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Portrait of Stanley B. Prusiner
Photo: Christopher Michel, Own work · CC BY 4.0 via Wikimedia Commons

Nobel Prize in Physiology or Medicine · 1997

Stanley B. Prusiner

He showed that a misfolded protein with no genes can spread infection in the brain, explaining mad cow disease and related dementias.

The Nobel citation: “for his discovery of Prions - a new biological principle of infection”
Born
May 28, 1942, Des Moines, IA, USA
Affiliation at the time
University of California School of Medicine, USA

Medicine prize

1997

Awarded alone.

Age that year

55years

Born in 1942.

Sources cited

17

Fact-checked September 24, 2026.

  • His hunt began in 1972, when a patient he admitted as a young neurology resident turned out to be dying of Creutzfeldt-Jakob disease, a rare and always fatal brain illness.
  • He coined the word prion in 1982, from 'proteinaceous infectious particle'. Many virologists refused to believe an infection could exist without DNA or RNA.
  • Early experiments meant waiting about 200 days for infected mice to fall ill. Switching to hamsters, which sicken faster, sped up the work.
  • While his idea was under attack, the Howard Hughes Medical Institute stopped funding him and UCSF at first denied him tenure, a decision it later reversed.
  • His grandfather Ben came to the United States from Moscow as a boy in 1896 and grew up in Sioux City, Iowa, among many other Russian Jewish immigrants.

The breakthrough

Prions: infectious proteins that carry no genes (1974-1997)

Every germ known before the 1980s, from bacteria to viruses, carries genes made of DNA or RNA that tell it how to copy itself. Prusiner studied a group of rare, always fatal brain diseases that did not seem to follow that rule: scrapie in sheep, kuru in New Guinea, and Creutzfeldt-Jakob disease (CJD) in people. They could pass from one brain to another, yet the body mounted no immune defense, and the infectious agent survived chemical treatments that destroy genes. Starting in 1974 he spent years purifying the agent from infected animal brains. Every test pointed to a protein and no genes, and in 1982 he named it a prion. In 1984 his team and collaborators found that the prion protein is made by an ordinary gene carried by every animal they tested, including humans. The answer to the puzzle was shape. The same protein can fold in two ways: a normal form found on the surface of nerve cells, and a misfolded form that is extremely tough and clumps together. The misfolded form acts as a template, pushing normal copies to refold its way in a slow chain reaction that kills brain cells. Picture one bent paper clip that can bend every straight clip it touches. Mutations in the gene explained why some families inherit these diseases.[1],[2],[3],[5]

“The best science often emerges from situations where results carefully obtained do not fit within the accepted paradigms.”
Stanley B. Prusiner, From his Nobel autobiography (1997), reflecting on the years when most scientists rejected the prion idea.[1]

What it meant for humanity

Prusiner's work gave medicine a cause and a mechanism for a whole class of fatal brain diseases. Before it, doctors called them slow virus infections and could not explain how one illness could be inherited, caught from someone else, or arise on its own. The prion idea explained all three: a faulty gene, exposure to misfolded protein, or a rare spontaneous misfold. The Nobel committee's 1997 summary noted that 85 to 90 percent of CJD cases arise spontaneously, 10 to 15 percent come from mutations in the prion gene, and a few were caused by medical treatments, such as growth hormone extracted from human pituitary glands. The same summary described how the misfolded protein resists temperatures above 100 degrees Celsius and enzymes that digest proteins, and attributed mad cow disease (BSE) in British cattle to contaminated feed. After a new variant of CJD linked to BSE appeared in people in 1996, about 233 people worldwide died of it through 2023. Europe's disease-control agency names bans on feeding processed animal protein to farm animals, first imposed in the UK in 1988, as the main preventive measure, and US health officials say feed bans drastically cut BSE in cattle. His Nobel lecture tells how CJD was about 30 times more common among Libyan Jews living in Israel than among other Israelis. Investigators first blamed eating sheep brain, but the patients all turned out to carry the same mutation in the prion gene. The prion idea also led to better diagnosis. The RT-QuIC test uses a patient's spinal fluid to trigger misfolding of normal prion protein in a test tube, and the UK's national CJD unit reports 92 percent sensitivity and 100 percent specificity. Prusiner has since argued that similar misfolding drives Alzheimer's and Parkinson's disease, an idea that has shaped research but is not universally accepted.

  • The Nobel committee said Prusiner added prions to the list of known infectious agents alongside bacteria, viruses, fungi and parasites.[2]
  • In 2004 his team made prion protein in bacteria, folded it into fibers and injected it into mice, which developed a brain disease that could pass to other mice. The team presented this as strong evidence that the protein alone infects.[6]
  • The RT-QuIC spinal-fluid test, which works by seeding prion misfolding in a test tube, detects sporadic CJD with 92% sensitivity and 100% specificity at the UK's national CJD unit.[9]
  • Variant CJD, the human form linked to mad cow disease, killed 233 people worldwide from 1996 to 2023, by US CDC count. Bans on animal protein in cattle feed, begun in the UK in 1988, are the main measure against it.[13],[14]
  • In 2012 he argued that prion-like misfolding helps explain Alzheimer's, Parkinson's and other brain-wasting diseases, and in 2015 his team reported evidence that a Parkinson's-related protein acts as a prion in multiple system atrophy.[7],[8]

Impact in numbers

Prusiner's main contribution is understanding. He established that a protein alone, by changing shape, can carry an infection, which added a new principle to biology and gave a single explanation for CJD, kuru, scrapie and mad cow disease. That framework now shapes how doctors diagnose CJD, how researchers explain inherited forms of these diseases, and how many scientists study Alzheimer's and Parkinson's. We make no quantified claims. Deaths from variant CJD prevented by animal-feed bans cannot fairly be credited to him: the first feed ban began in the UK in 1988, while the prion idea was still disputed. Treatments that halt prion diseases are still being developed. An honest account keeps this contribution in words rather than inventing a number.

HealthFundamental science

No number is given here on purpose. Some contributions cannot be counted honestly, and we would rather describe them than invent a figure.

The double edge

No harm to the public from Prusiner's discoveries is documented. The controversies concern credit, conduct and funding. In the 1960s others, including the British radiobiologist Tikvah Alper, had already suggested that the scrapie agent might lack nucleic acid, and a historian of the prion debate notes that a popular talk Prusiner gave in the early 1980s did not mention their work. A 1986 Discover magazine article accused him of trying to block critical papers and of undercutting rival researchers, and afterward he refused interviews with science writers for almost a decade. For nearly ten years the tobacco company R.J. Reynolds funded his lab with more than $3.7 million, through a grant program that also served to polish the company's image while smoking was under attack. Some scientists, such as Yale's Laura Manuelidis, long argued that a virus was still involved, and his later claim that Alzheimer's and Parkinson's are prion diseases is not universally accepted.

  • Minor

    Credit for the protein-only idea

    Tikvah Alper, Ian Pattison and J.S. Griffith had speculated in the 1960s that the scrapie agent might contain no nucleic acid. A 2011 history of the prion debate observes that a talk Prusiner gave for non-specialists in the early 1980s left out their work, making the idea seem to have started with him.[12]

  • Minor

    Combative handling of critics

    A 1986 Discover article by Gary Taubes described efforts by Prusiner to derail publication of papers critical of his work and to undermine other researchers' findings. The article led him to refuse interviews with science writers for almost a decade.[12]

  • Minor

    Tobacco-company funding

    R.J. Reynolds gave his research more than $3.7 million over nearly a decade, a source Prusiner acknowledged in his Nobel autobiography. A historian who studied the company's records describes the grant program as part of a public-relations effort by a firm under fire over the health dangers of smoking.[1],[12]

  • Minor

    Contested claims beyond CJD

    Critics such as Laura Manuelidis and Robert Rohwer argued that the prion protein might instead be a receptor for a hidden virus. Prusiner himself acknowledged in 2014 that there was no universal acceptance that prions cause Alzheimer's, Parkinson's or ALS.[12],[17]

Against the odds

Prusiner belongs to a generation of American Jews who met far fewer barriers than their grandparents. His family's story began under harsher conditions. His grandfather Ben left Moscow as a boy in 1896, five years after Russian authorities expelled about 20,000 Jews from the city and abolished its Jewish community organization. Ben settled in Sioux City, Iowa, among other Russian Jewish immigrants. In the United States, many medical schools held Jewish admissions down with informal quotas from the 1920s, and the evidence suggests these lasted into the 1950s. Prusiner entered medical school at the University of Pennsylvania in the mid-1960s, after that era, and his autobiography does not describe facing antisemitism himself. His struggle was scientific. Proposing that an infection could exist without genes put him against a core belief of biology. The Howard Hughes Medical Institute stopped funding him, UCSF first denied him tenure before reversing the decision, and he recalled that critics' personal attacks, amplified by the press, were at times vicious and caused his wife great distress. He kept going with support from close colleagues and private funders.

  • 1891

    Persecution

    Russian authorities expelled about 20,000 Jews from Moscow in 1891. Prusiner's paternal grandfather emigrated from Moscow to the United States as a young boy in 1896.[1],[15]

  • —

    Quota

    American medical schools restricted Jewish admissions with informal quotas from the 1920s, and there is evidence they lasted into the 1950s. Prusiner entered medical school in the mid-1960s, after that period.[1],[16]

  • —

    Other

    Because his results contradicted accepted science, the Howard Hughes Medical Institute ended its support and UCSF initially refused him tenure, a decision later reversed.[1],[11]

Jewish background

Both parents JewishCulturally Jewish

Prusiner was born in Des Moines, Iowa, to Lawrence Prusiner, an architect, and Miriam (Spigel) Prusiner. In his Nobel autobiography he writes that his paternal grandfather, Ben, emigrated from Moscow to the United States as a young boy in 1896 and, like Prusiner's father, grew up in Sioux City, Iowa, among many other Russian Jews. In a 2017 oral-history interview for the American Academy of Neurology he spoke of his Jewish mother, recalling the magazine clippings about doctors she mailed him while he was in college. He has said little in public about religious practice.[1],[10]

Key dates

  1. May 28, 1942

    Born in Des Moines, Iowa. His father soon leaves to serve in the US Navy in the Pacific during World War II.[1],[4]

  2. 1952

    Family moves to Cincinnati, Ohio, where he later attends Walnut Hills High School.[1]

  3. 1963

    As a chemistry student at the University of Pennsylvania, starts his first research project, on hypothermia, and stays at Penn for medical school.[1]

  4. 1968

    Completes medical studies at Penn after research on brown fat in Stockholm, then trains at UCSF and does three years of research at the NIH.[1]

  5. September 1972

    Two months into his neurology residency at UCSF, admits a woman dying of Creutzfeldt-Jakob disease and becomes fascinated by its mysterious cause.[1],[3]

  6. July 1974

    Joins the UCSF faculty and sets up a laboratory to study scrapie.[1]

  7. April 9, 1982

    Publishes evidence in Science that the scrapie agent needs a protein but not nucleic acid, and proposes the word prion.[5]

  8. 1984

    With colleagues, finds that the prion protein is encoded by a normal gene present in all animals tested, including humans.[2]

  9. December 1986

    A critical Discover magazine article questions his claims and conduct, part of years of public dispute over prions.[12]

  10. 1997

    Awarded the unshared Nobel Prize in Physiology or Medicine for discovering prions, a new biological principle of infection.[2],[4]

  11. July 30, 2004

    His team reports synthetic prions made from bacterial protein that cause transmissible brain disease in mice.[6]

  12. June 22, 2012

    Argues in Science that prion-like misfolding plays a unifying role in Alzheimer's, Parkinson's and other neurodegenerative diseases.[7]

  13. 2014

    Publishes Madness and Memory, his account of the discovery of prions and the resistance it met.[17]

  14. 2015

    His team reports evidence that alpha-synuclein prions cause multiple system atrophy, a disease related to Parkinson's.[8]

Sources

  1. 1.Stanley B. Prusiner - Biographical · NobelPrize.org (Nobel Prize Outreach), 1997
  2. 2.Press release: The Nobel Prize in Physiology or Medicine 1997 · The Nobel Assembly at Karolinska Institutet / NobelPrize.org, 1997
  3. 3.Prions (Nobel Lecture, 8 December 1997) · NobelPrize.org (Nobel Prize Outreach), 1997
  4. 4.Stanley B. Prusiner - Facts · NobelPrize.org (Nobel Prize Outreach)
  5. 5.Novel proteinaceous infectious particles cause scrapie (Prusiner SB, Science 216:136-144) · Science / PubMed, 1982
  6. 6.Synthetic mammalian prions (Legname G et al., Science 305:673-676) · Science / PubMed, 2004
  7. 7.A unifying role for prions in neurodegenerative diseases (Prusiner SB, Science 336:1511-1513) · Science / PubMed, 2012
  8. 8.Evidence for alpha-synuclein prions causing multiple system atrophy in humans with parkinsonism (Prusiner SB et al., PNAS 112:E5308-17) · PNAS / PubMed, 2015
  9. 9.RT-QuIC: a new test for sporadic CJD (Green AJE, Practical Neurology 19:49-55) · Practical Neurology (BMJ) / PubMed, 2019
  10. 10.Interview with Doctor Stanley B. Prusiner (AAN Oral History Project, interviewed by Douglas J. Lanska and Lauren E. Klaffke) · American Academy of Neurology, 2017
  11. 11.A conversation with Stanley Prusiner · Journal of Clinical Investigation, 2024
  12. 12.Creating Controversy: Science Writers, Corporate Funders, and Non-expert Scientists in the Debate over Prions (1982-1997), PhD thesis by Patricia Ann Liu · University of Toronto, Institute for the History and Philosophy of Science and Technology, 2011
  13. 13.Factsheet about variant Creutzfeldt-Jakob disease · European Centre for Disease Prevention and Control
  14. 14.Clinical Overview of Variant Creutzfeldt-Jakob Disease · US Centers for Disease Control and Prevention
  15. 15.Moscow (Jewish Encyclopedia, 1906) · JewishEncyclopedia.com, 1906
  16. 16.Jewish American Heritage Month: The Forgotten History of Quotas in American Medical School Admissions · Himmelfarb Health Sciences Library, George Washington University, 2023
  17. 17.Madness and Memory: A Conversation with Nobel Laureate Stanley B. Prusiner, M.D. · Yale University Press, 2014

Fact-checked on September 24, 2026 by a separate AI fact-checking pass that re-opened the sources, with 8 corrections made. How we check

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