FIG 1.

ZIKV replication is reduced in IRE1α knockout cells. (A) The IRE1α knockout A549 cells were generated by the CRISPR/Cas9 technique. Two different knockout cell lines (IRE1α^Ko-1 and IRE1α^Ko-2) were confirmed by Western blotting. (B) Confirmation of IRE1α knockout efficiency by DNA sequencing. (C to F) Viral replication levels in IRE1α^Ko A549 cells. Control cells and IRE1α^Ko cells were infected with ZIKV at an MOI of 3. Then, the cells were harvested at 24 h p.i. for qRT-PCR (C), Western blotting (D), flow cytometry (E), and plaque assay (F). (G) Multistep virus growth assay. Control cells and IRE1α^Ko cells were infected with ZIKV at an MOI of 0.01. The supernatants were collected at 24, 48, 72, and 96 h p.i. for the measurement of viral titers by standard plaque assay. Human β-ACTIN mRNA level was measured as an internal control for qRT-PCR. Data are shown as means ± SD from at least three independent experiments. ##, P < 0.01; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 (unpaired, two-tailed Student t test).