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. 2023 Jun 29;8:96. doi: 10.1038/s41541-023-00691-1

Fig. 8. Longevity of humoral immune responses induced by IN immunization.

Fig. 8

The longevity of the induced humoral immune responses was measured in 8-week old mice given three IN immunizations at a 4-week interval with 10 μg RBD with either NE or NE/IVT. a Serum RBD-specific IgG titers were followed for 25 weeks after the last boost. Neutralizing antibody titers in sera were compared between the (b) NE/10 RBD, or (c) NE/IVT/10 RBD groups 6 or 25 weeks after the final immunization. Titers were measured against WT, B.1.617.2, B.1.351, and B.1.1.529 SARS-CoV-2 variants using lentivirus pseudoviruses. (data shown as mean ± SEM (n = 5/grp)); (*p < 0.05, **p < 0.01 by Mann–Whitney U test shown in Supplementary Table 1).