Figure 3
Protection from SARS-CoV-2 challenge. Female BALB/c mice were immunized subcutaneously with Co WPV, Flu WPV, Co/Flu WPV, or PBS as the control group, and sample collection and virus challenge experiments were conducted as shown in Fig. 1a (n = 10/group). At 22 days post-vaccination, the animals were challenged with 105 PFU of mouse-adapted SARS-CoV-2 (SARS-CoV-2 MA-P10). Following virus challenge, body weight change was monitored (a) and lung viral loads were measured at 3 and 5 dpi (b and c). Mean and SD are shown. Statistical analysis was performed using Kruskal–Wallis test with Dunn’s multiple comparisons tests. **p < 0.01. Some lung tissues harvested at 5 dpi were used to analyze lung pathology by H&E and immunohistochemistry to detect SARS-CoV-2 nucleocapsid and macrophage (F4/80) and neutrophil (Ly-6G) markers (d). Each lung section is a representative of 5 lung sections analysed. Gene expression levels of pro-inflammatory cytokines and chemokines were measured using real-time RT-PCR (e). Gene expression levels are presented as fold changes relative to the non-infected control group. Mean and SD are shown. Statistical analyses were performed on dCt values using two-way ANOVA with Sidak’s multiple comparisons test. The * and # symbols indicate statistical significance between the non-infected group and infected groups and between unvaccinated (PBS) and vaccinated groups, respectively. *p < 0.05, **p < 0.01, ***p < 0.001 ****p < 0.0001 and #p < 0.05, ##p < 0.01, ###p < 0.001 ####p < 0.0001.
