umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Evaluation of the presence of virulence-associated factors in Vibrio cholerae non-O1 non-O139 isolates from clinical and environmental sources
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Sun Nyunt Wai)
National Institute of Cholera and Enteric Diseases, P-33 C. I. T. Road, Scheme-XM, Beliaghata, Kolkata 700 010, India.
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Sun Nyunt Wai)
Umeå University, Faculty of Medicine, Molecular Biology (Faculty of Medicine). (Sun Nyunt Wai)
Show others and affiliations
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The broad group non-O1 non-O139 Vibrio cholerae presumably causes clinical diseases due to properties distinct from V. cholerae O1 and O139 serogroups in which cholera toxin is the hallmark of the infection. In this study, we screened for the presence of virulence-associated factors in V. cholerae non-O1 non-O139 strains isolated in Sweden. Six isolates from patients with different clinical manifestations and two environmental isolates were studied. None of the V. cholerae non-O1 non-O139 isolates carried the ctx or tcpA genes, but gene sequences for other putative virulence factors such as OmpU, cytolysin (VCC) and RTX were present. Significant differences in serum resistance were observed among the isolates independent of their encapsulation. The isolates were tested on Caenorhabditis elegans as an alternative host for analysis of factors associated with protection from natural predator grazing and environmental survival of V. cholerae. Three isolates caused lethality to C. elegans and also showed the strongest ability to resist killing by serum. We also observed that actin cross-linking activity and the level of protease secretion were different among the strains.

National Category
Cell and Molecular Biology
Research subject
Molecular Biology
Identifiers
URN: urn:nbn:se:umu:diva-30262OAI: oai:DiVA.org:umu-30262DiVA: diva2:281372
Available from: 2009-12-15 Created: 2009-12-15 Last updated: 2009-12-22Bibliographically approved
In thesis
1. Modulators of Vibrio cholerae predator interaction and virulence
Open this publication in new window or tab >>Modulators of Vibrio cholerae predator interaction and virulence
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Vibrio cholerae, the causal agent of cholera typically encodes two critical virulence factors: cholera toxin (CT), which is primarily responsible for the diarrhoeal purge, and toxin-co-regulated pilus (TCP), an essential colonisation factor. Nontoxigenic strains expressing TCP can efficiently acquire the CT gene through lysogenic conversion with CTXΦ, a filamentous phage that encodes CT and uses TCP as a receptor.  V. cholerae is a Gram-negative bacterium and a natural inhabitant of estuarine and coastal waters throughout both temperate and tropical regions of the world. In the aquatic environment, V. cholerae encounters several environmental stresses, such as change in salinity, UV stress, nutrient limitation, temperature fluctuations, viral infections and protozoan predation. To fully understand the pathogenic and virulence potential of V. cholerae, knowledge is required of its interactions with, not only human, but also environmental factors. By using the nematode Caenorhabditis elegans as host model, we were able to identify a previously uncharacterised protein, the extracellular protease PrtV. PrtV was shown to be required for the killing of. elegans and also necessary for survival from grazing by the ciliate Tetrahymena pyriformis and the flagellate Cafeteria roenbergensis. The PrtV protein, which belongs to a M6 family of metallopeptidases was cloned and purified for further characterisations. The purified PrtV was cytotoxic against the human intestinal cell line HCT8. By using human blood plasma, fibrinogen, fibronectin and plasminogen were identified as candidate substrates for the PrtV protease.

Outer membrane vesicles (OMVs) are released to the surroundings by most Gram-negative bacteria through “bulging and pinching” of the outer membrane.  OMVs have been shown to contain many virulence factors important in pathogenesis. Therefore, we investigated the association of PrtV with OMVs. PrtV was not associated with OMVs from the wild type O1 strain. In contrast, in an LPS mutant lacking two sugar chains in the core oligosaccharide PrtV was found to be associated with the OMVs. The OMV-associated PrtV was shown to be proteolytically and cytotoxically active.

V. cholerae strains are grouped into >200 serogroups. Only the O1 and O139 serogroups have been associated with pandemic cholera, a severe diarrhoeal disease.  All other serogroups are collectively referred to as non-O1 non-O139 V. cholerae. Non-O1 non-O139 V. cholerae can cause gastroenteritis and extraintestinal infections, but unlike O1 and O139 strains of V. cholerae, little is known about the virulence gene content and their potential to become human pathogens. We analysed clinical and environmental non-O1 non-O139 isolates for their putative virulence traits. None of them carry the genes encoding CT or the TCP, but other putative virulence factors were present in these isolates. The incidence of serum resistance was found to vary considerably and was independent of encapsulation. Three strains were strongly serum-resistant, and these same strains could also kill C. elegans.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2009. 64 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1312
Keyword
Vibrio cholerae, Caenorhabditis elegans, PrtV, outer membrane vesicles, non-O1 non-O139, serum resistance
National Category
Cell and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-30211 (URN)978-91-7264-918-7 (ISBN)
Public defence
2010-01-22, Major Groove, Försörjningsvägen byggnad 6L, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2009-12-22 Created: 2009-12-14 Last updated: 2009-12-22Bibliographically approved

Open Access in DiVA

No full text

Search in DiVA

By author/editor
Lindmark, BarbroRompikuntal, PramodDongre, MiteshWai, Sun
By organisation
Molecular Biology (Faculty of Medicine)
Cell and Molecular Biology

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 86 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf