Fig. 3.

Inhibition of the binding of S protein to hACE2. ECD-Nano (A), S1-Nano (C), and RBD-Nano (E) were added to 293T-hACE2 cells in the presence or absence of antisera at a dilution ratio of 1:10. Confocal fluorescence analysis confirmed that all three nanoparticles could specifically bind to hACE2 due to the presence of the RBD structure. After treatment with the corresponding antiserum, the colocalization signal was significantly weakened, which indicated that the antibody production induced in mice immunized with the nanoparticle vaccine had a certain neutralizing effect. The yellow area/green area of each group was analyzed and is shown in B, D and F. n = 3; error bar, SEM; ** p < 0.01, *** p < 0.001, **** p < 0.0001.