Fig. 4.

Broad protective efficacy of dNS1-RBD against SARS-CoV-2 challenge in Syrian hamsters co-housed transmission model after two-dose vaccination. (a) The hamsters after two-dose vaccination were challenged by prototype and Omicron strain of SARS-CoV-2 at 3 months after vaccination respectively. The hamsters treated with virus protectant were used as placebo controls. (b, e) Changes in the body weights of hamsters were recorded following cohousing exposure. The average weight loss of each group at 7 dpi is indicated as a colored number. Data are shown as mean ± SD. Significant differences compared to the placebo group were analyzed using two-way repeated-measures ANOVA with Dunnett’s multiple comparisons test. (c, f) Viral loads of lung tissue obtained at 5 dpi from hamsters challenged were determined by TCID50 assay. Data are shown as mean ± SD; significance was determined by two-tailed Student’s t-test. Symbols represent individual hamsters. (d, g) Comprehensive pathological scores of the hamster lungs. Scores were determined based on the severity and percentage of injured areas for the whole lung tissue collected from the indicated animal. Significance compared to the placebo group was determined by two-tailed Student’s t-test. (h, i) H&E staining of lung sections from tested hamsters collected on day 5 after cohousing exposure. Views of the whole lung lobes (4 independent sections) are presented in the above panel (scale bars, 1 mm), and the areas in the small black boxes are enlarged in the lower panel (scale bars, 100 μm).