Prions are misfolded forms of proteins that behave in an infectious manner. They do so by causing other proteins they encounter to misfold as well. A prion disease is a disease that results from this misfolding. Some examples of prion diseases include Mad Cow Disease, Scrapie, and Creutzfeldt-Jakob disease. In mammals, all known prion diseases are actually caused by the same prion protein, known as PrP; the abbreviation actually stands for “prion protein.”