Genetics of Polyoma Virus and Simian Virus 40
Polyoma virus and simian virus 40 (SV40) are the smallest known tumor viruses. Their genomes are double-stranded circular DNA molecules, approximately 3.4 × 106 daltons in molecular weight, sufficient to code for the synthesis of approximately 200,000 daltons of protein. Infection of cells by polyoma and SV40 results in alterations in cell growth properties, sometimes leading to malignancy. Cells having altered growth properties are referred to as “transformed” or “neoplastic,” and the process which leads to the acquisition of new growth properties is called “cell transformation.” It should be emphasized that viral genes are not the only determinants of altered cell growth properties. Cellular genes and regulatory systems are major factors in the emergence of a malignant cell from a normal population. Therefore, a description of cell transformation by tumor viruses necessarily requires an understanding of the interaction between viral and cellular regulatory systems.
KeywordsCold Spring Harbor Simian Virus Restrictive Temperature Permissive Temperature Helper Virus
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