This work might help explain why some people develop severe forms of COVID, while others have no symptoms. Because the answer might lie in the proteins to which the immune system has already been exposed. The study thus reveals that certain agents, including certain nutrients, contain proteins similar to some found in SARS-CoV-2. So, exposure to these proteins causes our immune system to react when it encounters the virus.
Towards new immunotherapies or new vaccines?
SARS-CoV-2 is a new virus, however it shares characteristics with other viruses but also with many existing biological molecules, encountered on a daily basis: proteins present in bacteria, human cells, vaccines and even foods may all share similarities with those of SARS-CoV-2. Scientists here hypothesize that similarities between SARS-CoV-2 and other common proteins may affect our susceptibility to the virus.
When our body is attacked by a pathogen, virus or bacteria, it triggers an immune response which involves antibodies. These immune proteins stick to specific parts of the pathogen and contribute to its destruction. After the initial infection has cleared, white blood cells called memory T and B cells retain the memory of the pathogen, or at least parts of its structure. These cells will be ready to mount an immune response very quickly if they ever encounter it once more.
The study tests these antibody cross-reactions, linked to this “immune memory” associated with proteins encountered in the past, by evaluating the ability of these antibodies to bind to 180 different proteins from common foods, 2 different vaccines and 15 proteins bacterial and viral. The antibodies reacted most strongly with a common gut bacterium called E. faecalis and a vaccine once morest diphtheria, tetanus and pertussis. Interestingly, the antibodies also reacted very strongly once morest proteins found in common foods, including broccoli, toasted almonds, pork, cashews, milk, soy, and pineapple.
Eating for immunity?
Unfortunately, this immunity developed once morest a type of food is usually characterized by a food allergy. And only people with such allergies seem to be able to make antibodies once morest these foods, says lead author Dr. Aristo Vodjani of Cyrex Laboratories (Arizona). And while these agents can provide some protection once morest SARS-CoV-2, they will not replace vaccines. Furthermore, additional tests are needed to confirm that these proteins do indeed confer significant protection in humans and, where appropriate, if the antibody response is short-lived or memory, longer-term.
These data may nevertheless help explain the variable responses to COVID infection, and with more research, lead to more effective treatments or better vaccines. It might also be useful to assess an individual’s susceptibility to the virus even before any infection.