Thought this might interest you prion-watchers.
BSE: BREEDING RESISTANCE
A ProMED-mail post
Date: 12 April, 1999
From: Jane Pritchard
Source: FSNET, Science Daily [edited]
The complete original article is available through American Chemical
The research is detailed in the peer-reviewed journal Biochemistry,
published by the American Chemical Society (ACS), the world's largest
scientific society. It was released on the ACS Web April 9 and appears
in the print edition of the journal on April 27.
University of California researchers say a newly determined structure
of the biological particles called prions may help explain how they
cause infectious deadly diseases. Aberrant prions cause scrapie in
sheep, bovine spongiform encephalopathy (BSE or "mad cow disease") in
cows, and various afflictions in people. The scientists say their
finding might explain prion disease variety and eventually lead to
breeding disease-resistant animals.
Prions are proteins normally found in the brain of all animals.
Changes in their three-dimensional structure can cause infectious,
fatal neurodegenerative disorders. Further, altered prions seem to act
as templates that convert normal prions to the infectious form.
Relatively few people suffer from prion diseases, but they cause large
problems in sheep flocks and cattle herds. The disease rarely passes
between species, but there is evidence that people can be infected by
eating tainted beef. The economic and political consequences of such
scares have made understanding the novel mechanisms of prion diseases
a very visible quest.
Dr. Stanley B. Prusiner, from the University of California at San
Francisco (UCSF), was awarded the 1997 Nobel Prize in Physiology or
Medicine for discovering prions. He is a collaborator on the current
"Our structural studies show that an important part of the prion
protein exhibits multiple structures," according to co-author and UCSF
pharmaceutical chemist Thomas L. James, Ph.D. He says specific area
"marks the region susceptible to the structural change from the normal
cellular form to the infectious form of the protein."
James adds that "the multiple structures evident are probably related
to the different types of prion diseases which an individual can
potentially get." Prion variants affect different parts of the human
brain, causing either Creutzfeldt-Jakob disease (CJD), Fatal Familial
Insomnia (FFI), Kuru, or Gerstmann-Straussler-Scheinker (GSS) disease.
To reduce risks to laboratory workers, the scientists studied a prion
protein from Syrian hamsters. They describe the normal prion structure
and show the region of structural instability. James says that area
coincides with a sequence of genetic instructions in which different
mutations can lead to various diseases. Further, he claims that their
structure provides a chemical explanation for the variety of
Previous epidemiological studies, in both humans and sheep, showed
individuals with positively charged amino acid residues in certain
regions of their normal prions do not get prion diseases. James says
their 3-D structure shows those residues to be fairly close to one
another. "This suggests," he asserts, "that breeding animals with
mutations to positively charged residues in that region will produce a
scrapie-resistant or BSE (mad cow disease) -resistant herd."
Michele Gale-Sinex, communications manager
Center for Integrated Ag Systems
UW-Madison College of Ag and Life Sciences
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