ULTRASTRUCTURAL STUDIES IN THE LYTIC PHASE OF PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY IN AIDS PATIENTS

Brain fragments from eight cases (four autopsies and four biopsies) of patients with acquired immune deficiency syndrome (AIDS) with JC viru s (JCV) lytic infections were examined ultrastructurally. Particular e fforts were made to look for virions and their subcellular distributio n in cells not usually involved by papovavirus infection. The cellular and subcellular distribution of virions was investigated with emphasi s on cell types not normally associated with papovavirus infection. Th e pattern of JCV infection was as follows: 1) oligodendrocytes; nucleu s only, 7 cases; cytoplasm only, no cases; 2) astrocytes (normal and ' 'bizarre''); nucleus and cytoplasm, two cases; cytoplasm only, four ca ses; 3) macrophages; nucleus and cytoplasm, one case; cytoplasm only, four cases; and 4) neurons; nucleus and cytoplasm, two cases; cytoplas m only, three cases. Perivascular, endothelial, ependymal, and microgl ial cells were never infected. Our ultrastructural data indicate that cell types other than oligodendrocytes can be involved productively by JCV in the lytic phase of progressive multifocal leukoencephalopathy (PML) in AIDS patients. Neuronal cells, especially, can be infected pr oductively by the JCV, and this should be considered in clinical inter pretation of cortical symptoms and signs in suspected or proven cases of PML.