Thus, expansion of this AGO subfamily in C. elegans may represent a unique strategy of host adaptation to viral infection, distinct or in addition to the strategy used by insects in which the evolution rate of antiviral RNAi factors DCR2 and AGO2 is much faster than that of their miRNA pathway counterparts DCR1 and AGO1 [61],[62]. The gene discussed is AGO1; the disease is viral infectious disease.