Unraveling the Puzzle: ABO Blood Group, Secretor Status, and Integrins in Susceptibility to SARS-CoV-2

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Since its emergence in late 2019, COVID-19 has spread rapidly across the globe, causing significant morbidity and mortality. While the severity of the disease varies from person to person, researchers have been tirelessly investigating the factors that contribute to an individual’s susceptibility to infection.

One intriguing finding has been the association between blood type and COVID-19. Among the blood types, individuals with blood group O have shown a lower frequency of infection and potentially a milder course of the disease. This article delves into the captivating relationship between blood type O and COVID-19, highlighting the latest research and possible implications.

Understanding Blood Types:

Before exploring the connection between blood type and COVID-19, it is crucial to grasp the basics of blood types. Human blood is categorized into different groups based on the presence or absence of certain antigens on the surface of red blood cells. The most common classification system includes four major blood types: A, B, AB, and O. Additionally, blood can be Rh-positive or Rh-negative, referring to the presence or absence of the Rh antigen.

The Link Between Blood Type O and COVID-19:

Numerous studies conducted worldwide have consistently shown that individuals with blood type O have a lower susceptibility to COVID-19. In contrast, those with blood types A, B, and AB appear to be more vulnerable. For instance, a study published in the New England Journal of Medicine in June 2020 analyzed over 1,600 COVID-19-positive individuals in Italy and Spain. The researchers found that people with blood type O had a lower risk of infection compared to individuals with other blood types.

Another study published in Blood Advances in July 2020 evaluated data from over 473,000 individuals in Denmark. The results revealed that individuals with blood type O had a lower risk of contracting COVID-19 compared to individuals with other blood types. Moreover, the study also indicated that blood type A was associated with a higher risk of severe disease manifestations.

Possible Explanations:

While the exact mechanisms behind the association between blood type O and COVID-19 remain unclear, several hypotheses have been proposed:

  • Genetic Variations: It is well-established that blood types are genetically determined. Certain genetic variations associated with blood type O may confer protection against COVID-19. However, more research is needed to identify the specific genes involved.
  • Antibody Responses: Some studies suggest that individuals with blood type O may produce antibodies that are more effective at neutralizing the SARS-CoV-2 virus. This enhanced immune response could potentially explain the lower infection rates and milder disease course observed in blood type O individuals.
  • Blood Group Antigens: Blood group antigens are not only found on red blood cells but also on other cells and tissues throughout the body. These antigens may interact with the SARS-CoV-2 virus, influencing its ability to enter and infect host cells. It is possible that the absence or structure of certain blood group antigens in blood type O individuals might impede viral entry and replication.

A new research ….

Previous studies have reported an association between ABO blood group and susceptibility to various viruses, including SARS-CoV-2. It has been observed that viral particles carry A and B blood group antigens that correspond to the host cell’s ABO type.

This suggests that pre-existing anti-A and anti-B antibodies in the recipient’s blood may reduce the infectivity and number of viral particles, leading to a lower susceptibility to infection. In other words, protection against COVID-19 infection may be linked to ABO blood group incompatibility between the virus-producing host and the recipient.

Additionally, the recipient secretor status, which is encoded by the fucosyltransferase 2 (FUT2) gene, has been shown to influence susceptibility to infection by noro- and rotaviruses. The FUT2 gene is responsible for facilitating high levels of ABH antigens in secretions and on mucosal surfaces.

A genome-wide association study (GWAS) has demonstrated that individuals with blood group O and non-secretor status are less susceptible to SARS-CoV-2 compared to individuals with non-O blood groups and secretor status.

Furthermore, there is evidence to suggest that SARS-CoV-2 may use integrins as cellular receptors. Integrins are transmembrane surface molecules involved in cell-to-cell interaction, cell migration, and intercellular signaling processes. The viral spike proteins of SARS-CoV-2 contain a conserved amino acid motif called arginine-glycine-aspartic acid (Arg-Gly-Asp/RGD), which can bind to integrin heterodimers.

Several other viruses, such as West Nile virus, human cytomegalovirus, and Kaposi’s sarcoma-associated virus, have also been found to bind to integrins.

The integrin subunit beta 3 (ITGB3) gene, which codes for the protein product integrin beta-3 chain, is of particular interest due to its presence in platelets. A single nucleotide polymorphism (SNP) in the ITGB3 gene has been associated with platelet antigen polymorphism and may play a role in susceptibility to viral infections.

Despite the understanding of the role of ABO blood group, secretor status, and integrins in viral infections, there are currently no studies specifically investigating their impact on susceptibility to SARS-CoV-2. To address this gap, a study was conducted using incidents of unprotected exposure among hospital healthcare workers caring for COVID-19 patients.

The study examined the frequency of infection among participants with different levels of pre-existing anti-A and anti-B antibodies, carriers and non-carriers of various erythrocyte and platelet blood group antigens, and different integrin genotypes.

The inspiration for this study came from a similar setup used during the early SARS epidemic in 2003, where accidental exposure and infection scenarios showed a lower frequency of infection in participants with blood group O. The current study aimed to determine if similar associations exist between ABO blood group, secretor status, integrin genotypes, and susceptibility to SARS-CoV-2.

It is important to note that the majority of the participants in this study were female, as the gender ratio in the healthcare system was skewed towards females. This gender imbalance should be considered when interpreting the results.

By elucidating the mechanisms underlying individual variability in susceptibility to SARS-CoV-2, we can gain valuable insights into the development of effective prevention and treatment strategies. Understanding the role of ABO blood group, secretor status, and integrins in the context of SARS-CoV-2 infection may help identify individuals who are at higher or lower risk of severe disease and guide targeted interventions.

In conclusion, the association between ABO blood group, secretor status, integrins, and susceptibility to SARS-CoV-2 represents an intriguing area of research. Further studies are needed to fully understand the underlying mechanisms and to validate the findings of the current study.

The knowledge gained from these investigations will contribute to our understanding of the complex interplay between host factors and viral infections, ultimately leading to more effective strategies for controlling and preventing COVID-19.


reference link : https://www.sciencedirect.com/science/article/pii/S0171298523000670#ab005

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