Effect of virus infection on levels of transcripts for cellular genes

Malignant rabbit fibroma virus (MV) induces tumors composed of proliferating cells, principally fibroblasts, and vasculature. These tumors are associated with large amounts of collagen and other connective tissue proteins. We studied the effect of MV infection on levels of mRNA for alpha 1 chains of collagens type I, III and V in RK-13 fibroblasts and alpha 2 chain of collagen type I. MV infection induces expression of specific collagen genes at particular time points after infection in vitro. Expression of these collagen genes is clearly different in MV-infected cells compared to uninfected cells. Transcript levels for a cellular transcription factor that regulates expression of alpha 1 chain type I collagen, cbf-a, were increased in MV-infected cells prior to the increase in type I collagen mRNA. The virus infection also specifically induced increased levels of mRNA for the cellular transcription factors c-fos and SP1. MV infection is therefore associated with increased levels of specific cellular mRNAs, and is correspondingly associated with increased mRNA for transcription factors that may regulate transcription of these genes. The ability of malignant fibroma virus to influence expression of cellular genes may be exerted through the cells' own transcription regulatory apparatus.