Human polyomavirus 2

Human polyomavirus 2, commonly referred to as the JC virus or John Cunningham virus, is a type of human polyomavirus. It was identified by electron microscopy in 1965 by ZuRhein and Chou, and by Silverman and Rubinstein. It was later isolated in culture and named using the initials of a patient by the name of John Cunningham from whom it was isolated and had developed progressive multifocal leukoencephalopathy (PML). The virus causes leukoencephalopathy and other diseases only in cases of immunodeficiency, as in AIDS or during treatment with immunosuppressive drugs (e.g. in organ transplant patients).