Figure 4. IL-13 enhances SARS2-N501Y_MA30-induced disease in vivo.

6-10 week-old BALB/c mice were intranasally infected by 1,000 PFU of SARS2-N501Y_MA30 after a 4-day pretreatment of 2.5 μg/day intranasal IL-13 or vehicle. (a) Survival rate and (b) weight were monitored daily. n = 4-6 mice for each group; mean ± SEM; for % starting weight of Veh + Virus vs IL-13+Virus, *p<0.05; p-values in weight change and survival curve are Student's unpaired t test and log-rank (Mantel-Cox) tests, respectively. (c) Quantification of virus loads at 5 dpi in homogenized mouse lungs by plaque assay using VeroE6 cells. n = lung tissue from 4 mice; p value: Student's unpaired t test. (d) Representative sections from uninfected mouse lungs treated with vehicle or IL-13treatment and stained with diastase-pretreated periodic acid-Schiff (dPAS). Note the increased dPAS+ staining of the epithelium (arrows) and within the airway (asterisk), (e) Representative sections from infected mouse lungs with vehicle or IL-13 treatment and stained with H&E (top) or immunostained for SARS-CoV-2 N protein. Note the edema (asterisk, top right image) and hyaline membranes (arrows, top right image). Note the expansive N protein staining in the bottom right versus bottom left representative images. Histopathology staining from 4 mice/group. (f) Ordinal histopathological scoring of airway goblet cell metaplasia (mucus-producing goblet cells) (top panel), edema/hyaline membrane (middle panel), and SARS-CoV-2 N protein expression (bottom panel) in lungs from mock or infected mice. mean ± SEM; *p<0.05; p value: Student's unpaired t test