Overview of IgA Antibody in SARS-CoV-2 Infection
Human IgA includes iga1 and iga2 subclasses. while iga2 is mostly confined to the gut and is more abundant than iga1 in the distal intestine, iga1 is released in both systemic and mucosal compartments. Both iga1 and iga2 encompass an N-glycosylated Fc segment that outcompetes influenza viruses for binding to sialic acid receptors on target cells besides interacting with both joining chain and secretory component segments. IgA can modulate excessive immune responses in inflammatory diseases and it is more effective in recruiting neutrophils for cell killing. According to previous research, IgA has been proven to be active against several pathogens, including rotavirus, poliovirus, influenza virus, and SARS-CoV-2. For years, secretory IgA (sIgA) has been described as the first barrier against pathogens at mucosal surfaces. sIgA can agglutinate bacteria, disturb bacterial motility, neutralize bacterial toxins, and also inhibit bacterial adherence to the epithelium, thereby preventing pathogen dissemination to the circulation. These potent effects of IgA have been assessed against multiple gastrointestinal pathogens such as Salmonella typhimurium, Shigella flexneri, Clostridioides difficile, and against some viruses. In particular, IgA exerts a neutralizing action on the Sendai virus, human immunodeficiency virus, and influenza virus. Researchers have recently shown that IgA is more effective than IgG at neutralizing SARS-CoV-2.
Researches of IgA Antibody in SARS-CoV-2 Infection
As a mucosal targeted virus, SARS-CoV-2 secretory IgA plays an important role in early defense and virus containment. The serum concentration of IgA decreases one month after the onset of symptoms while neutralizing IgA can still be detected in saliva for a longer time. Human monoclonal IgA antibodies that cross-react with SARS-CoV and SARS-CoV-2 spike proteins can neutralize SARS-Cov-2 infection in vitro when converted to sIgA. The secretory IgA in the intestine and the monomeric IgA in the serum are clonally related. SARS-CoV-2 specific sIgA has been detected in the milk of mothers infected with SARS-CoV-2, indicating that sIgA is produced against infection and passed to the newborn for protection.
Fig. 1 Therapeutic potential of IgA. (Sterlin, 2021)
Another report described an alternative way for the neutralization of intracellular viruses through IgA binding to tripartite motif-containing 21 (TRIM 21), which is expressed in various tissue types and not just immune cells. After binding, TRIM 21 targets the virus-IgA complex for proteasomal degradation in an antibody-dependent intracellular neutralization process. IgA also mediates protection against microbial infection via its interaction with the FcαRI. It has been demonstrated that infusion of antigen-specific IgA in human FcαRI transgenic mice, but not wild-type mice, results in enhanced clearance of Mycobacterium tuberculosis or Bordetella pertussis. Based on these observations, passive transfer of specific IgA and active immunization may be effective strategies to fight viral and bacterial infections.
Services at Creative Biolabs
In the context of the COVID-19 pandemic, all factors influencing SARS-CoV-2 infection have been gradually revealed, including IgA antibodies. Focusing on non-IgG antibodies over years, Creative Biolabs has accumulated rich experience. We have also thrown our sights on the role IgA plays in SARS-CoV-2 infection and work on it. With all these efforts we made and the strong foundations accumulated from years of practice, we are confident in providing our clients with reliable services including but not limited to:
- Non-IgG Antibody Discovery
- Non-IgG Antibody Engineering
- Non-IgG Antibody Production and Purification
- Non-IgG Antibody Characterization
- Non-IgG Antibody PK/PD Evaluation
- Non-IgG Antibody Developability Improvement
If you are interested in our services or you have any other requirements for non-IgG antibodies, please don't hesitate to contact us for more information.
- Sterlin, D. and Gorochov, G. When Therapeutic IgA Antibodies Might Come of Age. Pharmacology. 2021, 106(1-2): 9-19.
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