Fig. 1: Fibrinogen interaction with SARS-CoV-2 spike.
From: Fibrin drives thromboinflammation and neuropathology in COVID-19
a,b, Binding enzyme-linked immunosorbent assay (ELISA) of spike to fibrinogen (a) or fibrin (b). Kd, dissociation constant. A450, absorbance at 450 nm. c, Fibrinogen immunoprecipitation (IP) with spike. d, Spike and fibrinogen immunoreactivity in the lungs at 3 d.p.i. Representative of five Beta-infected WT mice. Scale bar, 300 μm. e, Peptide array of fibrinogen chains Aα, Bβ and γ blotted with spike. The binding signal intensity is shown (white to orange). f, Scanning electron microscopy (SEM) images and quantification of the fibrin clot fibre radius in human plasma with spike. The fibre radius distribution was determined in n = 25 (plasma) and n = 28 (plasma with spike) images from three biologically independent experiments (generalized linear mixed-effects model with Holmes multiple correction; Methods) and the fibre radius proportion (<0.05 µm) was determined from n = 3 biologically independent experiments (two-sided paired t-test; Methods). Scale bar, 1 µm. FOV, field of view. g, The turbidity of fibrin polymerization with spike in human plasma. h, Immunoblot (IB) analysis of fibrin degradation by plasmin representative from five (0, 2 and 4 h) or three (1 and 6 h) biologically independent experiments. i, ROS in BMDMs stimulated with fibrin and/or spike. n = 6 (unstimulated and spike) and n = 3 (fibrin or fibrin with spike) biologically independent experiments. a.u., arbitrary units. j, Fibrin γC domain and spike-binding epitope γ364–395 (red). Alanine scanning of γ377–395 blotted with His–spike. The binding of spike to Ala-substituted peptides is shown. The residues that are required for binding are indicated in yellow. k, Competitive ELISA of 5B8-huFc (5B8 with human IgG1 Fc region) or huIgG1 versus spike for binding to fibrin. n = 3 biologically independent experiments. l, ROS in BMDMs stimulated with fibrin and/or spike treated with 5B8 or IgG2b. n = 3 biologically independent experiments. Representative data of n = 3 (a–c) or n = 4 (g) biologically independent experiments. For i and l, statistical analysis was performed using one-way analysis of variance (ANOVA) with Tukey’s multiple-comparison test. Data are mean ± s.e.m. Gel source data are provided in Supplementary Fig. 1.
