| 1. |
- Styer, Katie L, et al.
(författare)
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Yersinia pestis kills Caenorhabditis elegans by a biofilm-independent process that involves novel virulence factors.
- 2005
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Ingår i: EMBO Reports. - : EMBO. - 1469-221X .- 1469-3178. ; 6:10, s. 992-997
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Tidskriftsartikel (refereegranskat)abstract
- It is known that Yersinia pestis kills Caenorhabditis elegans by a biofilm-dependent mechanism that is similar to the mechanism used by the pathogen to block food intake in the flea vector. Using Y. pestis KIM 5, which lacks the genes that are required for biofilm formation, we show that Y. pestis can kill C. elegans by a biofilm-independent mechanism that correlates with the accumulation of the pathogen in the intestine. We used this novel Y. pestis-C. elegans pathogenesis system to show that previously known and unknown virulence-related genes are required for full virulence in C. elegans. Six Y. pestis mutants with insertions in genes that are not related to virulence before were isolated using C. elegans. One of the six mutants carried an insertion in a novel virulence gene and showed significantly reduced virulence in a mouse model of Y. pestis pathogenesis. Our results indicate that the Y. pestis-C. elegans pathogenesis system that is described here can be used to identify and study previously uncharacterized Y. pestis gene products required for virulence in mammalian systems.
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| 2. |
- Bartra, Sara Schesser, et al.
(författare)
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Calcium-regulated type III secretion of Yop proteins by an Escherichia coli hha mutant carrying a Yersinia pestis pCD1 virulence plasmid.
- 2006
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 74:2, s. 1381-6
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Tidskriftsartikel (refereegranskat)abstract
- A series of four large deletions that removed a total of ca. 36 kb of DNA from the ca. 70-kb Yersinia pestis pCD1 virulence plasmid were constructed using lambda Red-mediated recombination. Escherichia coli hha deletion mutants carrying the virulence plasmid with the deletions expressed a functional calcium-regulated type III secretion system. The E. coli hha/pCD1 system should facilitate molecular studies of the type III secretion process.
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| 3. |
- Bartra, Sara Schesser, et al.
(författare)
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Resistance of Yersinia pestis to complement-dependent killing is mediated by the Ail outer membrane protein
- 2008
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 76:2, s. 612-622
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Tidskriftsartikel (refereegranskat)abstract
- Yersinia pestis, the causative agent of plague, must survive in blood in order to cause disease and to be transmitted from host to host by fleas. Members of the Ail/Lom family of outer membrane proteins provide protection from complement-dependent killing for a number of pathogenic bacteria. The Y. pestis KIM genome is predicted to encode four Ail/Lom family proteins. Y. pestis mutants specifically deficient in expression of each of these proteins were constructed using lambda Red-mediated recombination. The Ail outer membrane protein was essential for Y. pestis to resist complement-mediated killing at 26 and 37 degrees C. Ail was expressed at high levels at both 26 and 37 degrees C, but not at 6 degrees C. Expression of Ail in Escherichia coli provided protection from the bactericidal activity of complement. High-level expression of the three other Y. pestis Ail/Lom family proteins (the y1682, y2034, and y2446 proteins) provided no protection against complement-mediated bacterial killing. A Y. pestis ail deletion mutant was rapidly killed by sera obtained from all mammals tested except mouse serum. The role of Ail in infection of mice, Caenorhabditis elegans, and fleas was investigated.
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| 4. |
- Schesser Bartra, Sara, et al.
(författare)
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Intracellular survival of Yersinia spp. in macrophages requires outer membrane protein A (OmpA)
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In order to grow, multiply and disseminate within their hosts, Yersinia spp. must be able tosurvive encounters with host phagocytic cells such as macrophages. Yersinia pestis and Yersinia pseudotuberculosis both have the ability to survive within the phagolysosome of macrophages which may be important in early stages of the infection. These organisms also employ a T3SS toactively prevent phagocytosis. The ability of Y. pestis KIM mutants defective in the expression of outer membrane proteins to survive and proliferate in the presence of RAW 264.7 macrophage-like cells was evaluated. A Y. pestis KIM ΔompA mutant exhibited a significant defect in proliferation in the presence of macrophages. A similar defect could be produced by overexpressing the negative regulatory sRNA MicA, which down regulates OmpA expression. The ΔompA mutant exhibited no defect in the T3SS-mediated secretion or injection of Yops; however, this mutant showed a defect in intra macrophage survival in gentamicin protection assays. These studies suggest that the Yersinia spp. OmpA protein is a virulence factor that is required for survival within macrophages.
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| 5. |
- Zhang, Shu-sheng, et al.
(författare)
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Plasminogen activator Pla of Yersinia pestis utilizes murine DEC-205 (CD205) as a receptor to promote dissemination
- 2008
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 283:46, s. 31511-21
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Tidskriftsartikel (refereegranskat)abstract
- Yersinia pestis, a Gram-negative bacterium that causes bubonic and pneumonic plague, is able to rapidly disseminate to other parts of its mammalian hosts. Y. pestis expresses plasminogen activator (PLA) on its surface, which has been suggested to play a role in bacterial dissemination. It has been speculated that Y. pestis hijacks antigen-presenting cells, such as macrophages (MPhis) and dendritic cells, to be delivered to lymph nodes to initiate dissemination and infection. Both alveolar MPhis and pulmonary dendritic cells express a C-type lectin receptor, DEC-205 (CD205), which mediates antigen uptake and presentation. However, no ligand has been identified for DEC-205. In this study, we show that the invasion of alveolar MPhisby Y. pestis depends both in vitro and in vivo on the expression of PLA. DEC-205-expressing MPhis and transfectants, but not their negative counterparts, phagocytosed PLA-expressing Y. pestis and Escherichia coli K12 more efficiently than PLA-negative controls. The interactions between PLA-expressing bacteria and DEC-205-expressing transfectants or alveolar MPhis could be inhibited by an anti-DEC-205 antibody. Importantly, the blockage of the PLA-DEC-205 interaction reduced the dissemination of Y. pestis in mice. In conclusion, murine DEC-205 is a receptor for PLA of Y. pestis, and this host-pathogen interaction appears to play a key role in promoting bacterial dissemination.
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