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Study Suggests Gene Mutation Underlies Some Mad Cow Disease

Posted on: Saturday, 13 September 2008, 17:30 CDT

U.S. researchers reported on Friday that a rare genetic mutation may underlie some cases of mad cow disease in cattle and its discovery may help shed light on where the epidemic started.

They believe BSE may sometimes arise spontaneously in cattle, as the mutation, in an Alabama cow that tested positive in 2006 for bovine spongiform encephalopathy, or BSE, is identical to one that causes a related brain-wasting disease in humans.

“Cattle producers must never let down their guard against BSE because cattle anywhere, at any time, can develop the disease,” said Jurgen Richt of Kansas State University.

The researchers said the finding may support a 2005 theory that the BSE epidemic in cattle could be traced to feed contaminated with cattle remains from India.

Forcing the destruction of millions of animals, BSE or mad cow disease swept through British dairy herds in the 1980s . No one ever found where it came from but most experts thought at the time it came from cattle feed that contained the remains of sheep infected with a similar disease called scrapie.

Although cattle were never known to develop BSE before the epidemic, some experts say the report lends credence to the idea that they may have.

BSE, scrapie and a human version called Creutzfeldt-Jakob disease, or CJD, are brain-destroying illnesses called transmissible spongiform encephalopathies. In some cases, animals or people that eat brain and nervous system material from victims of these diseases can develop them, too.

Misfolded infectious protein fragments called prions pass them along.

A very rare, fatal and incurable disease called variant CJD has been found in people who ate infected beef products. It has affected just 167 people so far.

Many countries now ban the use of meat and other parts from mammals in food for cattle. They also ban the use of potentially infectious tissues such as brain and spinal cord in human food.

"There are tendencies around the world, now that the feed-borne epidemic has gone down, to relax these rules and regulations," Richt said.

"So if we have these genetic cases popping up here and there and we don't have our mitigations in place, we will have another epidemic somewhere."

Rich suggested breeding the gene out of cattle. "We can clean the world cattle herd of that mutation."

CJD is also known to pop up spontaneously in the human population. A genetic mutation causes the disease in one in a million people globally.

The brain of the Alabama cow was tested and found a mutation identical to the prion gene mutation that causes some cases of CJD, Richt and colleagues said.

They said in the report it is probably rare in cattle, found in fewer than one in 2,000.

However, the animal passed along its mutation to its heifer

Source: redOrbit staff

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