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. Author manuscript; available in PMC: 2009 Jun 29.
Published in final edited form as: Cell. 2007 Aug 10;130(3):413–426. doi: 10.1016/j.cell.2007.07.039

Figure 2. Antiviral Silencing in Flies and Worms.

Figure 2

(A) The Drosophila pathway is conceptually similar to a linear antiviral silencing pathway in plants. Although R2D2 heterodimerizes with Dcr2, it is required for loading but not dicing of viRNA; the Armitage (Armi) protein allows assembly of the RISC holoenzyme. The box illustrates the involvement of Dcr1 and AGO1 in the miRNA pathway leading to translational repression. This pathway can be disrupted at multiple points by VSRs (red).

(B) Antiviral silencing in C. elegans has been inferred through studies of artificial infection systems. ALG, RDE-1, and SAGO are worm AGOs that recruit miRNAs, 1st siRNAs, and 2nd siRNAs, respectively. RRF-1 is thought to produce 2nd siRNAs or to copy RNAs (cRNAs) directly from RDE3-stabilized templates. SID-1 may possibly take up viral dsRNAs into cells. These pathways can be disrupted at multiple points by endogenous suppressors (red).