Fig. 4: RBD-HR/trimer vaccine induced strong T cell immune response in vivo.

a The levels of IFN-γ and IL-4 in the supernatants of spleen lymphocytes from immunized mice were detected by ELISA after stimulation with RBD (10 μg/ml) for three days. b, c The number of RBD-specific IL-4 or INF-γ-producing memory T cells in spleen were analyzed by flow cytometry after stimulation with RBD. Memory T cells were gated on CD44^high B220⁻MHC-II⁻ CD4⁺ or CD8⁺. d The percentage of effector memory (CD44⁺CD62L⁻) of CD4 or CD8 T cells in spleen. e The percentage of central memory (CD44⁺CD62L⁺) of CD4 or CD8 T cells in spleen. f The frequency of T follicular helper cells (CD4⁺CXCR5⁺PD-1⁺) and germinal center B cells (CD19⁺GL7⁺CD95⁺) in spleen were analyzed by flow cytometry. n = 5 mice each group in a–f. Spleen samples in a–f were collected on day 49 after the first vaccination, and isolation of lymphocytes was performed as described in Methods. Data are presented as mean values ± SEM. P values were conducted by one-way ANOVA analysis followed by Tukey’s multiple comparison post hoc test in a–f. Source data are provided as a Source Data file.