Fig. 4. Analysis of lung pathology in SARS-CoV-2 infected K18-hACE2 mice.
K18-hACE2 mice (group size n = 10) were immunized with the indicated vaccines and challenged with 105 pfu of SARS-CoV-2-SD614G via the nasal route. Five animal groups of each vaccine group were euthanized at day 5 pi, while the remaining animals of each group were sacrificed at day 14 pi. a Lung and brain tissue sections were analyzed by immunohistochemistry (IHC) using a rabbit polyclonal antibody directed to the SARS-CoV nucleoprotein antigen. Lung and brain sections prepared from mock-infected non-vaccinated animals served as control. Arrows indicate lung and brain areas where the viral nucleoprotein antigen was detected. In parallel, lung and brain tissue sections were stained by hematoxylin-eosin (HE). Arrow heads indicate perivascular/peribronchiolar infiltration. Stars mark tissue consolidation. Large size and small size bars indicate 100 and 500 µm, respectively. b, c Histopathological scoring of lung tissue sections obtained on days 5 (b) and 14 (c) pi. Mean values and SD are indicated. Statistically significant differences as computed by the one-way ANOVA test are shown (*p < 0.05; **p < 0.01).