Laboratory mice infected with the agent of scrapie--a brain-wasting disease of sheep--show high levels of the scrapie agent in their heart several hundred days after being infected in the brain, indicating that heart infection might be a new aspect of this disease, according to a research paper released online today by the journal Science.
Collaborators in the work include scientists at the Rocky Mountain Laboratories (RML), part of the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health.
"Undoubtedly, this work will enable scientists to pursue new theories about the effects of these deadly brain wasting diseases," says NIH Director Elias A. Zerhouni, M.D. "The implications of this research could be vital to our efforts to slow or stop these diseases."
"Although much work remains to be done, the diseased hearts seen in this mouse study have similarities to human amyloid heart disease, which is potentially significant," says NIAID Director Anthony S. Fauci, M.D.
Scrapie belongs to a group of diseases called prion diseases, also known as transmissible spongiform encephalopathies, or TSEs, because of the sponge-like holes created in the brain. In addition to scrapie in sheep, prion diseases include Creutzfeldt-Jacob disease in humans, mad cow disease in cattle and chronic wasting disease in deer and elk. The cause of prion diseases, still under debate, may be abnormal aggregated forms of prion protein.
The new research has provided cardiologists an animal model in which to study heart amyloidosis, a family of heart diseases that affect humans, says Bruce Chesebro, M.D., an RML virologist and a senior author of the new paper. Amyloidoses involve waxy protein deposits that stiffen the heart, limit its pumping ability and typically lead to fatal heart stoppage.
"Although several types of protein are known to form heart amyloid, this is the
Contact: Ken Pekoc
NIH/National Institute of Allergy and Infectious Diseases