Our corps produces its own drugs: antibodies. Produced by some of our immune cells as a result of infection, they are ready to act quickly in the event of a new intrusion of the same virus or bacterium. By analyzing the blood of convalescents from Covid-19, Chinese researchers have isolated a highly neutralizing antibody. Called 4A8, it binds to an unexpected part of the virus and is the subject of a publication in Science.
Antibodies from the blood of healed people
This is the principle of vaccines. By injecting us with a harmless version of a microorganism, our corps get an easy win and throw the production of his army of antibodies. These the latter attach themselves in a highly specific manner to molecules characteristic of the invader, which are called “epitopes”. In the case of the SARS-CoV-2 virus responsible of Covid-19, the most common epitope in antibodies isolated from the blood of cured people is the precise area of the virus entering contact with the cell to be infected. This fragment of the virus, located on the viral protein S or Spike, is responsible of the interaction with the ACE2 receptor. Present on the surface of our cells, this ACE2 protein thus allowsinfection.
A new neutralizing antibody
In China, however, a team discovered an effective antibody targeting another epitope. By analyzing the blood of ten convalescents of Covid-19, they isolated the antibody 4A8, which recognizes the opposite end of the protein Spike, by report to the one who comes in contact with ACE2. However, laboratory tests show that this antibody ” has a strong neutralizing power Of SARS-CoV-2. How can this antibody preventinfection without blocking the site of contact between the virus and the cell? You should know that the function of a protein is intimately linked to its conformation in space, and that the latter can evolve. In the case of the viral protein Spike, it turns out that it must first change conformation according to precise steps before it can enter contact with ACE2. According to their structural analyzes of these proteins, the researchers therefore assume that the antibody 4A8 could, prevent these modifications by attaching to the other end of the viral protein Spike, and thereby preventing interaction.
Antibody cocktail
The researchers have patented the antibody 4A8 and hope to be able to add them to known anti-Covid-19 antibodies in order to increase the effectiveness of the treatment. This antibody “cocktail” would in fact multiply the areas of action and prevent the virus from escaping through a timely mutation.
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Iceland BipBip & sciencesetavenir.fr
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