Figure 5.

Frequency of B cells and fold increase in the frequency of GC B cells in the lymph nodes (LNs) of immunize mice: C57BL/6 mice were immunized i.m. with MERS-RBD-Fd with or without alum and rASP-1 alone or together using different combinations and/or formulations (Table 1 and X-axis legend). The draining LNs were harvested on day 7 post-2nd immunization and the frequency of GC B cells per LN was analyzed. (A) Representative flow cytometry plot in each immunization group. (B) The frequency B cells per LN as well as (C) the fold-increase in the frequency of GC B cells per LN was analyzed. The frequency of GC B cells per LN in all the adjuvanted-vaccine groups was normalized against the RBD vaccine group (G2). (D) The fold increase in the frequencies of GC B cells per LN in groups G5 and G6 were correlated with the NT₅₀ titers determined in each serum sample of the corresponding mice. The experiment was repeated at least twice with 3 to 5 mice per group and the data are represented as mean and standard error. “+” indicates the presence and “−“ indicates the absence of the protein or adjuvants in the formulation. Statistics was performed using one-way ANOVA with Tukey’s multiple comparison. p < 0.05: *, p < 0.01: **, p < 0.001: ***, p < 0.0001: ****. Spearman correlation was performed to determine the association of GC B cells with neutralizing antibody titers.