Fig. 3. Induction of potent cellular immunity by COReNAPCIN^®.

Mice were i.m. injected at days 0 and 21 with 0.05 (light pink), 0.5 (pink) or 3 µg (purple) of COReNAPCIN^®. Animals in the control group received PBS injection (gray). Splenocytes from five mice each group, were collected at day 21 post boost and subjected for the following assays. a–g Following stimulation with SARS-CoV-2 Spike peptide pool for 8 h, the frequency of Spike specific CD44 ^high IFN-γ⁺cells (b, c), CD8⁺ IFN-γ⁺ cells (d, e) and CD4⁺ IFN-γ⁺ cells (f, g) in both mouse strains, were quantified using flow cytometry. Representative dot plots in (a) showing flow cytometry gating summary used for measuring IFN-γ-producing Spike specific T cell populations in C57BL/6 splenocytes. h, i BALB/c splenocytes were restimulated with two SARS-CoV-2 Spike peptide pool (S1 and S2) for 18 h and IFN-γ-secreting T cells were quantified with an ELISpot assay. In (h), the representative images of ELISpot wells, columns from left to right are: responses of splenocytes to S1 SARS-CoV-2 peptide pool (as duplicate), S2 SARS-CoV-2 peptide pool (as duplicate), DMSO (a negative control), and PHA (an unspecific positive control). Each row represents an individual mouse.). In bar plots, each data point is shown and the height of each bar represents the mean. All statistical analyses were performed using one-way ANOVA followed by multiple comparisons Dunn’s post-hoc test. A p value less than 0.05 (*P < 0.05, **P < 0.01, ***P < 0.001) was assumed to be statistically significant.