Serological studies provide critical insights into the COVID-19 immune response

As vaccine testing progresses and public health authorities prepare for an increase in cases of COVID-19, it is essential to understand how the body protects against SARS-CoV-2 infection.New research published in Clinical and translational immunologyProvides a clearer picture of the protective antibodies induced by this virus, their role in serious illness, and what is needed for complete protection.

It is based on a study of serum samples collected from 32 hospitalized COVID-19 patients and 17 asymptomatic subjects who had antibodies to SARS-CoV-2, the virus that causes COVID-19. Immunologist Sean Diehl, Ph. of the University of Vermont (UVM). D. and colleagues found that antibody levels correlated with disease severity.

“Some people expected sick patients to be low in these antibodies because this was an early stage of the pandemic, but we found the opposite,” said “high antibody levels in sick patients. It is likely to reflect the high viral load estimated, “said Diehl. In sick patients. This finding has also been confirmed by others in a cohort of COVID-19 patients in Boston and Seattle.

Among the COVID-19 patients admitted, there were 13 illness patients who needed a longer period of time. intensive care unit (ICU) Care in which antibody levels increased to stay in the ICU longer than in COVID-19 patients who did not require admission to the ICU. Researchers also found that hospitalized COVID-19 patients had previously been exposed to SARS-CoV-2 and generally had higher antibodies than patients who developed mild illness but did not require hospitalization. I found a level. These samples were created in collaboration with UVM Gary An, Professor MD, and UVM Eline van den Broek-Altenburg, Ph.D. Collected from a serological survey of 174 ICU healthcare professionals as part of a community serum survey of 454 people in collaboration with an associate professor.

The researchers are Florian Krammer, Ph.D., a colleague of Diehl at Mount Sinai School of Medicine. A serological assay developed by SARS-CoV-2 virus was used to measure serum antibodies targeting specific domains of the spike protein of SARS-CoV-2 virus. It is called the receptor binding domain. Antibodies that target this domain, abbreviated as “RBD-S,” can prevent the virus from infecting cells. Therefore, it is regarded as the best candidate for the protective antibody reaction, which is an important goal of vaccine development.

According to Diehl, not all serological tests currently in use specifically measure antibodies that recognize RBD. Data from others suggest that up to 90 percent of the virus-neutralizing activity (ie, protective function) found in COVID-19 sera is due to RBD antibodies. There is limited data from other serological tests that do not focus on RBD to support that these antibodies may be protective.

In this study, the UVM team first defined the time of antibody development after the onset of COVID symptoms and determined that activity occurred in just 5 days and remained high after 6 weeks. In addition, there was no difference in anti-RBD-S antibodies between men and women, despite evidence that men are more likely to die of COVID-19 than women.Surprisingly many Elderly patientPeople over the age of 80 showed as strong an antibody response as 40 in this study. This was inconsistent with the general belief that the elderly have a weak immune response. Another insight was that the few individuals who died did not have different levels of antibodies than those who recovered.

“This is really good news,” says Diehl. “This is because outpatient COVID-19 patients who developed intermediate antibody levels did not develop serious illness and did not require hospitalization, so the vaccine achieves the highest possible RBD-S antibody levels. I think it means that it may not be necessary. “

Researchers acknowledge that full defense is likely to require multiple arms of the immune response, to identify the level at which a person is protected and to determine how long these antibodies last. States that an extensive antibody test needs to be performed.

“We are currently doing further research to find out how these are done. antibody COVID-19 helps prevent you from getting sick again, “says Diehl.

Courtesy of Lerner Medical College, University of Vermont