Fig. 2: Neutralizing antibody and antigen-specific memory B cell responses.

Participants were vaccinated with Ad5-CoV5T, mbO5 or Ad5-nCoV on day 0, serum samples were collected at week 0, 2, 4, 12, and 24 for antibody detection, PBMCs were collected at week 0, 4, and 24 for RBD or spike-specific memory B cell detection. Serum SARS-CoV-2 XBB.1.5 (a) and BA.5.2 (b) live virus neutralizing antibody titers over time. Dotted lines indicate the limit of detection for the assay, titers below the limit were assigned a value of 2. Bars show geometric mean values with the 95% confidence interval (CI). c Frequencies of SARS-CoV-2 RBD- or spike-specific (WT⁺ or BA.5⁺ or XBB.1.5⁺) memory B cells over time. Bars show geometric mean values with the 95% CI. d Multi-reactivity profiles of RBD-specific memory B cells. Frequencies (e) and percents (f) of WT⁺ BA.5⁺ XBB.1.5⁺, WT⁺ BA.5⁺ XBB.1.5^-, WT⁺ BA.5^- XBB.1.5⁺, WT^- BA.5⁺ XBB.1.5⁺, WT⁺ BA.5^- XBB.1.5^-, WT^- BA.5⁺ XBB.1.5^- and WT^- BA.5^- XBB.1.5⁺ RBD-specific memory B cells over time. Plots show geometric mean values with the 95% CI in (e) and mean values with the 95% CI in (f). Statistics in (a, b, e, f) were calculated using unpaired nonparametric two-tailed Kruskal-Wallis test with Dunn’s correct for multiple comparisons. Statistics in (c) were calculated using paired nonparametric two-tailed Friedman test with Dunn’s correct for multiple comparisons. N = 26 for Ad5-CoV5T group, n = 29 for mbO5 group and n = 27 for Ad5-nCoV group. The neutralizing antibody detection was measured in duplicate, the antigen-specific memory B cell detection was measured in a single tube per sample due to the limited number of PBMCs. P-values marked in red in (e, f) indicate comparisons between Ad5-CoV5T group and mbO5 group, p-values marked in blue indicate comparisons between Ad5-nCoV group and mbO5 group.