title: The Dot/Icm effector SdhA is necessary for virulence of Legionella pneumophila in Galleria mellonella and A/J mice.
abstract: Legionella pneumophila is an intracellular bacterium that resides within amoebae and macrophages in a specialized compartment termed the Legionella-containing vacuole (LCV). As well as providing an intracellular niche for replication, the LCV helps to prevent the release of bacterial components into the cytoplasm. Recognition of these components as danger signals by the host activates immune responses leading to clearance of the bacterium. Here, we examined the role of two important virulence factors of L. pneumophila, the potent danger signal flagellin and the translocated Dot/Icm type IVB secretion system effector SdhA, which is crucial to maintain LCV integrity, in the Galleria mellonella infection model. We demonstrate that flagellin expression does not contribute to virulence, replication, or induction of clearance mechanisms. Conversely, SdhA expression is important for virulence. We found that in the absence of SdhA, the LCV in hemocytes showed signs of instability and leakage. Furthermore, in contrast to wild-type L. pneumophila, a ΔsdhA mutant caused a transient depletion of hemocytes and reduced mortality. Analysis of the ΔsdhA mutant in the A/J mouse model also showed a significant replication defect. Together, our data underline the crucial importance of SdhA in infection across different model organisms.
authors: MRC Centre for Molecular Bacteriology and Infection, Division of Cell and Molecular Biology, Imperial College London, London, United Kingdom.
authors: Clare R
authors: CR
authors: Harding
authors: Charlotte A
authors: CA
authors: Stoneham
authors: Ralf
authors: R
authors: Schuelein
authors: Hayley
authors: H
authors: Newton
authors: Clare V
authors: CV
authors: Oates
authors: Elizabeth L
authors: EL
authors: Hartland
authors: Gunnar N
authors: GN
authors: Schroeder
authors: Gad
authors: G
authors: Frankel
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D005260:Female; D005408:Flagellin / Q000378:metabolism; D005420:Flavoproteins / Q000378:metabolism*; D006434:Hemocytes / Q000378:metabolism / Q000382:microbiology; D007814:Larva / Q000382:microbiology; D016952:Legionella pneumophila / Q000378:metabolism / Q000472:pathogenicity*; D007876:Legionellosis / Q000382:microbiology; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D009036:Moths / Q000382:microbiology*; D021381:Protein Transport; D037521:Virulence Factors / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D005420:Flavoproteins; C084271:SdhA protein, Bacteria; D037521:Virulence Factors; D005408:Flagellin
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