Long COVID: Virus persists in brain, hamster study finds

A study conducted by researchers at the Pasteur Institute on hamsters shows that the COVID-19 virus "infects the brain and persists for up to 80 days" in a part of the brain, accompanied by signs of "depression, memory problems and anxiety."
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Research is underway around the world to understand the causes of post-COVID syndrome, also known as long COVID, which affected 4% of the French adult population at the end of 2022, according to Public Health France. This syndrome manifests itself through profound fatigue, neurological disorders, breathing difficulties, headaches, etc.
The Pasteur Institute study, published in the journal Nature Communications on July 22, tends to show that the COVID-19 virus "persists long-term in the brainstem and disrupts neuronal activity," the researchers summarize in a press release released Tuesday.
They studied the effects of COVID-19 infection "on the central nervous system" of hamsters, "up to 80 days after the acute phase of infection."
They observed that "genes related to metabolism and neuron activity are deregulated in the brains of these animals, similar to what happens in neurodegenerative diseases" such as Parkinson's disease with "dysregulation of the dopamine pathway."
The virus thus appears to "have an impact on the production of dopamine," which is involved in "the regulation of emotions and memory," explains one of the researchers, Anthony Coleon, in the press release.
Analyses showed that despite a low viral load, the virus could continue to infect new cells, suggesting that it could persist "quietly" in the brainstem.
According to Guilherme Dias de Melo, lead author of the study, it "highlights for the first time, in an animal model, the long-term biological consequences" of COVID-19.
After identifying "a list of genes deregulated in the long term" by the virus, the researchers will continue their work "to understand how the infection induces the loss of function of dopamine neurons," he says.
Researchers have already found "signs of persistence of the virus" of COVID-19 in the body, "alteration of the immune response and an autoimmune response", recalls the World Health Organization (WHO), according to which the pandemic has caused 20 million deaths worldwide.
LE Journal de Montreal