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. 2021 Nov 17;24(12):103379. doi: 10.1016/j.isci.2021.103379

Figure 6.

Figure 6

Intranasal immunization of mice with BC-PIV/S-2PM elicited nasal wash IgA antibody against RBD of SARS-CoV-2 S, together with neutralizing IgG antibody against RBD of the S

IN, intranasal; IM, intramuscular administration.

(A) Timeline and protocol of the vaccination. Four independent experiments gave similar results, and one representative result is shown in panels (B–E).

(B) A comparison of the efficacy of the vaccine injection route. One-shot vaccination was performed for serum IgG ELISAs with S1 and RBD, respectively, at day 28 after immunization (n = 3 for each group). IM, intramuscular route; IN, intranasal route. The endpoint dilutions of the antibody titer of each mouse in ELISAs are shown. Bars indicate mean values. The Kruskal–Wallis test with the Dunn's post hoc test with Holm–Bonferroni p value adjustment was used. ∗p < 0.05.

(C) Prime and boost intranasal vaccination of mice with BC-PIV/S-2PM elicits a higher serum IgG antibody titer against S1 and RBD, respectively, than single-shot vaccination (n = 5 or 6 for each group). 1x, prime alone; 2x, homologous prime and boost. The endpoint dilutions of the antibody titer of each mouse in ELISAs are shown. Bars indicate mean values. The Kruskal–Wallis test with the Dunn's post hoc test with Holm–Bonferroni p value adjustment was used. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001.

(D) Prime and boost intranasal vaccination of mice with BC-PIV/S-2PM elicits higher nasal wash IgA antibody titers against S1 and RBD, respectively, than single-shot vaccination. 1x, prime alone; 2x, homologous prime and boost. PBS (700 μL) was used to flush the nasal mucosa in each vaccinated mouse and then subjected to further dilution for an ELISA (n = 5 or 6 for each group). The endpoint dilutions of the antibody titer of each mouse in ELISAs are shown. Bars indicate mean values. The Kruskal–Wallis test with the Dunn's post hoc test with Holm–Bonferroni p value adjustment was used. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001.

(E) The induction of serum neutralizing activity from intranasally vaccinated mice was revealed by the inhibition of the binding between hACE2 and RBD of SARS-CoV-2 S (SARS-CoV-2 surrogate virus neutralization test). Homologous prime and boost immunization (2x) was carried out (n = 4 for each group). The numbers 1–4 represent each individual mouse.