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Intracellular replication of Salmonella within epithelial cells is associated with filamentous structures containing

F Garcia-del Portillo1, M B Zwick, K Y Leung

  • 1Biotechnology Laboratory, University of British Columbia, Vancouver, Canada.

Infectious Agents and Disease
|August 1, 1993
PubMed

Insights

Salmonella typhimurium forms unique lysosomal structures within host cells, crucial for bacterial replication. These structures, rich in lysosomal membrane glycoproteins, depend on viable bacteria and host cell microtubules.

Area of Science:

  • Cell Biology
  • Microbiology
  • Immunology

Background:

  • Salmonella typhimurium invades host cells, residing within vacuoles.
  • The precise mechanisms of Salmonella-containing vacuole (SCV) maturation and interaction with host organelles are not fully understood.
  • Lysosomal targeting is a critical step in the intracellular fate of many pathogens.

Purpose of the Study:

  • To investigate the targeting of Salmonella-containing vacuoles to lysosomes in HeLa cells.
  • To characterize the structures formed by SCVs during infection.
  • To determine the host and bacterial factors involved in SCV-lysosome interactions.

Main Methods:

  • Infection of cultured HeLa epithelial cells with S. typhimurium.
  • Immunofluorescence microscopy to detect lysosomal membrane glycoproteins (LGPs) and bacterial colocalization.
  • Analysis of SCV morphology and association with host cell structures.
  • Assessment of the role of viable bacteria, microtubule network, and intravacuolar pH.

Main Results:

  • Intracellular S. typhimurium colocalized with vacuoles containing human LGPs (hlamp-1 and hlamp-2) starting at 2 hours postinfection.
  • Long, stable, LGP-rich filamentous structures connected to SCVs appeared at 4-6 hours postinfection.
  • Formation of these structures required viable intracellular bacteria, an intact microtubule network, and acidic intravacuolar pH.
  • These structures were absent in cells infected with Yersinia enterocolitica or S. typhimurium replication-defective mutants.

Conclusions:

  • S. typhimurium actively induces the formation of unique LGP-rich filamentous structures linked to SCVs.
  • These structures are essential for intracellular bacterial replication and are distinct from previously described tubular lysosomes.
  • The formation process highlights a novel interaction between S. typhimurium and the host lysosomal system.

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