In Drosophila, where the action mechanism of the RNAi machinery has been investigated at the molecular level, it was shown that R2D2 is involved in the loading of siRNAs, the small RNAs generated by Dicer-2, onto Ago-2, which is the central effector in the RISC complex involved in defense against transposable elements and viral infections [17], [20]. Here, AGO2 is linked to viral infectious disease.