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. 2022 May 10;8:43. doi: 10.1038/s41421-022-00411-4

Fig. 1. Intranasal administration of IPRF-induced robust IgG and IgA responses against SARS-CoV-2.

Fig. 1

C57BL/6 mice (n = 10) were i.n. immunized with 10 μg IPRF, equal molar of RBD, or PBS. a Antibody levels in sera of immunized mice were evaluated weekly after prime and boost vaccination. b The viral neutralization antibody titer (NAbs) of vaccinated sera and nasal mucosal collected on day 42 was evaluated using a pseudovirus neutralization assay. c The hACE2-transgene mice (n = 10) were i.n. immunized with 10 μg IPRF, equal molar of RBD or PBS twice on days 0 and 14. Mice were challenged with authentic SARS-CoV-2 6 weeks post the boost dose. Five mice in each group were euthanized 2 days post challenge. The other five mice in each group were euthanized 1 week post challenge. Viral RNA copies in the lung of each mouse were determined by qRT-PCR and plotted as log10 copies per mL. d–f C57BL/6 mice (n = 10) were i.n. or i.m. immunized with 10 μg IPRF. d RBD-specific IgA response in sera and nasal mucosal homogenate supernatant on day 42 was measured by ELISA. e Vaccinated mouse nasal mucosal collected on day 42 was evaluated using a WT pseudovirus neutralization assay. f The neutralization activity was evaluated using an Omicron pseudovirus neutralization assay. g The hACE2-transgene mice (n = 8) were i.n. or i.m. immunized with 10 μg IPRF or PBS twice on days 0 and 14. Mice were challenged with authentic SARS-CoV-2 12 weeks post the boost dose. Mice in each group were euthanized 3 days post challenge. Viral RNA copies in the nasal of each mouse were determined by qRT-PCR and plotted as log10 copies per mL. The data shown are presented as mean ± SEM. P values were determined by one-way ANOVA with multiple comparison tests. ns, not significant; *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.