missing graphicsWhat causes mad cow disease? Prions. Prions are also at the origin of other neurodegenerative diseases such as Creutzfeldt-Jakob disease, Kuru, Gerstmann-Straussler-Scheinker disease and some forms of fatal insomnia. These are all prion diseases found in humans. Prion disease of cattle is what we know as mad cow disease. Prions also exist in other animals such as sheep, mink, mule deer, moose, cats and some others. So what's so special about prions? Unlike other neurodegenerative diseases caused by protein misfolding, altered proteins, abnormal gene splicing, improper expression, or ineffective elimination of proteins that slowly leads to disease by accumulation, prions cause disease by acting as an infectious agent. One abnormal prion protein is enough to transform into itself all the normal prion proteins present. How do prions do this? Scientists are still not sure how exactly a protein is able to turn another protein into itself. Many experiments are conducted to shed light on his mysterious abilities. On this site we hope to explain one such experiment involving the effect of pH on the structure of prion proteins. Wait...Prions? Prion proteins? Which is which? Prions is the name given to infectious protein agents. Prion protein (PrPC) is the normal cellular protein that can become an infectious agent. Mad Cow Disease Official Home Page The prion is a recently discovered pathogen that is very different from pathogens known today; namely viruses and bacteria. Unlike bacteria, no antibiotic can cure prions. They are not typical of a prokaryotic organism or a eukaryotic organism, all that is present in this pathogen is the PrPSc protein. This is the mutated form of the PrPC protein, encoded by a chromosomal gene. These two proteins differ in their spatial protein structures and their susceptibility to enzymatic digestion. PrPC is completely destroyed during enzymatic digestion, while PrPSc is resistant to any form of digestion. Viruses usually contain nucleic acid, proteins, and other constituents that aid in the creation of more viral progeny. As for prions, they multiply by infecting the PrPC protein and transforming it into a complex like it, the PrPSc protein. Prions exist in multiple molecular forms while viruses exist in a single form with a distinct ultrastructural morphology. Another difference between the virus and the prion is that viruses almost always provoke an immune response in the host they are infecting.