Characterization of the IFN-I Response in Subjects Who Experienced Severe or Mild Forms of COVID-19

Type I interferon (IFN-I) production is triggered by the detection of viral molecules, such as strands of viral RNA or DNA, by receptors known as PRRs (Pattern Recognition Receptors) present on many cell types. These interferons are secreted in minimal concentrations but can activate neighboring cells to secrete over 700 proteins with antiviral properties (inhibition of viral replication, destabilization of viral membranes, etc.). Thus, the IFN-I response serves as the immune system's first line of defense during a viral infection. Very early in the COVID-19 pandemic, several research teams, including ours, identified a defect in the type I interferon response in about one in five subjects with severe COVID-19. In-depth studies have shown that 5 to 20% of these patients with severe COVID-19 disease have genetic mutations affecting genes involved in the activation cascade of the IFN-I pathway or produce autoantibodies that neutralize IFN-I, significantly impairing the effectiveness of their IFN-I response. However, to date, not all causes of IFN-I response alteration are clearly identified, and 80% of patients suffering from severe COVID-19 do not appear to have evident genetic predispositions or anti-IFN-I autoantibodies, with the techniques currently available. This suggests the presence of other risk factors or causes that could potentially lead to alterations in the IFN-I response. The gut microbiota is recognized for its influence on host health and immunity. SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus 2) infection has been associated with altered gut microbiota and correlated with inflammatory and immune responses. However, the association between dysbiosis and IFN-I response has yet to be studied in humans. Therefore, to improve the management of individuals affected by viral respiratory infections, it seems essential to explore alterations in the IFN-I response to identify individuals potentially at risk of developing severe forms. It is kno