Entry and survival ofSalmonella typhimuriumin dendritic cells and presentation of recombinant antigens do not require macrophage-specific virulence factors

Macrophages have long been regarded as the main target encountered bySalmonella typhimurium, a Gram-negative facultative intracellular pathogen that invades the intestinal mucosa.S. typhimurium , however, are first internalized by dendritic cells. To gain new insights into the interactions betweenSalmonella and the dendritic cells, we compared the fate of wild-typeS. typhimurium and the virulence-attenuated PhoP constitutive (PhoPc ) strain. The PhoPc strain is impaired for entry and survival in mammalian cells and is poorly processed by macrophages for antigen presentation on MHC class II molecules. Here, we show that bone marrow-derived dendritic cells can similarly process and present a foreign antigen expressed by the invasive wild-type and the attenuated PhoPc S. typhimurium . This property correlates with equivalent entry and survival efficiencies of both strains in dendritic cells. In addition,Salmonella strains mutated inmgtCB ,sseC , andorfL genes required for macrophage survival showed no defect in survival in dendritic cells. Together, these results indicate that uptake ofSalmonella by dendritic cells and subsequent antigen processing and presentation do not depend on virulence factors important in macrophages.