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Virus related to simian-virus 40 (SV40) was isolated from brains of two patients with progressive multifocal leukoencephalopathy, a human demyelinating disease. Virus was grown in cell cultures of primary African green-monkey kidney inoculated with cultures of cells derived from patients' brains. Electron microscopy showed virus-like particles resembling papovaviruses in the brain of one patient and in monkey-kidney cell cultures infected with both virus isolates. Immunologic studies using fluorescent and neutralizing antibodies indicate a close relation between the isolated viruses and SV40.
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Weiner et al. (1972) studied this question.
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