Dictyostelium discoideumis a molecularly amenable host model system for several human pathogens, includingLegionella pneumophila, Mycobacterium avium, Mycobacterium marinum, Pseudomonas aeruginosa, andCryptococcus neoformans. Dictyosteliumwild-type cells have proven useful in screening and identifying numerous bacterial und fungal virulence factors. Moreover,Dictyosteliummutant cells can be used to identify genetic host determinants of susceptibility and resistance to infections. Marker genes such as the green fluorescence protein (GFP) gene allow the in vivo monitoring of infection-relevant host factors. Here, we present methods that have already contributed to the deciphering of important aspects of theDictyostelium-Legionellainteraction. Moreover, the described phagocytosis assay, infection assay, and the confocal in vivo monitoring of GFP-tagged host factors can easily be adapted to other host-pathogen interactions.
