title: Letter: Enveloped virions in PML.
mesh_terms: D001921:Brain / Q000473:pathology*; D006801:Humans; D007968:Leukoencephalopathy, Progressive Multifocal / Q000473:pathology*; D027383:Papillomaviridae / Q000648:ultrastructure*; D027382:Polyomaviridae