Sludge Watch ==> Prions - leaching from landfills- prions ingested in clay more infectious

[Maureen Reilly]

Sludgewatch Admin: Yikes!


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http://pubs.acs.org/subscribe/journals/esthag-w/2007/july/science/nl_prions.html

Science News –
July 11, 2007
Soil can make prions more infectious

CDC

This spongy brain tissue is infected with the prions that cause 
Creutzfeldt–Jakob disease, a transmissible spongiform encephalopathy.

Prions, the misfolded proteins suspected of causing various transmissible 
neurodegenerative diseases, including bovine spongiform encephalopathy (BSE) 
or mad cow disease, have been extracted from soil seemingly in their whole 
and wholly infectious state. Now, new research published in PLoS Pathogens 
(2007, DOI: 10.1371/journal.ppat.0030093) on July 6, shows that these prions 
can be even more infectious in soil than in a free state. As soil proves to 
be a possibly dangerous reservoir for prions, the new research has 
implications for oral transmission of BSE and related diseases.
Judd Aiken of the University of Wisconsin Madison and colleagues fed 
hamsters montmorillonite clay inoculated with active prion proteins. More 
than 7 months later, all the hamsters that received oral doses of the 
clay–prion mixture fell ill. Of the control group of hamsters inoculated 
with prions directly, only 38% showed symptoms after the same incubation 
period. (Other soil types also caused enhanced infection rates.)

Aiken’s co-worker Joel Pedersen, a soil scientist at the university’s 
Molecular and Environmental Toxicology Center, and colleagues previously 
found indications that clays could bind prion proteins and allow them to 
maintain their infectivity (PLoS Pathogens 2006, DOI 
10.1371/journal.ppat.0020032). This followed work published in ES&T and 
elsewhere last year on the behavior of prions in soil. The new work is the 
first to show the effects of clay–prion mixtures on animals.

The high infection rate underscores the potential for spreading 
transmissible spongiform encephalopathies, or TSE, in the environment. These 
diseases include scrapie in sheep and goats, BSE in cows, chronic wasting 
disease in elk and deer, and Creutzfeldt–Jakob disease in humans. "If there 
is no contact with buried prions, the risk is minimal," Pedersen says. 
"Leaching from landfill[s] is the larger concern." Two issues further 
complicate the overall picture of prion transmission: The amounts of TSE 
agents in the environment remain small, and different soils have varying 
binding properties, depending on their mineralogy.

—NAOMI LUBICK