actively inhibits the production of extracellular vesicles by human neutrophils.

is the etiologic agent of the plague. A hallmark of plague is subversion of the host immune response by disrupting host signaling pathways required for inflammation. This non-inflammatory environment permits bacterial colonization and has been shown to be essential for disease manifestation.

Approaches for the Inactivation of .

Introduction: is the gram-negative, facultative intracellular bacterium that causes the disease known as plague. Due to the risk for aerosol transmission, a low infectious dose, and the acute and lethal nature of pneumonic plague, research activities with require Biosafety Level 3 (BSL-3) facilities to provide the appropriate safeguards to minimize accidental exposures and environmental release. However, many experimental assays cannot be performed in BSL-3 due to equipment availability, and thus require removal of samples from the BSL-3 laboratory to be completed.

Draft genome sequences of evolutionary distant species representatives.

is the etiological agent of human plague. However, certain evolutionarily divergent subspecies have different host specificities and virulence capacity compared to the more commonly studied strains with pandemic potential. This resource examines 10 diverse isolates representing some of the most understudied subspecies commonly referred to as Pestoides.

Distinct mechanisms of type 3 secretion system recognition control LTB4 synthesis in neutrophils and macrophages.

Leukotriene B4 (LTB4) is an inflammatory lipid produced in response to pathogens that is critical for initiating the inflammatory cascade needed to control infection. However, during plague, Yersinia pestis inhibits the timely synthesis of LTB4 and subsequent inflammation. Using bacterial mutants, we previously determined that Y.

Distinct Mechanisms of Type 3 Secretion System Recognition Control LTB Synthesis in Neutrophils versus Macrophages.

Leukotriene B4 (LTB) is critical for initiating the inflammatory cascade in response to infection. However, colonizes the host by inhibiting the timely synthesis of LTB and inflammation. Here, we show that the bacterial type 3 secretion system (T3SS) is the primary pathogen associated molecular pattern (PAMP) responsible for LTB production by leukocytes in response to and , but synthesis is inhibited by the Yop effectors during interactions.

Type 3 secretion system induced leukotriene B4 synthesis by leukocytes is actively inhibited by Yersinia pestis to evade early immune recognition.

Subverting the host immune response to inhibit inflammation is a key virulence strategy of Yersinia pestis. The inflammatory cascade is tightly controlled via the sequential action of lipid and protein mediators of inflammation. Because delayed inflammation is essential for Y.

Microneedle array delivery of recapitulates bubonic plague.

Fleas transmit directly within the dermis of mammals to cause bubonic plague. Syringe-mediated inoculation is widely used to recapitulate bubonic plague and study pathogenesis. However, intradermal needle inoculation is tedious, error prone, and poses a significant safety risk for laboratorians.

Droplet Tn-Seq identifies the primary secretion mechanism for yersiniabactin in Yersinia pestis.

Nutritional immunity includes sequestration of transition metals from invading pathogens. Yersinia pestis overcomes nutritional immunity by secreting yersiniabactin to acquire iron and zinc during infection. While the mechanisms for yersiniabactin synthesis and import are well-defined, those responsible for yersiniabactin secretion are unknown.

Validated Preclinical Mouse Model for Therapeutic Testing against Multidrug-Resistant Pseudomonas aeruginosa Strains.

The rise in infections caused by antibiotic-resistant bacteria is outpacing the development of new antibiotics. The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are a group of clinically important bacteria that have developed resistance to multiple antibiotics and are commonly referred to as multidrug resistant (MDR). The medical and research communities have recognized that, without new antimicrobials, infections by MDR bacteria will soon become a leading cause of morbidity and death.

Fluorescent sensors of siderophores produced by bacterial pathogens.

Siderophores are iron-chelating molecules that solubilize Fe for microbial utilization and facilitate colonization or infection of eukaryotes by liberating host iron for bacterial uptake. By fluorescently labeling membrane receptors and binding proteins, we created 20 sensors that detect, discriminate, and quantify apo- and ferric siderophores. The sensor proteins originated from TonB-dependent ligand-gated porins (LGPs) of Escherichia coli (Fiu, FepA, Cir, FhuA, IutA, BtuB), Klebsiella pneumoniae (IroN, FepA, FyuA), Acinetobacter baumannii (PiuA, FepA, PirA, BauA), Pseudomonas aeruginosa (FepA, FpvA), and Caulobacter crescentus (HutA) from a periplasmic E.

Siderophore-mediated zinc acquisition enhances enterobacterial colonization of the inflamed gut.

Zinc is an essential cofactor for bacterial metabolism, and many Enterobacteriaceae express the zinc transporters ZnuABC and ZupT to acquire this metal in the host. However, the probiotic bacterium Escherichia coli Nissle 1917 (or "Nissle") exhibits appreciable growth in zinc-limited media even when these transporters are deleted. Here, we show that Nissle utilizes the siderophore yersiniabactin as a zincophore, enabling Nissle to grow in zinc-limited media, to tolerate calprotectin-mediated zinc sequestration, and to thrive in the inflamed gut.

Yersiniabactin contributes to overcoming zinc restriction during infection of mammalian and insect hosts.

causes human plague and colonizes both a mammalian host and a flea vector during its transmission cycle. A key barrier to bacterial infection is the host's ability to actively sequester key biometals (e.g.

Successful Intratracheal Treatment of Phage and Antibiotic Combination Therapy of a Multi-Drug Resistant Murine Model.

Background: Pseudomonas aeruginosa (PsA) is a common etiology of bacteria-mediated lower respiratory tract infections, including pneumonia, hospital acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP). Given the paucity of novel antibiotics in our foreseeable pipeline, developing novel non-antibiotic antimicrobial therapies saliently targeting drug resistant PsA isolates remains a priority. Lytic bacteriophages (or phages) have come under scrutiny as a potential antimicrobial for refractory bacterial infections.

FDA Public Workshop Summary: Advancing Animal Models for Antibacterial Drug Development.

The U.S. Food and Drug Administration (FDA) hosted a public workshop entitled "Advancing Animal Models for Antibacterial Drug Development" on 5 March 2020.

Lemon Exosome-like Nanoparticles-Manipulated Probiotics Protect Mice from Infection.

is the leading cause of antibiotic-associated colitis. Here, we report that lemon exosome-like nanoparticles (LELNs) manipulated probiotics to inhibit infection (CDI). LELN-manipulated GG (LGG) and ST-21 (STH) (LELN-LS) decrease CDI mortality via an LELN-mediated increase in bile resistance and gut survivability.

Recombinant Human Plasma Gelsolin Improves Survival and Attenuates Lung Injury in a Murine Model of Multidrug-Resistant Pneumonia.

Background: Plasma gelsolin (pGSN) is an abundant circulating protein quickly consumed by extensive tissue damage. Marked depletion is associated with later poor outcomes in diverse clinical circumstances. Repletion with recombinant human (rhu)-pGSN in animal models of inflammation lessens mortality and morbidity.

Redundant and Cooperative Roles for Yersinia pestis Yop Effectors in the Inhibition of Human Neutrophil Exocytic Responses Revealed by Gain-of-Function Approach.

causes a rapid, lethal disease referred to as plague. actively inhibits the innate immune system to generate a noninflammatory environment during early stages of infection to promote colonization. The ability of to create this early noninflammatory environment is in part due to the action of seven Yop effector proteins that are directly injected into host cells via a type 3 secretion system (T3SS).

Robust Th1 cellular and humoral responses generated by the Yersinia pestis rF1-V subunit vaccine formulated to contain an agonist of the CD137 pathway do not translate into increased protection against pneumonic plague.

Yersinia pestis is the causative agent of plague and is a re-emerging pathogen that also has the potential as a biological weapon, necessitating the development of a preventive vaccine. Despite intense efforts for the last several decades, there is currently not a vaccine approved by the FDA. The rF1-V vaccine adjuvanted with Alhydrogel is a lead candidate subunit vaccine for plague and generates a strong Th2-mediate humoral response with a modest Th1 cellular response.

Intracellular Assays to Monitor Survival and Growth of Yersinia pestis Within Macrophages.

Yersinia pestis is able to survive and replicate within macrophages, while also being able to live in the extracellular milieu of the host. Assays that facilitate better understanding of how Y. pestis survives intracellularly and subverts normal host antimicrobial defenses require the ability to monitor intracellular Y.

The Evolution of SlyA/RovA Transcription Factors from Repressors to Countersilencers in .

Gene duplication and subsequent evolutionary divergence have allowed conserved proteins to develop unique roles. The MarR family of transcription factors (TFs) has undergone extensive duplication and diversification in bacteria, where they act as environmentally responsive repressors of genes encoding efflux pumps that confer resistance to xenobiotics, including many antimicrobial agents. We have performed structural, functional, and genetic analyses of representative members of the SlyA/RovA lineage of MarR TFs, which retain some ancestral functions, including repression of their own expression and that of divergently transcribed multidrug efflux pumps, as well as allosteric inhibition by aromatic carboxylate compounds.

Inflammasome-Independent Leukotriene B Production Drives Crystalline Silica-Induced Sterile Inflammation.

Silicosis is a lung inflammatory disease caused by chronic exposure to crystalline silica (CS). Leukotriene B (LTB) plays an important role in neutrophilic inflammation, which drives silicosis and promotes lung cancer. In this study, we examined the mechanisms involved in CS-induced inflammatory pathways.

Targets the Host Endosome Recycling Pathway during the Biogenesis of the -Containing Vacuole To Avoid Killing by Macrophages.

has evolved many strategies to evade the innate immune system. One of these strategies is the ability to survive within macrophages. Upon phagocytosis, prevents phagolysosome maturation and establishes a modified compartment termed the -containing vacuole (YCV).

Impact of Gentamicin Concentration and Exposure Time on Intracellular .

The study of intracellular bacterial pathogens in cell culture hinges on inhibiting extracellular growth of the bacteria in cell culture media. Aminoglycosides, like gentamicin, were originally thought to poorly penetrate eukaryotic cells, and thus, while inhibiting extracellular bacteria, these antibiotics had limited effect on inhibiting the growth of intracellular bacteria. This property led to the development of the antibiotic protection assay to study intracellular pathogens .

Crystal structure of Yersinia pestis virulence factor YfeA reveals two polyspecific metal-binding sites.

Gram-negative bacteria use siderophores, outer membrane receptors, inner membrane transporters and substrate-binding proteins (SBPs) to transport transition metals through the periplasm. The SBPs share a similar protein fold that has undergone significant structural evolution to communicate with a variety of differentially regulated transporters in the cell. In Yersinia pestis, the causative agent of plague, YfeA (YPO2439, y1897), an SBP, is important for full virulence during mammalian infection.

Zinc transporters YbtX and ZnuABC are required for the virulence of Yersinia pestis in bubonic and pneumonic plague in mice.

A number of bacterial pathogens require the ZnuABC Zinc (Zn) transporter and/or a second Zn transport system to overcome Zn sequestration by mammalian hosts. Previously we have shown that in addition to ZnuABC, Yersinia pestis possesses a second Zn transporter that involves components of the yersiniabactin (Ybt), siderophore-dependent iron transport system. Synthesis of the Ybt siderophore and YbtX, a member of the major facilitator superfamily, are both critical components of the second Zn transport system.