Fig. 4: SNVac-L promoted antigen cross-presentation to elicit robust antigen-specific T-cell response.

a Schematic illustration to show the preparation of SNVac for spatiotemporally-tailored antigen cross presentation with innate immune stimulation. b, c DLS analysis and representative TEM images of SNVac. OVA was selected as the model antigen (n = 3 biologically independent replicates). The experiment was repeated three times independently with similar results. Scale bar = 500 nm. d Representative CLSM images to show the SNVac distribution in DC. OVA was labeled with FITC (green), the nuclei and endosome were stained with DAPI (blue) and Lyso-Tracker (red), respectively (n = 3 biologically independent replicates). The experiment was repeated twice independently with similar results. Scale bars = 10 μm. e Quantitative analysis of the frequency of matured BMDC (CD86⁺ in CD11c⁺ cells) (n = 3 biologically independent replicates). The experiment was repeated three times independently with similar results. f The secretion of IFN-β in the supernatant of BMDC (n = 3 biologically independent replicates). The experiment was repeated three times independently with similar results. g Quantitative analysis of the frequency of antigen-presented DC (SIINFEKL-H2Kb⁺ in CD11c⁺ cells) (n = 3 biologically independent replicates). The experiment was repeated three times independently with similar results. h Quantitative analysis of the proliferation level of T cells after co-cultured with BMDC (n = 3 biologically independent replicates). The experiment was repeated twice independently with similar results. i Representative fluorescence images and signal quantification of the idLN after free OVA or SNVac injection (n = 3 biologically independent mice). The experiment was repeated twice independently with similar results. j Representative fluorescence micrographs of the idLN at 6 h after SNVac injection (n = 3 biologically independent mice). The experiment was repeated twice independently with similar results. Scale bars = 100 μm. k Quantitative analysis of the cellular uptake of SNVac by CD11c⁺ DC and CD11b⁺ macrophages in the idLN (n = 3 biologically independent mice). The experiment was repeated twice independently with similar results. l Experimental timeline for the evaluation of SNVac-L-elicited antigen-specific immune response in vivo. m Quantitative analysis of the frequency of activated macrophages (CD80⁺CD86⁺ in CD11b⁺ cells) in the idLN (n = 5 biologically independent mice). n Quantitative analysis of the frequency of matured DC (CD80⁺CD86⁺ in CD11c⁺ cells) in the idLN (n = 5 biologically independent mice). o Quantitative analysis of the frequency of antigen-presented DC (SIINFEKL-H2Kb⁺ in CD11c⁺ cells) in the idLN (n = 5 biologically independent mice). p Quantitative analysis of the frequency of antigen-specific T cells (SIINFEKL-H2Kb tetramer⁺ in CD3⁺CD8⁺ cells) in the spleen (n = 5 biologically independent mice). q Quantitative analysis of the OVA-specific killing effect in vivo (n = 5 biologically independent mice). The ratio of CFSE^high to CFSE^low cells reflects the level of OVA-specific antitumor immunity. r Heatmap of the secretion of TNF-α and IFN-γ by splenocytes after re-stimulation by SIINFEKL peptide (n = 5 biologically independent mice). s Schematic illustration of the SNVac-L-induced antigen cytosolic release and STING pathway activation to promote antigen cross-presentation and T-cell activation. Unless specified otherwise, the data are presented as mean ± SD. Statistical significance was calculated via unpaired two-tailed Student’s t-test (i, k) or one-way ANOVA with Tukey’s test (e−h, m−q), and P-values were indicated. Source data are provided as a Source Data file. The elements in Fig. 4l were created by Adobe Illustrator, and the elements in Fig. 4a, s were created by Adobe Photoshop.