(DTN)--Rogue proteins linked to those that cause BSE can form in muscle, not just in those tissues which have been seen as risky, according to research published March 19 that could hurt the global meat business, reported Reuters.
U.S. researchers said in a study published in the Proceedings of the National Academy of Sciences they had discovered for the first time that the abnormal proteins, or prions, can spread in the muscle tissue of mice.
A team led by Stanley Prusiner, who won the Nobel prize for his work on prions, reported, at least in mice, high levels of prions can collect in muscles as well as in the central nervous system and lymphatic tissues.
If the same findings hold true for cattle and sheep, they may challenge existing beliefs that only neural and lymphatic tissues are potential carriers of prions--the rogue proteins thought to cause bovine spongiform encephalopathy (BSE) and its deadly human equivalent, variant Creutzfeldt-Jakob Disease (vCJD).
The research may also suggest laws aimed at protecting the food supply, including procedures to ensure meat does not contain any neurological or lymphatic tissues, may be insufficient to cut the risk of brain-wasting prion diseases.
However, the authors of the study cautioned the results were preliminary, and it was too soon to know if prions form naturally in the muscle of animals infected with such illnesses.
Reacting quickly to the new research, French scientists scrambled to test cattle muscle for the agent that causes BSE.
Marc Eloit, president of the French food safety agency's committee on prion diseases, said samples were being taken from muscles of at least one cow that tested positive for BSE and results of the tests were due within a week.
Eloit said the research from Prusiner and his colleagues was "surprising" because it showed a high level of infectiousness in the muscle of mice that were given a brain injection of a strain of prion disease.
"That's the first surprising point. The second is that the infectiousness is very different depending on the muscles. It is higher in hind legs. In fact, they only found it there--not in the fore legs, not in the back, head or neck," he said.
In Brussels the European Union's executive arm said Prusiner's study would be evaluated but other research had never shown prions in muscle tissue of cattle, which were very different from mice.
"The Commission has had a look at these studies and welcomes Mr Prusiner's study and the European scientific committee will evaluate this," said European Commission spokeswoman Beate Gminder.
"But the Commission would recall that numerous studies have been carried out on bovine animals affected by BSE and these have never proved the existence of the prion in muscle tissue," she added.
"The structure and the metabolism of mice cannot be compared with that of bovine animals or that of human beings, but the Commission does nevertheless take on board Prusiner's advice to carry out studies on this," she added.
Prions have puzzled scientists since they were discovered. Normally present in the brain and other tissue of mammals they can take on an abnormally folded form that causes the brain to become spongy and eventually to wither.
Prions can propagate, clump up and cause disease without the use of any kind of genetic material at all, unlike viruses, bacteria and parasites.
They are blamed for a range of diseases known as transmissible spongiform encephalopathies, including BSE in cattle and vCJD in humans.
At least 100 people in Britain, France and Ireland have died from vCJD.