[Transmissible spongiform encephalopathies (prion diseases)--molecular principles and in vitro models].

Prion diseases are rare neurodegenerative and transmissible diseases affecting humans and mammals. The infectious agent of these deadly disease has been termed prion since in many respects this agent behaves differently from viruses. The prion hypothesis which was put forth by Stanley Prusiner in 1982 holds that the infectious agent consists of a conformationally changed normal cellular protein (PrPC). PrPC is a copper-binding protein of yet unknown function. PrPSc (the conformationally changed protein) in addition to its association with infectivity seems to have neurotoxic properties which are mediated by microglia in the CNS. Future research will have to concentrate on the dynamics of the conformational change from PrPC to PrPSc and understanding the neurotoxic mechanisms in prion diseases.