The CpxAR signaling system confers a fitness advantage for flea gut colonization by the plague bacillus.

Unlabelled: The adaptation of , the flea-borne plague agent, to fluctuating environmental conditions is essential for the successful colonization of the flea vector. A previous comparative transcriptomic analysis showed that the Cpx pathway of is up-regulated in infected fleas. The CpxAR two-component system is a component of the envelope stress response and is critical for maintaining the integrity of the cell.

and Plague: some knowns and unknowns.

Since its first identification in 1894 during the third pandemic in Hong Kong, there has been significant progress of understanding the lifestyle of , the pathogen that is responsible for plague. Although we now have some understanding of the pathogen's physiology, genetics, genomics, evolution, gene regulation, pathogenesis and immunity, there are many unknown aspects of the pathogen and its disease development. Here, we focus on some of the knowns and unknowns relating to and plague.

Preclinical safety and efficacy characterization of an LpxC inhibitor against Gram-negative pathogens.

The UDP-3--(-3-hydroxyacyl)--acetylglucosamine deacetylase LpxC is an essential enzyme in the biosynthesis of lipid A, the outer membrane anchor of lipopolysaccharide and lipooligosaccharide in Gram-negative bacteria. The development of LpxC-targeting antibiotics toward clinical therapeutics has been hindered by the limited antibiotic profile of reported non-hydroxamate inhibitors and unexpected cardiovascular toxicity observed in certain hydroxamate and non-hydroxamate-based inhibitors. Here, we report the preclinical characterization of a slow, tight-binding LpxC inhibitor, LPC-233, with low picomolar affinity.

A Widefield Light Microscopy-Based Approach Provides Further Insights into the Colonization of the Flea Proventriculus by Yersinia pestis.

Yersinia pestis (the agent of flea-borne plague) must obstruct the flea's proventriculus to maintain transmission to a mammalian host. To this end, Y. pestis must consolidate a mass that entrapped Y.

Antibiotic Therapy of Plague: A Review.

Plague-a deadly disease caused by the bacterium -is still an international public health concern. There are three main clinical forms: bubonic plague, septicemic plague, and pulmonary plague. In all three forms, the symptoms appear suddenly and progress very rapidly.

Interplay between Yersinia pestis and its flea vector in lipoate metabolism.

To thrive, vector-borne pathogens must survive in the vector's gut. How these pathogens successfully exploit this environment in time and space has not been extensively characterized. Using Yersinia pestis (the plague bacillus) and its flea vector, we developed a bioluminescence-based approach and employed it to investigate the mechanisms of pathogenesis at an unprecedented level of detail.

Plasminogen Activator.

The Gram-negative bacterium causes plague, a fatal flea-borne anthropozoonosis, which can progress to aerosol-transmitted pneumonia. overcomes the innate immunity of its host thanks to many pathogenicity factors, including plasminogen activator, Pla. This factor is a broad-spectrum outer membrane protease also acting as adhesin and invasin.

A refined model of how Yersinia pestis produces a transmissible infection in its flea vector.

In flea-borne plague, blockage of the flea's foregut by Yersinia pestis hastens transmission to the mammalian host. Based on microscopy observations, we first suggest that flea blockage results from primary infection of the foregut and not from midgut colonization. In this model, flea infection is characterized by the recurrent production of a mass that fills the lumen of the proventriculus and encompasses a large number of Y.

Polymorphism in the LcrV Antigen Enables Immune Escape From the Protection Conferred by an LcrV-Secreting in a Pseudotuberculosis Mouse Model.

Yersinioses caused by , and are significant concerns in human and veterinary health. The link between virulence and the potent LcrV antigen has prompted the latter's selection as a major component of anti- vaccines. Here, we report that (i) the group of species encompassing and produces at least five different clades of LcrV and (ii) vaccination of mice with an LcrV-secreting only protected against strains producing the same LcrV clade as that of used for vaccination.

Nutrient depletion may trigger the Yersinia pestis OmpR-EnvZ regulatory system to promote flea-borne plague transmission.

The flea's lumen gut is a poorly documented environment where the agent of flea-borne plague, Yersinia pestis, must replicate to produce a transmissible infection. Here, we report that both the acidic pH and osmolarity of the lumen's contents display simple harmonic oscillations with different periods. Since an acidic pH and osmolarity are two of three known stimuli of the OmpR-EnvZ two-component system in bacteria, we investigated the role and function of this Y.

To block or not to block: The adaptive manipulation of plague transmission.

The ability of the agent of plague, , to form a biofilm blocking the gut of the flea has been considered to be a key evolutionary step in maintaining flea-borne transmission. However, blockage decreases dramatically the life expectancy of fleas, challenging the adaptive nature of blockage. Here, we develop an epidemiological model of plague that accounts for its different transmission routes, as well as the within-host competition taking place between bacteria within the flea vector.

Transcriptomic studies and assessment of Yersinia pestis reference genes in various conditions.

Reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR) is a very sensitive widespread technique considered as the gold standard to explore transcriptional variations. While a particular methodology has to be followed to provide accurate results many published studies are likely to misinterpret results due to lack of minimal quality requirements. Yersinia pestis is a highly pathogenic bacterium responsible for plague.

Curative Treatment of Severe Gram-Negative Bacterial Infections by a New Class of Antibiotics Targeting LpxC.

The infectious diseases caused by multidrug-resistant bacteria pose serious threats to humankind. It has been suggested that an antibiotic targeting LpxC of the lipid A biosynthetic pathway in Gram-negative bacteria is a promising strategy for curing Gram-negative bacterial infections. However, experimental proof of this concept is lacking.

Characterization of the protective immune response to Yersinia pseudotuberculosis infection in mice vaccinated with an LcrV-secreting strain of Lactococcus lactis.

Background: Pseudotuberculosis is an infection caused by the bacterial enteropathogen Yersinia pseudotuberculosis and is considered to be a significant problem in veterinary medicine. We previously found that intranasal administration of a recombinant Lactococcus lactis strain that secretes the low-calcium response V (LcrV) antigen from Y. pseudotuberculosis (Ll-LcrV) confers protection against a lethal Y.

High susceptibility of MDR and XDR Gram-negative pathogens to biphenyl-diacetylene-based difluoromethyl-allo-threonyl-hydroxamate LpxC inhibitors.

Objectives: Inhibitors of uridine diphosphate-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase (LpxC, which catalyses the first, irreversible step in lipid A biosynthesis) are a promising new class of antibiotics against Gram-negative bacteria. The objectives of the present study were to: (i) compare the antibiotic activities of three LpxC inhibitors (LPC-058, LPC-011 and LPC-087) and the reference inhibitor CHIR-090 against Gram-negative bacilli (including MDR and XDR isolates); and (ii) investigate the effect of combining these inhibitors with conventional antibiotics.

Methods: MICs were determined for 369 clinical isolates (234 Enterobacteriaceae and 135 non-fermentative Gram-negative bacilli).

Drug design from the cryptic inhibitor envelope.

Conformational dynamics plays an important role in enzyme catalysis, allosteric regulation of protein functions and assembly of macromolecular complexes. Despite these well-established roles, such information has yet to be exploited for drug design. Here we show by nuclear magnetic resonance spectroscopy that inhibitors of LpxC--an essential enzyme of the lipid A biosynthetic pathway in Gram-negative bacteria and a validated novel antibiotic target--access alternative, minor population states in solution in addition to the ligand conformation observed in crystal structures.

Evaluation of the Role of the opgGH Operon in Yersinia pseudotuberculosis and Its Deletion during the Emergence of Yersinia pestis.

The opgGH operon encodes glucosyltransferases that synthesize osmoregulated periplasmic glucans (OPGs) from UDP-glucose, using acyl carrier protein (ACP) as a cofactor. OPGs are required for motility, biofilm formation, and virulence in various bacteria. OpgH also sequesters FtsZ in order to regulate cell size according to nutrient availability.

Superantigenic Yersinia pseudotuberculosis induces the expression of granzymes and perforin by CD4+ T cells.

Bacterial superantigens (SAgs) are immunostimulatory toxins that induce acute diseases mainly through the massive release of inflammatory cytokines. Yersinia pseudotuberculosis is the only Gram-negative bacterium known to produce a SAg (Y. pseudotuberculosis-derived mitogen [YPM]).

Functional and structural analysis of HicA3-HicB3, a novel toxin-antitoxin system of Yersinia pestis.

The mechanisms involved in the virulence of Yersinia pestis, the plague pathogen, are not fully understood. In previous research, we found that a Y. pestis mutant lacking the HicB3 (YPO3369) putative orphan antitoxin was attenuated for virulence in a murine model of bubonic plague.

Yersinia pestis requires the 2-component regulatory system OmpR-EnvZ to resist innate immunity during the early and late stages of plague.

Plague is transmitted by fleas or contaminated aerosols. To successfully produce disease, the causal agent (Yersinia pestis) must rapidly sense and respond to rapid variations in its environment. Here, we investigated the role of 2-component regulatory systems (2CSs) in plague because the latter are known to be key players in bacterial adaptation to environmental change.

New insights into how Yersinia pestis adapts to its mammalian host during bubonic plague.

Bubonic plague (a fatal, flea-transmitted disease) remains an international public health concern. Although our understanding of the pathogenesis of bubonic plague has improved significantly over the last few decades, researchers have still not been able to define the complete set of Y. pestis genes needed for disease or to characterize the mechanisms that enable infection.