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, wrote 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….
