Fig. 3: Humoral immune responses in ICO-RBD nanovaccine-immunized BALB/c mice. | Nature Communications

Fig. 3: Humoral immune responses in ICO-RBD nanovaccine-immunized BALB/c mice.

From: Rationally designed multimeric nanovaccines using icosahedral DNA origami for display of SARS-CoV-2 receptor binding domain

Fig. 3

a Schematic illustration of the vaccination schedule and grouping information. The mice were randomly divided into 8 groups and were priming- and boost-vaccinated with the indicated vaccines containing prototype RBD at week 0 and 3, respectively. The red drop symbols indicate blood sampling and sera collection. SARS-CoV-2 RBD-specific IgG titers in serum, measured at week 2 (b) and 5 (c) by ELISA (n = 8 mice). Spycatcher-RBD proteins (prototype) were used to coat 96-well ELISA plates. d Time-titer curves of RBD-specific IgG titers measured every 3 weeks (n = 8 mice). e, f Pseudovirus neutralization test of the sera collected at week 5 and 14, as represented by the inhibitory dilution value to achieve 50% neutralization (ID50; n = 6 mice). g Percentages of RBD+ cells in IgG+ MBCs (B220+CD38+) in splenocytes at week 14, as detected by flow cytometry (n = 6 mice). h Percentages of central memory T cells (CD44+CD62L+) in CD3+CD8+ T cells in splenocytes at week 14, as detected using flow cytometry (n = 6 mice). i Percentages of effector memory T cells (CD44+CD62L-) in CD3+CD8+ T cells in splenocytes at week 14, as detected using flow cytometry (n = 6 mice). j, k Percentages of LLPCs (EpCAMhiCXCR3−) in RBD+ bone marrow plasma cells (BMPCs, B220-CD138+) and RBD+ splenic plasma cells (SPPCs, B220-CD138+) at week 30, as detected using flow cytometry (n = 6 mice). l Serum titers of IgG against variants, measured at week 5 by ELISA (n = 8 mice). Different RBD proteins were used to coat 96-well ELISA plates, including prototype (Wuhan-Hu-1 strain), Alpha [B.1.1.7], Beta [B.1.351], Gamma [P.1], Delta [B.1.617.2] and Omicron [BA.1, BA.2, BA.2.75, BQ.1.1, XBB and XBB.1.5]. The data are presented as the mean ± SEM in panels b–f and l, and the mean ± SD in panels g–k. The data were processed on GraphPad Prism 8. Statistical significance (P value) was calculated by one-way ANOVA followed by Tukey’s test in panels b, c and e–k, a two-tailed unpaired t test in panel l. **P < 0.01; ***P < 0.001. ns, P > 0.05, no significant difference. Source data are provided as a Source Data file.

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