Figure 6. Pre-exposure to DENV results in lower activation of B and T cells.

(a) Frequency of activated B cells (CD20⁺CD3⁻CD14⁻CD69⁺) were statistically higher compared to their basal level in the naïve cohort at 24 and 48 h.p.i. (b,c) T cells were measured by flow cytometry 0, 1, 2, 7, 10 and 15 d.p.i of ZIKV. (b) CD4 T cells (CD3⁺CD4⁺CD69⁺) showed statistically higher activation at 24 and 48 h and on days 10 and 15 p.i. in the naïve compared to their own baseline values while DENV-immune macaques had higher frequency only at 24 and 48 h p.i. Comparison of frequency of activation of B and CD4⁺ T cells inside cohorts related to their own baseline values was performed using a two-tailed unpaired t-test with Sidak–Bonferroni correction. (c) CD8 T cell (CD3⁺CD8⁺CD69⁺) subsets showing significant higher frequency in naïve cohort at 24 and 48 h and on days 7 and 10 p.i. Comparison of frequency of activation of CD8⁺ T cells between two cohorts was performed using a two-tailed unpaired t-test with Sidak–Bonferroni correction. Median values are shown in orange and black lines for DENV-immune and naïve macaques, respectively. Black circles represent individual naïve macaques, and blue and magenta squares represent individuals previously exposed to either DENV-1 or DENV-2, respectively.