Intracellular replication of Salmonella typhimurium strains in specific subsets of splenic macrophages in vivo.
We used flow cytometry and confocal immunofluorescence microscopy to study the localization of Salmonella typhimurium in spleens of infected mice. Animals were inoculated intragastrically or intraperitoneally with S. typhimurium strains, constitutively expressing green fluorescent protein. Independently of the route of inoculation, most bacteria were found in intracellular locations 3 days after inoculation. Using a panel of antibodies that bound to cells of different lineages, including mononuclear phagocyte subsets, we have shown that the vast majority of S. typhimurium bacteria reside within macrophages. Bacteria were located in red pulp and marginal zone macrophages, but very few were found in the marginal metallophilic macrophage population. We have demonstrated that the Salmonella SPI-2 type III secretion system is required for replication within splenic macrophages, and that sifA(-) mutant bacteria are found within the cytosol of these cells. These results confirm that SifA and SPI-2 are involved in maintenance of the vacuolar membrane and intracellular replication in vivo.
Salcedo
S P
SP
Department of Infectious Diseases, Centre for Molecular Microbiology and Infection, Imperial College School of Medicine, The Flowers Building, Armstrong Road, London SW7 2AZ, UK.
Noursadeghi
M
M
Cohen
J
J
Holden
D W
DW
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001426:Bacterial Proteins; D002455:Cell Division / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D017930:Genes, Reporter; D006023:Glycoproteins / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051907:Lysosomal Membrane Proteins; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D009154:Mutation; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012486:Salmonella typhimurium / Q000235:genetics / Q000502:physiology*; D013154:Spleen / Q000166:cytology* / Q000187:drug effects; D013301:Streptolysins / Q000494:pharmacology
D015703:Antigens, CD; D001426:Bacterial Proteins; D006023:Glycoproteins; D008164:Luminescent Proteins; D051907:Lysosomal Membrane Proteins; D008562:Membrane Glycoproteins; C421862:SifA protein, Salmonella; D013301:Streptolysins; C025964:streptolysin O; D049452:Green Fluorescent Proteins