Fig. 5

T cell response of mRNA vaccines modified with different signal sequences. Lymphocytes from the spleen and lymph nodes were collected on day 84, as outlined in Fig. 4A, and subsequently stimulated with SARS-CoV-2 S protein peptide pools. (A) Representative flow cytometry diagrams of IL-6 group and (B) quantifications of intracellular cytokines in CD4⁺ and CD8⁺ memory T cells from the spleen (n = 4) were provided. The gating strategy was detailed in Figure S4. ELISpot assays were conducted to determine the presence of IFN-γ⁺ T cells in (C) spleens and (D) lymph nodes (n = 3), with images and quantitative data shown respectively. The results were presented as the mean ± SEM, n = 3. ^*P < 0.05, ^**P < 0.01, ^***P < 0.001