Figure 4. wP:wP prime:boost vaccination is highly efficient at producing secondary B cell responses, including GCs, PCs, and systemic memory B cells, shortly after the boost.

(A) AID-Cre-EYFP mice were primed and boosted (day 30) with homologous and heterologous combinations of the aP and wP vaccines or injected with alum (ctr). Three doses of tamoxifen were administrated at days 7, 10, and 31. Mice were analyzed at day 35. Total cell numbers and isotype distribution of EYFP⁺ GC (B) or EYFP⁺ memory (C) B cells were determined by flow cytometry in dLNs. (E) Cell numbers (relative to 10⁵ splenocytes) and isotype distribution of EYFP⁺ memory B cells were determined by flow cytometry in the spleen. EYFP⁺ PCs were assessed by flow cytometry in dLNs (D) or spleen (F), and cell counts were reported similarly in the graphs. Each point in the plots represents an individual mouse. At least 2 independent experiments were performed for each analysis. Means (±SEM) are shown. Kruskal-Wallis analysis with uncorrected Dunn’s test was performed to compare the different conditions. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.