Fig. 4.

Prophylatic effects of F61 or F61/H121 cocktail against delta SARS-CoV-2 (B.1.617.2) in K18-hACE2 mice. A–B Body weights, survival curves, and viral RNA loads in the lungs of K18-hACE2 mice treated with different doses of antibodies (1.25, 5, 10, and 20 ​mg/kg) F61 (A) or F61+H121 (B) cocktail via the intranasal route before infection with 200 TCID₅₀ delta variant. C Body weights, survival curves, and viral RNA loads in the lungs of K18-hACE2 mice treated with 20 ​mg/kg F61or F61+H121 cocktail via intranasal route before infection with 1000 TCID₅₀ delta variant. D–E Body weights, survival curves and lung virus RNA detected by qRT-PCR of K18-hACE2 mice treated with a low dose antibodies (5 ​mg/kg or 1.25 ​mg/kg; D for F61, E for F61+H121 cocktail) via intranasal route before infection with 1000 TCID₅₀ of delta variants. Viral RNA loads were determined using qRT-PCR. Body weight curve values represent means ​± ​standard errors of the means (n ​= ​3–6 mice/group). Significant differences between the antibody treatment group and negative control are shown. All data points of virus load in the lungs are shown, along with the medians. ns, P ​> ​0.05; ∗, P ​< ​0.05; ∗∗, P ​< ​0.0001, as determined by Student's t test. Limit of detection (LOD), 500 copies/mL.