Fig 1: Lethal SARS-CoV-2 infection caused coagulation/ fibrinolysis abnormalities in AC70 hACE2 Tg mice.The concentration of D-dimers at 4 d.p.i. (A), the kinetics of Plasminogen Activator (t-PA) (B) and the concentration of tissue Plasminogen Activator Inhibitor-1 (PAI-1) at 4 d.p.i. (C) detected by ELISA-based analysis in gamma irradiated EDTA-plasma specimens derived from uninfected control and virally challenged mice (n = 5 per group). The average of plasmin activity and the individual differences of mock-infected versus CoV-2-infected mice at 4 dpi were depicted in (D) and (E), respectively, showing significantly reduced plasmin activities in mice upon infection (p < 0.05 **p = 0.0035, ****p<0.0001). Combined data were derived from two independently conducted experiments. (F&G) Fibrin depositions. To visualize the fibrin depositions, paraffin sections of lungs from mice infected with 105 TCID50 of SARS-CoV-2 (F) and Mock (G) were stained with Martius Scarlet Blue (MSB). Fibrins (arrows in F; red-colored) could only be detected within the lumen of a vein of infected, but not mock-infected (G), mice, with bluish, gray-colored background of platelets. Representative images from two independent experiments were shown.