Progressive multifocal leukoencephalopathy. Neuropathology and virus isolation.

Mechanism of demyelination in progressive multifocal leukoencephalopathy (PML) was elucidated by demonstrating ultrastructurally the relationship between the affected glial cells and myelin sheaths. The myelinating cells in the central nervous system, namely oligodendroglias, were specifically attacked by PML-virus with eventual primary destruction of myelin sheaths. An attempt to isolate PML-virus from the autopsy material was made. The presence of virus particles in the extracts from the brain, reactions of virions with antibodies and evidence of virus proliferation in the primary human fetal glial cell culture were shown by various techniques including negative staining, immunofluorescence, immunoelectron microscopy, and electron micrography. The isolated virus was antigenically identical with JC type of papovaviruses.