PROGRESSIVE MULTIFOCAL LEUKOENCEPHALOPATHY - IN-SITU JC VIRAL DETECTION WITH TERMINALLY BIOTIN-LABELED, SITE-SPECIFIC OLIGONUCLEOTIDE PROBES

We describe a classic case of progressive multifocal leukoencephalopat hy (PML) proven by histologic, ultrastructural, and immunocytochemical analysis in a 58 yo female with a history of deteriorating neurologic status and a brain mass observed on magnetic resonance imaging. The p resence of JC viral genomes was confirmed by a rapid 70 min automated in situ DNA hybridization assay utilizing either commercially availabl e, nick translated, whole genomic DNA probes or site specific, synthet ic 3' multibiotinylated 18 mer oligonucleotide probes constructed to h ybridize with the JC virus tandem repeat or agnoprotein gene regions. All probes localized JC virus genomes in the nuclei of enlarged, swoll en oligodendrocytes and rare bizarre astrocytes, but the oligonucleoti de probes showed stronger hybridization signals when the probe concent rations were equalized. The most potent in situ hybridization signals were obtained when a nonsense 15 mer composed of 5 repeating units of the sequence 5'-TAG-3' was added as a spacer at the 3' end of the olig onucleotide probe to extend the 3' multibiotin affinity label. Affinit y labeled, synthetic oligonucleotides provide a rational and cost effe ctive approach to molecular neuroviral diagnostics in PML.