In general, many studies have led to the conclusion that flies that contain mutations in genes that encode components of the siRNA pathway (including DCR2 and AGO2) or the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathway, are not only more sensitive to infection by several viruses, but also harbor higher viral titers than their wild-type counterparts. The gene discussed is AGO2; the disease is infection.