for its rescue. Cells with suppressed avian sarcoma virus genome were suitable for preparation of different recombinant viruses.