Figure 2.
Neutralizing antibody response raised by one or two doses of sa-mRNA S and sa-mRNA S-N vaccines in BALB/c mice
(A) BALB/c female mice (n = 10) were immunized once (one dose) or twice (two doses, 3 weeks apart) with 1.0 μg of sa-mRNA S (blue) or sa-mRNA S-N (red). Serum samples collected at day 43 were tested in a live virus microneutralization (MN) assay for homologous original virus (B) or an assay on inhabitation of angiotensin-converting enzyme 2 (ACE2) binding by SARS-CoV-2 S ectodomain (Secto) protein with sequences from original virus (C). Each dot represents an individual serum sample, and the column represents the geometric mean for the group. Green dots and column (B) represent MN results for the reference convalescent plasma, eight convalescent plasma samples from CSL plasma, and a pooled plasma sample from the National Institute for Biological Standards and Control. The dotted line in each panel represents the lower limit of quantitation for the assay. Statistical analysis by two-way ANOVA with Tukey’s multiple comparison test was performed using GraphPad Prism 9.1.0. ∗p < 0.05. ∗∗p < 0.01. ∗∗∗p < 0.001. ∗∗∗∗p < 0.0001. ns, not significant (p ≥ 0.05).