Cells and prions: A license to replicate

Prion diseases are neurodegenerative, infectious disorders characterized by the aggregation of a misfolded isoform of the cellular prion protein (PrPC). The infectious agent - termed prion - is mainly composed of misfolded PrPSc. In addition to the central nervous system prions can colonize secondary lymphoid organs and inflammatory foci. Follicular dendritic cells are important extraneural sites of prion replication. However, recent data point to a broader range of cell types that can replicate prions. Here, we review the state of the art in regards to peripheral prion replication, neuroinvasion and the determinants of prion replication competence.