Figure 4.

Immunogenicity of NDV-HXP-S after intranasal and intramuscular administration to rats. IgG antibody levels against wild type spike from SARS-CoV-2 (A) and NDV virus preps (B) were measured by ELISA in sera from vaccinated rats at days 0, 15 and 30 after the first vaccine dose administration. In both cases, antibody levels are expressed as area under the curve (AUC). The neutralization capacity of serum antibodies against the authentic USA-WA1/2020 SARS-CoV-2 isolate at day 30 after the first vaccine dose administration is shown in (C), and titers are expressed as inhibitory dilution 50% (ID₅₀, right panel). As a control, the inhibitory concentration 50% (IC₅₀ - μM) of the virus polymerase inhibitor remdesivir is shown (right panel). Geometric mean with geometric standard deviation (SD) for the IN control, IM control, IN vaccinated, IM vaccinated, and IN-IM vaccinated groups is shown in all panels. In (A–C), all vaccinated groups showed statistically significant differences vs their respective controls. The IN-IM administered group was compared with the IM control group. Statistically significant differences between the IN, IM and IN-IM groups are shown. Statistical significance is indicated as follows: *P ≤ 0.0270; **P ≤ 0.0032; ***P ≤ 0.002; ****P < 0.0001.