TASS, November 30. Molecular biologists have compared the work of the immunity of people who have had COVID-19 in an explicit and implicit form. It turned out that the immunity of the latter reacted unusually strongly to the infection. Scientists have published preliminary results of the study in the electronic scientific library bioRxiv.
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Many carriers of the new type of coronavirus (SARS-CoV-2) carry the infection without visible signs of health and well-being. At the same time, about 20% develop pneumonia, severe damage to the lungs and other organs. On the one hand, because of this, there are fewer potential victims of the virus, and on the other hand, it is more difficult for doctors to control the spread of the disease, since asymptomatic patients spread the virus as actively as people who are admitted to hospitals with a diagnosis of COVID-19.
Therefore, scientists are trying to understand how the infection develops in asymptomatic patients and how the immune system responds to it, as well as whether the pattern of antibody production differs after the disease ends. So far, scientists do not have an unambiguous answer to this question.
The hidden power of immunity
Thanks to a new study, European and Singaporean molecular biologists, led by Professor Antonio Bertoletti at the National University of Singapore, have uncovered unique yet unexpected features of how the immune system of recovered asymptomatic patients reacted to SARS-CoV-2. In their work, the researchers analyzed blood samples from about five hundred Singaporean migrants who contracted the coronavirus in May-July this year.
Some of them ended up in hospitals, while others suffered the infection without visible symptoms. Thanks to this, scientists were able to compare the response of their immunity to the coronavirus. Researchers removed T cells from blood samples and watched how they interacted with fragments of the SARS-CoV-2 coat protein.
At first, scientists assumed that the immunity of asymptomatic patients reacted relatively weakly to the causative agent of COVID-19. This should protect them from an overly powerful immune response, which often aggravates the course of the disease and can even lead to the death of the patient. In reality, everything was the other way around – the T cells of asymptomatic patients reacted to the virus more actively than the immunity of hospitalized patients.
This was manifested in the fact that the body of asymptomatic patients produced unusually large amounts of the “antiviral” protein interferon-gamma, as well as various interleukins – signaling molecules, some of which help the development of inflammation and activation of the immune system, while the other suppresses them. The more traces of coronavirus were in the culture medium, the more molecules of all three types were produced by T cells of asymptomatic patients.
The immunity of carriers of the full form of COVID-19 worked differently. Their T cells produced comparatively large amounts of interleukin-6 and interleukin-1-beta molecules, which help inflammation develop, but they produced little of interleukin-2 and interleukin-10, which suppress them.
That is, the immunity of both groups of patients reacted to the virus in completely different ways. This may explain why asymptomatic patients do not have characteristic symptoms associated with an overly violent immune response to the penetration of coronavirus into the body.
At the same time, scientists found that the number of T cells that can fight infection in the body of asymptomatic patients fell much faster than those Singaporeans who were hospitalized with COVID-19. This must be taken into account when assessing the duration of immunity from the coronavirus, as well as when developing subsequent measures to contain its spread, the scientists concluded.
It should be added that the scientists’ article was not reviewed by independent experts or reviewed by the editors of scientific journals, as is usually the case in such cases. Therefore, the conclusions from it and similar articles should be treated with caution.
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