Health
Prions can replicate
NEWS IN BRIEF — Posted Aug. 23, 2004
New research findings show that prions can make disease-causing copies of themselves without the presence of viral DNA or RNA.
Researchers produced a prion protein that can trigger the development of a neurological disorder in mice that is similar to mad cow disease, according to a study published in the July 30 Science.
For their study, researchers, including Stanley B. Prusiner, MD, of the University of California, San Francisco, who won the 1997 Nobel Prize in Medicine for his discovery of prions, produced prion protein fragments in bacteria, folded them into larger protein structures called amyloid fibrils and then injected them into the brains of susceptible mice.
The mice began exhibiting signs of disease in their central nervous systems between 380 and 660 days after the injections. The amyloid form of the prion protein, which is thought to cause prion disease, was also found in the brains of the diseased mice.
Unlike viruses, bacteria, fungi and parasites, prions contain no DNA or RNA.
Instead, they are a type of protein normally found within cells in humans and other organisms. In some cases the structure of prions can change into a folded, disease-causing form. These abnormal proteins appear to convert other, normal prions to the abnormal shape.
Many scientists believe this conversion process leads to several dementing diseases in humans, including Creutzfeldt-Jakob disease. Similar diseases in animals include mad cow disease in cattle and scrapie in sheep. Misfolded proteins also contribute to other age-related neurological diseases such as Alzheimer's and Parkinson's diseases.
Note: This item originally appeared at http://www.ama-assn.org/amednews/2004/08/23/hlbf0823.htm.
