A “ghost” of the coronavirus was found to remain in the intestines

Particles of SARS-CoV-2 (blue; artificially colored) buds from dying enterocytes.Credit: Steve Gschmeissner / SPL

In the turmoil of the first months of the coronavirus pandemic, oncologist and geneticist Ami Bhatt was intrigued by widespread reports of vomiting and diarrhea in people infected with SARS-CoV-2. rice field. Bat and her colleagues were interested in the possible association of the virus with gastrointestinal symptoms and began collecting stool samples from people with COVID-19.

Gastroenterologist Timon Adolf, thousands of miles from Bert’s lab at Stanford School of Medicine in California, was puzzled by the explanation of intestinal symptoms in infected people. Adolf of the Innsbruck Medical College in Austria and his colleagues also began collecting specimens — gastrointestinal tissue biopsy.

Two years after the pandemic, the foresight of scientists was rewarded.Both teams recently announced results1,2 Fragments of SARS-CoV-2 suggest that they may remain in the intestine for several months after the initial infection. The findings increase the pool of evidence supporting the hypothesis that the “ghosts” of the coronavirus, a persistent fragment of the virus, may be calling them. It contributes to a mysterious state called long COVID.

Still, Bhatt encourages scientists to keep their minds open and warns that researchers have not yet identified the link between the persistent virus fragment and the long COVID. ..

Long COVID is often defined as a symptom that persists for more than 12 weeks after an acute infection. Over 200 symptoms are associated with disability and can range in severity from mild to debilitating. Theories about its origin vary and include harmful immune responses. Many researchers believe that the combination of these factors contributes to the global burden of disease.

Early hints that the coronavirus could stay in the body began to work3 Published in 2021 by Saurabh Mehandru, a gastroenterologist at Mount Sinai School of Medicine in New York City, and his colleagues. By then, it was clear that the cells lining the intestine would display the proteins that the virus would use to invade the cells. This enables SARS-. CoV-2 that infects the intestines.

Mehandru and his team discovered viral nucleic acids and proteins in gastrointestinal tissue collected from people diagnosed with COVID-19 on average four months ago. Researchers have also studied memory B cells of participants, who are the core players of the immune system. The team discovered that the antibodies produced by these B cells continued to evolve. This suggests that 6 months after the initial infection, the cells are still responding to the molecule produced by SARS-CoV-2.

Inspired by this study, Bhatt and her colleagues continued to flush viral RNA into the stool 7 months after the first mild or moderate SARS-CoV-2 infection, even after the respiratory symptoms were over. I found that there are people.1..

The virus goes to the intestines

According to Adolf, the 2021 paper inspired the team to look at biopsy samples for signs of coronavirus. Thirty-two of the 46 study participants infected with mild COVID-19 were found to show evidence of viral molecules in the intestine 7 months after acute infection. -One-third of those 32 had long COVID symptoms.

However, all participants in this study suffer from inflammatory bowel disease, autoimmune disease, and Adolf said his data indicate that these people have an active virus, or that the viral substance causes a long COVID. It warns that it has not proved that.

In the meantime, more studies suggest that the viral reservoir prolongs beyond the intestine. Another research team studied tissue collected from autopsy of 44 people diagnosed with COVID-19 and found evidence of viral RNA in many sites, including the heart.Eyes and brainFourViral RNA and protein were detected by 230 days after infection. This study has not yet been peer reviewed.

Virus hideout

Almost all people in that sample had severe COVID-19, but another study of two people with mild COVID-19 followed by long COVID symptoms showed viral RNA in the appendix and breast. FoundFive.. Joe Yeong, a pathologist at the Agency for Science, Technology and Research’s Institute for Molecular Cell Biology, is a co-author of this report and has not been peer-reviewed, but speculates that the virus may have invaded and hidden. doing. It appears in immune cells called macrophages and is found in various tissues of the body.

All of these studies support the potential for long-term viral reservoirs to contribute to long-term COVID, but researchers need to do more work to finally show the link. It is necessary to document that the coronavirus is evolving in those who do not. It is immunodeficient and such evolution should be associated with long COVID symptoms. “Currently, we have anecdotal evidence, but there are many unknowns,” says Mehandru.

Bhatt hopes that samples will be available to test the virus reservoir hypothesis. For example, the National Institutes of Health is conducting a large study called RECOVER aimed at addressing the causes of long COVIDs and collecting biopsies from below. The intestines of some participants.

But Shen says you don’t have to wait for a billion-dollar study to increase the sample. An organization of people with a long COVID contacted him and offered to send samples from members who had a biopsy for various reasons, including a diagnosis of cancer. After the infection, he says, “it’s really random and the tissue can come from anywhere, but they don’t want to wait.”

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