A new study published Wednesday in the Journal Blood Advances found that SARS-CoV-2 has a special affinity for the blood group A antigen found in respiratory cells.

The research provides the first direct association between the virus and blood group antigens, which could explain why type A people are more likely to be infected. Their results could also clarify why these patients have more severe conditions.

“If patients are more likely to contract the virus because they express blood group A, they may also be more likely to be infected by more SARS-CoV-2 virions, which has been associated with more serious progression of the disease ”, explained Sean R. Stowell, from Harvard Medical School (USA), who led the research group.

Coronavirus has a protein on its surface, specifically within protein S, called the receptor-binding domain through which it attaches itself to host cells.

The so-called RBD therefore plays a key role in the infection process. Understanding their bonding preferences is critical to deciphering why not all individuals appear to be equally susceptible to the virus.

Researchers evaluated the performance of the RBD synthesized in the laboratory according to the different blood types, which had already been seen to affect the course of the disease in a differential way.

The team measured the protein’s affinity for group A, B, and O antigens on the surface of red blood cells and on cells of the respiratory tract.

Stowell and his colleagues found that RBD had a strong preference for binding to blood group A antigen from throat and lung cells.

COVID did not show such an affinity for red blood cells of blood group A or antigens of the other blood groups as in both types of cells.

The team found the same preference in the earlier SARS-CoV coronavirus, responsible for severe acute respiratory syndrome (SARS).

“Since binding to red blood cells does not improve the known ability of the virus to cause infection or spread to other people, there was probably less evolutionary selection for this preference for group A antigen to also exist on red blood cells”, explains the researcher.

The article adds to the body of studies linking the AOB blood system to susceptibility to disease. Previous research also published in Blood Advances has already shown that people in group A and AB may be at higher risk for severe clinical conditions.

Another article in the same journal associated blood group 0 with a lower risk of Covid-19 as well as a less severe course of the disease. The New England Journal of Medicine also published research that reached the same results.

Better understanding how ABO antigens attract the virus, Stowell says, could allow the design of substances that mimic blood groups to inhibit or prevent infection.

“There is still much to do, but these are some of the possible directions that this research could take,” he concluded.

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