Fig. 1

Wild-type RBD mRNA vaccine induces protective and Th1-biased immune responses against SARS-CoV-2. A Immunization, blood draw, AAV/hACE2 transduction, and wild-type SARS-CoV-2 (Wuhan strain) challenge schedule. B Serum IgG binding to recombinant SARS-CoV-2 RBD measured by ELISA. C Serum neutralizing activity against SARS-CoV-2 D614G, Beta, and Delta pseudovirus measured by pseudovirus neutralization assay. Plotted values represent geometric mean of 50% neutralizing titers (NT₅₀). D Serum neutralizing activity against SARS-CoV-2 wild-type, Beta, and Delta virus measured by live virus micro-neutralization assay. Plotted values represent geometric mean of 50% neutralizing titers (NT₅₀). E Body weight change of SARS-CoV-2 challenged mice. F Infectious viral load in lung of the challenged mice measured by Median Tissue Culture Infectious Dose (TCID₅₀) assay 5 days post challenge. G Serum IgG1 or IgG2a binding to recombinant SARS-CoV-2 wild-type RBD measured by ELISA. H, I IFN-γ (H) and IL-4 (I) secretion of RBD-stimulated splenocytes of control and vaccinated mice measured by Multiplex assay. Statistical comparisons between control and vaccinated mice were determined by unpaired T test. Statistical comparisons across groups were determined by one-way ANOVA with Tukey’s multiple comparisons test. *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001. ns, non-significant. Dotted line indicates the limit of detection. See also Additional file 1: Fig. S1