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[Preprint]. 2021 Mar 10:2021.02.05.21251182. [Version 2] doi: 10.1101/2021.02.05.21251182

Figure 2. A single dose of a spike-derived mRNA vaccine elicits a strong recall response.

Figure 2.

IgG (A), IgA (B) and IgM (C) end-point antibody titers specific to the receptor binding domain of the Wuhan-Hu-1 variant were measured in serum collected from donors previously infected with SARS-CoV-2 before and after one or two immunizations with the Pfizer/BioNTech or Moderna mRNA vaccines by ELISA, as indicated. Endpoint titers measured in sera from uninfected donors following two vaccine doses are shown for comparison (gray dots). (D) Frequency of Wuhan-Hu-1 RBD-specific IgG+ memory B cells (live, IgD−, CD19+, CD20+, CD3−, CD14, CD56−, singlet, lymphocytes) in PBMC from previously infected donors was measured before and after one or two immunizations. The frequency of S6P-specific IgG+ (E) and IgA+ (F) memory B cells in PBMC previously infected donors were measured before and after one or two immunizations. The frequency of memory B cells from uninfected donors following two vaccine doses are shown for comparison in D-F (gray dots). (G) The frequency of S-specific CD4+ T cells expressing IFN-γ and/or IL-2 and/or CD40L in PBMC from previously infected donors was measured before and after one or two immunizations. The frequency of S-specific CD4+ T cells in PBMC from uninfected donors following two vaccine doses are shown for comparison (gray dots). Experiments were performed once. Significant differences in infected donors before or after vaccination (A-D) or between pseudoviruses (E) were determined using a Wilcoxon signed rank test (*p<0.05, ** p<0.01 and ***p<0.001). Significant differences between previously infected and uninfected donors (A-D) were determined using a Wilcoxon rank sum test (*p<0.05, **p<0.01 and **p<0.001).