Simian Virus 40 capsid. The genome is closed circular double-stranded DNA. First identified in 1960 in cultures of rhesus monkey kidney cells that were being used to produce polio vaccine, SV40 has been detected in human cancers, although whether SV40 causes cancer in humans remains controversial. Rendering is colored by radial depth-cue to highlight surface topography. View is along the 2-fold icosahedral symmetry axis. Individual small spheres are atoms making up the proteins.