Incomplete viral genome in a non-virogenic mouse tumour cell line (RVP3) transformed by Prague strain of avian sarcoma virus.

Two cell lines, RVP3 and RVA4, derived originally from mouse tumors induced by the Prague and Schmidt-Ruppin strain of RSV, respectively, were studied. tall attempts failed to induce infectious virus production in RVP3 cells by fusion with chicken fibroblasts even if the cells were infected with avian leukosis viruses. Also, attempts to rescue the viral genome by transfection were unsuccessful. RVP3 cells harboured 31-45% of the viral genome sequences, as was shown by molecular hybridization, and therefore they were designated cryptovirogenic. The tumour cell line RVA4 did not contain any detectable viral sequences. The significance of the detection of the incomplete Rous virus genome sequences in mammalian cells is discussed.