Fig. 10.
Infectious challenge of Balb/c mice with SARS-CoV-2 after single treatment with Ad5-RBD or Ad5-S administered intranasally (II). The left lung was subjected to histological (H/E; a-c) and immunohistochemical (SARS-CoV-2 nucleoprotein, hematoxylin counterstain; d-f) examination on day 3 post intranasal infection with 2 × 105 plaque-forming units of the beta variant of SARS-CoV-2. Unvaccinated animal no. 3 (a, d): There is extensive SARS-CoV-2 nucleoprotein expression in bronchial and bronchiolar epithelial cells and, focally (arrow heads) in the parenchyma. Ad5-RBD vaccinated mouse no. 1 (b, e): The lung is widely unaltered and there is no evidence of viral antigen expression. Ad5-S vaccinated animal no. 1 (c, f): The lung is widely unaltered and there is no evidence of viral antigen expression. Bars = 1 mm.