JC Papovavirus in progressive multifocal leukoencephalopathy.

Brain tissue from seven patients with progressive multifocal leukoencephalopathy was tested for the presence of papovaviruses. JC virus, ahuman papovavirus, was identified in all seven cases. Virus was isolated in tissue culture from extracts from each of four patients and was detected by immunofluorescence in sections from the other three. The new osolates were indistinguishable from the prototypical JC strain serologically and in all biological characteristics examined. Thus JC virus has, to date, been associated with 20 cases of progressive multifocal leukoencephalopathy.