Fig. 6.

Neuronal migration is impaired during ZIKV infection. (A) Plasmid encoding GFP DNA was electroporated into E19 brains ex utero before production of slice cultures. Twenty-four hours later, the slice cultures were infected with 10⁵ pfu of the indicated ZIKV isolates and at 4 dpi, were fixed and stained with pan-flavivirus antibody against the E glycoprotein (ZIKV-E), antibody against cortical layers 2–4 marker Tbr1, and DAPI. ZIKV infection appeared to limit neuronal precursor migration into the most superficial layers (corresponding to layers 2/3). (Scale bar: 250 µm.) (B) The cortical plate was divided into six regions of equal size, and the percentage of GFP fluorescent intensity in each sector over the whole six sectors was calculated. (C) Distribution of GFP positive cells within each sector for mock and ZIKV-infected slices. The number 1 is the pial surface, and 6 is the deepest cortical plate layer. ZIKV infection significantly reduced the number of neuronal precursors migrating into the outer neocortex (bin 1) and significantly increased the number of neuronal precursors remaining in the inner neocortex (bin 6). Data represented as mean ± SEM for each condition in each bin in C. Unpaired t test was used to determine significance (*P < 0.05, n = 3 embryonic brains across different replicate experiments). (D) Sections from A were stained with antibody against the E glycoprotein (ZIKV-E) and antibody against vimentin to mark the radial glia progenitor (RGP) basal processes, which are the fibers upon which bipolar neurons migrate, and with DAPI. ZIKV infection perturbed the RGP scaffold compared with control slices. (Scale bar: 250 μm for A and D.)