Prion proponent wins Nobel for medicine.
Prusiner coined the term prion, for proteinaceous infectious particle, in 1982 to label this protein--the first proposed infectious agent containing neither DNA nor RNA.
Some scientists still consider Prusiner's prion theory unproved because purified prions have not been shown to cause disease. Moreover, no one has shown how prions inveigle their harmless, normal counterparts in the body to become prions themselves, nor has anyone described the function of those normal proteins. Some researchers still suspect that a slow-acting virus plays a hidden role in the infection process.
Others regard Prusiner's prion research as visionary, not least because it faced doubt and scorn at the start. The Nobel prize "is a wonderful recognition of a huge amount of work," says Fred E. Cohen, a structural biologist at San Francisco who works with Prusiner.
The Nobel committee in Stockholm said Prusiner has amassed enough evidence to show that prions cause brain diseases. Prions joined a lineup of tiny thugs that includes bacteria, viruses, fungi, and parasites.
When Prusiner began studying brain diseases 25 years ago, he knew that certain ailments could be transmitted by moving brain tissue from an infected person or animal to a healthy one, but he didn't know what the agent of infection was. In 1982, he and his colleagues resurrected an untested concept that the agent might be a protein.
Prusiner reaped a whirlwind of derision and praise that has yet to die down. After a highly critical article in a 1986 issue of Discover, Prusiner stopped talking to the press for a decade.
His work continued, however. A prion, he showed, can induce proteins in the body to fold into its own warped form, becoming prions themselves. In 1984, he and his colleagues cloned the gene that encodes the protein's normal version, called PrP. Prions apparently evade the immune system because the body can't distinguish them from PrPs.
They are different, however. PrPs are soluble in some detergents, but prions are not. Also, PrPs can be digested by the enzyme protease, whereas prions are partially resistant. Such distinctions enable prions to start a chain reaction that causes spongiform encephalopathies, or tiny holes in the brain, Prusiner holds.
One such affliction in humans, Creutzfeldt-Jakob disease (CJD), causes dementia, tremors, and death. Other prion ailments include kuru, a human disease in Papua New Guinea spread by ritualistic cannibalism; two very rare hereditary brain diseases in humans; scrapie in sheep; and mad cow disease. In recent years, British researchers have found that a variant form of Ill as deadly as the classical disease, has emerged in humans (SN: 10/4/97, p. 212).
Prusiner's prion theory stands as the most widely accepted explanation of these diseases.
Laura Manuelidis, a neuropathologist at Yale University School of Medicine, appreciates Prusiner's work, although she doubts that prions are the sole cause of the ailments.
"I would have been happier if they had given Prusiner the Nobel prize for discovering a molecule that's very important in these diseases," she says. "[So far] there isn't a single infectious agent that doesn't have nucleic acid." It can take years to find viruses, as the 10-year hunt for the hepatitis C virus proved.
"[Prusiner's] is a revolutionary kind of work that advances ideas that are considered by some to be controversial," says Allen Roses, a neurologist at Glaxo Wellcome in Research Triangle Park, N.C. "It's a very, very convincing argument. It's up to the viral people to do the experiments to show [a virus] is there. He's done everything to show it's not."
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|Title Annotation:||Stanley B. Prusiner|
|Date:||Oct 11, 1997|
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