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Popularization of research advances on COVID-19

Immunity

Can some antibodies make the illness worse?

Used as prevention or therapy, neutralising antibodies (NAbs) can help control the COVID-19 pandemic. They mainly target the RBD (Receptor Binding Domain) of the spike viral protein, thus blocking entry of the virus into the target cell. But certain NAbs, less powerful, also target the NTD (N-Terminal Domain). Conversely, certain so-called “facilitating” antibodies are able […]

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Analysis of the CD4 T lymphocyte response

As well as humoral immunity (antibody immunity), which plays an essential role against viral infection, cellular immunity (T lymphocytes) is also very important. Lymphocytes are made up of B lymphocytes, which produce antibodies; CD8 T lymphocytes, often called cytotoxic T lymphocytes, which destroy infected cells; and CD4 T lymphocytes, known as helpers. The T CD4 […]

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Assessment of antibody responses against SARS-CoV-2

The rapid spread of SARS-CoV-2 can be attributed to the fact that the world’s population was for the most part immunologically naïve. Although we have learned to better understand the virus, many questions remain unanswered. What we know today is that 4 endemic human coronaviruses (HCoVs: alpha- and beta-coronaviruses, NL63, 229E) cause respiratory infections that […]

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Which domains of the spike do antibodies target?

The majority of vaccines developed against SARS-CoV-2 enable the production of antibodies targeting the spike (S) surface protein of the virus. This comports several domains, the main one being the RBD (Receptor Binding Domain) that binds with the ACE2 cellular receptor to enable entry of the viral particle into the cell. The role of other […]

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Non-conventional viral peptides presented at the surface of infected cells

Several studies have shown that the T response (cellular immunity) is vital to immunity and to the elimination of SARS-CoV-2. In the pathophysiology of COVID-19, it is therefore imperative to better understand how infected cells interact with the immune system. The infected cell has viral antigens (protein fragments recognized by antibodies) at its surface revealed […]

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Antibodies that could worsen the illness

The spike (S) surface protein of SARS-CoV-2 is the main protein embedded in the virus’ envelope. On its surface we find different domains, notably the RBD (Receptor Binding Domain) and the NTD (N Terminal Domain). The RBD binds with the ACE2 cellular receptor to enable the virus to enter the cell. Patients infected by SARS-CoV-2 […]

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Memory B lymphocytes could be more prevalent in young children

Vaccination or natural infection enables the production by the organism of antibodies directed against the pathogen (against the SARS-CoV-2 virus, for example). Antibodies are produced by the B lymphocytes which multiply clonally when they encounter the pathogen. Some of these antibodies become long-life memory B lymphocytes that protect the organism against re-infection. The humoral immune […]

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Antibodies appear too late in severe cases

Although the majority of COVID-19 cases are asymptomatic or benign, some patients develop respiratory, vascular or neurological complications. Several recent studies have linked recovery from the illness with the effectiveness of the immune response. Despite antibody reaction being in general effective following SARS-CoV-2 infection, those factors leading to severe or fatal cases are still poorly […]

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Some antibodies could block the fusion of infected cells

The first stages of infection by SARS-CoV-2 involve the interaction of the spike with the ACE2 cellular receptor followed by the fusion of the viral membrane with the plasma membrane of the cell. The S1 domain of the spike governs the interaction with the ACE2 through its RBD (Receptor Binding Domain) and undergoes several structural […]

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Powerful neutralizing antibodies may target the N-terminal of the spike protein

The absence of pre-existing immunity against SARS-CoV-2 coupled with its high interhuman transmissibility led to the COVID-19 pandemic that we are currently experiencing. Several vaccines are now available, but it will still be some time before we have adequate vaccine coverage due to the time scales of production and distribution. In addition, the protection the […]

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