Fig. 2: Immunization with OTS constructs provides full protection against SARS-CoV-2 challenge in sensitive preclinical K18-hACE2 mice model.
a, Intranasal inoculation of age-matched K18-hACE2 mice (n = 12 mice per group) with OTS4–5, OTS7–8, OTS4-5-7-8 and OTS-206, and subsequent challenge with WT at 21 dpi (n = 12 mice per group, n = 6 mice in OTS4–5 and OTS7–8 groups). A mock (vaccinated and challenged with culture media) and a naïve control group (vaccinated with only media, but infected with challenge virus) were included. Data were obtained from one experiment. Overview created with BioRender.com. b,c, Pre-challenge survival (b, %) and body weight (c) (n = 12 mice (OTS), n = 8 (mock), group mean ± s.e.m.) loss showed correlation between increased OTS modifications and improved outcomes. d,e, All OTS constructs provided full protection against challenge infection in terms of survival (d) and body weight (e) (n = 12 mice in naïve, OTS-4-5-7-8, OTS-206 and OTS4–5 (until 7 dpi) and OTS7–8 (until 6 dpi) groups; n = 6 mice in OTS4–5 (from 7 dpi onwards), n = 10 mice in OTS7–8 at 6 dpi and n = 6 mice from 7 dpi onwards; n = 8 mice in the mock group) (group mean ± s.e.m.). f, Clinical scores post challenge were high only in naïve mice (group mean ± s.e.m.). g, Viral genome copies in nose and lung samples were significantly reduced for the vaccinated animals (n = 3 mice in OTS4–5, OTS7–8 groups; n = 6 mice in OTS4-5-7-8, OTS-206 groups; n = 4 in mock group, n = 10 in naïve group). h, At 5–6 dpc, no infectious virus was detectable in nose and lung samples of the vaccinated animals. i,j, Histopathological scores (i) and immunohistochemical analysis (j) of lung sections demonstrate protection in OTS-construct-inoculated mice. Scale bar, 500 μm. Statistical significance was calculated using two-sided ordinary two-way ANOVA with Tukey´s multiple-comparisons test (compare columns (simple effect within rows), 95% CI) for c and e; and two-sided, unpaired, non-parametric multiple t-test with Mann–Whitney test (compare ranks, 95% CI) for g–i. Violin plots in g–i show individual samples with mean values (middle lines).
