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. 2021 Jun 25;12:700926. doi: 10.3389/fimmu.2021.700926

Figure 4.

Figure 4

SARS-CoV-2 hardly induced type I IFN expression in human cells. (A–C) HEK293 cells were infected with influenza A virus, SeV, or SARS-CoV-2 at MOI = 1. Total RNA was extracted at the indicated time points, and RT-qPCR determined viral RNAs and IFN-β mRNA expression levels. The data represents the mean ± SD (n = 3). The data shown is representative of at least two independent experiments. (D, E) A549 (D) and human ACE2 overexpressing HEK293 cells (ACE2-Tg) (E) cells were infected with SARS-CoV-2 at MOI = 1. Total RNA was extracted at the indicated time points, and RT-qPCR determined viral RNAs and IFN-β mRNA expression levels. The data represent the mean ± SD (n = 3). The data shown is representative of at least two independent experiments. (F–H) WT and Riplet KO HEK293 ACE2 Tg cells were infected with SARS-CoV-2 at MOI = 0, 0.1, 1, and 5. Total RNA was extracted at 18 h after infection, and RT-qPCR determined IFN-β mRNA, IP-10 and SARS-CoV-RNA expression levels. The data are expressed as fold increase compared with expression level at 0 hr, and represent the mean ± SD (n = 3, *p < 0.05, t-test). The data shown is representative of at least two independent experiments.