Oncogenicity And Cell Transformation By Papovavirus SV40: The Role Of The Viral Genome

Publisher Summary This chapter evaluates the available knowledge of simian virus 40 (SV40) oncogenesis and assesses the implications for carcinogenesis by DNA-tumor viruses as a whole. It summarizes different tests that can be employed to detect virus-induced changes in SV40-transformed cells. Inoculation of such cells into susceptible hosts usually results in the production of tumors, the ultimate criterion necessary to establish that malignant transformation has indeed occurred. Fusion or cocultivation of the transformed cell with normal susceptible cells may sometimes succeed in the rescue of infectious virus. The optimum conditions required to elicit the production of virus from a majority of the transformed cells have not yet been established. Transformed cells are usually immune to superinfection by the transforming virus. Nucleic acid hybridization experiments indicate that multiple copies of the SV40 genome is present, probably integrated into the host cell chromosome. Virus-specific mRNA is present in the transformed cells. The extent of the transcription of the viral genome seems to vary from one transformed cell line to the next. No relationships have been established between the extent of transcription in a given transformed cell line and the number and/or magnitude of virus-specific changes of that cell line. A series of in vitro tests may detect a variety of surface changes on the transformed cells. These tests include immunofluorescence, agglutination, cytotoxicity, colony inhibition, and mixed hemadsorption.