Genome-wide studies and other observational studies have found an association between ABO(H) blood group and the likelihood of SARS-CoV-2 infection. The mechanism by which the ABO(H) antigens (namely blood group A) influence the likelihood of infection is still elusive, but the SARS-CoV-2 receptor-binding domain (RBD) is similar to other lectins that bind blood group antigens. In order to investigate the association between blood group antigens and coronavirus infections, researchers cloned the SARS-CoV-2 RBD and incubated the construct with glycan arrays of either Type-1 ABO antigens (expressed on respiratory epithelial cells), Type-II ABO antigens (expressed on RBCs), or control glycans. The study found minimal binding of SARS-CoV-2 RBD to ABO(H) Type II glycans expressed on RBCs. However, the RBD preferentially bound blood group A Type 1 glycans expressed on respiratory epithelial cells but not blood group B or O(H) Type II glycans. Additional studies are needed to confirm that these results contribute directly to susceptibility of infection.
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