JC virus genomes in progressive multifocal leukoencephalopathy: Detection using a sensitive non-radioisotopic in situ hybridization method

JC virus genomes have been localized in formalin‐fixed, paraffin‐embedded brain tissues of two cases of known progressive multifocal leukoencephalopathy by in situ hybridization utilizing a biotinylated JC virus DNA probe. A three‐stage immunoperoxidase system with gold–silver amplification of the diaminobenzidine substrate was used to visualize biotinylated nucleic acid hybrids. Dot–blot quantification of this visualization system indicates that subpicogramme amounts of biotinylated DNA can be detected. Optimal detection of the virus genomes in the brain tissues required a microwave irradiation step prior to hybridization. JC virus genomes were observed in the nuclei of enlarged oligodendrocytes and of some bizarre astrocytes. No other cell types were found to harbour the genomes.