Progressive multifocal leukoencephalopathy (PML) is a fatal demyelinating disease in the central nervous system caused by a ubiquitous human polyomavirus designated as JC virus (JCV). PML affects individuals with decreased immune competence and is now one of the common opportunistic infections in patients with AIDS. JCV DNAs in the brain of PML patients contain various PML-type regulatory regions that were generated from the archetypal regulatory region during persistence. Recently, many studies have suggested that detection of JCV DNA from the cerebrospinal fluid (CSF) may offer a tool for diagnosing PML. However, in all of these studies, coding sequences within the T antigen or capsid protein gene have been targeted for amplification. To amplify the JCV regulatory region, we established a nested PCR that could efficiently amplify the regulatory region from most JCV subtypes prevalent in the world. Using this PCR, we amplified JCV regulatory regions from the CSF samples from 4 patients strongly suspected of PML, whereas amplification was negative from 80 CSF samples from patients without PML. Sequencing of the amplified fragments revealed that they had unique deletions and/or duplications. Furthermore, in 3 PML patients, we analyzed the structures of regulatory regions derived from the brain as well as CSF. In each of these cases, the major regulatory sequence of both origins were identical. This finding indicates that JCV DNA in brain lesions is excreted in the CSF. Since the structure of PML-type JCV regulatory regions are unique to individual patients, the current PCR, if the amplified fragments are sequenced, can eliminate false positives that may arise from contaminations.
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