Figure 2.

Vaccination of single-dose HD-Ad-FS protected hACE2 mice from SARS-Cov2 in the upper airway and lungs. (A) Schematic timeline of single-dose hACE2 experiment. The hACE2 mice were immunized with a single-dose of HD-Ad-FS (single-FS) or HD-Ad-control (single-control) at 5x10⁹ vp via intranasal delivery. Three weeks after immunization, the hACE2 mice were intranasally challenged with SARS-CoV-2 at 1x10⁵ TCID₅₀. Animal samples were harvested at day 3 post-infection (dpi). (B) RNA levels of SARS-CoV-2 in oropharyngeal swabs were determined with RT-qPCR. (C) RNA levels of SARS-CoV-2 in the lungs were determined with RT-qPCR. (D) The titers of infectious SARS-CoV-2 in the lungs were measured with TCID₅₀ assay. (E) RNA levels of SARS-CoV-2 in the spleens (left) and hearts (right) were measured with RT-qPCR. (F) FS-specific IgG response in serum were determined with ELISA. The starting dilution was 1:25. (G) Serum neutralizing activities against SARS-CoV-2 and VOCs were measured with neutralization assays. Dots represent individual mice (n=6). The dotted lines represent the LOD of the assays. For RT-qPCR, the LOD was set to 100 E copies/sample. Statistical analyses were performed by Mann-Whitney test, two-tailed. Bars and errors represent geometric mean with geometric SD. *p<0.05, **p<0.01, and ns, not significant. Data represent one independent animal experiment with indicated biological replicates.