Extended Data Fig. 3: BBV152-induced memory B cells correlates with antibody titers and persisted in circulation at least up to 6 months post-vaccination.
The RBD-specific memory B cells were enumerated in the R848 + IL2 stimulated B cells utilizing the antigen-specific ELIspot analysis. Representative ELIspot images of IgG+, IgM+ and IgA+ memory B cells against RBD of ancestral SARS-CoV-2 and its variants in (a) vaccinated and (b) recovered COVID-19 subjects. ‘Total’ represent the frequency of total B cells captured using anti-IgG, -IgM or -IgA antibody. Proportion of SARS-CoV-2-RBD-specific antibody secreting cells (ASCs) was measured by calculating the percentage of antigen-specific B cells in the total corresponding isotype of ASCs in 1 million PBMCs. Correlation of RBD-specific IgG+ memory B cells with (c) RBD binding IgG, (d) pseudovirus neutralizing antibodies, and (e) persistence of IgG+ memory B cells over the days post vaccination, and (f) RBD binding IgG, (g) pseudovirus neutralizing antibodies, and (h) persistence of IgG+ memory B cells over the days post-diagnosis of COVID-19, in BBV152 vaccination and recovery from mild COVID-19, respectively. Dotted line represents the cut-off for positivity. Statistics by (c-d, f-g) two-tail Pearson correlation coefficient. ns: non-significant.
