Fig. 2: BBV152 generates memory B cells with potent cross-reactivity to SARS-CoV-2 variants.
a, Experimental design for measuring SARS-CoV-2-specific memory B cells and their isotype in FluoroSpot assay utilizing the PBMCs from vaccinated (BBV152, n = 39) and recovered (COVID-19, n = 24) individuals. b–d, Proportion of SARS-CoV-2-RBD-specific ASCs calculated in the total corresponding isotype of ASCs in 1 million PBMCs for IgG+ ASCs (b), IgA+ ASCs (c) and IgM+ ASCs (d) in vaccination and infection. Black bars indicate median. e–j, Comparison of the frequency of ancestral SARS-CoV-2 RBD-specific memory B cells and their reactivity to RBD protein of variants Alpha, Beta, Gamma and Kappa for IgG+ ASCs (e), IgA+ ASCs (f) and IgM+ ASCs (g) in BBV152, and for IgG+ ASCs (h), IgA+ ASCs (i) and IgM+ ASCs (j) in COVID-19. k,l, In a subset of samples, reactivity of RBD-specific memory B cells of all three isotypes was determined against the Delta variant in BBV152 (k) (n = 17) and COVID-19 (l) (n = 7). Fold reduction in RBD-reactive B cells against variants over the RBD-specific B cells to ancestral virus is depicted at the top of the graph for each variant. m, Comparison of the quantitative reduction in IgG+ memory B cells against multiple variants between vaccination and natural infection. Dotted lines represent the cut-off over the threshold of memory B cell isotypes observed in PBMCs from pre-pandemic healthy donors. Schematic in a was created using Biorender. Statistics by two-tailed Mann-Whitney test (b–d), one-way ANOVA followed by Dunnett’s multiple comparisons (e–j) and two-tailed Wilcoxon signed-rank test (k,l).
