1980 Articles

Early Mutants of Polyoma Virus (dl8 and dl23) with Altered Transformation Properties: Is Polyoma Virus Middle T Antigen a Transforming Gene Product?

Griffin, B. E.; Ito, Y.; Novak, U.; Spurr, N.; Dilworth, S.; Smolar, N.; Pollack, Robert; Smith, K.; Rifkin, D. B.

The questions raised by Dulbecco (1975)—“Is transformation the result of provirus integration … or is it the consequence of the expression of genes present in the provirus?”—have not yet been satisfactorily answered. However, several lines of evidence from recent experiments on many different tumor viruses, as presented in this volume, strongly suggest that viral gene expression is required for transformation, the best evidence still arising from studies on the avian RNA tumor viruses (see Vogt 1977; Hanafusa 1977). With regard to polyoma virus, evidence also exists which indicates that viral gene expression is needed. Studies by Seif and Cuzin (1977) on transformation induced in rat cells by temperature-sensitive tsA mutants of polyoma virus suggest that the transformed phenotype is a complex interplay between various types of controls, including expression of a virus-coded protein, as well as cellular changes induced by the virus or selected for during growth in culture. Data...