Figure 2. Neutralization activity of antibody responses elicited by the Sputnik V vaccine.

(A) Schematic of the Spike substitutions that make up the variants being evaluated in this study. The amino acid positions and corresponding ‘Ancestral’ sequence of the Wuhan isolate is shown. The prevailing WT sequence now has a D614G substitution. All the variants and mutants have D614G. (B) Neutralization activity of individual serum samples against rcVSV-CoV2-S with the WT, variant (B.1.1.7 or B.1.351), or mutant E484K spike proteins. Neutralization is represented by the reciprocal 50% inhibitory dilution factor (1/IC₅₀). Sera samples with no appreciable neutralization against a given virus were assigned a defined 1/IC₅₀ value of 1.0, as values ≤1 are not physiological (Grey shaded area). Dashed line indicates the lowest serum dilution tested (1/IC50 = 20). Geometric mean titers (GMT and 95% CI) for the neutralizing activity of all vaccine sera are indicated below each of the viral spike proteins examined . NS; not significant, *; p<0.05, p < 0.01; ** are adjusted p values from non-parametric one-way ANOVA with Dunn’s multiple comparisons test. (C) For each serum sample, the fold-change in IC₅₀ (reciprocal inhibitory dilution factor) against the indicated variant and mutant spike proteins relative to its IC₅₀ against wild-type (WT) spike (set at 1) is plotted. Adjusted p values were calculated as in (B). Medians are represented by the bars and whiskers demarcate the 95% CI. Neutralization dose-response curves were performed in triplicates, and the mean values from each triplicate experiment are shown as the single data points for each sera sample.