Studies suggest that mild covid-19 can elicit antibodies that can last a lifetime

A study published in Nature on Monday found that mild cases of covid-19 remain infected with persistent antibody protection, and repeated bouts of the disease are likely to be rare. Suggests.

“There were reports that antibodies declined quickly after being infected with the virus that causes covid-19. But that’s a misunderstanding of the data. It’s normal for antibody levels to drop after an acute infection, but not to zero. Here, antibody-producing cells were found 11 months after the first symptoms. These cells are alive and produce antibodies for the lives of the rest of the people. This is a long-lasting immunity. It’s a strong proof of what to do, “said senior author Dr. Ali Ellebedy. Associate Professor of Pathology and Immunology, Medicine and Molecular Microbiology.

During viral infection, antibody-producing immune cells proliferate rapidly and circulate in the blood, pushing antibody levels high in the air. When the infection is cleared, most of these cells die and blood antibody levels drop. A small population of antibody-producing cells, called long-lived plasma cells, migrate to the bone marrow and settle there, where they continuously secrete low-level antibodies into the bloodstream to prevent another encounter with the virus.

The key to understanding whether Covid-19 leads to long-term antibody protection lies in the bone marrow, as Ellebedy recognized. To investigate whether people who have recovered from mild cases of Covid-19 have long-lived plasma cells that produce antibodies that specifically target the virus that causes covid-19, SARS-CoV-2. In addition, Ellebedy collaborated with co-author Iskra Pusic, an associate professor of medicine. Ellebedy was already working with co-author Rachel Presti, Associate Professor of Medicine, and Jane O’Halloran, MD, PhD, Assistant Professor of Medicine, on a project to track antibody levels in blood samples of covid-19 survivors. ..

The team had already enrolled 77 participants and provided blood samples approximately one to three months after the initial infection. Most participants had mild cases of covid-19. Only 6 people were hospitalized.

With the help of Pusic, Ellebedy et al. Collected bone marrow from 18 of the participants 7 or 8 months after the initial infection. Five of them came back after four months and provided a second bone marrow sample. For comparison, scientists also obtained bone marrow from 11 people who had never experienced covid-19.

As expected, blood antibody levels in covid-19 participants dropped rapidly in the first few months after infection and then almost leveled off, with some antibodies detectable even 11 months after infection. In addition, 15 of 19 bone marrow samples from people who had covid-19 contained antibody-producing cells that specifically targeted the virus that causes covid-19. Such cells were still found in 5 people who returned to provide a second bone marrow sample after 4 months. According to scientists, none of the 11 people who had never experienced covid-19 had such antibody-producing cells in their bone marrow.

“Mild covid-19-infected individuals remove the virus from their bodies 2-3 weeks after infection, so there is no virus that provokes a vigorous immune response 7-11 months after infection,” Ellebedy said. I have. “These cells aren’t dividing. They just sit in the bone marrow and secrete antibodies and are quiescent. They’ve been doing this ever since the infection was cleared.

Researchers speculate that immunity may last longer in people who are infected and asymptomatic. However, it has not yet been investigated whether people who have tolerated more severe infections will be protected from future bouts of the disease, they said.

“It can go in either direction,” said Jackson Turner, the lead author of pathology and immunology instructors. “Inflammation plays a major role in severe covid-19, and too much inflammation can lead to a defective immune response, but on the other hand, the reason people really get sick is often in the body. It is not clear because there are a lot of viruses in the body. It is not clear because a lot of viruses can improve the immune response. Repeated studies on people with moderate to severe infections from re-infection You need to understand if it can be protected. “

Ellebedy and colleagues are currently investigating whether vaccination also induces long-lived antibody-producing cells.