SiRNA screens using Drosophila cells to identify host factors required for infection.

Drosophila melanogaster offers a powerful model system for interrogating interactions between host cells and human bacterial pathogens. Brucella, a gram-negative, facultative intracellular bacterium is the causative agent of brucellosis, a zoonotic disease of global consequence. Over the past several decades, pathogen factors that mediate Brucella infection have been identified. However, host factors that mediate infection have remained obscure. We have used the power of the Drosophila S2 cell system to identify and characterize host factors that support infection by Brucella melitensis. Host protein inositol-requiring enzyme 1 (IRE1α), a transmembrane kinase and master regulator of the eukaryotic unfolded protein response, was shown to play an important role in regulating Brucella infection, thereby providing the first glimpse of host mechanisms that are subverted by the pathogen to support its intracellular lifestyle. Furthermore, our study also established the Drosophila S2 cell as a powerful system for elucidating Brucella host factors. Here, we describe a protocol for using the Drosophila S2 cell system for studying the Brucella-host interaction.