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Non-invasive Providencia alcalifaciens strains fail to attach to HEp-2 cells
S Khashe1, D J Scales, S L Abbott
1Microbial Diseases Laboratory, Division of Communicable Disease Control, 2151 Berkeley Way, Berkeley, California 94704-1011, USA.
Abstract:
We investigated the adherence properties of six P. alcalifaciens strains with previously characterized differential invasive capabilities in HEp-2 cells. Highly invasive strains were found to attach to HEp-2 cell monolayers within 2 h post-infection and in large numbers on the eukaryotic cell surfaces within 3 h post-infection. In contrast, weakly or non-invasive P. alcalifaciens strains were non-adherent to HEp-2 cells even at 3 h post-infection. Highly invasive isolates were found to weakly bind F-actin using the fluorescent actin staining assay although these strains were negative for Escherichia coli attachment and effacing gene (eaeA) of enteropathogenic E. coli (EPEC). These results suggest that the strain variation in the ability of P. alcalifaciens to invade HEp-2 cells previously noted by several investigators may be linked to expression of key adhesin(s) on the cell surface of invasive isolates.
Insights
Highly invasive Pseudomonas alcalifaciens strains rapidly adhere to HEp-2 cells, unlike non-invasive strains. This adherence is linked to bacterial adhesins, not the E. coli attachment and effacing gene (eaeA).
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Pseudomonas alcalifaciens exhibits variable invasive capabilities in host cells.
- Understanding bacterial adherence is crucial for elucidating infection mechanisms.
Purpose of the Study:
- To investigate the adherence properties of P. alcalifaciens strains with differential invasive capabilities in HEp-2 cells.
- To correlate adherence with invasive potential and identify potential adhesins.
Main Methods:
- HEp-2 cell infection assays to assess bacterial adherence.
- Fluorescent actin staining assay to evaluate F-actin binding.
- Screening for the Escherichia coli attachment and effacing gene (eaeA).
Main Results:
- Highly invasive P. alcalifaciens strains demonstrated rapid and significant adherence to HEp-2 cells within 2-3 hours post-infection.
- Weakly or non-invasive strains showed no significant adherence to HEp-2 cells.
- Highly invasive strains weakly bound F-actin and were negative for the eaeA gene.
Conclusions:
- Strain-dependent adherence is a key factor in the invasion of HEp-2 cells by P. alcalifaciens.
- Invasive P. alcalifaciens isolates likely express specific adhesins mediating cell surface attachment.
- The mechanism of invasion by these strains differs from that of enteropathogenic E. coli (EPEC).