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. 2023 Feb 23;41(13):2184–2197. doi: 10.1016/j.vaccine.2023.02.057

Fig. 7.

Fig. 7

AKS-452 PBMC assessment of SP/RBD-specific T cell responses via IFN-γ ELISPOT assay. The IFN-γ ELISPOT assay was used to quantitate the frequency of SP/RBD-specific IFN-γ-producing T cells in PBMC samples stimulated by the SP/RBD of Original Washington, Delta, or Omicron SARS-CoV-2 strains. PBMC samples were obtained from subjects who received AKS-452 (cohorts 1 and 2) or mRNA 1273 (Moderna; 2 doses 28 days apart) vaccines collected at days 0, 28 (for cohort 1), 56 (for cohort 2), 90 and 180. For each subject’s sample, the mean of triplicate spot-forming cells (SFCs) of negative control DMSO cultures was subtracted from the mean of triplicate SFCs of SP/RBD-stimulated cultures to generate the net-SFC value. Reported is the ratio (Stimulation Index; SI) of the mean net-SFCs from each post-vaccination day divided by the mean net-SFC of the respective day 0 for each subject’s sample. A “positive responder” sample was defined as having an SI of at least 2 and an increase in the total number of net-SFCs ≥ 25 per 106 PBMCs, and the proportion (and percentage) are reported per cohort per timepoint. For each viral variant, log-transformed SI values of responders (log10 SI values > 1) were subjected to an ANOVA model with “cohort” and “day” as fixed effects and a “random subject effect” in which p values were adjusted for multiplicity (Tukey-Kramer between days within a cohort); *, p ≤ 0.05; **, p ≤ 0.01; ***, p ≤ 0.001; ****, p ≤ 0.0001. Comparisons for day 180 mean SI values among Cohorts 1, 2, and mRNA1273 were evaluated using a correction for multiplicity (Dunnett) that showed no significant differences.