Progress Made in Protein Linked to Mad Cow Disease

Researchers have for the first time made a prion in the laboratory and used it to demonstrate that the misfolded proteins are indeed the sole cause of mad cow disease, the American and German scientists said Thursday.

The research, published in the journal Science, may also help open the way to a treatment for the currently untreatable and incurable family of prion diseases, which include not only mad cow, but Creutzfeldt-Jakob disease, which afflicts humans, and a related human form of CJD caused by eating mad cow-infected beef.

“Our study demonstrates that misfolding a particular segment of the normal prion protein is sufficient to transform the protein into infectious prions,” said lead researcher Giuseppe Legname at UC San Francisco.

The researchers created a synthetic prion by using bacteria to grow prion fragments and folding them into larger protein structures.

They injected these into the brains of mice bred to be susceptible to transmissible spongiform encephalopathies such as bovine spongiform encephalopathy -- mad cow disease -- CJD and others. The mice started showing symptoms in about a year, the researchers reported.

Prions are protein particles that naturally exist in the body, but they become misfolded in the TSE diseases and infectious.

“We now have a tool for exploring the mechanism by which a protein can spontaneously fold into a shape that causes disease,” said Legname’s UCSF colleague Stanley Prusiner, who won a Nobel Prize in 1997 for his discovery of prions.

Prusiner said in a statement he hoped the findings would lead to methods to study other brain-destroying diseases such as Parkinson’s and Alzheimer’s.