Fig. 2: Serum E proteins promote thrombosis in vivo.

a Wild-type (WT) mice were intravenously injected with the E protein (0.5, 1, 2 and 4 μg per mouse) or PBS. Four hours later, mouse models of pulmonary embolism (PE) were induced by intravenous injection of collagen and epinephrine. b The presence of the E protein on platelets in lung embolism of mice. Immunofluorescence staining on lung section from the E-treated mouse model of PE was performed with anti-SARS-CoV-2 E protein (red), and anti-CD41 (green) antibodies. Nuclei were stained with 4′,6-diamidino-2-phenylindole (DAPI). Scale bar = 10 μm. c Representative field on hematoxylin-eosin (HE) stained lung sections in each group. Scale bar = 100 μm. Results in b and c were confirmed in five independent experiments. d Quantification of the number of lung embolisms per visual field on lung sections. The number of lung thrombi was 13.72 ± 3.96 in PBS-treated WT mice, 13.64 ± 4.28 in E-treated (0.5 μg) WT mice, 14.44 ± 4.51 in E-treated (1 μg) WT mice, 16.20 ± 4.67 in E-treated (2 μg) WT mice, and 22.00 ± 4.74 in E-treated (4 μg) WT mice. Data are mean ± SD of 25 counts from 5 mice in each group. e WT mice were treated with the E protein (4 μg per mouse) or PBS, and then the inferior vena cava (IVC) stenosis model was performed. f Representative image of the thrombi isolated from mouse IVC. g The thrombus weight was 8.40 ± 1.14 mg in PBS-treated mice, and 13.60 ± 1.14 mg in the E-treated mice (n = 5). Data are presented as mean ± SD. h Immunofluorescence staining of the E protein (red), CD41(green), DAPI in thrombi section isolated from the E-treated mouse after IVC model. Scale bar = 10 μm. Data were analyzed by the Kruskal–Wallis test (d) or 2-tailed Mann–Whitney U test (g). Source data are provided as a Source Data file.