scholarly journals Interaction between Burkholderia pseudomallei and Acanthamoeba Species Results in Coiling Phagocytosis, Endamebic Bacterial Survival, and Escape

2000 ◽  
Vol 68 (3) ◽  
pp. 1681-1686 ◽  
Author(s):  
Timothy J. J. Inglis ◽  
Paul Rigby ◽  
Terry A. Robertson ◽  
Nichole S. Dutton ◽  
Mandy Henderson ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Rapid Onset ◽  
Cellular Interactions ◽  
Bacterial Survival ◽  
Phagocytic Cells ◽  
Free Living ◽  
Intracellular Location ◽  
Serovar Typhimurium

ABSTRACT Burkholderia pseudomallei causes melioidosis, a potentially fatal disease whose clinical outcomes include rapid-onset septicemia and relapsing and delayed-onset infections. Like other facultative intracellular bacterial pathogens, B. pseudomallei is capable of survival in human phagocytic cells, but unlike mycobacteria, Listeria monocytogenes, andSalmonella serovar Typhimurium, the species has not been reported to survive as an endosymbiont in free-living amebae. We investigated the consequences of exposing Acanthamoeba astronyxis, A. castellani, and A. polyphaga to B. pseudomallei NCTC 10276 in a series of coculture experiments. Bacterial endocytosis was observed in all three Acanthamoeba species. A more extensive range of cellular interactions including bacterial adhesion, incorporation into amebic vacuoles, and separation was observed with A. astronyxis in timed coculture experiments. Amebic trophozoites containing motile intravacuolar bacilli were found throughout 72 h of coculture. Confocal microscopy was used to confirm the intracellular location of endamebic B. pseudomallei cells. Transmission electron microscopy of coculture preparations revealed clusters of intact bacilli in membrane-lined vesicles inside the trophozoite cytoplasm; 5 × 102 CFU of bacteria per ml were recovered from lysed amebic trophozoites after 60 min of coculture. Demonstration of an interaction between B. pseudomallei and free-living acanthamebae in vitro raises the possibility that a similar interaction in vivo might affect environmental survival ofB. pseudomallei and subsequent human exposure. Endamebic passage of B. pseudomallei warrants further investigation as a potential in vitro model of intracellular B. pseudomallei infection.

scholarly journals Mycobacterium tuberculosis Alters the Metalloprotease Activity of the COP9 Signalosome

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Lia Danelishvili ◽  
Lmar Babrak ◽  
Sasha J. Rose ◽  
Jamie Everman ◽  
Luiz E. Bermudez
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cop9 Signalosome ◽  
Virulence Determinants ◽  
Bacterial Survival ◽  
Phagocytic Cells ◽  
Content Type ◽  
Metalloprotease Activity ◽  
Macrophage Protein

ABSTRACT Inhibition of apoptotic death of macrophages by Mycobacterium tuberculosis represents an important mechanism of virulence that results in pathogen survival both in vitro and in vivo. To identify M. tuberculosis virulence determinants involved in the modulation of apoptosis, we previously screened a transposon bank of mutants in human macrophages, and an M. tuberculosis clone with a nonfunctional Rv3354 gene was identified as incompetent to suppress apoptosis. Here, we show that the Rv3354 gene encodes a protein kinase that is secreted within mononuclear phagocytic cells and is required for M. tuberculosis virulence. The Rv3354 effector targets the metalloprotease (JAMM) domain within subunit 5 of the COP9 signalosome (CSN5), resulting in suppression of apoptosis and in the destabilization of CSN function and regulatory cullin-RING ubiquitin E3 enzymatic activity. Our observation suggests that alteration of the metalloprotease activity of CSN by Rv3354 possibly prevents the ubiquitin-dependent proteolysis of M. tuberculosis-secreted proteins. IMPORTANCE Macrophage protein degradation is regulated by a protein complex called a signalosome. One of the signalosomes associated with activation of ubiquitin and protein labeling for degradation was found to interact with a secreted protein from M. tuberculosis, which binds to the complex and inactivates it. The interference with the ability to inactivate bacterial proteins secreted in the phagocyte cytosol may have crucial importance for bacterial survival within the phagocyte.

scholarly journals A Mouse Model Of Binge Alcohol Consumption andBurkholderiaInfection

2018 ◽  
Author(s):  
Victor Jimenez ◽  
Ryan Moreno ◽  
Erik Settles ◽  
Bart J Currie ◽  
Paul Keim ◽  
...  
Keyword(s):  
Alcohol Consumption ◽  
Binge Drinking ◽  
Burkholderia Pseudomallei ◽  
Alcohol Exposure ◽  
Model Systems ◽  
Phagocytic Cells ◽  
Intracellular Invasion ◽  
The Impact

AbstractBackgroundBinge drinking, a common form of alcohol consumption, is associated with increased mortality and morbidity; yet, its effects on the immune system’s ability to defend against infectious agents are poorly understood.Burkholderia pseudomallei, the causative agent of melioidosis can occur in healthy humans, yet binge alcohol use is progressively being recognized as a major risk factor. Although our previous studies demonstrated that binge alcohol exposure results in reduced alveolar macrophage function and increasedBurkholderiavirulencein vitro, no experimental studies have investigated the outcomes of binge alcohol onBurkholderiaspp. infectionin vivo.Principal FindingsWe used the close genetic relatives ofB. pseudomallei, B. thailandensisE264 andB. vietnamiensis, as useful BSL-2 model systems. Eight-week-old female C57BL/6 mice were administered alcohol comparable to human binge drinking episodes (4.4 g/kg) or PBS intraperitoneally 30 min before a non-lethal intranasal infection. In an initialB. thailandensisinfection (3 x 105), bacteria accumulated in the lungs and disseminated to the spleen in alcohol administered mice only, compared with PBS treated mice at 24 h post-infection (PI). The greatest bacterial load occurred withB. vietnamiensis(1 x 106) in lungs, spleen, and brain tissue by 72 h PI. Pulmonary cytokine expression (TNF-α, GM-CSF) decreased, while splenic cytokine (IL-10) increased in binge drunk mice. Increased lung and brain permeability was observed as early as 2 h post alcohol administrationin vivo.Trans-epithelial electrical resistance (TEER) was significantly decreased, while intracellular invasion of non-phagocytic cells increased with 0.2% v/v alcohol exposurein vitro.ConclusionsOur results indicate that a single binge alcohol dose suppressed innate immune functions and increased the ability of less virulentBurkholderiastrains to disseminate through increased barrier permeability and intracellular invasion of non-phagocytic cells.Author SummaryBurkholderia pseudomalleicauses the disease melioidosis, which occurs in most tropical regions across the globe. Exposure rarely evolves to significant disease in the absence of specific comorbidities, such as binge alcohol intoxication. In susceptible hosts, the disease is primarily manifested as pneumonic melioidosis and can be rapidly fatal if untreated. In this study, we utilizedB. thailandensis, a genetically similar strain toB. pseudomallei, and opportunisticB. vietnamiensis, a known human pathogen that utilizes similar virulence strategies asB. pseudomalleiin immunocompromised and cystic fibrosis patients. The study investigates the impact of a single binge alcohol episode on infectivity and immune responsein vivo. We show that a single binge alcohol episode prior to inhalingBurkholderiaspecies increases bacterial spread to the lungs and brain. We also identify alcohol-induced tissue permeability and epithelial cell invasion as modes of action for greater bacterial spread and survival inside the host. Our results support the public health responses being developed in melioidosis-endemic regions that emphasize the nature of binge drinking as a prime concern, especially around potential times of exposure to environmentalB. pseudomallei.

scholarly journals A Superoxide-Hypersusceptible Salmonella enterica Serovar Typhimurium Mutant Is Attenuated but Regains Virulence in p47phox−/− Mice

2002 ◽  
Vol 70 (5) ◽  
pp. 2614-2621 ◽  
Author(s):  
Angela van Diepen ◽  
Tahar van der Straaten ◽  
Steven M. Holland ◽  
Riny Janssen ◽  
Jaap T. van Dissel
Keyword(s):  
Salmonella Enterica ◽  
Defense Mechanisms ◽  
Mononuclear Phagocytes ◽  
Wild Type ◽  
Phagocytic Cells ◽  
Bacterial Counts ◽  
Innate Defense ◽  
Serovar Typhimurium

ABSTRACT Salmonella enterica serovar Typhimurium is a gram-negative, facultative intracellular pathogen that predominantly invades mononuclear phagocytes and is able to establish persistent infections. One of the innate defense mechanisms of phagocytic cells is the production of reactive oxygen species, including superoxide. S. enterica serovar Typhimurium has evolved mechanisms to resist such radicals, and these mechanisms could be decisive in its ability to survive and replicate within macrophages. Recently, we described a superoxide-hypersusceptible S. enterica serovar Typhimurium mutant strain, DLG294, that carries a transposon in sspJ, resulting in the lack of expression of SspJ, which is necessary for resistance against superoxide and replication within macrophages. Here we show that DLG294, which is a 14028s derivative, hardly induced any granulomatous lesions in the livers upon subcutaneous infection of C3H/HeN (Ityr) mice with 3 × 104 bacteria and that its bacterial counts were reduced by 3 log units compared to those of wild-type S. enterica serovar Typhimurium 14028s on day 5 after infection. In contrast, DLG294 replicated like wild-type S. enterica serovar Typhimurium 14028s and induced a phenotypically similar liver pathology in p47phox−/− mice, which are deficient in the p47phox subunit of the NADPH oxidase complex and which do not produce superoxide. Consistent with these results, DLG294 reached bacterial counts identical to those of wild-type S. enterica serovar Typhimurium 14028s in bone marrow-derived macrophages from p47phox−/− mice and in X-CGD PLB-985 cells at 24 h after challenge. These results indicate that SspJ plays a role in the bacterium's resistance to oxidative stress and in the survival and replication of S. enterica serovar Typhimurium both in vitro and in vivo.

scholarly journals Contribution of Proton-Translocating Proteins to the Virulence of Salmonella enterica Serovars Typhimurium, Gallinarum, and Dublin in Chickens and Mice

2003 ◽  
Vol 71 (6) ◽  
pp. 3392-3401 ◽  
Author(s):  
A. K. Turner ◽  
L. Z. Barber ◽  
P. Wigley ◽  
S. Muhammad ◽  
M. A. Jones ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Salmonella Enterica ◽  
Acid Tolerance ◽  
Phagocytic Cells ◽  
Live Vaccines ◽  
Serovar Typhimurium ◽  
Old Mice ◽  
In Vitro Survival

ABSTRACT We investigated the attenuating effects of a range of respiratory chain mutations in three Salmonella serovars which might be used in the development of live vaccines. We tested mutations in nuoG, cydA, cyoA, atpB, and atpH in three serovars of Salmonella enterica: Typhimurium, Dublin, and Gallinarum. All three serovars were assessed for attenuation in their relevant virulence assays of typhoid-like infections. Serovar Typhimurium was assessed in 1-day-old chickens and the mouse. Serovar Gallinarum 9 was assessed in 3-week-old chickens, and serovar Dublin was assessed in 6-week-old mice. Our data show variation in attenuation for the nuoG, cydA, and cyoA mutations within the different serovar-host combinations. However, mutations in atpB and atpH were highly attenuating for all three serovars in the various virulence assays. Further investigation of the mutations in the atp operon showed that the bacteria were less invasive in vivo, showing reduced in vitro survival within phagocytic cells and reduced acid tolerance. We present data showing that this reduced acid tolerance is due to an inability to adapt to conditions rather than a general sensitivity to reduced pH. The data support the targeting of respiratory components for the production of live vaccines and suggest that mutations in the atp operon provide suitable candidates for broad-spectrum attenuation of a range of Salmonella serovars.

Inhibition of Salmonella enterica serovar Typhimurium Type Ⅲ Secretion System and Infection Using Small Molecule Quercitrin

2021 ◽  
Author(s):  
Qingjie Li ◽  
Lianping Wang ◽  
Shuang Liu ◽  
Jingwen Xu ◽  
Zeyu Song ◽  
...  
Keyword(s):  
Biological Activities ◽  
Secretion System ◽  
Bacterial Invasion ◽  
Bacterial Survival ◽  
Reporter System ◽  
Western Blot Assay ◽  
Systemic Analysis ◽  
Serovar Typhimurium

Abstract AimsThis study was conducted to screen the type Ⅲ secretion system (T3SS) inhibitors of Salmonella enterica serovar Typhimurium (S. Typhimurium) from natural compounds. Through systemic analysis the pharmacological activity and action mechanism of candidate compounds in vivo and in vitro. Methods and resultsUsing an effector-β-lactamase fusion reporter system in S. Typhimurium, we discovered that quercitrin could block effector SipA translocation into eukaryotic host cell without affecting bacterial growth, and inhibit invasion or epithelial cells damage. Using β-galactosidase activity and Western blot assay, it was found that quercitrin significantly inhibits the expression of SPI-1 genes (hilA and sopA) and effectors (SipA and SipC). The animal experiment results indicated that quercitrin reduces mortality, pathological damages and colony colonization of infected mice. ConclusionsSmall-molecule inhibitor quercitrin directly inhibits the founction of T3SS in S. Typhimurium, and provids a potential alternative antimicrobial against Salmonella infection.Significance and impact of the studyNatural compounds have become valuable resources for antibacterials discovery due to their widely structures and biological activities. However, the potential targets and molecular action mechanisms of candidate compounds responsible for anti-infections remain elusive. The T3SS plays a crucial role in bacterial invasion and pathogenesis process in S. Typhimurium. Compared with traditional antibiotics, small molecular compounds can inhibit the T3SS of Salmonella and achieve the effect of anti-infection. They have less pressure on bacterial survival and are not easy to produce drug resistance. This provides strong evidence for development novel anti-virulence drugs against Salmonella infection.

scholarly journals Needle-Free Delivery of Acetalated Dextran-Encapsulated AR-12 Protects Mice from Francisella tularensis Lethal Challenge

2016 ◽  
Vol 60 (4) ◽  
pp. 2052-2062 ◽  
Author(s):  
Ky V. Hoang ◽  
Heather Curry ◽  
Michael A. Collier ◽  
Hassan Borteh ◽  
Eric M. Bachelder ◽  
...  
Keyword(s):  
Francisella Tularensis ◽  
Lethal Challenge ◽  
Content Type ◽  
Human Macrophages ◽  
Gentamicin Treatment ◽  
Significant Toxicity ◽  
Serovar Typhimurium ◽  
Spectrum Activity

ABSTRACTFrancisella tularensiscauses tularemia and is a potential biothreat. Given the limited antibiotics for treating tularemia and the possible use of antibiotic-resistant strains as a biowarfare agent, new antibacterial agents are needed. AR-12 is an FDA-approved investigational new drug (IND) compound that induces autophagy and has shown host-directed, broad-spectrum activityin vitroagainstSalmonella entericaserovar Typhimurium andF. tularensis. We have shown that AR-12 encapsulated within acetalated dextran (Ace-DEX) microparticles (AR-12/MPs) significantly reduces host cell cytotoxicity compared to that with free AR-12, while retaining the ability to controlS.Typhimurium within infected human macrophages. In the present study, the toxicity and efficacy of AR-12/MPs in controlling virulent type AF. tularensisSchuS4 infection were examinedin vitroandin vivo. No significant toxicity of blank MPs or AR-12/MPs was observed in lung histology sections when the formulations were given intranasally to uninfected mice. In histology sections from the lungs of intranasally infected mice treated with the formulations, increased macrophage infiltration was observed for AR-12/MPs, with or without suboptimal gentamicin treatment, but not for blank MPs, soluble AR-12, or suboptimal gentamicin alone. AR-12/MPs dramatically reduced the burden ofF. tularensisin infected human macrophages, in a manner similar to that of free AR-12. However,in vivo, AR-12/MPs significantly enhanced the survival ofF. tularensisSchuS4-infected mice compared to that seen with free AR-12. In combination with suboptimal gentamicin treatment, AR-12/MPs further improved the survival ofF. tularensisSchuS4-infected mice. These studies provide support for Ace-DEX-encapsulated AR-12 as a promising new therapeutic agent for tularemia.

scholarly journals Biological Relevance of Colony Morphology and Phenotypic Switching by Burkholderia pseudomallei

2006 ◽  
Vol 189 (3) ◽  
pp. 807-817 ◽  
Author(s):  
Narisara Chantratita ◽  
Vanaporn Wuthiekanun ◽  
Khaemaporn Boonbumrung ◽  
Rachaneeporn Tiyawisutsri ◽  
Mongkol Vesaratchavest ◽  
...  
Keyword(s):  
Burkholderia Pseudomallei ◽  
Vaccine Development ◽  
Colony Morphology ◽  
Phenotypic Switching ◽  
Type I ◽  
Type Ii ◽  
Altered Expression ◽  
Replication Fitness

ABSTRACT Melioidosis is a notoriously protracted illness and is difficult to cure. We hypothesize that the causative organism, Burkholderia pseudomallei, undergoes a process of adaptation involving altered expression of surface determinants which facilitates persistence in vivo and that this is reflected by changes in colony morphology. A colony morphotyping scheme and typing algorithm were developed using clinical B. pseudomallei isolates. Morphotypes were divided into seven types (denoted I to VII). Type I gave rise to other morphotypes (most commonly type II or III) by a process of switching in response to environmental stress, including starvation, iron limitation, and growth at 42°C. Switching was associated with complex shifts in phenotype, one of which (type I to type II) was associated with a marked increase in production of factors putatively associated with in vivo concealment. Isogenic types II and III, derived from type I, were examined using several experimental models. Switching between isogenic morphotypes occurred in a mouse model, where type II appeared to become adapted for persistence in a low-virulence state. Isogenic type II demonstrated a significant increase in intracellular replication fitness compared with parental type I after uptake by epithelial cells in vitro. Isogenic type III demonstrated a higher replication fitness following uptake by macrophages in vitro, which was associated with a switch to type II. Mixed B. pseudomallei morphologies were common in individual clinical specimens and were significantly more frequent in samples of blood, pus, and respiratory secretions than in urine and surface swabs. These findings have major implications for therapeutics and vaccine development.

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