scholarly journals A predation assay using amoebae to screen for virulence factors unearthed the first W. chondrophila inclusion membrane protein

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
C. Kebbi-Beghdadi ◽  
L. Pilloux ◽  
A. Croxatto ◽  
N. Tosetti ◽  
T. Pillonel ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Cosmid Library ◽  
Inclusion Membrane ◽  
Virulence Proteins ◽  
Type Three Secretion System ◽  
Animal Pathogens ◽  
Cell Cytosol ◽  
Adverse Pregnancy ◽  
Type Three Secretion ◽  
Host Cell Cytosol

AbstractWaddlia chondrophila is an intracellular bacterium phylogenetically related to the well-studied human and animal pathogens of the Chlamydiaceae family. In the last decade, W. chondrophila was convincingly demonstrated to be associated with adverse pregnancy outcomes in humans and abortions in animals. All members of the phylum Chlamydiae possess a Type Three Secretion System that they use for delivering virulence proteins into the host cell cytosol to modulate their environment and create optimal conditions to complete their life cycle. To identify W. chondrophila virulence proteins, we used an original screening approach that combines a cosmid library with an assay monitoring resistance to predation by phagocytic amoebae. This technique combined with bioinformatic data allowed the identification of 28 candidate virulence proteins, including Wimp1, the first identified inclusion membrane protein of W. chondrophila.

An inhibitory mechanism of action of coiled‐coil peptides against type three secretion system from enteropathogenicEscherichia coli

2019 ◽  
Vol 25 (3) ◽  
Author(s):  
Mariano Larzábal ◽  
Hector A. Baldoni ◽  
Fernando D. Suvire ◽  
Lucrecia M. Curto ◽  
Gabriela E. Gomez ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Coiled Coil ◽  
Secretion System ◽  
Inhibitory Mechanism ◽  
Type Three Secretion System ◽  
Type Three Secretion

scholarly journals Plasmid composition in Aeromonas salmonicida subsp. salmonicida 01-B526 unravels unsuspected type three secretion system loss patterns

BMC Genomics ◽  
2017 ◽  
Vol 18 (1) ◽  
Author(s):  
Katherine H. Tanaka ◽  
Antony T. Vincent ◽  
Jean-Guillaume Emond-Rheault ◽  
Marcin Adamczuk ◽  
Michel Frenette ◽  
...  
Keyword(s):  
Secretion System ◽  
Aeromonas Salmonicida ◽  
Type Three Secretion System ◽  
Type Three Secretion

scholarly journals Type Three Secretion System-Dependent Microvascular Thrombosis and Ischemic Enteritis in Human Gut Xenografts Infected with Enteropathogenic Escherichia coli

2017 ◽  
Vol 85 (11) ◽  
Author(s):  
Einat Nissim-Eliraz ◽  
Eilam Nir ◽  
Irit Shoval ◽  
Noga Marsiano ◽  
Israel Nissan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Blood Vessels ◽  
Secretion System ◽  
Infection Model ◽  
Apical Surface ◽  
Muscularis Mucosa ◽  
Human Gut ◽  
Type Three Secretion System ◽  
Type Three Secretion ◽  
Ischemic Enteritis

ABSTRACT Enteropathogenic Escherichia coli (EPEC) is a leading cause of severe intestinal disease and infant mortality in developing countries. Virulence is mediated by a type three secretion system (T3SS), causing the hallmark attaching and effacing (AE) lesions and actin-rich pedestal formation beneath the infecting bacteria on the apical surface of enterocytes. EPEC is a human-specific pathogen whose pathogenesis cannot be studied in animal models. We therefore established an EPEC infection model in human gut xenografts in SCID mice and used it to study the role of T3SS in the pathogenesis of the disease. Following EPEC O127:H6 strain E2348/69 infection, T3SS-dependent AE lesions and pedestals were demonstrated in all infected xenografts. We report here the development of T3SS-dependent intestinal thrombotic microangiopathy (iTMA) and ischemic enteritis in ∼50% of infected human gut xenografts. Using species-specific CD31 immunostaining, we showed that iTMA was limited to the larger human-mouse chimeric blood vessels, which are located between the muscularis mucosa and circular muscular layer of the human gut. These blood vessels were massively invaded by bacteria, which adhered to and formed pedestals on endothelial cells and aggregated with mouse neutrophils in the lumen. We conclude that endothelial infection, iTMA, and ischemic enteritis might be central mechanisms underlying severe EPEC-mediated disease.

Parasitophorous vacuoles of Leishmania mexicana acquire macromolecules from the host cell cytosol via two independent routes

1999 ◽  
Vol 112 (5) ◽  
pp. 681-693
Author(s):  
U.E. Schaible ◽  
P.H. Schlesinger ◽  
T.H. Steinberg ◽  
W.F. Mangel ◽  
T. Kobayashi ◽  
...  
Keyword(s):  
Host Cell ◽  
Lucifer Yellow ◽  
Cysteine Proteinase ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Anion Transporter ◽  
Infected Cells ◽  
Lysobisphosphatidic Acid ◽  
Cell Cytosol ◽  
Host Cell Cytosol

The intracellular parasite Leishmania survives and proliferates in host macrophages. In this study we show that parasitophorous vacuoles of L. mexicana gain access to cytosolic material via two different routes. (1) Small anionic molecules such as Lucifer Yellow are rapidly transported into the vacuoles by an active transport mechanism that is sensitive to inhibitors of the host cell's organic anion transporter. (2) Larger molecules such as fluorescent dextrans introduced into the host cell cytosol are also delivered to parasitophorous vacuoles. This transport is slower and sensitive to modulators of autophagy. Infected macrophages were examined by two novel assays to visualize and quantify this process. Immunoelectron microscopy of cells loaded with digoxigenin-dextran revealed label in multivesicular endosomes, which appeared to fuse with parasitophorous vacuoles. The inner membranes of the multivesicular vesicles label strongly with antibodies against lysobisphosphatidic acid, suggesting that they represent a point of confluence between the endosomal and autophagosomal pathways. Although the rate of autophagous transfer was comparable in infected and uninfected cells, infected cells retained hydrolyzed cysteine proteinase substrate to a greater degree. These data suggest that L. mexicana-containing vacuoles have access to potential nutrients in the host cell cytosol via at least two independent mechanisms.

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