| 1. |
- Bize, Ariane, et al.
(författare)
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A unique virus release mechanism in the Archaea
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:27, s. 11306-11311
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about the infection cycles of viruses infecting cells from Archaea, the third domain of life. Here, we demonstrate that the virions of the archaeal Sulfolobus islandicus rod-shaped virus 2 (SIRV2) are released from the host cell through a mechanism, involving the formation of specific cellular structures. Large pyramidal virus-induced protrusions transect the cell envelope at several positions, rupturing the S-layer; they eventually open out, thus creating large apertures through which virions escape the cell. We also demonstrate that massive degradation of the host chromosomes occurs because of virus infection, and that virion assembly occurs in the cytoplasm. Furthermore, intracellular viral DNA is visualized by flow cytometry. The results show that SIRV2 is a lytic virus, and that the host cell dies as a consequence of elaborated mechanisms orchestrated by the virus. The generation of specific cellular structures for a distinct step of virus life cycle is known in eukaryal virus-host systems but is unprecedented in cells from other domains.
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| 2. |
- Marteyn, Benoit, et al.
(författare)
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Modulation of Shigella virulence in response to available oxygen in vivo
- 2010
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 465:7296, s. 355-358
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Tidskriftsartikel (refereegranskat)abstract
- Bacteria coordinate expression of virulence determinants in response to localized microenvironments in their hosts. Here we show that Shigella flexneri, which causes dysentery, encounters varying oxygen concentrations in the gastrointestinal tract, which govern activity of its type three secretion system (T3SS). The T3SS is essential for cell invasion and virulence(1). In anaerobic environments (for example, the gastrointestinal tract lumen), Shigella is primed for invasion and expresses extended T3SS needles while reducing Ipa (invasion plasmid antigen) effector secretion. This is mediated by FNR (fumarate and nitrate reduction), a regulator of anaerobic metabolism that represses transcription of spa32 and spa33, virulence genes that regulate secretion through the T3SS. We demonstrate there is a zone of relative oxygenation adjacent to the gastrointestinal tract mucosa, caused by diffusion from the capillary network at the tips of villi. This would reverse the anaerobic block of Ipa secretion, allowing T3SS activation at its precise site of action, enhancing invasion and virulence.
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| 3. |
- Paz, Irit, et al.
(författare)
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Galectin-3, a marker for vacuole lysis by invasive pathogens
- 2010
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Ingår i: Cellular Microbiology. - : Hindawi Limited. - 1462-5814 .- 1462-5822. ; 12:4, s. 530-544
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Tidskriftsartikel (refereegranskat)abstract
- P>Shigella bacteria invade macrophages and epithelial cells and following internalization lyse the phagosome and escape to the cytoplasm. Galectin-3, an abundant protein in macrophages and epithelial cells, belongs to a family of beta-galactoside-binding proteins, the galectins, with many proposed functions in immune response, development, differentiation, cancer and infection. Galectins are synthesized as cytosolic proteins and following non-classical secretion bind extracellular beta-galactosides. Here we analysed the localization of galectin-3 following entry of Shigella into the cytosol and detected a striking phenomenon. Very shortly after bacterial invasion, intracellular galectin-3 accumulated in structures in vicinity to internalized bacteria. By using immuno-electron microscopy analysis we identified galectin-3 in membranes localized in the phagosome and in tubules and vesicles that derive from the endocytic pathway. We also demonstrated that the binding of galectin-3 to host N-acetyllactosamine-containing glycans, was required for forming the structures. Accumulation of the structures was a type three secretion system-dependent process. More specifically, existence of structures was strictly dependent upon lysis of the phagocytic vacuole and could be shown also by Gram-positive Listeria and Salmonella sifA mutant. We suggest that galectin-3-containing structures may serve as a potential novel tool to spot vacuole lysis.
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| 4. |
- Racine, Antoine, et al.
(författare)
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Dietary Patterns and Risk of Inflammatory Bowel Disease in Europe : Results from the EPIC Study
- 2016
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Ingår i: Inflammatory Bowel Diseases. - 1078-0998 .- 1536-4844. ; 22:2, s. 345-354
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Tidskriftsartikel (refereegranskat)abstract
- Background: Specific nutrients or foods have been inconsistently associated with ulcerative colitis (UC) or Crohn’s disease (CD) risks. Thus, we investigated associations between diet as a whole, as dietary patterns, and UC and CD risks.Methods: Within the prospective EPIC (European Prospective Investigation into Cancer) study, we set up a nested matched case–control study among 366,351 participants with inflammatory bowel disease data, including 256 incident cases of UC and 117 of CD, and 4 matched controls per case. Dietary intake was recorded at baseline from validated food frequency questionnaires. Incidence rate ratios of developing UC and CD were calculated for quintiles of the Mediterranean diet score and a posteriori dietary patterns produced by factor analysis.Results: No dietary pattern was associated with either UC or CD risks. However, when excluding cases occurring within the first 2 years after dietary assessment, there was a positive association between a “high sugar and soft drinks” pattern and UC risk (incidence rate ratios for the fifth versus first quintile, 1.68 [1.00–2.82]; Ptrend ¼ 0.02). When considering the foods most associated with the pattern, high consumers of sugar and soft drinks were at higher UC risk only if they had low vegetables intakes.
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| 5. |
- van Schaik, Fiona D. M., et al.
(författare)
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Serological markers predict inflammatory bowel disease years before the diagnosis
- 2013
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Ingår i: Gut. - : BMJ. - 1468-3288 .- 0017-5749. ; 62:5, s. 683-688
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Tidskriftsartikel (refereegranskat)abstract
- Objective Anti-neutrophil cytoplasmic antibodies and anti-Saccharomyces cerevisiae mannan antibodies (ASCAs) have been detected in the serum of patients with ulcerative colitis (UC) and Crohn's disease (CD) and their unaffected family members. The aim of this study was to establish the value of serological markers as predictors of UC and CD. Design Individuals who developed CD or UC were identified from the European Prospective Investigation into Cancer and Nutrition (EPIC) study. At recruitment, none of the participants had a diagnosis of CD or UC. For each incident case, two controls were randomly selected matched for centre, date of birth, sex, date of recruitment and time of follow-up. Serum of cases and controls obtained at recruitment were analysed for ASCA IgG, ASCA IgA, perinuclear anti-neutrophil cytoplasmic antibody (pANCA), antibodies against Escherichia coli outer membrane porin C (OmpC) and flagellin CBir1. Conditional logistic regression was used to determine risk of CD and UC. Receiver operating characteristic curves were constructed to test accuracy. Results A total of 77 individuals were diagnosed with CD and 167 with UC after a mean follow-up of 4.5 (SD 3.2) and 4.4 (SD 3.1) years following blood collection, respectively. Combinations of pANCA, ASCA, anti-CBir1 and anti-OmpC were most accurate in predicting incident CD and UC (area under curve 0.679 and 0.657, respectively). The predictive value of the combination of markers increased when time to diagnosis of CD or UC decreased. Conclusion A panel of serological markers is able to predict development of CD and UC in individuals from a low-risk population.
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