Fusion injection of Rous Sarcoma virus proteins into Rous sarcoma virus-transformed, non-producing hamster cells causes release of infectious virus.

Purified virus proteins from transformation-defective (td) mutants of Rous sarcoma virus PrA or PrB were trapped in human erythrocyte ghosts which, after resealing, were fusion-injected into hamster RBH cells or rat TWERC cells. These cell lines are non-productively transformed by subgroup C Rous sarcoma virus. After fusion injection the hamster RBH cells released transforming subgroup C Rous sarcoma virus. No infectious virus could be rescued from rat TWERC cells. Since previous experiments have shown that fusion injection of the purified Rous sarcoma virus protein p15 into hamster RBH cells caused cleavage of the precursor protein pr76 to form the virus group-specific antigen (gag) but did not induce infectious virus, we conclude that in addition to p15 other virus proteins are required to induce virus rescue in hamster RBH cells.