Science

France issues moratorium on prion research after fatal brain disease strikes two lab workers

Émilie Jaumain in 2010, the year she was exposed to prions during a lab accident. She died in 2019 at age 33.

ARMEL HOUEL

PARIS—Five public research institutions in France have imposed a 3-month moratorium on the study of prions—a class of misfolding, infectious proteins that cause fatal brain diseases—after a retired lab worker who handled prions in the past was diagnosed with Creutzfeldt-Jakob disease (CJD), the most common prion disease in humans. An investigation is underway to find out whether the patient, who worked at a lab run by the National Research Institute for Agriculture, Food and Environment (INRAE), contracted the disease on the job.

If so, it would be the second such case in France in the past few years. In June 2019, an INRAE lab worker named Émilie Jaumain died at age 33, 10 years after pricking her thumb during an experiment with prion-infected mice. Her family is now suing INRAE for manslaughter and endangering life; her illness had already led to tightened safety measures at French prion labs.

The aim of the moratorium, which affects nine labs, is to “study the possibility of a link with the [new patient’s] former professional activity and if necessary to adapt the preventative measures in force in research laboratories,” according to a joint press release issued by the five institutions yesterday.

“This is the right way to go in the circumstances,” says Ronald Melki, a structural biologist at a prion lab jointly operated by the French national research agency CNRS and the French Alternative Energies and Atomic Energy Commission (CEA). “It is always wise to ask questions about the whole working process when something goes wrong.” “The occurrence of these harsh diseases in two of our scientific colleagues clearly affects the whole prion community, which is a small ‘familial’ community of less than 1000 people worldwide,” Emmanuel Comoy, deputy director of CEA’s Unit of Prion Disorders and Related Infectious Agents, writes in an email to Science. Although prion research already has strict safety protocols, “it necessarily reinforces the awareness of the risk linked to these infectious agents,” he says.

In Jaumain’s case, there is little doubt she was infected on the job, according to a paper published in The New England Journal of Medicine (NEJM) in 2020. She had variant CJD (vCJD), a form typically caused by eating beef contaminated with bovine spongiform encephalopathy (BSE), or mad cow disease. But Europe’s BSE outbreak ended after 2000 and vCJD virtually disappeared; the chance that someone of Jaumain’s age in France would contract food-borne vCJD is “negligible or non-existent,” according to the paper.

A scientist with inside knowledge says the new patient, a woman who worked at INRAE’s Host-Pathogen Interactions and Immunity group in Toulouse, is still alive. French authorities were apparently alerted to her diagnosis late last week. The press release suggests it’s not yet clear whether the new case is vCJD or “classic” CJD, which is not known to be caused by prions from animals. Classic CJD strikes an estimated one person per million. Some 80% of cases are sporadic, meaning they have no known cause, but others are genetic or contracted from infected human tissues during transplantations. The two types of CJD can only be distinguished through a postmortem examination of brain tissue.

Lab infections are known to occur with many pathogens, but exposure to CJD-causing prions is unusually risky because there are no vaccines or treatments and the condition is universally fatal. And whereas most infections reveal themselves within days or weeks, CJD’s average incubation period is about 10 years.

For Jaumain, who worked at INRAE’s Molecular Virology and Immunology Unit in Jouy-en-Josas, outside Paris, that long period of uncertainty began on 31 May 2010, when she stabbed her left thumb with a curved forceps while cleaning a cryostat—a machine that can cut tissues at very low temperatures—that she used to slice brain sections from transgenic mice infected with a sheep-adapted form of BSE. She pierced two layers of latex gloves and drew blood. “Émilie started worrying about the accident as soon as it had happened, and mentioned it to every doctor she saw,” says her widower, Armel Houel.

In November 2017, Jaumain developed a burning pain in her right shoulder and neck that worsened and spread to the right half of her body over the following 6 months, according to the NEJM paper. In January 2019, she became depressed and anxious, suffering memory impairment and hallucinations. “It was a descent into hell,” Houel says. She was diagnosed with “probable vCJD” in mid-March of that year and died 3 months later. A postmortem confirmed the diagnosis.

The occurrence of these harsh diseases in two of our scientific colleagues clearly affects the whole prion community.

Emmanuel Comoy, French Alternative Energies and Atomic Energy Commission

INRAE only recently admitted the likely link between Jaumain’s illness and the accident. “We recognize, without ambiguity, the hypothesis of a correlation between Emilie Jaumain-Houel’s accident … and her infection with vCJD,” INRAE chair and CEO Philippe Mauguin wrote in a 24 June letter to an association created by friends and colleagues to publicize Jaumain’s case and lobby for improvements in lab safety. (Science has obtained a copy of the letter, which has not been made public.)

Jaumain’s family has filed both criminal charges and an administrative suit against INRAE, alleging a range of problems at Jaumain’s lab. She had not been trained in handling dangerous prions or responding to accidents and did not wear both metal mesh and surgical gloves, as she was supposed to, says Julien Bensimhon, the family’s lawyer. The thumb should have been soaked in a bleach solution immediately, which did not happen, Bensimhon adds.

Independent reports by a company specializing in occupational safety and by government inspectors have found no safety violations at the lab; one of them said there was a “strong culture” of risk management. (Bensimhon calls the reports “biased.”)

The government inspectors’ report concluded that Jaumain’s accident was not unique, however. There had been at least 17 accidents among the 100 or so scientists and technicians in France working with prions in the previous decade, five of whom stabbed or cut themselves with contaminated syringes or blades. Another technician at the same lab had a fingerprick accident with prions in 2005, but has not developed vCJD symptoms so far, Bensimhon says. “It is shocking that no precautionary measures were taken then to ensure such an accident never happened again,” he says.

In Italy, too, the last person to die of vCJD, in 2016, was a lab worker with exposure to prion-infected brain tissue, according to last year’s NEJM paper, although an investigation did not find evidence of a lab accident. That patient and the lab they worked at have not been identified.

After Jaumain’s diagnosis, “We contacted all the research prion labs in France to suggest they check their safety procedures and remind staff about the importance of respecting them,” says Stéphane Haïk, a neuroscientist at the Paris Brain Institute at Pitié-Salpêtrière Hospital who helped diagnose Jaumain and is the corresponding author on the paper. Many labs tightened procedures, according to the government inspectors’ report, for instance by introducing plastic scissors and scalpels, which are disposable and less sharp, and bite and cut-resistant gloves. A team of experts from the five research agencies is due to submit proposals for a guide to good practice in prion research to the French government at the end of this year.

The scientific community has long recognized that handling prions is dangerous and an occupational risk for neuropathologists, says neuropathologist Adriano Aguzzi of the University of Zurich. Aguzzi declined to comment on the French CJD cases, but told Science his lab never handles human or bovine prions for research purposes, only for diagnostics. “We conduct research only on mouse-adapted sheep prions, which have never been shown to be infectious to humans,” Aguzzi says. In a 2011 paper, his team reported that prions can spread through aerosols, at least in mice, which “may warrant re-thinking on prion biosafety guidelines in research and diagnostic laboratories,” they wrote. Aguzzi says he was “totally shocked” by the finding and introduced safety measures to prevent aerosol spread at his own lab, but the paper drew little attention elsewhere.

The moratorium will “obviously” cause delays in research, but given the very long incubation periods in prion diseases, the impact of a 3-month hiatus will be limited, Comoy says. His research team at CEA also works on other neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease, and will shift some of its efforts to those.

Although Jaumain’s diagnosis upset many in the field, it hasn’t led to an exodus among researchers in France, Haïk says: “I know of only one person who resigned because they were so worried.”

With reporting by Martin Enserink.

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