Akademik

Pruisner was born in Des Moines, Iowa, and qualified as an MD at the University of Pennsylvania in 1968. In 1972 he began a residency at the University of California School of Medicine, San Francisco, where he was appointed professor of neurology in 1980 and professor of biochemistry in 1988.

Early in his career in 1972, Pruisner, following the death of a patient from Creutzfeldt-Jakob disease (CJD), discovered that virtually nothing was known about the condition. It was thought to be one of a class of diseases known as transmissible spongiform encephalopathies (TSEs), which include scrapie in sheep, the more familiar BSE in cattle, and kuru and CJD in man. Following the work of Carleton Gajdusek, it was proposed that CJD and the other TSEs were probably caused by slow viruses and could be transmitted by injecting extracts from diseased brains into healthy animal brains.

Pruisner began to suspect that something unusual was going on when he read reports suggesting that the agent responsible for scrapie could lack both DNA and RNA. Working with infected hamster brains, he established that procedures known to damage nucleic acids failed to lessen the infection whereas steps that denatured proteins did reduce infectivity. In 1982 he introduced the term prion (standing for proteinaceous infectious particle) to refer to an agent that is distinct from viruses, bacteria, fungi and all other known causes of disease and is responsible for scrapie and other TSEs.

He went on to claim that scrapie prions contained a single protein, PrP (prion protein), which was shown to consist of some 15 amino acids. A gene for PrP was found in the chromosomes of hamsters, mice, humans, and all other examined mammals. Why then did not all mammals suffer from prion diseases? Because, Pruisner argued, PrP could be found in two forms: PrP^c, normal cellular protein and PrP^Sc, the abnormal disease-causing form.

Although it has as yet proved impossible to produce infections with synthesised PrP, and although it is widely held that, at best, prions are only partly responsible for the numerous TSEs, Pruisner was awarded the 1997 Nobel Prize for physiology or medicine for “finding a new biological principle of infection.”