Fig 2.

IRE1α is required for optimal HCoV-OC43 infection. (A–C) HCT-8 cells were transfected with siRNA targeting IRE1α or non-targeting control siRNA and then infected with HCoV-OC43 at an MOI of 0.01. RNA was harvested 48-hour post-infection, and the relative abundance of spliced XBP1 (A), ERDJ4 (B), and HCoV-OC43 viral RNA (C) were determined by quantitative RT-PCR. (D–H) HCT-8 cells were treated with IRE1α nuclease inhibitor 4μ8C, structurally similar negative control AMC or DMSO solvent control prior to infection with HCoV-OC43 at an MOI of 0.01 (D–F) or an MOI of 1 (G–H). RNA was harvested 48-hour post-infection (D–F) or at the indicated time point (G and H), and the relative abundance of spliced XBP1 (D), ERDJ4 (E), and HCoV-OC43 viral RNA (F–H) was determined by quantitative RT-PCR. HCoV-OC43 viral RNA abundance at the indicated time points (G and H) is calculated relative to the first time point. Data are means ± SD of six (A–C) or four (D–H) replicates and are representative of three (A–F) and two (G and H) independent experiments, respectively. *P < 0.05, **P < 0.01, ***P < 0.001 by unpaired t-test.