JC VirusPolyomavirusPolyomavirus InfectionsLeukoencephalopathy, Progressive MultifocalAntigens, Polyomavirus TransformingTumor Virus InfectionsAntigens, Viral, TumorMerkel cell polyomavirusDNA, ViralViral Regulatory and Accessory ProteinsBK VirusNeurogliaCapsid ProteinsGene Expression Regulation, ViralVirus ReplicationCarcinoma, Merkel CellBase SequenceMolecular Sequence DataCell LineCoronavirus Infections