The American researcher Dr Stanley B. Prusiner won the Nobel Prize for medicine yesterday for his discovery of prions, agents thought to cause Alzheimer's disease as well as human and animal forms of BSE.
Other scientists hailed Dr Prusiner's ground-breaking work and said he had developed "a totally new concept in biology".
Prions, derived from "proteinaceous infectious particle", spread fatal diseases which may be inherited, transmitted, or occur spontaneously, such as BSE, scrapie in sheep, and the kuru disease in New Guinea.
Dr Prusiner (55), a professor at the University of California at San Francisco, began his research 25 years ago after one of his patients died of dementia resulting from Creutzfeld-Jakob Disease (CJD).
It had previously been shown that CJD could be transmitted through extracts of diseased brains. In 1982, Dr Prusiner discovered the prion protein after producing a preparation derived from diseased hamster brains.
In 1984, he and his colleagues in California isolated a gene probe and subsequently showed that the prion gene was found in all animals and man, but that the prion could fold into two distinct formations, one diseased and one normal.
In its citation, the Nobel committee hailed Dr Prusiner's discovery of "an entirely new genre of disease-causing agents". His research "provides important insights that may furnish the basis to understand the biological mechanisms" underlying "dementia-related diseases, for example, Alzheimer's Disease, and establishes a foundation for drug development and new types of medical treatment strategies."
Dr Prusiner, who works in the university's department of neurology, "added prions to the list of well-known infectious agents including bacteria, viruses, fungi, and parasites," the citation added.
Kuru, spread from human to human via cannibalism, disappeared almost entirely once people stopped eating human brains. The discovery of kuru won Dr Carleton Gajdusek of the US the 1976 Nobel Prize for medicine. Thanks to Dr Prusiner, what was once believed to be a slow-working virus in victims of kuru has been proven to be prions.
Dr Prusiner endured intense scepticism in the scientific community when he claimed that prions provoke diseases without any genetic support, such as DNA. But he was able to define the precise nature of the new agent.
"He really deserved this award. It has been very hard for Prusiner to prove the existence of prions," said Dr Susan Michelson of the Pasteur Institute in Paris.
Prions possess an innate capacity to convert their structures into highly stabile conformations that ultimately result in the formation of harmful particles, the causative agents of several deadly brain diseases of the dementia type in humans and animals.
The 76th American to win the Nobel Prize for medicine, Dr Prusiner will receive a medal and a cheque for £686,059 ($1 million) in Stockholm on December 10th.