Fig. 7: Protection against SARS-CoV-2 variants of concern in pCTV-WS immunized Syrian hamsters.

a PRNT50 was evaluated using different SARS-CoV-2: Wuhan strain (B lineage), Delta, Gamma and Omicron variants in sera samples from pCTVØ (black circles) or pCTV-WS (colored lines) immunized hamsters [n = 4–5, pCTVØ and n = 4–10, pCTV-WS]. Viral load b and SARS-CoV-2 RNA copy number c in lung samples of pCTVØ (black circles) or pCTV-WS (green circles) immunized hamsters and challenged with the Delta variant of SARS-CoV-2 at 4 DPI [n = 4–5 hamsters/group]. Viral load d and SARS-CoV-2 RNA copy number e in lung samples of pCTVØ (black circles) or pCTV-WS (blue circles) immunized hamsters and challenged with the Gamma variant of SARS-CoV-2 at 4 DPI [n = 4–5 hamsters/group]. Viral load in nasal wash f and lung g of pCTVØ (black bar) or pCTV-WS (pink bar) immunized hamsters and challenged with the Omicron variant at 3 DPI [n = 4–5 hamsters/group]. SARS-CoV-2 RNA copy number in nasal wash h and lung tissue i of pCTVØ (black circles) or pCTV-WS (pink circles) immunized hamsters and challenged with the Omicron variant at 3 and 6 DPI [n = 4–5 hamsters/group]. Histopathological sections of lungs from pCTVØ j–l, or pCTV-WS m–o immunized hamsters and challenge with the Delta, Gamma and Omicron variants at 4 DPI, respectively. Inflammatory infiltrate (black arrow), perivascular inflammatory infiltrate (red arrow), alveolar septal thickening (yellow arrow), vascular congestion (blue arrow), edema (arrow head) and hemorrhage (green arrow) at 1.1×, 10×, and 20× magnification [n = 4-5 hamsters/group]. The statistical analysis was performed using unpaired t-test or Mann-Whitney U test, according to data distribution. *p < 0.05; **p < 0.01; ***p < 0.001.