Figure 4.

Anti-spike IgG titers and neutralization titers induced by S-Vac formulation and commercial vaccine in mice. BALB/c mice (n = 8/group) were immunized on Days 0 and 14 with formulations containing spike purified protein from ancestral Wuhan (2µg) or commercial Gam-COVID-Vac-rAd26/rAd5 or AZD1222/ChAdOx1 vaccines delivered intramuscularly. Serum collected on Day 14 was analyzed by ELISA to determine the levels of S-specific IgG. Sera titers were obtained by plotting the OD 492 nm vs. log curve of the reciprocal of the dilution in the GraphPad Prism program. Titers of Panel (A) are expressed as the inverse of the inflection point dilution of the curve. For statistical analysis, antibody titers were log-transformed and then analyzed by a one-way ANOVA with Bonferroni’s multiple comparisons test. For all treatments, the titers detected after the second dose were significantly different from those found after the first dose (p<0.0001). Neutralizing titers were measured by 50% inhibition for the pseudotyped virus (CoV2pp-GFP) in immunized and non-immunized mice (B). Absolute inhibitory concentration was calculated as the corresponding point between the 0% and 100% assay controls. Fifty % inhibition was defined by the controls for all the samples on the same plate. Data in panel (B) is presented as the fold change of CoV2pp-GFP related to the minimum value detected in immunized animals. For statistical analysis, one-way ANOVA with Bonferroni`s multiple comparisons test was used. *p < 0.05; ***p<0.001.