Transcription of the SV40 Genome in Transformed Cells and during Lytic Infection

Cultured cells respond largely in two different ways to infection by Simian vacuolating virus (SV40), a small DNA-containing oncogenic virus. For example, the BSC-1 line of African green monkey cells are permissive to SV40, i.e., the virus can multiply and produce infectious progeny, eventually killing the host (lytic infection). On the other hand, the 3T3 line (Todaro and Green, 1963) of mouse cells is restrictive to SV40, i.e., the virus cannot multiply and cannot produce infectious progenies, although it can enter the cell and express some of its gene functions (abortive infection). As much as 50% (Todaro and Green, 1966) of the abortively infected mouse cells acquire the heritable changes of growth properties known as transformation, an equivalent process of carcinogenesis.