Food allergies, a bulwark against Covid-19?

What if the way we react to Covid was linked to past allergies, like certain food allergies? This is the hypothesis formulated and verified by a team of American researchers. Cross-immunity, a new avenue for vaccines?

Why do some people escape contamination by the virus responsible for Covid, and not others? Why do some have symptoms, while others have few or no symptoms? These are the kinds of questions that have preoccupied researchers for almost 3 years now, because even if we understand the disease better and better, many questions remain for the moment without firm and definitive answers.

That concerning the capacity to resist the virus is one of them. Is this immunity innate, thanks to our blood group or genetic predispositions? Or acquired, due to prior exposure to proteins that resemble those of Sars-CoV-2? This last hypothesis is that of cross-immunity. It has notably been studied by an American team, whose study has just been published in the journal Frontiers in Immunology.

Broccoli and pineapple

A quick reminder: when our body is attacked by a pathogen, virus or bacteria, it triggers an immune response to neutralize it. To do this, it produces antibodies, proteins from white blood cells that attach to specific parts of the pathogen and contribute to its destruction. Once the infection has cleared, memory T and B cells retain, as their name suggests, the memory of all or part of the pathogen. And will therefore be able to react very quickly if he presents himself again.

However, it turns out that Sars-CoV-2 (and its many variants) shares a certain number of characteristics with other viruses – rhinoviruses for example, but not only. Certain proteins found in bacteria, vaccines, human cells and even food can also bear similarities to the coronavirus… and potentially trigger an immune reaction.

The researchers tested their hypothesis on proteins from common foods, vaccines, bacteria and viruses. The antibodies reacted most strongly with a common gut bacterium, called E.faecalis, and a vaccine against diphtheria, tetanus and whooping cough. And, significantly, with protein found in broccoli, toasted almonds, pork, cashews, milk, soy, and pineapple.

False good idea

Would the solution then be to favor these foods to immunize? It’s unlikely, and not really recommended: if the absorption of a food triggers an immune reaction, it’s because… you are allergic to it. This “solution” is therefore, at this stage, not one, and researchers do not consider these agents as a substitute for current vaccines. On the other hand, additional tests are needed to confirm that these proteins do confer real protection and, if so, whether it is short-term or long-term protection.

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