Prions Are Deadly Proteins
Infectious prions have a trusty accomplice in causing deadly neurological disease, according to research by Geisel biochemist Surachai Supattapone, M.D., Ph.D. Normal, noninfectious prion proteins are usually found in the brain. But when prion proteins misfold, they can become infectious and trigger a number of fatal brain disorders, such as mad cow disease or Creutzfeldt-Jakob disease in humans.
TSEs are caused by a deadly protein called a prion (PREE-on). As such, TSEs also are referred to as prion disease. The critical factor is that prions are unstoppable. The pathogen spreads through the bodily fluids and cell tissue of its victims. All tissue is infectious just because of the contact with the contaminated blood.
TSEs also include Creutzfeldt-Jakob disease, Parkinson’s, Huntington’s, mad cow disease and chronic wasting disease in the deer family. Few, if any, mammals are immune. There is no cure.
Dr. Stanley Prusiner, an American neuroscientist from the University of California at San Francisco, earned a Nobel Prize in 1997 for discovering and characterizing deadly prions and prion disease. President Obama awarded Prusiner the National Medal of Science in 2010 to recognize the importance of his research. According to Prusiner, TSEs all are on the same disease spectrum, which is more accurately described as prion disease. He claims that all TSEs are caused by prions.
What puzzles scientists is that infectious prions (simply called “prions”), unlike viruses, have no nucleic acids—no DNA or RNA—yet they are able to create distinct, self-propagating strains of prion diseases. Most scientists believe in a protein-only hypothesis in which prions create different strains of disease on their own, and many believe that the hypothesis may apply to other diseases as well, such as Alzheimer’s disease and Parkinson’s disease.
But Supattapone is doubtful. If a prion contains just a single protein, without other essential molecules, “it’s hard to explain why the strains exist first of all,” he says. Another problem with the protein-only hypothesis, he adds, is that “nobody has been able to make infectious prions from just the prion.”
Through a purification process, Supattapone, with Geisel biochemist Nathan Deleault, determined that when a noninfectious prion protein is mixed with a certain phospholipid molecule, named phosphatidylethanolamine (PE), the combination creates an infectious prion. This experiment was the first time anyone had formed infectious prions from only two components (prion protein and PE) and without any nucleic acids.