Transmissible spongiform encephalopathies: the story of a pathogenic protein.

An overview is provided from the first description of the transmissible spongiform encephalopathies (TSE) to recent major discoveries in this research field. The TSE are a group of diseases in animal and in man caused by a unique pathogen: the prion protein. The exact nature of the etiological agent or the prion protein is thought to be a misfolded protein. Although current research has provided a wealth of data indicating that a structural isoform of the prion protein is the responsible pathogen, this hypothesis is not yet experimentally proven.