Figure 6. Protective role of CD8⁺ T cells against ZIKV infection in mice.

LysMCre⁺IFNAR^fl/fl were treated with depleting anti-CD8 or isotype control antibody on days 3 and 1 before infection with 10⁵ FFU of MR766 or FSS13025. Mice were sacrificed and tissues harvested at 6, 8 and 10 days post-infection. The levels of infectious virus in the (A) serum, (B) spleen, (C) brain, and (D) sciatic nerve were quantified using BHK-21 cell-based FFA. A two-way ANOVA test was used to compare the levels of infectious ZIKV between the isotype and the anti-CD8 antibody-administered groups for all time points and tissues. (E) On day 120 after infection with MR766 or FSS13025, 7.5 × 10⁶ CD8⁺ T cells were transferred into 5-week-old naive mice one day before challenge with 10⁵ FFU of MR766 or FSS13025. For controls, CD8⁺ T cells were isolated from naive LysMCre⁺IFNAR^fl/fl mice. Infectious ZIKV was quantified. Mann-Whitney test was used to compare naïve CD8⁺ T cells vs. ZIKV-immune CD8⁺ T cells. (F) Seven-week-old WT and CD8α^−/− were treated with 2 mg of IFNAR-blocking antibody at day -1, and then inoculated subcutaneously with 10⁵ PFU of mouse adapted Dakar 41519 ZIKV strain at day 0. Survival was monitored for 21 days in both groups and reported for WT (n=15, Black square) and CD8^−/− (n=11, Red circle) mice. Pooled data from three independent experiments are represented and the log-rank (Mantel-cox) test was used to compare groups.