Analysis of Legionella infection using RNAi in Drosophila cells

RNA interference (RNAi) is the process of specific gene silencing by the use of double-stranded RNA (dsRNA). In cultured Drosophila cells, RNAi methodologies are well established and easily executed: dsRNA, when added to the cell culture medium, is efficiently internalized by the cells and, through the activity of endogenous processing machinery, targets the specified mRNA for degradation resulting in reduced levels of its encoded protein. This technique has proven very useful in studying the role of host genes during Legionella pneumophila infections, as it allows the effect of host factor depletion on intracellular growth of the bacterium to be examined. In this chapter we present the methods commonly used in our laboratory to study intracellular growth of L. pneumophila using dsRNA in Drosophila cells.