INTERFERON INHIBITS BOVINE PAPILLOMAVIRUS TRANSFORMATION OF MOUSE CELLS AND INDUCES REVERSION OF ESTABLISHED TRANSFORMANTS

Mouse L cell interferon reduced the level of bovine papillomavirus (BPV-1) induced transformation of mouse C127 cells approximately 20-fold. Continued treatment of established BPV-1 transformed mouse cells with mouse L cell interferon lead to a reduction in the copy number of the plasmid viral genomes present in these transformed cells. Flat revertants were selected from two independent transformed lines carried 60 generations in the presence of 200 units/ml of interferon. These flat revertants had the biologic characteristics of their untransformed parent C127 cells which included low cell saturation density and the inability to form colonies in soft agar. The revertants could be retransformed by BPV and each of 8 different revertant lines examined was found to be “cured” of their viral DNA sequences as determined by Southern blot hybridization.