Fig. 3
HD-Ad_RBD protects the upper and lower respiratory tracts against SARS-CoV-2 infection. A Experimental scheme. hACE2 mice were immunized intranasally with HD-Ad_RBD using a prime-boost regimen at a dose of 5 × 109 viral particles. Three weeks after the second vaccination, the animals were challenged intranasally with 105 TCID50 of SARS-CoV-2. At day 1, 3 and 5 post-infection, mice were euthanized, and the lungs, spleen and heart were harvested for viral burden and cytokine analysis. B Titers of infectious SARS-CoV-2. The number of infectious virus particles in the lungs were determined by CPE assays. C–F RNA levels of SARS-CoV-2 determined by qRT-PCR. Viral RNA levels in the lung, spleen, heart, and oropharyngeal swabs were measured at the indicated time points by qRT-PCR. G Neutralizing activity of sera against SARS-CoV-2. Sera from mice at different time points after SARS-CoV-2 infection were collected and the levels of neutralizing antibody were measured. Each dot represents an animal. Bars and errors represent the geometric mean with geometric SD. The red dotted lines indicate the limit of detection (LOD) of the assays. Statistical analyses were performed by Mann–Whitney test: *p < 0.05; **p < 0.01; ***p < 0.001. H The percentage of weight loss (mean ± SEM) of animals at the indicated time points after SARS-CoV-2 infection. Statistical analysis was performed by two-way ANOVA: *p < 0.05. I The percentage of weight loss of individual animal at the indicated time points post infection