Figure 5. Persistence of GC B cells and local and systemic memory B cells is favored by the wP vaccine.

(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 50 days after boost injection. Cell numbers of EYFP⁺ GCs (B) and cell numbers and isotype distribution of total GC B cells (C) or EYFP⁺ memory B cells (D) were assessed by flow cytometry in dLNs and reported in the graphs. (E) Cell numbers and isotype distribution of EYFP⁺ memory B cells were assessed by flow cytometry in spleen. Numbers of IgG1⁺ ASCs against pooled proteins (PT, PRN, FHA, Fim2,3) (F) or numbers of IgG1⁺ and IgG2⁺ ASCs against sonicated Bp (G) were determined by a memory B cell ELISPOT assay performed 5 days after in vitro activation of splenocytes in the presence of IL-2 and R848. Each point in the graphs 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.