International Proficiency Test Targeting a Large Panel of Botulinum Neurotoxin Sero- and Subtypes in Different Matrices.

Detection of botulinum neurotoxins (BoNTs) involves a combination of technical challenges that call for the execution of inter-laboratory proficiency tests (PTs) to define the performance and ease of implementation of existing diagnostic methods regarding representative BoNT toxin-types spiked in clinical, food, or environmental matrices. In the framework of the EU project EuroBioTox, we organized an international proficiency test for the detection and quantification of the clinically relevant BoNT/A, B, E, and F sero- and subtypes including concentrations as low as 0.5 ng/mL.

Caveolin-1 protects endothelial cells from extensive expansion of transcellular tunnel by stiffening the plasma membrane.

Large transcellular pores elicited by bacterial mono-ADP-ribosyltransferase (mART) exotoxins inhibiting the small RhoA GTPase compromise the endothelial barrier. Recent advances in biophysical modeling point toward membrane tension and bending rigidity as the minimal set of mechanical parameters determining the nucleation and maximal size of transendothelial cell macroaperture (TEM) tunnels induced by bacterial RhoA-targeting mART exotoxins. We report that cellular depletion of caveolin-1, the membrane-embedded building block of caveolae, and depletion of cavin-1, the master regulator of caveolae invaginations, increase the number of TEMs per cell.

, an oral pathobiont associated with colorectal cancer, epigenetically reprograms human colonocytes.

Recently, an intestinal dysbiotic microbiota with enrichment in oral cavity bacteria has been described in colorectal cancer (CRC) patients. Here, we characterize and investigate one of these oral pathobionts, the Gram-positive anaerobic coccus . We identified two phylotypes (A and B) exhibiting different phenotypes and adhesion capabilities.

Cytotoxic necrotizing factor 1 hinders colon tumorigenesis induced by colibactin-producing in mice.

Colorectal cancer (CRC) patients are frequently colonized by colibactin-producing (CoPEC) (>40%), which enhances tumorigenesis in mouse models of CRC. We observed that 50% of CoPEC also contains the gene, which encodes cytotoxic necrotizing factor-1 (CNF1), an enhancer of the eukaryotic cell cycle. The impact of its co-occurrence with colibactin (Clb) has not yet been investigated.

Optineurin links Hace1-dependent Rac ubiquitylation to integrin-mediated mechanotransduction to control bacterial invasion and cell division.

Extracellular matrix (ECM) elasticity is perceived by cells via focal adhesion structures, which transduce mechanical cues into chemical signalling to conform cell behavior. Although the contribution of ECM compliance to the control of cell migration or division is extensively studied, little is reported regarding infectious processes. We study this phenomenon with the extraintestinal Escherichia coli pathogen UTI89.

The gene is associated with an expanding ST131 30Rx/C2 subclade and confers a competitive advantage for gut colonization.

Epidemiological projections point to acquisition of ever-expanding multidrug resistance (MDR) by , a commensal of the digestive tract and a source of urinary tract pathogens. Bioinformatics analyses of a large collection of genomes from EnteroBase, enriched in clinical isolates of worldwide origins, suggest the Cytotoxic Necrotizing Factor 1 (CNF1)-toxin encoding gene, , is preferentially distributed in four common sequence types (ST) encompassing the pandemic MDR lineage ST131. This lineage is responsible for a majority of extraintestinal infections that escape first-line antibiotic treatment, with known enhanced capacities to colonize the gastrointestinal tract.

C910 chemical compound inhibits the traffiking of several bacterial AB toxins with cross-protection against influenza virus.

The development of anti-infectives against a large range of AB-like toxin-producing bacteria includes the identification of compounds disrupting toxin transport through both the endolysosomal and retrograde pathways. Here, we performed a high-throughput screening of compounds blocking Rac1 proteasomal degradation triggered by the Cytotoxic Necrotizing Factor-1 (CNF1) toxin, which was followed by orthogonal screens against two toxins that hijack the endolysosomal (diphtheria toxin) or retrograde (Shiga-like toxin 1) pathways to intoxicate cells. This led to the identification of the molecule C910 that induces the enlargement of EEA1-positive early endosomes associated with sorting defects of CNF1 and Shiga toxins to their trafficking pathways.

Synergistic interaction between pH and NaCl in the limits of germination and outgrowth of Clostridium sporogenes and Group I Clostridium botulinum vegetative cells and spores after heat treatment.

Group I Clostridium botulinum and Clostridium sporogenes are physiologically and genetically closely related. Both are widely distributed in the environment and can cause foodborne botulism. In this work, a physiological study was conducted with 37 isolates from spoiled canned food and five referenced strains of C.

Correction: Interaction of Saccharomyces boulardii with Salmonella enterica Serovar Typhimurium Protects Mice and Modifies T84 Cell Response to the Infection.

[This corrects the article DOI: 10.1371/journal.pone.

DHA-containing phospholipids control membrane fusion and transcellular tunnel dynamics.

Metabolic studies and animal knockout models point to the critical role of polyunsaturated docosahexaenoic acid (22:6, DHA)-containing phospholipids (DHA-PLs) in physiology. Here, we investigated the impact of DHA-PLs on the dynamics of transendothelial cell macroapertures (TEMs) triggered by RhoA inhibition-associated cell spreading. Lipidomic analyses showed that human umbilical vein endothelial cells (HUVECs) subjected to a DHA diet undergo a 6-fold enrichment in DHA-PLs at the plasma membrane (PM) at the expense of monounsaturated oleic acid-containing PLs (OA-PLs).

Identification of adipocytes as target cells for Leishmania infantum parasites.

Leishmania infantum is the causative agent of visceral leishmaniasis transmitted by the bite of female sand flies. According to the WHO, the estimated annual incidence of leishmaniasis is one million new cases, resulting in 30,000 deaths per year. The recommended drugs for treating leishmaniasis include Amphotericin B.

Conformational Insights into the Control of CNF1 Toxin Activity by Peptidyl-Prolyl Isomerization: A Molecular Dynamics Perspective.

The cytotoxic necrotizing factor 1 (CNF1) toxin from uropathogenic constitutively activates Rho GTPases by catalyzing the deamidation of a critical glutamine residue located in the switch II (SWII). In crystallographic structures of the CNF1 catalytic domain (CNF1), surface-exposed P768 and P968 peptidyl-prolyl imide bonds (X-Pro) adopt an unusual conformation. Here, we show that mutation of each proline residue into glycine abrogates CNF1 in vitro deamidase activity, while mutant forms of CNF1 remain functional on RhoA in cells.

Adaptation of in a Medium Mimicking a Diabetic Foot Environment.

is the most prevalent pathogen isolated from diabetic foot infections (DFIs). The purpose of this study was to evaluate its behavior in an in vitro model mimicking the conditions encountered in DFI. Four clinical strains were cultivated for 16 weeks in a specific environment based on the wound-like medium biofilm model.

Toxemia in Human Naturally Acquired Botulism.

Human botulism is a severe disease characterized by flaccid paralysis and inhibition of certain gland secretions, notably salivary secretions, caused by inhibition of neurotransmitter release. Naturally acquired botulism occurs in three main forms: food-borne botulism by ingestion of preformed botulinum neurotoxin (BoNT) in food, botulism by intestinal colonization (infant botulism and intestinal toxemia botulism in infants above one year and adults), and wound botulism. A rapid laboratory confirmation of botulism is required for the appropriate management of patients.

Dewetting: From Physics to the Biology of Intoxicated Cells.

Pathogenic bacteria colonize or disseminate into cells and tissues by inducing large-scale remodeling of host membranes. The physical phenomena underpinning these massive membrane extension and deformation are poorly understood. Invasive strategies of pathogens have been recently enriched by the description of a spectacular mode of opening of large transendothelial cell macroaperture (TEM) tunnels correlated to the dissemination of EDIN-producing strains of Staphylococcus aureus via a hematogenous route or to the induction of gelatinous edema triggered by the edema toxin from Bacillus anthracis.

Cellular microbiology: Bacterial toxin interference drives understanding of eukaryotic cell function.

Intimate interactions between the armament of pathogens and their host dictate tissue and host susceptibility to infection also forging specific pathophysiological outcomes. Studying these interactions at the molecular level has provided an invaluable source of knowledge on cellular processes, as ambitioned by the Cellular Microbiology discipline when it emerged in early 90s. Bacterial toxins act on key cell regulators or membranes to produce major diseases and therefore constitute a remarkable toolbox for dissecting basic biological processes.

Neuronal selectivity of botulinum neurotoxins.

Botulinum neurotoxins (BoNTs) are highly potent toxins responsible for a severe disease, called botulism. They are also efficient therapeutic tools with an increasing number of indications ranging from neuromuscular dysfunction to hypersecretion syndrome, pain release, depression as well as cosmetic application. BoNTs are known to mainly target the motor-neurons terminals and to induce flaccid paralysis.

Revisiting Old Ionophore Lasalocid as a Novel Inhibitor of Multiple Toxins.

The ionophore lasalocid is widely used as a veterinary drug against coccidiosis. We found recently that lasalocid protects cells from two unrelated bacterial toxins, the cytotoxic necrotizing factor-1 (CNF1) from and diphtheria toxin. We evaluated lasalocid's capacity to protect cells against other toxins of medical interest comprising toxin B from , Shiga-like toxin 1 from enterohemorrhagic and exotoxin A from .

Public Health Risk Associated with Botulism as Foodborne Zoonoses.

Botulism is a rare but severe neurological disease in man and animals that is caused by botulinum neurotoxins (BoNTs) produced by and atypical strains from other and non- species. BoNTs are divided into more than seven toxinotypes based on neutralization with specific corresponding antisera, and each toxinotype is subdivided into subtypes according to amino acid sequence variations. Animal species show variable sensitivity to the different BoNT toxinotypes.

UBTD1 is a mechano-regulator controlling cancer aggressiveness.

Ubiquitin domain-containing protein 1 (UBTD1) is highly evolutionary conserved and has been described to interact with E2 enzymes of the ubiquitin-proteasome system. However, its biological role and the functional significance of this interaction remain largely unknown. Here, we demonstrate that depletion of UBTD1 drastically affects the mechanical properties of epithelial cancer cells via RhoA activation and strongly promotes their aggressiveness.

Ezrin enrichment on curved membranes requires a specific conformation or interaction with a curvature-sensitive partner.

One challenge in cell biology is to decipher the biophysical mechanisms governing protein enrichment on curved membranes and the resulting membrane deformation. The ERM protein ezrin is abundant and associated with cellular membranes that are flat, positively or negatively curved. Using and cell biology approaches, we assess mechanisms of ezrin's enrichment on curved membranes.