JC VirusPolyomavirusPolyomavirus InfectionsLeukoencephalopathy, Progressive MultifocalTumor Virus InfectionsBK VirusViral Regulatory and Accessory ProteinsAntigens, Polyomavirus TransformingAntigens, Viral, TumorDNA, ViralNeurogliaMerkel cell polyomavirusCarcinoma, Merkel CellBase SequenceMerkel CellsMolecular Sequence DataCapsid ProteinsGene Expression Regulation, ViralPolyomaviridaeVirus ReplicationY-Box-Binding Protein 1NFI Transcription FactorsCell LineUrineSimian virus 40Genome, ViralImmunocompromised HostGenes, ViralPolymerase Chain ReactionViral Proteins