Fig. 9: Persistence of vaccine-induced neutralizing antibodies and T-cell responses in COVISHIELDTM (n = 10) vaccinees.
a Antibody IgG levels to nucleocapsid and spike protein of SARS-CoV-2 were measured at baseline (BL), 2 weeks (Wk), 3-, 6- and 12-months (M) post-vaccination (PV) in serum samples by MSD V-PLEX COVID-19 Coronavirus Panel 1 (IgG). b Neutralizing antibody (% inhibition) against ancestral spike protein measured at baseline (BL), 2 weeks (Wk), 3- and 12-months (M) post-vaccination (PV) in serum samples by MSD V-PLEX SARS-CoV-2 panel 25 (ACE2). Assay cut-off value is denoted in purple and highest pre-pandemic cut-off in black. Whole Blood collected at baseline (BL), 2 weeks (wk), 3- and 12-months (M) post-vaccination were stimulated with spike peptide pool (1 µg/ml) for 20 hr. CD4+ and CD8 + T-cells were analyzed for intracellular expression of total cytokine+ cells (IFN-γ or IL-2 or TNF-α) obtained from Boolean gating in FlowJo. One-way ANOVA and Friedman test with Dunn’s multiple comparisons test was used. c Correlations between total cytokine+ T-cells and corresponding neutralizing antibody responses against SARS-CoV-2 Wuhan Spike. Spearman’s correlation coefficient (r) and significance values (P) are indicated. Longitudinal multifunctional spike-specific d CD4+ and e CD8 + T-cells in vaccinees. Boolean gates were created from the individual cytokines (IFN-γ, IL-2, TNF-α) in FlowJo to divide responding cells into 7 distinct subsets corresponding to all possible combinations of these functions. The data was subsequently plotted using SPICE software. Statistical significance was analyzed using Wilcoxon signed-rank sum test. Background subtracted and log data analyzed in all cases. P < 0.05 was considered statistically significant.
