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Updated: Oct 17, 2026
Use of Shigella flexneri to Study Autophagy-Cytoskeleton Interactions
Published on: September 9, 2014
The development of a FACS-based strategy for the isolation of Shigella flexneri mutants that are deficient in
M Rathman1, N Jouirhi, A Allaoui
1Unité de Pathogénie Microbienne Moléculaire, INSERM U389, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France. mrathman@pasteur.fr
Abstract:
In the disease course of bacillary dysentery, pathogenic Shigella flexneri invade colonic epithelial cells and spread both within and between host cells. The ability to spread intercellularly allows the organism to infect an entire epithelial layer without significant contact with the extracellular milieu. Using fluorescence activated cell sorter (FACS)-based technology, we developed a rapid and powerful selection strategy for the isolation of S. flexneri mutants that are unable to spread from cell to cell. The majority of mutants identified using this strategy harbour mutations that affect the structure of their lipopolysaccharide or the ability of the bacteria to move intracellularly via actin-based motility; both factors have previously been shown to be essential for cell-to-cell spread. However, using a modified strategy that eliminated both of these types of mutants, we identified several mutants that provide us with evidence that bacterial proteins of the type III secretion system, which are essential for bacterial entry into host cells, also play a role in cell-to-cell spread.
Insights
Shigella flexneri causes bacillary dysentery by spreading between colonic cells. This study identified new bacterial mechanisms, including type III secretion system proteins, involved in this crucial cell-to-cell spread.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Bacillary dysentery is caused by Shigella flexneri, which invades and spreads through colonic epithelial cells.
- Intercellular spread allows Shigella to infect epithelial layers efficiently, minimizing extracellular exposure.
Purpose of the Study:
- To develop a selection strategy for isolating Shigella flexneri mutants with impaired cell-to-cell spread.
- To identify novel bacterial factors, beyond lipopolysaccharide structure and actin-based motility, that contribute to intercellular spread.
Main Methods:
- Utilized fluorescence-activated cell sorting (FACS)-based technology for rapid mutant selection.
- Employed a modified selection strategy to exclude known spread-deficient mutants (lipopolysaccharide and actin-based motility defects).
Main Results:
- Identified mutants with defects in lipopolysaccharide structure and intracellular actin-based motility, confirming their known roles in spread.
- Discovered novel mutants, via the modified strategy, indicating a role for type III secretion system proteins in bacterial cell-to-cell spread.
Conclusions:
- The type III secretion system, essential for host cell entry, also plays a significant role in Shigella flexneri's intercellular spread.
- This finding expands our understanding of Shigella pathogenesis and provides new targets for therapeutic intervention.
