Common soil mineral degrades the nearly indestructible prion

Jan 14, 2009 by Terry Devitt

(PhysOrg.com) -- In the rogues' gallery of microscopic infectious agents, the prion is the toughest hombre in town.

Warped pathogens that lack both DNA and RNA, prions are believed to cause such fatal brain ailments as chronic wasting disease (CWD) in deer and moose, mad cow disease in cattle, scrapie in sheep and Creutzfeldt-Jakob disease in humans. In addition to being perhaps the weirdest infectious agent know to science, the prion is also the most durable. It resists almost every method of destruction from fire and ionizing radiation to chemical disinfectants and autoclaving, which reduce prion infectivity but fail to completely eliminate it.

Now, however, a team of Wisconsin researchers has found that a common soil mineral, an oxidized from of manganese known as birnessite, can penetrate the prion's armor and degrade the protein.

The new finding, which was reported earlier this month (Jan. 2) in the Journal of General Virology, is important because it may yield ways to decontaminate soil and other environments where prions reside.

"Prions are resistant to many of the conventional means of inactivating pathogens," says Joel Pedersen, a UW-Madison environmental chemist and the senior author of the new study. For example, autoclaving, a standard method for sterilization in the laboratory, will reduce the concentration of prions in solution, but fails to eliminate them altogether, as it does for virtually all other types of pathogens.

Because prions infect both wild and domesticated animals, the agent can contaminate barnyards and other areas where infected livestock are kept, as well as persist in natural environments where deer, elk and other animals can become infected by contact with contaminated soil.

Other studies have shown that prions can survive in the soil for at least three years, and that soil is a plausible route of transmission for some animals, Pedersen says. "We know that environmental contamination occurs in deer and sheep at least," he notes.

Prion reservoirs in the soil, Pedersen explains, are likely critical links in the chain of infection because the agent does not appear to depend on vectors — intermediate organisms like mosquitoes or ticks — to spread from animal to animal.

That the birnessite family of minerals possessed the capacity to degrade prions was a surprise, Pedersen says. Manganese oxides like birnessite are commonly used in such things as batteries and are among the most potent oxidants occurring naturally in soils, capable of chemically transforming a substance by adding oxygen atoms and stripping away electrons. The mineral is most abundant in soils that are seasonally waterlogged or poorly drained.

"A variety of manganese oxide minerals exist and one of the most common is birnessite. They are common in the sense that you find them in many soils, but in low concentrations," says Pedersen. "They are among the strongest oxidants in soil."

The new study, which was led by Fabio Russo of the University of Naples and Christopher J. Johnson of UW-Madison, was conducted on prions in solution in the laboratory. The group's working hypothesis, according to Pedersen, is that the mineral oxidizes the prion, a chemical process that can be seen in things like iron oxidizing to form rust or how cut pears and apples turn brown when exposed to oxygen.

The next step, Pedersen says, is to mix the mineral with contaminated soil to see if it has the same effect. If it does, birnessite may become a useful tool for cleaning up contaminated farmyards and other places where the prion may be concentrated in the soil.

"I expect that its efficacy would be somewhat diminished in soil," says Pedersen. "It's something we'll explore."

Provided by UW-Madison

Explore further: Killer bees test a double win for Australian honeybees

Related Stories

How to alert drivers to fatigue

20 minutes ago

Frank Black is a professional truck driver, having clocked up nearly three decades travelling the breadth of Australia. But every time he gets into his cab, Black thinks about driver fatigue; over the years ...

Killer bees test a double win for Australian honeybees

30 minutes ago

A genetic test that can prevent the entry of 'killer' bees into Australia and worldwide spread has been created by researchers at the University of Sydney and their collaborators at York University in Canada.

Rising carbon dioxide levels stunt sea shell growth

30 minutes ago

Scientists have discovered that stunted growth can be a genetic response to ocean acidification, enabling some sea creatures to survive high carbon dioxide levels, both in the future and during past mass ...

Protecting our rights to privacy and digital dignity

33 minutes ago

How many of us read the terms and conditions when signing up to a social media account or downloading a new app? And does agreeing to these rules offer us any real protection from big business looking to ...

Recommended for you

Killer bees test a double win for Australian honeybees

30 minutes ago

A genetic test that can prevent the entry of 'killer' bees into Australia and worldwide spread has been created by researchers at the University of Sydney and their collaborators at York University in Canada.

Viral proteins may regulate human embryonic development

1 hour ago

A fertilized human egg may seem like the ultimate blank slate. But within days of fertilization, the growing mass of cells activates not only human genes but also viral DNA lingering in the human genome from ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

vivcollins
not rated yet Jan 14, 2009
Good news if its a practical soil treatment

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.