Figure 3
GP∆-delta DNA vaccine induced neutralizing antibodies against delta variant. (a) Animal protocol for the control pVAX (intramuscularly; IM), parental DNA (IM), GP∆-delta DNA (IM), or GP∆-delta DNA (intradermally; ID) vaccines using PJI. Control or DNA vaccine was injected three times at 2-week intervals. (b) Antibody titers for ancestral and delta spikes, measured using ELISA. *p < 0.01 vs. pVAX1 IM group (Two-way ANOVA with Tukey’s multiple comparison test). (c) The neutralizing activity of vaccine-induced antibodies, as determined through VSV-based pseudo-typed viruses carrying the SARS-CoV-2 spike (ancestral or delta variant). The values show the 50% inhibitory dose of serum. *p < 0.01 vs. pVAX1 IM group. **p < 0.05 vs. parental IM group (Two-way ANOVA with Tukey’s multiple comparison test. (d) and (e) Correlation between ID50 values of immunized serum samples on the pseudo-typed virus and IgG antibody titer for spike. (d): Ancestral spike, (e): delta variant spike. R2, coefficient of determination. Data are shown as mean ± SEM. See also Supplementary Fig. 4.
