Mad Cow disease, which was thought to spread in humans only if they consume infected brain or intestinal tissues of infected cow, may have other routes of entry. If the study done on mice by a group of researchers led by Adriano Aguzzi at the University Hospital of Zurich, Switzerland holds true then BSE / CJD testing programmers will have to change their ways and practices in what could turn into another major problem for the beef industry.
Since earlier screening showed Prions, that cause BSE, are present only in specific organs like brain and intestines, "the assumption has been that other parts are safe to eat," says Aguzzi.
"People in countries with BSE still eat steak because the authorities say if you stay away from the brain and lymphoid tissue, you should be safe. However, most Prion testing has been done in healthy animals. If you have a sick cow, these rules may no longer apply."
Aguzzi’s study showed inflammation can let the disease causing protein Prion to be replicated (produced) in other parts of the animal body which were earlier thought to be safe for consumption. The mice used in the study were having inflammation due to several reasons including kidney and liver diseases. It was seen in all the cases that chronic inflammation leads to a build up of prion proteins in organs that are usually Prion free.
"The organ transforms itself into a bioreactor for Prions," says Aguzzi.
The mice having inflammation due to diabetes had its pancreas full of the Prions while the organ in healthy mice was left unaffected.
Researchers have not yet worked out how exactly inflammation leads to Prion production and the spread of deadly protein in other parts of the body. However, they feel that it has got something to do with the cells playing role in the immune system. These cells produce a substance called lymphotoxin to fight invading pathogens. Aguzzi feels that the lymphotoxin starts a reaction that turns a normal cell into a prion producing bioreactor. They have observed that mice lacking the lymphotoxin receptors lack prion disease in inflamed organs.
