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[Internalization and replication of Edwardsiella tarda in HEp-2 cells]
1College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095.
Abstract:
It is demonstrated that Edwardsiella tarda possesses the ability to invade cultured epithelial HEp-2 cells by both lysis-counting assay and thin-section electron microscopy. Among fifteen strains of E. tarda, 6 strains internalized into HEp-2 cells and located mainly in vesicles. After internalization, the bacteria replicated in the host cells and then released into medium. Pretreatment of the HEp-2 cells with various concentration of cytochalasin D (0.1-5.0 micrograms/ml) or cytochalasin B (2.5-10.0 micrograms/ml) significantly reduced the amount of internalized bacteria in a dose-dependent manner. While pretreatment of HEp-2 cells with 0.25-100 mumol/L colchicine did not show any effect on the invasiveness of E. tarda. This strongly indicates that microfilaments are required for the internalization of E. tarda into HEp-2 cells and that microtubules are not involved in the entrance of E. tarda into HEp-2 cells.
Insights
Edwardsiella tarda invades HEp-2 cells, replicating within them. Bacterial entry requires host cell microfilaments, but not microtubules, indicating a specific cellular mechanism for invasion.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Edwardsiella tarda is a Gram-negative bacterium known to cause opportunistic infections in humans and aquatic animals.
- Understanding the mechanisms of bacterial invasion into host cells is crucial for developing effective therapeutic strategies.
Purpose of the Study:
- To investigate the invasion mechanism of Edwardsiella tarda into cultured HEp-2 cells.
- To determine the role of host cell cytoskeleton components, specifically microfilaments and microtubules, in E. tarda internalization.
Main Methods:
- HEp-2 cells were infected with various strains of E. tarda.
- Bacterial internalization was assessed using lysis-counting assays and confirmed by thin-section electron microscopy.
- The effect of cytochalasin D, cytochalasin B, and colchicine on bacterial invasion was evaluated.
Main Results:
- Six out of fifteen E. tarda strains successfully invaded HEp-2 cells, with bacteria primarily located within intracellular vesicles.
- Pretreatment of HEp-2 cells with cytochalasin D and cytochalasin B significantly inhibited E. tarda internalization in a dose-dependent manner.
- Colchicine treatment did not affect the invasiveness of E. tarda into HEp-2 cells.
Conclusions:
- Edwardsiella tarda invades HEp-2 cells and replicates within them before release.
- The internalization process of E. tarda into HEp-2 cells is dependent on host cell microfilaments.
- Microtubules are not involved in the entry of E. tarda into HEp-2 cells.