A lab accident in France likely led to a woman’s death from prions 9 years later

As the co-author of Mad Cows and Mother’s Milk (1997) I couldn’t let this slide.

A lab accident in 2010 likely led to a woman’s untimely death nearly a decade later, according to doctors in France. In a recent case study, they describe how a woman in her early 30s developed a universally fatal brain disorder years after she had pierced her skin with equipment used to handle infectious rogue proteins called prions.

Prions are a type of protein that exist naturally in our brains. Ordinarily, they’re thought to be harmless, though their exact function remains a mystery. But rarely, they can transform into a misfolded version that compels normal prions to change shape, too. Over years or even decades, this cascade of misfolded prions destroys the brain from the inside out, leaving behind signature sponge-like holes under a microscope. Because of these holes, prion diseases are also medically known as transmissible spongiform encephalopathies.

Prion diseases often happen with no clear rhyme or reason — native prions just seem to spontaneously pull a heel turn. Other times, a person’s inherited genetics are to blame. But what makes prions even scarier is that they can be also infectious, spreading from one person to another or across different species of animals.

In the 1980s and 1990s, scientists noticed outbreaks of cows that were developing their own prion disease, which became popularly known as mad cow disease. Years later, we began seeing people develop a never-before-seen sort of prion disease, which was eventually traced to them eating contaminated beef (meanwhile, the cows were being infected from eating animal feed that contained brain matter from other infected cows and possibly sheep). Medically, this infectious type of prion disease became known as variant-Creutzfeldt-Jakob disease (vCJD), to distinguish it from the classic version that’s the most common but still very rare prion disease in humans.

The young woman had been a lab technician in a research facility studying prions in 2010, according to a case study published in the New England Journal of Medicine this month. One day in May, she was using a pair of curved forceps to handle frozen, prion-infected brain samples taken from mice genetically engineered to develop human prions, when the forceps slipped and stabbed into her thumb. Though she was wearing two pairs of protective gloves, the sharp ends pierced her skin and drew blood. She was only 24 at the time.

About seven and a half years later, in November 2017, she began experiencing a burning pain down her right shoulder and neck. Her condition worsened over the next year, to the point of memory impairment, visual hallucinations, and muscle stiffness along her right side by January 2019. Eventually, 19 months after the onset of symptoms, she died. Tests before her death strongly suggested she had vCJD, which was confirmed post-mortem.

It’s possible that the woman might have caught vCJD through eating tainted beef made before sharp shifts in the meat processing industry came along that seemed to end the threat of mad cow disease in the 1990s. But that would be very unlikely, according to the authors, because vCJD isn’t thought to take longer than a decade to show up after exposure in people with the woman’s genetic makeup. Nearly all known cases of vCJD have been in people who share a specific but relatively common genetic variation of their prion gene, called MM, which the women also carried. But the timing does work out if you assume she caught vCJD through the lab accident.

Prion diseases remain incredibly rare, and even in cases where they are infectious, genetics seem to strongly influence the risk of actually becoming sick (only a few hundred cases of vCJD have ever been reported worldwide). But this isn’t the first time that a case of vCJD has been linked to exposure in a lab, according to the authors, suggesting that more could be done to keep scientists and technicians safe during the valuable work they do to understand these utterly mysterious things. Prions are notoriously very hard to “kill” using traditional decontamination methods, which provides an added source of concern for medical procedures involving the brain.

New blood tests can detect prions

Tine Hesman Saey of Science News reports a new blood test can detect even tiny amounts of infectious proteins called prions, two new studies show.

prion-test-dec-16Incurable prion diseases, such as mad cow disease (BSE) in cattle and variant Creutzfeldt-Jakob disease (vCJD) in people, result from a normal brain protein called PrP twisting into a disease-causing “prion” shape that kills nerve cells in the brain. As many as 30,000 people in the United Kingdom may be carriers of prions that cause vCJD, presumably picked up by eating BSE-tainted beef. Health officials worry infected people could unwittingly pass prions to others through blood transfusions. Four such cases have already been recorded. But until now, there has been no way to screen blood for the infectious proteins.

In the test, described December 21 in Science Translational Medicine, magnetic nanobeads coated with plasminogen — a protein that prions grab onto — trap prions. Washing the beads gets rid of the rest of the substances in the blood. Researchers then add normal PrP to the beads. If any prions are stuck to the beads, the infectious proteins will convert PrP to the prion form, which will also stick to the beads. After many rounds, the researchers could amplify the signal enough to detect vCJD prions in all the people in the studies known to have the disease.

No healthy people or people with other degenerative brain diseases (including Alzheimer’s and Parkinson’s) in either study had evidence of the infectious proteins in their blood. And only one of 83 people with a sporadic form of Creutzfeld-Jakob disease tested positive. Those results indicate that the test is specific to the vCJD prion form, so a different test is needed to detect the sporadic disease. 

In two cases, researchers detected prions in frozen blood samples collected 31 months and 16 months before people developed vCJD symptoms.

Beneficial role clarified for brain protein associated with BSE

Studying mice and zebrafish, researchers from Washington University School of Medicine in St. Louis and the University of Zurich have shown that the proteins — when properly folded — play a vital role in nerve cell function by maintaining the insulation around axons, the nervous system’s electrical “wiring.”

prionThe study appears August 8 in the journal Nature.

Improperly formed prion proteins that cause disease are infectious because they hijack their neighbors, resulting in misfolded proteins and setting off a domino effect that spreads through the brain destroying tissue. Although the role of prion proteins in these fatal brain diseases is well-known, scientists have long puzzled over the normal function of the protein, called PrPC.

“Previous studies have suggested a role for prion proteins in maintaining neurons, but until now, no one knew how the properly folded versions of the proteins function,” said co-author Kelly R. Monk, PhD, an associate professor of developmental biology at Washington University. “It’s surprising to see that the protein has a role in maintaining the structure of nerve cells, considering that a misfolded version of PrPC is known to cause fatal brain diseases.”

Past work by the researchers at the University of Zurich demonstrated that mice lacking PrPC had disruptions in the insulation surrounding axons, but the reasons for the disruptions were unclear. The new study demonstrates that PrPC binds to Schwann cells, which are cells that provide support for the brain’s neurons. Schwann cells produce the nerve-insulating protein called myelin and then wrap this insulation around the long, thin axons. Properly insulated axons enable the rapid propagation of nerve signals. Specifically, PrPC binds to a docking site on Schwann cells called Gpr126.

In past work, Monk and her Washington University colleagues demonstrated that the docking site on cells played an important role in nerve formation during embryonic development in zebrafish and in mice. But the new study identifies roles for both Gpr126 and PrPC in maintaining the integrity of neurons through adulthood.

When either of these components is missing, Monk said mice experience a gradual loss of interactions between Schwann cells and axons, with a resulting loss of of myelin. Without this important insulation, walking progressively becomes more difficult for mice, and they eventually reach a state of paralysis.

“We have identified a definitive function for the normal prion protein and clarified how it works on a molecular level,” said senior author Adriano Aguzzi, MD, PhD, of the University of Zurich. “Our study answers a question that has been intensely researched since the prion gene’s discovery in 1985.”

The researchers said the findings may have implications for understanding and eventually treating nerve disorders that result from the loss of the insulating myelin sheaths, such as Charcot-Marie-Tooth disease and other devastating peripheral neuropathies.

Prions in plants

Prions, the misfolded proteins that are known for causing degenerative illnesses in animals and humans, may have been spotted for the first time in plants.

Prion%20ProteinsResearchers led by Susan Lindquist, a biologist at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, report that they have found a section of protein in thale cress (Arabidopsis) that behaves like a prion when it is inserted into yeast.

In plants, the protein is called Luminidependens (LD), and it is normally involved in responding to daylight and controlling flowering time. When a part of the LD gene is inserted into yeast, it produces a protein that does not fold up normally, and which spreads this misfolded state to proteins around it in a domino effect that causes aggregates or clumps. Later generations of yeast cells inherit the effect: their versions of the protein also misfold.

This does not mean that plants definitely have prion-like proteins, adds Lindquist — but she thinks that it is likely. “I’d be surprised if they weren’t there,” she says. To prove it, researchers would need to grind up a plant and see whether they could find a protein such as LD in several different folded states, as well as show that any potential prion caused a misfolding cascade when added to a test-tube of protein. Lindquist adds that because she’s not a plant scientist — her focus is on using yeast to investigate prions — she hasn’t tried these experiments. The study is reported on 25 April in the Proceedings of the National Academy of Sciences.

 

Wow, man, that would be awesome

On Friday, researchers with the National Center for Scientific Research in France announced they had reported in the September 5th edition of the Journal of Neuroscience that the administration of the nonpsychoactive cannabinoid cannabidiol (CBD) inhibits prion accumulation in the brain and protects neurons against prion toxicity.

It only took until Monday for the Australian National Organisation for the Reform of Marijuana Laws (Norml) to adopt the paper as its own.

Norml spokesman Chris Fowlie said the discovery added to the scientific evidence supporting Australian Green MP Metiria Turei’s bill to legalise the medicinal use of cannabis, stating,

"[It] should be supported by any MP with a clear head. Unfortunately most politicians act like mad cows whenever cannabis is mentioned."