Deletion of Cytoplasmic Double-Stranded RNA Sensors Does Not Uncover Viral Small Interfering RNA Production in Human Cells

Figures

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  FIG 1. Functional validation of RIG-I- and MDA5-deficient cell line generated by CRISPR-Cas9 technology. (A) Schematic representation of the RIG-I and MDA5 domain structure, the guide RNAs, and the Sanger sequence obtained. CTD, C-terminal domain. (B) Western blotting for RIG-I, MDA5, and tubulin as a loading control. Control and RIG-I- and MDA5-deficient (KO) cells were mock treated or stimulated with 200 ng poly(I⋅C) for 24 h. See Fig. S1 in the supplemental material for the complete image. (C) Control and KO cells were treated with 200 ng of poly(I⋅C) or mock treated for 24 h, and the induction of IFN-β, ISG15, and OAS1 mRNA was measured by RT-qPCR. (D) Control and KO cells were infected with yellow fever virus 17D (YFV17D) at an MOI of 0.1, and the induction of IFN-β mRNA was measured by RT-qPCR over time (hpi, hours postinfection). Data are presented as means and standard deviations from biological triplicates. One representative experiment of three independent repeats is shown. Statistical significance was determined using Student’s t test (***, P < 0.001; **, P < 0.01; *, P < 0.05).

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  FIG 2. Size profile of viral small RNAs obtained from control cells and RIG-I- and MDA5-deficient (KO) cells after infection for 24 h with SINV at an MOI of 0.1, for 48 h with YFV17D at an MOI of 0.1, or for 16 h with CBV3 at an MOI of 0.01. Small RNAs were mapped to the sense (blue bars) and antisense (red bars) strands of the viral genome, allowing 1 mismatch. Sense and antisense reads are presented on different scales, as antisense reads were very scarce. RPM, reads per million.