Fig. 3. Neutralization of VOCs by immune sera from PTX-COVID19-B vaccinated mice.

(A) Schematic representation of S proteins from SARS-CoV-2 VOCs, highlighting mutated amino acids compared to the ancestral Wuhan-Hu-1 isolate (triangles denoting deletions and rhombuses denoting replacements). (B to D) Neutralization of pseudoviruses bearing S protein from VOCs and Wuhan-Hu-1 isolate. C57BL/6 mice immune sera shown in Fig. 2 (A and B) were used in the neutralization. Shown in (B) are ID₅₀ titers across all pseudoviruses except VOC Delta. Shown in (C) are pairwise comparisons of the ID₅₀ titers between VOCs and the Wuhan-Hu-1 isolate. Shown in (D) is a pairwise comparison of the ID₅₀ titers between VOC Delta and the Wuhan-Hu-1 isolate. The numbers above the brackets in (C) and (D) are the ratios of the median ID₅₀ titers against the VOCs to the titers against Wuhan-Hu-1 isolate (blue, 10-μg PTX-COVID19-B group; red, 1-μg PTX-COVID19-B group). Each symbol represents one mouse. *P < 0.05 as determined by two-tailed paired t test.