Could 2003 SARS Antibodies Fight Coronavirus?

Many wonder about the duration of the'immunity conferred by antibody after infection with coronavirus of the Covid-19. Three months ? Six months ? A year ? And why not … 17 years old? Researchers from the New York University School of Medicine (UW Medicine) identified neutralizing antibodies in a patient who was infected with SARS-CoV during the'epidemic from 2003 even better: one of the antibodies has been shown to be effective against SARS-CoV-2 current, at least in vitro, according to a study published in Nature May 18.

SARS-CoV-1 and SARS-CoV-2: many common points

The two coronaviruses share a lot of common points. Both belong to the sarbocovirus subgenus. Some 80% of their amino acids coding for protein surface, those used by immune cells to identify the virus, are the same. Like SARS-CoV, SARS-CoV-2 uses the ACE2 receptor to attach to the surface of the cell to be infected. This suggests that certain antibodies effective against SARS 2003 can also act against the new coronavirus. To verify this, researchers from theUW Medicine, in collaboration with the California startup Vir Biotechnology, have taken from the patient's immune cells B, those which "record" the passage of the virus in the body and produce antibodies to fight it.

They searched among antibodies produced by these cells and targeting surface proteins and discovered that one of them, named S309, makes it possible to neutralize the new coronavirus by attacking a section of the surface protein near the site of attachment to the cell host. " This antibody recognizes a binding site conserved by many sarbocoviruses, and not only by SARS and Covid-19. This is probably the reason why it is able to act against all related coronaviruses "Says David Veesler, biochemist at UW Medicine. This antibody would also be insurance against a possible mutation of the coronavirus. " Even if Sars-CoV-2 continues to evolve, it could be quite difficult for it to become resistant to the neutralizing activity of S309 Corroborates Herbert Virgin, the scientific director of Vir. " In addition, the S309 has a powerful effect in vitro which commits to recruiting the rest of the immune system to kill already infected cells ", He adds.

A potential antibody candidate for treatment

If the antibody proves effective during tests on living organisms, it could constitute a new avenue of treatment, anticipates David Veesler. Many laboratories and startups are already working on antibody cocktails against SARS-CoV-2. " But the research is focused on antibodies from patients who have had Covid-19, whereas here we are talking about a patient who developed SARS 17 years ago, which allows us to identify the antibodies much more effective quickly " During the tests, the immune response against SARS-CoV-2 was further improved by combining this antibody with others. Vir Biotechnology has already launched the production of these cocktails with the GlaxoSmithKline laboratory.

Are patients infected in 2003 immunized against Covid-19?

Difficult to conclude that patients who caught SARS in 2003 are immune to Covid-19. The study published here concerns only one case and only one antibody. In addition, the tests were conducted only in vitro. A 2011 study indicates that the level of B cells having recorded the immune memory of SARS-CoV-1 is "insignificant" six years after infection in 21 of the 23 patients analyzed. Nevertheless, lymphocytes T reagents to SARS-CoV-1 (which recognize and destroy the virus but do not produce antibodies) were detected in 61% of patients, especially those who suffered from severe forms of infection. Another meta-study of March 2023 indicates that 90% of patients still have IgG and neutralizing antibodies two years after infection, although the level is clearly decreasing. " Given that the SARS epidemic took place 17 years ago, the level of antibodies is probably insufficient to protect against SARS-CoV-2 ", Warn the authors, who note however that the vaccines tests developed against SARS-CoV could be effective against Covid-19.

Immunity after Covid-19: finally reassuring data

Article by Julien Hernandez, published on May 5, 2023

A recently published Chinese experience shows that there is a generally good humoral (antibody) and cellular (lymphocyte) immune response in patients who have recovered from Covid-19. What reduce a little our uncertainties on this subject and reassure us.

Doubt and uncertainty hovered regarding the immune response cured patients from Covid-19. Indeed, various cases of what appeared to be a second infection (even if other hypotheses were possible) have been reported around the world. In addition, the few pre-published experiences on the subject were more or less reassuring. A study recently published in the journal Immunity lifts the misty veil that reigns over the issue a little

A global immune response in the majority of patients

This recent study compared the different immune responses using analyzes of blood samples from different people who were either recently healed, either healed in recent weeks or never infected with SARS-CoV-2. The results are rather reassuring. In fact, the majority of former infected people have developed antibodies specific to SARS-CoV-2, in particular anti-protein S antibodies, one of the famous proteins which allows virus infecting our cells. On the other hand, too few antibodies directed towards other proteins of the virus have been produced; these productions are noted only in two patients.

Scientists have also light in the majority of patients a strong cellular immune response via T cells and they note a significant correlation between this response and the development of neutralizing antibodies. The increased presence of lymphocytes natural killer (NK) and mediators of innate immunity was also observed. This immune response seems to be able to act on all the viral proteins of SARS-CoV-2, unlike the antibodies produced which are often specific to a single protein.

Thanks to these various defense mechanisms, a new infection with SARS-CoV-2 seems unlikely as long as they are present. The only unfortunate point is the small sample of patients, only fourteen, but the batteries of tests carried out are long and expensive, and carrying them out on many patients would have been difficult to carry out.

Tracks for a better understanding

The authors conclude their article as follows: Our work provides a basis for further analysis of protective immunity against SARS-CoV-2 and understanding of the pathogenesis of Covid-19, particularly in severe cases. It will also have implications for the development of an effective vaccine against SARS-CoV-2 infection. " In fact, thanks to their study, we know a little more about immunity after infection with SARS-CoV-2 and how the various ramparts of immunity react to infection.

All of the studies on naturally acquired immunity provide leads for possible vaccines. Focusing on protein S has already worked well in the mouse. Thus, one could imagine a vaccine seeking to activate the anti-viral response of T lymphocytes, associated with a broader protection and correlated with a higher level of neutralizing antibodies in this study. Research on vaccines is underway and is greatly accelerating worldwide, although it takes time to Review and produce them. To deepen this subject, a recent article published in the journal Natureshows us in infographics the different mechanisms and different avenues explored for a vaccine.