The discovery that prions stay deadly despite sticking to soil comes as a surprise, because while many proteins can bind to soil, that binding usually changes their shapes and activities.

In a paper published in the journal PLoS Pathogens (April 14), scientists at the University of Wisconsin-Madison suggest that certain soil types serve as natural prion repositories in the wild. As animals regularly consume soil to meet their mineral needs, it's possible that prion-laden soil particles contribute to the transmission of prion disease such as CWD among animals.

CWD is a fatal, incurable condition that belongs to a family of prion-inflicted neurological disorders known as transmissible spongiform encephalopathies (TSE). Other TSEs include "mad cow" disease, sheep scrapie and Creutzfeldt-Jacob disease in humans.

After a long incubation period, deer and elk infected with CWD suffer neurological and behavioral problems such as staggering, shaking, and excessive salivation and urination. Over time, the animals literally waste away, often dying in woods and fields. Originally detected in the 1960s in Colorado and Wyoming, CWD is now present in 14 states and two Canadian provinces.

Prions are an incorrectly folded variation of a protein normally found in mammals, including humans.

"Prions most likely enter soil via excretion or from the carcasses of infected animals," says lead author Christopher Johnson, a UW-Madison doctoral student in the department of animal health and biomedical sciences. "Our results suggest that reducing the number of infected animals -- as has been done in the recent outbreak of CWD in Wisconsin -- could limit the potential for further (disease) spread. These results also suggest that other species that s
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13-Apr-2006