Fig. 2: Intranasal immunization with the two-component vaccine elicits superior mucosal and systemic cellular immune responses compared with Ad5_XBB.1.5 alone.

a, Left: representative flow cytometry graphs showing antigen-experienced CD8⁺ T_RM cells induced by Ad5_XBB.1.5 or the two-component vaccine. Right: the absolute number of CD8⁺ T_RM cells in BALF analysed by flow cytometry. Antigen-experienced T_RM cells were gated on CD44⁺CD69⁺CD103⁺. b, Absolute numbers of antigen-experienced CD4⁺ T_RM cells in BALF. c, ELISpot analysis of IFNγ-SFCs in BALF samples after stimulation with peptide pools of SARS-CoV-2 XBB.1.5 spike. d,e, Representative graphs and quantitative percentages of XBB.1.5 spike-specific IFNγ (d) and TNF (e)-producing memory T cells in lung tissue were analysed after stimulation with XBB.1.5 spike peptide pools. f,g, Frequency of T follicular helper cells (CD4⁺CXCR5⁺PD-1⁺) (f) and RBD_XBB.1.5-specific germinal centre B cells (CD19⁺GL7⁺CD95⁺) (g) in mediastinal lymph nodes (mLN). h, IFNγ-SFCs among splenocytes after stimulation with XBB.1.5 spike peptide pools. All tissue samples in Fig. 2, including BALF, lung, mLN and spleen samples, were collected at week 11 after the first immunization. In a–h, n = 6 mice per group; data are presented as mean ± s.e.m. P values between the RBD_XBB.1.5-HR and Ad5_Empty + RBD_XBB.1.5-HR groups, as well as between Ad5_XBB.1.5 and Ad5_XBB.1.5 + RBD_XBB.1.5-HR were calculated using two-tailed unpaired Student’s t-tests. NS, not significant.

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