Transformation in vitro of Mammalian Cells by Polyoma and Simian 40 Viruses*

Abstract

TMS paper analyses the transformation of cells from several animal species infected in vitro with polyoma virus (PV) and Simian virus 40 (SV40). Because these 2 viruses have been studied in greater detail and because their spectrum of action is a wide one, it is possible to compare in vitro transformation of different cells by the same virus and of the same cells by both viruses. The experimental findings reported indicate that the transformation of mouse, hamster and human cells in vitro by SV40 and PV is a complex and multistage process. The diversity of morphological manifestations; the variability of the chromosomal changes, and the random evolutionary pattern of various characteristics which have been examined are the expression of an acquired genetic instability of cells subjected to continuous environmental selective pressure.