Mice livers show prions move

Cattle Market & Farm Reports, Editorials
Feb 7, 2005
by WLJ
Rogue proteins like those that cause bovine spongiform encephalopathy (BSE)—found previously only in brain, nerve and lymph tissues —have now been located in the liver, kidney and pancreas in a study of rodents.
While the discovery raises the possibility that similar proteins could move into unanticipated parts of farm animals that have similar diseases, it isn't a reason for alarm, says researcher Adriano Aguzzi of the University Hospital of Zurich, Switzerland.
But, he adds, "There is reason to reappraise critically the way regulations that are already in place" are enforced.
Sick animals such as sheep and cows shouldn't enter the human food chain, said Aguzzi, the lead researcher in the study, said in a telephone interview.
"I think what is probably worth doing is to recheck whether all these regulations are implemented properly," he said. "But, I think this is nothing that should provoke a wave of panic."
Rogue proteins called prions are blamed for several brain-wasting diseases, including BSE, scrapie in sheep and variant Creutzfeldt-Jakob disease in humans.
These proteins had only been found in the brains, spinal cord and lymph tissues of infected people and animals. But Aguzzi's report, published online Feb. 3 by the journal Science, indicates that in at least some cases they can move to other parts of the body.
Inflammation, characterized by swelling, redness and pain, occurs in a number of diseases, such as hepatitis, which affects the liver.
"I think it certainly raises questions as to the current classification of risk organs, which essentially says the brain and lymphatic tissue is at risk, whereas everything else is rather safe," Aguzzi said. "So, I think that in the case of an inflammatory condition, I think that is no longer valid."
The finding "reinforces that you never say never," said Dr. William Hueston, director of the University of Minnesota's Center for Animal Health and Food Safety.
Hueston, who wasn't part of Aguzzi's research team, agreed that the finding isn't cause for alarm, saying it reinforces the reasons for inspecting animals in the food chain.
Dr. Robert B. Petersen, a professor of neuropathology at Case Western Reserve University in Cleveland, agreed that any risk is low since screening procedures would identify infected animals.
In addition, considering the low incidence of prion diseases, "it is unlikely that you would find an animal with chronic viral or bacterial infection and prion infection simultaneously," said Peterson, who wasn't involved in Aguzzi's research.
Jim Rogers, of the U.S. Agriculture Department's Animal and Plant Health inspection Service, said the agency already targets high-risk animals and don't need to change its procedures.
In the study, Aguzzi's team, which included researchers at the Institute f Neurology in London and at Yale University, raised mice that had chronic inflammatory disease of the liver, pancreas or kidney.
These mice were injected with prions from sheep suffering from scrapie. When the mice were studied, researchers found at least some prions had accumulated in the diseased organs. Aguzzi said he plans similar experiments on sheep.
The research was supported by the Swiss Federal Office for Education and Science, Swiss National Science Foundation, Swiss National Center for Competence in Research, University of Zurich, a grant from the Catello Family, the Association for the Promotion of the Academic New Generation, the Medical Research Council of the United Kingdom and the U.S. National Institutes of Health. — WLJ