As researchers around the world work to identify and address risk factors for severe COVID-19, there is additional evidence that certain blood types could be associated with greater risk of contracting the disease. A new Blood Advances study details one of the first laboratory studies to suggest that SARS-CoV-2, the virus that causes COVID-19, is particularly attracted to the blood group A antigen found on respiratory cells.
In the study, researchers assessed a protein on the surface of the SARS-CoV-2 virus called the receptor binding domain, or RBD. The RBD is the part of the virus that attaches to the host cells, so it is an important research target for understanding how infection occurs. The team assessed synthetic blood group antigens on respiratory and red blood cells found in blood group A, B, and O individuals, and analyzed how the SARS-CoV-2 RBD interacted with each unique blood type. They discovered that the RBD had a strong preference for binding to blood group A found on respiratory cells. It did not display a preference for blood group A red blood cells, or other blood groups found on respiratory or red cells. The capacity of the RBD to preferentially recognize and attach to the blood type A antigen found in the lungs of blood type A individuals may provide insight into the potential link between blood group A and COVID-19 infection.
"It is interesting that the viral RBD only really prefers the type of blood group A antigens that are on respiratory cells, which are presumably how the virus is entering most patients and infecting them," said study author Sean R. Stowell, MD, PhD, of Brigham and Women's Hospital. "Blood type is a challenge because it is inherited and not something we can change. But if we can better understand how the virus interacts with blood groups in people, we may be able to find new medicines or methods of prevention."
Based on their observations, the team sought to determine whether a similar binding preference existed for the RBD of SARS-CoV, the virus that causes severe acute respiratory syndrome (SARS). Although the makeup of the virus differs, the SARS-CoV RBD exhibited the same preference to bind to the group A antigens on respiratory cells.
Dr. Stowell and his team emphasized that their findings alone could not fully describe or predict how coronaviruses like SARS-CoV-2 and SARS-CoV would affect patients of various blood types. "Our observation is not the only mechanism responsible for what we are seeing clinically, but it could explain some of the influence of blood type on COVID-19 infection."
While further research is needed to understand that influence, the paper adds to findings from earlier Blood Advances studies suggesting a possible link between blood type and COVID-19 susceptibility and severity.