Figure 2. An integrating overview of RNA silencing and AGO-mediated translational repression of mRNA targets. RNA silencing is launched by viral double-stranded RNAs (dsRNAs) from different sources, which are processed into small interfering RNA molecules of 21–24 nucleotide (nt) by Dicer-like (DCL) proteins. Subsequently one strand of the siRNA duplexes is loaded into RNA-induced silencing complexes (RISCs) harboring an argonaute (AGO) effector protein. In light of post-transcriptional gene silencing (PTGS), AGO/sRNA complexes trigger viral RNA cleavage or translational repression. Although unclear, translation repression directed by sRNAs in plants seems to rely on AGO activity, which may act targeting ribosome assembly, interfering with 48S initiation complex formation, or translational initiation factors (eIFs). The AGO-RISC complex is further capable of repressing translation by preventing translation elongation or ribosomal recruitment. Viral suppressors of RNA silencing (VSRs) interfere in multiple steps of the antiviral RNA silencing pathway, including dicing inhibition, viral RNA loading, AGO inactivation and suppression of its translational inhibitory activity.