Studies show that the severity of Covid-19 is affected by the proportion of antibodies that target important viral proteins-health

Recent studies have shown that Covid-19 antibodies decline significantly within months of infection, and that mild cases of Covid-19 preferentially target different parts of the virus compared to severe cases. Became clear.

Findings published in Science Immunology identify a new link between the course of the disease and the patient’s immune response to it. They also regularly vaccinate to maintain a protective immune response, whether people can be re-infected, whether antibody tests to detect previous infections may underestimate the breadth of the pandemic. It raises concerns about whether it needs to be repeated.

“This is one of the most comprehensive studies of antibody immune responses to SARS-CoV-2 in people of all severity, from asymptomatic to fatal,” said Associate Scott Boyd. The doctor of medicine says. Professor of pathology. “We evaluated multiple time points and sample types, and also analyzed the levels of viral RNA in the patient’s nasopharyngeal swab and blood sample. This is one of the first big-picture views of the disease.”

In this study, people with severe Covid-19 were compared to the number of antibodies that target the proteins in the inner shell of the virus, which are antibodies that target the spike proteins that the virus uses to invade human cells. It turned out that the ratio of was low.

Boyd is the senior author of this study, published in Science Immunology on December 7. Other senior authors are Benjamin Pinsky, MD, Associate Professor of Pathology, and Peter Kim, Virginia and DK Ludwig Biochemistry Professor. The lead authors are research scientists Katharina Roltgen, Ph.D. is. Postdoctoral fellow Abigail Powell, Ph.D. And Oliver Wirz, Ph.D. Clinical instructor Brian Stevens, MD.

The virus binds to the ACE2 receptor

Researchers have come to the Stanford Healthcare Clinic, identified by either routine examinations at Stanford Healthcare or occupational health screening, or with Covid-19 symptoms, asymptomatic, mild, or severe. We surveyed 254 people in Covid-19. Of those with symptoms, 25 were treated as outpatients, 42 were hospitalized outside the intensive care unit, and 37 were treated in the intensive care unit. Twenty-five people died of the disease in this study.

SARS-CoV-2 binds to human cells through a surface structure called the spike protein. This protein binds to a receptor on human cells called ACE2. The binding allows the virus to invade and infect cells. Once inside, the virus peels its exodermis, revealing the inner shell that encloses the genetic material. Soon, the virus adopts the cell’s protein-producing mechanism to release more viral particles, which are released and infect other cells.

Antibodies that recognize and bind to peplomers block the ability to bind to ACE2 and prevent the virus from infecting cells, while antibodies that recognize other viral components may prevent the spread of the virus. It is low. Current vaccine candidates use some of the spike proteins to stimulate the immune response.

Boyd and his colleagues found levels of three antibodies (IgG, IgM, IgA) and the ratio of targeting viral spike proteins or the inner shell of the virus as the disease progressed and the patient recovered or became ill. Was analyzed. They also measured levels of viral genetic material in blood from nasopharyngeal samples and patients. Finally, they evaluated the effectiveness of the antibody to prevent the spike protein from binding to ACE2 in the laboratory dish.

“Previous studies evaluated the overall antibody response to infection, but compared the viral proteins targeted by these antibodies,” said Boyd. “The severity of the disease was found to correlate with the proportion of antibodies that recognize the domain of the peplomer protein compared to other non-protective viral targets. People who died of illness had more antibodies that recognized other parts of the virus. “

Substantial fluctuations in the immune response

Researchers, however, warned that while the study identified trends between groups of patients, there was still considerable variability in the immune response evoked by individual patients, especially those with serious illness. There is.

“It is unlikely that the antibody response is the only determinant of someone’s outcome,” Boyd said. “Some people with severe illness die and others recover. Some of these patients have a vigorous immune response, while others have a milder response. , And many other things are happening. There are other branches of the immune system involved. It should be noted that our results identify the correlation but do not prove a causal relationship. It is important.”

As in other studies, researchers found that asymptomatic, mildly ill people had lower overall antibody levels than those with severe illness. After recovery, IgM and IgA levels steadily decrease to low or undetectable levels in most patients over a period of about 1 to 4 months from the onset of symptoms or estimated infection date, and IgG levels are significantly higher. It has dropped to.

“This is in perfect agreement with what we see in other coronaviruses that are regularly epidemic and catch colds in our community,” Boyd said. “It is not uncommon for someone to re-infect within a year or sometimes earlier. It is unclear whether the immune response to SARS-CoV-2 vaccination is strong or lasts longer than the immune response from a natural infection. There is a good chance that it will be better, but there are still many questions that need to be answered. “

Void is co-chair of the SeroNet Serology Science Network at the National Cancer Institute and is one of the largest collaborative studies in the country to study the immune response to Covid-19. He is a Principal Investigator at the Center of Excellence at SeroNet at Stanford University, addressing important questions about the mechanism and duration of immunity to SARS-CoV-2.

“For example, if someone is already infected, do they need to be vaccinated? If so, how should they be prioritized?” Boyd said. “How can we adapt serum prevalence studies in vaccinated populations? How does immunity from vaccination differ from immunity caused by natural infections? And vaccines How protective is it? These are all very interesting and important questions. “

(This story is published from the news agency feed without changing the text.)

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