Recently, RNA interference has emerged as a method of choice for specifically knocking out expression of studied genes in a myriad of biological fields. The RNA interference (RNAi) is produced by the destruction of cellular RNAs homologous to small RNAs species called small interfering RNA (siRNA). In Caenorhabditis elegans, the siRNAs are derived from a long dsRNA deliver into the animal either by injection or by feeding the nematode with bacteria expressing the dsRNA trigger. In previous genetic screens, we and others have identified several rde (RNA interference-deficient) mutants that are required for RNAi in C. elegans [Tabara et al, Cell 99: 123-132 (1999), Ketting et al, Cell 99: 133-141 (1999)]. Among the isolated genes essential for RNA interference, the mutants alleles of
rde-1 and
rde-4 are required to produce RNAi initiated by exogenous dsRNA and are not required for transposon silencing like observed with
mut-7. In order to uncover new functions for RDE-1 and RDE-4, we have conducted a microarrays analysis on a mutant allele of each of them. In the class of genes up- or down-regulated in both
rde-1 and
rde-4 mutant background, we are observing cluster of genes associated to innate immunity response in C. elegans. This observation may uncover a new function for RNAi pathway genes in nematode. We are currently testing the possible role of
rde-1,
rde-4 and other rde genes in worm immunity.