dsRNAs are also a type of pathogen-associated molecular pattern (PAMP) that are detected by cellular innate immunity sensors named Pattern Recognition Receptors (PRRs) (4) . The interaction between a PAMP and a PRR triggers activation of the interferon (IFN) pathway in mammalian cells, which significantly changes the gene-expression profile in the cells and contributes to the well-documented off-target effect of RNAi. IFN induction is especially problematic in antiviral studies employing RNAi, where the antiviral effect of IFN must be distinguished from that of RNAi.