The Priess lab studies the development and specification of germ cells using the nematode C. elegans as a model. RNA-mediated gene interference (RNAi) was discovered in nematodes, and is widely thought to have a role in preventing viral infections. However, no natural viruses have ever been demonstrated in nematodes, though the genome sequence contains retroviral-like sequences that are thought to be fossils of past infection. The lab recently discovered that viral-like particles are, in fact, common in C. elegans germ cells, and identified the element responsible for the chronic infection. Current studies in the lab focus on whether genes involved in RNAi have roles in controlling the expression of this element, how the element impacts processes such as aging and stress resistance in C. elegans. These studies allow the vast array of genetic, cellular, and molecular tools available in the C. elegans system to be used to study basic questions of how retroelements are assembled and controlled.