Panel A shows diagram of the experimental protocol illustrating the timeline of immunization and analysis. Panel B shows line graph of ELISA quantification of anti RBD antibodies in serum measured every 3 to 5 days from day 0 to day 150 with vertical axis anti RBD total immunoglobulin BT50 and horizontal axis days post prime. Panel C shows line graph of ELISA quantification of immunoglobulin G anti RBD antibodies over the same period with vertical axis anti RBD immunoglobulin G BT50 and horizontal axis days post prime. Panel D shows scatter plot of serum anti RBD immunoglobulin M ELISA at day 0 and day 14 with vertical axis anti RBD immunoglobulin M BT50 and horizontal axis days post prime. Panel E shows flow cytometry gating of CD38 negative CD95 positive germinal center B cells pre gated on B220 positive cells in draining lymph nodes. Panel F shows scatter plot quantifying germinal center B cells over time with vertical axis percentage of germinal center B cells of B220 positive cells and horizontal axis days post prime. Panel G shows flow cytometry gating of Caspase 3 positive cells among CD138 intermediate to positive live dump negative cells. Panel H shows scatter plot quantifying Caspase 3 positive cells among CD138 intermediate to positive live dump negative cells with vertical axis percentage of Caspase 3 positive cells and horizontal axis mouse groups. Panel I shows flow cytometry gating of CD98 positive CD138 positive plasma cells pre gated on live dump negative cells in draining lymph nodes. Panel J shows scatter plot quantifying plasma cells over time with vertical axis percentage of plasma cells of live lineage negative cells and horizontal axis days post prime. Panel K shows flow cytometry gating of RBD positive cells among germinal center B cells in draining lymph nodes. Panel L shows scatter plot quantifying RBD positive cells over time with vertical axis percentage of Wu Hu 1 RBD positive cells of germinal center B cells and horizontal axis days post prime.
Primary vaccine responses. (A) Diagram of the experimental protocol. (B) ELISA quantification of anti-RBD antibodies in the serum measured every 3–5 days between day 0 and day 150. (C) As in B for IgG anti-RBD antibodies in the serum. Thin lines in B and C represent single mice; bold lines represent group mean. (D) Serum anti-RBD IgM ELISA 0 or 14 days after immunization. (E) Flow cytometric gating for CD38−CD95+ GC B cells pregated on B220+ cells in dLNs. (F) Quantification of GC B cells from E at the indicated time points after immunization. (G) Flow cytometric gating for caspase 3+ cells among CD138int/+ live Dump− cells. (H) Quantification of G among CD138int/+ live Dump− cells in dLNs 14 days after immunization. (I) Flow cytometric gating for CD98+ CD138+ PC pregated on live Dump− cells in the dLN. (J) Quantification of I at the indicated times after immunization. (K) Flow cytometric gating of RBD+ cells among GC B cells in the dLNs pregated for GC as in E. (L) Quantification of K at the indicated time points after immunization. Each dot in all dot plots represents one mouse. P values of nonparametric one-way ANOVA are shown. All experiments were performed at least twice. Additional day 28 data are presented in Fig. S2 B, C, and E. Bars in D, F, H, J, and L indicate the mean ± SD. **P < 0.01, *P < 0.05. dLNs, draining LNs.