Scientists identify prion pathway

Computer-generated images of a normal and an abnormal human prion protein Keystone Archive

Swiss scientists have discovered how prions - the infectious agents believed to cause mad cow disease and its human equivalent, new variant Creutzfeldt-Jakob disease - reach the brain.

The study was led by Professor Adriano Aguzzi at the Institute for Neuropathology of Zurich University Hospital.

The team has identified a set of proteins in the blood, called complement proteins, which help prions leave the digestive tract.

“It’s another little piece in the big puzzle of how prions reach and damage the brain,” Aguzzi told swissinfo. “Interfering with the function of these complement proteins may help prevent the spread of prions throughout the body.”

While no definitive link between prion diseases in animals and nvCJD in humans has been established, most scientists are convinced that eating meat from BSE infected cattle could be a cause of the fatal brain disease.

“We have reason to believe that many people throughout Europe may have infected themselves with BSE prions,” said Aguzzi. “For me, it is a top priority to devise ways of preventing these people from developing overt disease.”

Aguzzi’s laboratory is now investigating various steps in the transmission process.

“We have a whole set of experiments,” he said. “We want to understand how prions, once they are inside the gut, cross the membrane of the gut and get into the body proper.

“We want to know how they spread from there to the lymph nodes and to the tonsils and then we want to know how the prions travel from the tonsils to the brain.”

by Vincent Landon