Presence of papova-like viral particles in cerebrospinal fluid of AIDS patients with progressive multifocal leukoencephalopathy. An additional test for "in vivo" diagnosis.

: An "in vivo" diagnosis of progressive multifocal leukoencephalopathy (PML), a neurological opportunistic viral infection in AIDS patients, can be made only by brain biopsy. In order to identify viral particles, we examined the cerebrospinal fluid (CSF) of 15 AIDS patients with focal neurological signs by electron microscopy using negative staining technique. In 2 out of 3 patients with clinical and neuroradiological presumptive diagnosis of PML, the CSF examination revealed papova-like viral particles. Our results support the hypothesis that the severe cell-mediated immunodeficiency reactivates papovavirus from a latent state in the brain, leading to PML. Therefore, the CSF study by negative staining might be a useful test for an "in vivo" diagnosis of PML.