Stanley B. Prusiner
Wolf Prize Laureate in Medicine 1995/6
The Prize Committee for Medicine has unanimously decided that the Prize for 1995/6 be awarded to:
Stanley B. Prusiner
University of California,
School of Medicine
San Francisco, California, USA
“for discovering prions, new class of pathogens that cause important neurodegenerative disease by inducing changes in protein structute.”
Before the work of Professor Stanley B. Prusiner, infectious diseases were regarded as exclusively caused by nucleic acid-containing agents such as viruses, bacteria and parasites. A series of neurodegenerative diseases, such as Creutzfeld-Jakob and Gerstmann-Straussler-Scheinker disease existed in humans and scrapie and bovine spongiform encephalopathy (‘mad cow disease’) in farm animals, that had features suggesting they were transmittable but whose causative agents were not understood.
Prusiner demonstrated that the agents responsible for their transmission, which are called prions, were composed only of protein and were devoid of nucleic acid. After purifying prions from the brain, he discovered that they are composed of a special type of protein encoded by a chromosomal gene. In its normal form, this protein is called Prpc.
Prusiner showed that in lesions in animals with the neuro-degenerative disease scrapie, there is an abnormal form of this protein. This abnormal form has a unique structure and was called PrpSc. He discovered that PrpSc was derived from Prpc but differs in its three-dimensional conformation. PrpSc polymerizes to form amyloid. Amyloid plaques in the brains of animals and humans dying of prion diseases are composed of this abnormal protein. Prusiner found that PrpSc molecules can convert Prpc molecules into additional PrpSc molecules, the mechanism that accounts for the infectious nature of these diseases.
Prusiner’s studies have changed the way scientists and physicians think about central nervous system degenerative disorders. He has discovered a new principle of disease that has broad implications in biology and medicine.