The idea that proteins can cause deadly brain diseases and be infectious at the same time sounds no less crazy today than it did forty years ago.

Although the peak phase of mad cow disease should have dispelled the greatest doubts, documented in pictures of tumbling cows or piles of carcasses after mass slaughter, and a Nobel Prize recognized the erroneous idea of ​​an American neurologist in 1997 as the "discovery of a new biological principle of infection", the idea remains for some unimaginable.

Sonya Kastilan

Editor in the "Science" department of the Frankfurter Allgemeine Sunday newspaper.

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Stanley B. Prusiner published several studies in 1982 in which he described his experiments on scrapie, a sheep disease known since the 18th century, the mysterious cause of which he wanted to find.

With revolutionary results that sparked controversy among experts: no small "slow virus" was responsible for this "spongiform encephalitis", as had been assumed until then, but something completely different, contagious, which Prusiner now called "prions".

The pathogens were not viruses, bacteria, fungi or parasites, but infectious proteins with long-term effects.

Stanley Prusiner was forty years old when he gave this discovery a catchy name.

Born in 1942 in Des Moines, Iowa, and raised in Cincinnati, Ohio, he, who had been rather bored at school and had not shown much ambition, first studied chemistry in Philadelphia at the University of Pennsylvania, but then eventually went to college to find medicine.

He then did his military service at the National Institutes of Health.

After those three years, he felt ready to set up his own lab, as described in his 2014 memoir, Madness and Memory.

He just didn't know exactly in which direction he wanted to go.

So Prusiner returned to the University of California at San Francisco, where he had previously attended, and took a stint in neurology.

Degenerate into an unusable "tissue sponge".

The case of a patient there became a key experience for him: an attractive sixty-year-old with shining blue eyes, full of enthusiasm, as he remembers the first meeting, at the same time she seemed strangely absent.

The woman suffered from memory problems, could not name her own symptoms and had difficulties with fine motor skills in her hands;

a few months later she died of Creutzfeldt-Jakob disease.

Thus began his odyssey in 1972, which could be described as an obsession.

Prusiner wanted to find out what causes the human or animal brain to degenerate into an unusable "tissue sponge".

Ten years later he was sure of the prions.

His studies appeared in renowned specialist journals, and yet the research community was difficult to convince.

How should proteins, and even endogenous ones at that, be able to multiply without genetic information, neither on the basis of DNA nor RNA?

In the meantime, the concept of awkwardly folded protein molecules that force their defective structure onto well-formed versions, allowing them to fold over, is accepted not only for animal diseases such as scrapie or BSE and rare human diseases such as Creutzfeldt-Jakob or kuru.

The principle discovered by Stanley Prusiner also plays a role in other neurodegenerative diseases, such as Alzheimer's and Parkinson's.

Now he is praised as a visionary and no longer ostracized as a heretic or even compared to a "carpet dealer".