US, WASHINGTON (ORDO NEWS) — Scientists around the world are trying to develop a vaccine against coronavirus and predict how a pandemic will develop before the advent of a reliable prophylactic from Covid-19. But so far, no one has answered two important questions on which the creation of the vaccine and the situation with the infected depend: is the immune system capable of providing a substantial and lasting response to SARS-CoV-2? Can other coronaviruses provide any immunity to SARS-CoV-2?
A study published in Cell gives a positive answer to the first of these questions. It details aspects of the immune response in 20 adults who have recently recovered from coronavirus pneumonia. The results of the study show that the body’s immune system is able to recognize SARS-CoV-2 in several different ways. This dispels fears that the virus is able to evade the immune response and make vaccine development useless.
“What we see is a stable T-cell response to spine proteins [virus particles] and other proteins,” says biologist Alessandro Sette, one of the study’s authors. “People were very worried that Covid-19 supposedly did not cause immunity, and reports of reinfection reinforced these concerns, but now the knowledge that the average person produces a solid immune response should largely calm the alarm,” adds colleague Sette , Professor Shane Crotty.
In their earlier studies, Crotty and Sette using bioinformatics methods predicted which fragments of SARS-CoV-2 virus particles possess sufficient immunogenicity to activate T-lymphocytes. In a new work, scientists tested how well T cells isolated from Covid-19 patients who were ill recognize the predicted protein fragments or peptides. “We specifically decided to study people with the normal course of the disease and not requiring hospitalization to provide a reliable assessment of what the normal immune response looks like, since the virus can cause some very unusual things in individuals,” adds Alessandro Sette.
All subjects showed a pronounced CD4-T cell immune response – that is, activation of the so-called T-helpers in response to the antigen. T-helpers are cells that recognize an antigen and activate other types of cells of the immune system: in particular, B-lymphocytes that produce antiviral antibodies. Also, in all patients, virus-specific CD-8-T-lymphocytes, or T-killers, which destroy the cells of the body damaged by viruses, were detected.
Researchers also studied the response of T cells in blood samples that were collected between 2015 and 2018, long before the Covid-19 pandemic. Lymphocytes from many samples showed marked reactivity against SARS-CoV-2, although they were never exposed to this pathogen.
Scientists attribute this fact to the fact that people who have taken blood have previously encountered less dangerous types of coronaviruses. Nevertheless, it is not yet clear what level of immune defense the observed cross-reactivity of T lymphocytes provides. “Given the seriousness of the ongoing Covid-19 pandemic, any degree of cross-reactive immunity can have a significant impact on the overall course of the pandemic and is a key detail that epidemiologists should consider when making forecasts,” the authors conclude.
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