Figure 2.

Pathological Changes in HFH4-hACE2 Mouse Lung after SARS-CoV-2 Infection

Three to six euthanized mice were used to examine the pathological changes in the lungs 1, 3, 5, and 7 DPI, respectively.

(A) Mock-infected mice lacked lesions.

(B and C) Mouse lung 1 DPI showed multifocal lesion (B) with lymphocyte and macrophage infiltration (C, red arrow) and fibrin exudation (C, black arrow).

(D and G) Moderate interstitial pneumonia was observed 3 DPI with hyaline membrane formation (D, green arrow), inflammatory infiltration (G, red arrow), and fibrin exudation (G, black arrow).

(E, F, H, I, J–N) Mild peri-bronchial and peri-vascular infiltration were observed 5 DPI (E and H) and 7 DPI (J and M). Some infected mice 5 DPI (F), 7 DPI (K), and at death (L) suffered severe pneumonia with blocked terminal bronchioles, fibroplasia or organization, and hyaline membrane formation (I, green arrow; O, red arrow). Alveolar necrosis (I, N, and O, black arrow) and hyaline thrombus (N, red arrow) were observed in severely infected lungs. Martius Scarlet Blue (MSB) staining was performed to staining fibrin in the lung.

(P–R) Mock-infected mice served as control (P). Severely infected mice (Q) show hyaline membrane (R, green arrow) and hyaline thrombus (R, black arrow). Images were collected using a Pannoramic MIDI system.

Scale bar: 500 μm (A, B, D–F, J–L, P, and Q) and 100 μm (C, G–I, M–O, and R).

See also Figure S2.