Severe COVID-19 cases are linked to a pre-existing immune system failure where abnormal B cells produce autoantibodies that disable the body’s primary antiviral defense, according to a global study published in the journal Cell.
Type I Interferon Blockade in Severe COVID-19
Scientists investigating why the coronavirus proved deadly for millions worldwide examined type I interferons, a group of signaling proteins that form one of the body’s first lines of defense against viral infections. According to research published in Cell, these essential antiviral proteins failed to combat the coronavirus because affected patients harbored a large and diverse population of B cells targeting the interferons themselves. Under normal circumstances, type I interferons act as an early warning system, alerting nearby cells to a viral infection and triggering antiviral defenses before the virus spreads. In severe COVID-19 patients, however, autoantibodies neutralized these proteins, effectively disabling a key component of the immune response.
Global Collaboration and Structural Analysis
The research stems from a global investigation involving scientists affiliated with institutions in France, Switzerland, Canada, Spain, Belgium, Saudi Arabia, Sweden, Denmark, Italy, the United States, Estonia, and the United Arab Emirates. According to Rabih Halwani, Professor of Immunology at the University of Sharjah, the discovery is rooted in extensive somatic hypermutation. Researchers combined X-ray crystallography with AlphaFold3-based structural analyses using patient-derived monoclonal antibodies to examine hundreds of antibodies. This work revealed that the antibodies target three major B-cell epitopes covering all principal regions of type I interferons.
Pre-Existing Immune Defects and Affinity Maturation
Professor Halwani emphasized that this abnormal immune response was detectable before patients developed life-threatening viral disease, suggesting it was a pre-existing defect rather than a simple consequence of severe infection. The researchers tracked this back to a prolonged process called affinity maturation. While affinity maturation normally improves antibody binding strength against invading microbes, this process instead strengthened antibodies directed against the body’s own interferons. According to the findings, these insights may help clinicians identify patients at heightened risk not only from COVID-19, but also from seasonal influenza and future coronavirus pandemics, while informing new therapeutic strategies.
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