<prompt> Progressive multifocal leukoencephaloPathy is caused-Epstein-barr virusVaricella-zoster virusCytomegalo VirusJC Papovavirus  <response>: Harrisons principles of internal medicine. In PML oligodendrocytes have enlarged densely staining nuclei that contain viral inclusions formed by crystallinearrays of JC virus paicles. 