Study finds prions evolve despite lacking DNA

By John Fauber
Milwaukee Journal Sentinel

December 31, 2009

Though they are believed to be "lifeless," the infectious agents known as prions that cause a variety of fatal brain diseases in people and animals, including chronic wasting disease in deer, are capable of evolving like living organisms, according a new study.

The research, which has implications for eventual treatments for such diseases, is one of the first studies to suggest that something that is devoid of DNA or other genetic material can evolve in a Darwinian manner.

"It is really a novel concept," said Mark Beilke, a professor of medicine and chief of infectious disease at the Medical College of Wisconsin.

Beilke, who was not involved in the research, said teaching the prion theory even to medical students is difficult. The new paper, which was published online Thursday in the journal Science Express*, adds another complicated twist to the prion concept, said Beilke, who also practices at Froedtert Hospital and the Clement J. Zablocki Veterans Affairs Medical Center.

[* Abstract:
http://www.sciencemag.org/cgi/content/abstract/science.1183218
 ]

Beilke said the new finding makes sense.

Prions are abnormal versions of proteins made in the brain. Though they are believed to contain no genetic material they are able to replicate in the brain by causing normal prion protein to misfold. That misfolding can turn the normally harmless prion protein into infectious prions that cause incurable, fatal brain disorders such as chronic wasting disease, scrapie and mad cow disease in deer, sheep and cattle as well as Creutzfeldt-Jakob disease and variant mad cow disease in people.

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