Fig. 6: Intranasal immunization of Syrian hamsters with Nsp1-K164A/H165A induced potent humoral responses and protected against WA1/2020 challenge.

a Overall study design. b, c Serum IgG antibody titers at 0 (n = 7), 14 (n = 7–11), 28 (n = 4–7) days and IgA antibody titer at 28 (n = 4–9) days post-immunization measured by RBD (spike) binding ELISA (b) or anti-spike neutralizing antibody titers at 28 dpi (c). ****p < 0.0001, one-way ANOVA. d Weight loss profiles of immunized and convalescent hamsters after re-challenge with WA1/2020. Error bars in b and d indicate standard deviation. e─h Infectious viral titers detected in nasal wash samples collected at 1, 2, 3, and 4 dpc. Median Log₁₀ infectious titers at 1 dpc are 2.3 (IQR 2.3 to 3.1) for WA1/2020 convalescent hamsters, 3.8 (IQR 3.6 to 4.0) for ΔPRRA convalescent group, 3.8 (IQR 3.1 to 4.8) for Nsp1-N128S/K129E convalescent group, 2.3 (IQR 2.3 to 4.8) for Nsp1-K164A/H165A 10⁴ PFU vaccinated group, 3.2 (IQR 3.0 to 3.7) for 10³ PFU vaccinated group, 3.3 (IQR 2.5 to 4.5) for Nsp1-K164A/H165A 100 PFU vaccinated group, and 6.4 (IQR 5.3 to 7.1) for mock vaccinated hamsters. For e through l, **p < 0.01, ***p < 0.001, and ****p < 0.0001 based on one-way ANOVA. Sample sizes for b–h: for WA1/2020 (n = 7), ΔPRRA (n = 7), Nsp1-K164A/H165A (n = 4 per dose), Nsp1-N128S/K129E (n = 6), or unvaccinated (n = 9). i─j Infectious viral titers and sgRNA titers from tissues at 4 dpc, respectively. k, l infectious viral titers and sgRNA titers from tissues at 7 dpc, respectively. P-values are summarized based on the scheme: *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 using one-way ANOVA. Data shown in b–h reflect hamsters pooled from two independent experiments. Data shown in i–l reflect hamsters from one experiment. Each solid circle represents one animal. Source data are provided as a source data file.