SopE-Mediated Recruitment of Host Rab5 on Phagosomes Inhibits Salmonella Transport to Lysosomes

Phagocytosis is a process by which invading organisms are taken up by macrophages and targeted to the lysosomes, where they are degraded. However, many pathogens modulate this central process of macrophage-mediated killing by inhibiting their transport to the lysosomes through a variety of pathogen-derived mechanisms. Given the importance of Rab proteins in the regulation of intracellular transport pathways, we investigated the role of different host endocytic Rabs on the maturation of Salmonella -containing phagosomes in macrophages. Initially, we have developed a ligand mixing assay to measure the transport of the Salmonella -containing phagosomes to lysosomes. Using this assay we have shown that Salmonella decline their transport to the lysosomes. In order to determine whether inhibition of Salmonella transport to lysosomes is due to their sustained fusion with early endosomes, we have developed an in vitro fusion assay between Salmonella -containing phagosomes and early endosomes. Here, we have discussed how these methodologies are helpful to determine the mechanism of evasion of Salmonella transport to the lysosomes.