Prion Protein May Have Links to Other Neurological Diseases in Cattle

Author:  Liu Amy
Date:  October 2008

Scientists have found that the "prion" protein, a type of protein that causes the disease commonly known as mad cow disease, may play a role in other brain diseases affecting cattle. Researchers at the Veterinary Laboratories Agency published their findings in BMC Veterinary Research regarding the discovery of the prion protein's presence in the brains of cattle afflicted with other diseases known as idiopathic brainstem neuronal chromatolysis (IBNC).

Scientists have known that prion proteins cause disease in animals and humans due to their unique structure. Prions are protein molecules that are "misfolded" – that is, their structures are altered from their normal shapes. The misfolding of the prion propagates by transferring its misfolded properties into other proteins of the body, leading to many proteins becoming altered in shape. When prions infect cows, the misfolded proteins are known to cause diseases such as bovine spongiform encephalopathy in cattle, where proteins in the cow's brain to change in structure, leading to brain damage. The symptoms of BSE include the cow's inability to stand or coordinate movement and behavioral changes such as increased aggression. BSE is always fatal for cows.

If prions are transferred to humans, a deadly disease known as Creutzfeldt-Jakob disease may be contracted. Prions can infect humans through the consumption of infected animal meat. According to the NIH, symptoms of Creutzfeldt-Jakob disease include "rapidly progressive dementia," behavioral changes, and the eventual inability to move or speak.

Though this is the first time researchers have confirmed the association between IBNC and prion proteins, scientists have long known that IBNC is similar to prion protein-linked diseases in its symptoms seen in cattle. Scientists first discovered IBNC in 1988 when they examined the brains of cattle that exhibited symptoms of BSE. However, IBNC-afflicted cattle's brains lack the lesions seen in BSE.

Martin Jeffrey, head of the research team that published the findings, says that the research may have implications on the diagnosis of BSE and related diseases. Prion protein was found at abnormal levels in all 15 samples taken from the brains of IBNC-infected cattle, but the form of prions found was different from that of cattle infected by BSE. This may indicate that prion proteins cause more diseases than scientists had previously identified. These findings, Jeffrey says, "may have implications for diagnosis and recognition of typical forms of BSE as well as the related diseases in sheep, deer, and in man."

Written by: Amy Liu

Edited by: Jeffrey Kost

Published by: Hoi See Tsao