Figure 4. ZIKV infection induces apoptotic cell death in NPC cultures.

(A) Confocal microscopy of mock and ZIKV-infected NPC stained for cleaved caspase-3 (Casp3; red), DAPI (nuclei; blue), and ZIKV (in green). Scale bars = 20 μm. (B) Flow cytometry analysis for detection of apoptosis by Annexin V and 7AAD staining 48 h after mock or ZIKV infection. (C) Activity of caspases 3/7, 8 and 9, in mock- and ZIKV-infected cultures was determined using luminescence assays after 24 or 48 h of culture. Data represented as mean ± SEM. *p < 0.05; **p < 0.01; ***p < 0.001. (D) Flow cytometry analysis showing the percentage of Sox2⁺ cells in mock-infected and in ZIKV-infected cultures, in the absence and in the presence of Z-VAD (50 μM), 48 h after infection. (E) Quantification of viral RNA in cell pellets by RT-qPCR 24, 48 and 72 h after ZIKV infection in the presence of Z-VAD (50 μM). Data were normalized using an endogenous control gene (GAPDH), and are represented as mean ± SEM. *p < 0.05; **p < 0.01.