Uncovering the implications of IFN-I in severe COVID-19 neutrophil inflammasome (preprint)

Excessive inflammation defines COVID-19 pathophysiology. Neutrophils represent a critical arm of the innate immune response and are major mediators of inflammation. We conducted transcriptomic profiling of polymorphonuclear cells (PMNs), consisting mainly of mature neutrophils, which revealed a pronounced type I interferon (IFN-I) gene signature in severe COVID-19, compared to mild COVID-19 and healthy controls. Notably, low-density granulocytes (LDGs) from severe COVID-19 did not exhibit this signature and displayed a distinct immature neutrophil phenotype. PMNs from severe COVID-19 patients showed heightened nigericin-induced caspase1 activation but reduced responsiveness to exogenous inflammasome priming. Interestingly, while mature neutrophils efficiently released IL-1? upon inflammasome activation, they were poor producers of IL-18. Furthermore, IFN-I emerged as a priming stimulus for neutrophil inflammasomes, which was confirmed in a COVID-19 mouse model. Overall, these findings underscore the crucial role of neutrophil inflammasomes in driving inflammation during severe COVID-19 and opens promising avenues for targeted therapeutic interventions to mitigate the pathological processes associated with the disease.

Comparative analysis of BNT162b2, mRNA-1273 and ChAdOx1 COVID-19 vaccine induced antibody responses and the 3rd BNT162b2 vaccine induced neutralizing antibodies against Delta and Omicron variants (preprint)

Two COVID-19 mRNA and two adenovirus vector vaccines have been licensed in Europe and various vaccine combinations and dosing strategies have been exploited to maximize the immunity against COVID-19. Here, we show that among health care workers (n=328) two doses of BNT162b2, mRNA-1273, or ChAdOx1 as also a combination of an adenovirus vector and mRNA vaccines induces equally high levels of anti-SARS-CoV-2 spike antibodies and neutralizing antibodies against B.1 and B.1.617.2 when administrated with a long 12-week dose interval. Two doses of BNT162b2 with a short 3-week interval induce 2-3-fold lower titers of neutralizing antibodies compared to the long interval. Third mRNA vaccine dose for the short dose interval group increased the antibody levels 4-fold compared to the levels after the second dose. Importantly, sera from all three-times vaccinated neutralized B.1.1.529 (Omicron). The data indicates that a third COVID-19 mRNA vaccine dose efficiently induces cross-protective neutralizing antibodies against multiple variants.

A highly sensitive and specific SARS-CoV-2 spike- and nucleoprotein-based fluorescent multiplex immunoassay (FMIA) to measure IgG, IgA and IgM class antibodies (preprint)

Background. Validation and standardization of accurate serological assays are crucial for the surveillance of the coronavirus disease 2019 (COVID-19) pandemic and population immunity. Methods. We describe the analytical and clinical performance of an in-house fluorescent multiplex immunoassay (FMIA) for simultaneous quantification of antibodies against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleoprotein and spike glycoprotein. Furthermore, we calibrated IgG-FMIA against World Health Organisation (WHO) International Standard and compared FMIA results to an in-house enzyme immunoassay (EIA) and a microneutralisation test (MNT). We also compared the MNT results of two laboratories. Results. IgG-FMIA displayed 100% specificity and sensitivity for samples collected 13-150 days post-onset of symptoms (DPO). For IgA- and IgM-FMIA 100% specificity and sensitivity were obtained for a shorter time window (13-36 and 13-28 DPO for IgA- and IgM-FMIA, respectively). FMIA and EIA results displayed moderate to strong correlation, but FMIA was overall more specific and sensitive. IgG-FMIA identified 100% of samples with neutralising antibodies (NAbs). Anti-spike IgG concentrations correlated strongly ({rho}=0.77-0.84, P<2.2x10-16) with NAb titers. The NAb titers of the two laboratories displayed a very strong correlation ({rho}=0.95, P<2.2x10-16). Discussion. Our results indicate good correlation and concordance of antibody concentrations measured with different types of in-house SARS-CoV-2 antibody assays. Calibration against WHO international standard did not, however, improve the comparability of FMIA and EIA results. keywords: SARS-CoV-2, COVID-19, antibody, immunoassay, nucleoprotein, spike glycoprotein, WHO international standard, neutralising antibodies, microneutralisation, receptor-binding domain