Fig. 1

Figure 1. ZIKV infects one-cell stage embryo. The infection (n = 98) was performed by microinjecting embryos at 0 hpf with approximately 2 or 3 nL of ZIKV^BR (1 × 10⁷ PFU/mL, 2 a.p.) utilizing a M205C stereomicroscope coupled with an Injectman^® 4 microinjector. Another group (n = 83) was left without injection and formed the negative control group. Embryos were incubated in E2 0.5× medium at 28 °C, and viral RNA extracted from entire larvae was used for measurements via real-time quantitative PCR (qRT-PCR) after 3, 6, 12, 24, 48, and 72 hpf of the Zika viral load (A). Then, 72 hpf-infected larvae were sampled for qRT-PCR analysis of (B) IFNφ1, IFNφ3, and IFNφ4. cDNA was used in qRT-PCR reaction using primers specific for zebrafish, IL-1, TNF, IL-6, IL-8, and IL-34 (C), and iNOSa, iNOSb, NOX1, and NOX2 (D). The relative expression was normalized to the expression of EF-1a or GAPDH, and it is expressed as fold induction relative to the expression level in the control group (dotted line). For the analysis of gene expression, genes with fold change ≥1.5 were considered differentially expressed. ZIKV infection led to 14 and 16% of mortality (E), and a reduction of 17% of the head size was observed in ZIKV-injected larvae (F). Each bar represents the mean ± SEM. * p < 0.05 compared with the negative control group.