Figure 5.

Previous Infection Protected Mice from a Higher Dose of Virus Reinfection

Three surviving mice 21 DPI and three previously mock-infected mice were infected with 7 × 10⁵ TCID₅₀ SARS-CoV-2 at 21 DPI, respectively.

(A and B) Body weights (A) and survival outcomes (B) were monitored for up to 5 days.

(C) Mice were euthanized 5 DPI, and the viral loads were measured using RT-qPCR.

(D) Naive-infected mouse lung showed peri-bronchial and peri-vascular infiltration and edema with hyaline membrane formation.

(E) In contrast, previously challenged mice presented mild peri-bronchial and peri-vascular infiltration.

(F–I) Viral antigen was widely present in the naive-infected mouse lung (F) and brain (H) but barely observed in previously challenged mouse lung (G) and brain (I).

Error bars indicate the standard error. ND, not detected. Scale bar: 500 μm (D and E), 100 μm (F and G), and 200 μm (H and I).

See also Tables S4 and S5.