Fig. 1: FXa inhibits wild-type SARS-CoV-2 infection by targeting viral particles.

a, b FX protein levels in lungs (a) or plasma (b) of COVID-19 patients vs. non-COVID-19 donors, using IHC (a) and ELISA (b), respectively. The staining results shown in a are representative of at least two independent experiments with similar results. Scale bar, 50 μm. b n = 9 for COVID-19 patients and n = 4 for non-COVID-19 donors. c Post-diagnosis concentrations of FX in plasma of COVID-19 patients (n = 3) compared to non-COVID-19 donors (n = 3), as measured by ELISA. d, e HEK293T cells co-transfected with a plasmid encoding ACE2 and the other plasmid encoding FXa or an empty vector (EV) in the absence (d) or presence (e) of another plasmid encoding TMPRSS2 were infected by VSV-SARS-CoV-2. Infectivity of the cells was quantified by flow cytometry at 16, 24, 36, and 48 hpi (n = 4 or 5 biologically independent samples). f MA104 cells transduced with the plasmid encoding FXa (MA104-FXa) or an empty vector (MA104-EV) were infected with VSV-SARS-CoV-2. Infectivity of the cells was quantified by flow cytometry at 16, 24, 36, and 48 hpi (n = 3 biologically independent samples). g VSV-SARS-CoV-2 was pre-incubated with FXa at the indicated concentrations 1 hour before infection (n = 3 biologically independent samples). h MA104 and Vero E6 cells were infected with live wild-type SARS-CoV-2. At 24 hpi, infectivity was measured with an immuno-plaque assay. i Summary of data from h (n = 3 independent experiments for each cell line). j A549-ACE2 cells were infected with either authentic WT SARS-CoV-2 preincubated with 100 nM FXa for 1 hour, or the cells were treated with FXa at the time of viral infection. Infectivity was measured by immuno-plaque assays 24 hours post-infection. Representative infection and the summary data are presented at the left and right, respectively (n = 3 biologically independent samples). Data in b–g and i, j are presented as mean values ± standard deviation (SD) and statistical analyses were performed by two-sided Student’s t tests (b), one-way ANOVA models (c, i) and two-way ANOVA models (d–g, j). MFI data were log₂ transformed before running the statistical models. Source data are provided as a Source Data file.