The oncogenic DNA viruses: a review of in vitro transformation studies

Interferon and transcription of early virus-specific RNA in cells infected with simian virus 40

Treatment with interferon reduced the content of early virus-specific RNA, as well as the content of an early viral protein (T antigen), in monkey cells acutely infected with simian virus 40 (SV40). This unexpected finding suggests either that the action of interferon involves inhibition of the transcription of early SV40 messenger RNA, or that the SV40 genome contains a "proto-early" gene whose product is required for the transcription of the remaining early genes.

Effect of ultraviolet irradiation on the survival of simian virus 40 functions in human and mouse cells

The relative sensitivities to ultraviolet light of various simian virus 40 (SV40) functions were studied in human and mouse cells. Transformation appeared to be less ultraviolet (UV)-sensitive than either T or V antigen when all functions were compared in the same cell. However, the time course of both T- and V-antigen appearance was delayed with UV-irradiated virus, so that the survival curves of these functions changed with time. Mouse and human cells which were transformed by UV-SV40 all contained SV40 T antigen. Infectious virus could be recovered from many more transformants than would be expected from the infectivity in African green monkey kidney cells of the irradiated virus. The results suggest that human and mouse cells are capable of reactivating UV-damaged SV40.

Comparison of transformation and T antigen induction in human cell lines

Skin fibroblast cultures were established from eight individuals. These cell cultures, together with WI-38 cells, were examined for susceptibility to transformation by SV40 virus. Four transformation-susceptible cell lines (TS), established from patients with Down's syndrome, were found to be three to four times more susceptible to transformation than transformation-resistant cell lines (TR) from normal individuals. TR and TS cell lines were compared for their susceptibility to induction of SV40 T antigen. For dividing cells T antigen was detected in a higher percentage of TS cells than TR cells. For nondividing cells, the reverse was found; T antigen was detected in 10-fold more cells of the TR lines than in cells of the TS lines. Similar results were obtained after infection of cells with CELO virus. Titration of vaccinia virus and influenza virus A2/Scotland/49/57 indicated that TR and TS cells were equally sensitive to the former virus, but TR cells were three to five times more sensitive to influenza virus A2/Scotland/49/57 than were TS cells.

Simian virus 40-induced T and tumor antigens

Antigen extracts from simian virus 40 (SV40) transplanted hamster tumors were studied by rate-zonal centrifugation. Three species or molecular forms of antigen were demonstrated. The major antigen component corresponded to a molecular weight of 65,000 to 75,000, and two larger species were detectable in smaller quantities. Similar studies were carried out on SV40 virus-induced T antigen from BSC-1 cells. Three antigen components were again detected. Quantitative differences in the expression of "T" and tumor antigen species were reproducibly found.

Human diploid cell transformation by DNA extracted from the tumor virus SV40

The DNA isolated from simian virus 40 (SV40) can transform human fibroblast cells in tissue culture. Clonal lines of DNA-transformed human cells have been obtained that have properties characteristic of cells transformed by whole virus. They all contain SV40 T-antigen, and infectious virus can be recovered by cocultivation. This is the first demonstration of a permanent genetic alteration produced in human cells by purified DNA.