Fig 3.

Squalene emulsion elicits a rapid germinal center (GC) B cell response when formulated with pre-fusion stabilized (S-2P) spike protein. Mice were immunized with a single dose of unadjuvanted spike trimer protein or formulated in CAF01, aluminium hydroxide (AH) or squalene emulsion (SE) and GC B cell responses measured in the draining lymph node at seven days post immunization. a) GC B cell responses measured by flow cytometry (gated on Live B220⁺CD38⁻GL7⁺ cells). b) T follicular helper (Tfh) cells (gated on live B220-CD4+PD-1+CxCR5+ cells). Bars show mean ± SEM. Statistically significant differences are indicated by *, ** and *** (Kruskal Wallis test, using the spike trimer alone group as reference and significance levels of p < 0.05, p < 0.01 and p < 0.001 respectively). Figures represent five to ten mice per group from one experiment.