1) SV40 is an abbreviation for simian vacuolating virus 40 or simian virus 40, a polyomavirus that is found in both monkeys and humans. Like other polyomaviruses, SV40 is a DNA virus that has the potential to cause tumors, but most often persists as a latent infection.
The virus was first identified in 1959 in cultures of rhesus monkey kidney cells that were being used to produce polio vaccine. It was named for the effect it produced on infected monkey cells, which developed an unusual number of vacuoles. The virus has been found in many macaque populations in the wild, where it rarely causes disease. However, in monkeys that are immunodeficient�due to, for example, infection with simian immunodeficiency virus�SV40 acts much like the human JC and BK polyomaviruses, producing kidney disease and sometimes a demyelinating disease similar to PML. In other species, particularly hamsters, SV40 causes a variety of tumors, generally sarcomas.
The molecular mechanisms by which the virus reproduces and alters cell function were previously unknown, and research into SV40 vastly increased biologists' understanding of gene expression and the regulation of cell growth.
SV40 has not been proven to cause disease in humans, but several studies have suggested a link to cancer based on the presence of relatively large amounts of what may be SV40 DNA fragments in some tumor tissues, particularly mesotheliomas and non-Hodgkin's lymphoma. There is as yet no consensus on the meaning of these findings.