Prusiner won the 1997 Nobel Prize in Physiology or Medicine for his ground-breaking, yet controversial, work on a type of protein particle, a prion, that he hypothesized was responsible for a number of fatal neurodegenerative disorders, including Creutzfeldt-Jakob disease (CJD) and mad cow disease.

Prusiner was born on May 28, 1942, in Des Moines, Iowa. He earned his B.A., cum laude, at the University of Pennsylvania, in 1964, and then went on to receive an M.D. in 1968 from the same university. Prusiner then served his internship and residency at the prestigious University of California at San Francisco (UCSF) from 1968 to 1969, where he later served a residency in neurology. Prusiner soon became interested in neurodegenerative diseases. This interest was in part developed after one of his patients died of CJD, a disease of the cerebral cortex which leads to dementia and eventual death.

As a result of this experience, Prusiner learned...