Macrophage-dependent Induction of the Salmonella Pathogenicity Island 2 Type III Secretion System and Its Role in Intracellular Survival

Mol Microbiol. 1998 Oct;30(1):175-88. doi: 10.1046/j.1365-2958.1998.01048.x.

Abstract

Salmonella pathogenicity island 2 (SPI-2) encodes a putative type III secretion system necessary for systemic infection in animals. We have investigated the transcriptional organization and regulation of SPI-2 by creating gfp fusions throughout the entire gene cluster. These gfp fusions demonstrated that SPI-2 genes encoding structural, regulatory and previously uncharacterized putative secreted proteins are preferentially expressed in the intracellular environment of the host macrophage. Furthermore, the transcription of these genes within host cells was dependent on the two-component regulatory system SsrA/SsrB and an acidic phagosomal environment. Most SPI-2 mutants failed to replicate to the same level as wild-type strains in murine macrophages and human epithelial cells. In orally infected mice, SPI-2 mutants colonized the Peyer's patches but did not progress to the mesenteric lymph nodes. We conclude that SPI-2 genes are specifically expressed upon entry into mammalian cells and are required for intracellular growth in host cells in vivo and in vitro.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Artificial Gene Fusion
  • Calcium-Binding Proteins / genetics
  • Epithelial Cells / microbiology
  • Female
  • Flow Cytometry
  • Gene Expression Regulation, Bacterial
  • Gentamicins / pharmacology
  • Humans
  • Macrophages / microbiology*
  • Membrane Glycoproteins*
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Peyer's Patches / microbiology
  • Plasmids / genetics
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Peptide / genetics
  • Salmonella Infections, Animal / microbiology*
  • Salmonella typhimurium / genetics*
  • Salmonella typhimurium / growth & development
  • Salmonella typhimurium / pathogenicity*
  • Signal Transduction
  • Transcription, Genetic
  • Virulence / genetics

Substances

  • Calcium-Binding Proteins
  • Gentamicins
  • Membrane Glycoproteins
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Peptide
  • signal sequence receptor

Associated data

  • GENBANK/AF020808