Genomic analysis of isolated from surface water and animal sources in Chile reveals new T6SS effector protein candidates.

Type VI Secretion Systems (T6SS), widely distributed in Gram-negative bacteria, contribute to interbacterial competition and pathogenesis through the translocation of effector proteins to target cells. harbor 5 pathogenicity islands encoding T6SS (SPI-6, SPI-19, SPI-20, SPI-21 and SPI-22), in which a limited number of effector proteins have been identified. Previous analyses by our group focused on the identification of candidate T6SS effectors and cognate immunity proteins in genomes deposited in public databases.

SEN1990 is a predicted winged helix-turn-helix protein involved in the pathogenicity of serovar Enteritidis and the expression of the gene in the SPI-17.

Excisable genomic islands (EGIs) are horizontally acquired genetic elements that harbor an array of genes with diverse functions. ROD21 is an EGI found integrated in the chromosome of serovar Enteritidis ( ser. Enteritidis).

Identification and distribution of new candidate T6SS effectors encoded in Pathogenicity Island 6.

The type VI secretion system (T6SS) is a contact-dependent contractile multiprotein apparatus widely distributed in Gram-negative bacteria. These systems can deliver different effector proteins into target bacterial and/or eukaryotic cells, contributing to the environmental fitness and virulence of many bacterial pathogens. harbors five different T6SSs encoded in different genomic islands.

Transfer of T6SS from Gallinarum to Typhimurium Lacking T6SS Complements its Colonization Defect in Mice.

genus harbors five Type VI Secretion System (T6SS) gene clusters. The T6SS encoded in SPI-6 (T6SS) contributes to Typhimurium colonization of chickens and mice, while the T6SS encoded in SPI-19 (T6SS) of Gallinarum contributes to chicken colonization. Interestingly, the T6SS of Gallinarum complemented the defect in chicken colonization of a Typhimurium strain that lacks the T6SS, suggesting that both T6SSs are interchangeable.

Identification of Type VI Secretion Systems Effector Proteins That Contribute to Interbacterial Competition in Dublin.

The Type VI Secretion System (T6SS) is a multiprotein device that has emerged as an important fitness and virulence factor for many Gram-negative bacteria through the injection of effector proteins into prokaryotic or eukaryotic cells a contractile mechanism. While some effector proteins specifically target bacterial or eukaryotic cells, others can target both types of cells (trans-kingdom effectors). In , five T6SS gene clusters have been identified within pathogenicity islands SPI-6, SPI-19, SPI-20, SPI-21, and SPI-22, which are differentially distributed among serotypes.

Bioinformatic and experimental characterization of SEN1998: a conserved gene carried by the Enterobacteriaceae-associated ROD21-like family of genomic islands.

Genomic islands (GIs) are horizontally transferred elements that shape bacterial genomes and contributes to the adaptation to different environments. Some GIs encode an integrase and a recombination directionality factor (RDF), which are the molecular GI-encoded machinery that promotes the island excision from the chromosome, the first step for the spread of GIs by horizontal transfer. Although less studied, this process can also play a role in the virulence of bacterial pathogens.

Novel Template Plasmids pCyaA'-Kan and pCyaA'-Cam for Generation of Unmarked Chromosomal ' Translational Fusion to T3SS Effectors in .

The type III secretion systems (T3SS) encoded in pathogenicity islands SPI-1 and SPI-2 are key virulence factors of . These systems translocate proteins known as effectors into eukaryotic cells during infection. To characterize the functionality of T3SS effectors, gene fusions to the reporter of are often used.

SopB- and SifA-dependent shaping of the Salmonella-containing vacuole proteome in the social amoeba Dictyostelium discoideum.

The ability of Salmonella to survive and replicate within mammalian host cells involves the generation of a membranous compartment known as the Salmonella-containing vacuole (SCV). Salmonella employs a number of effector proteins that are injected into host cells for SCV formation using its type-3 secretion systems encoded in SPI-1 and SPI-2 (T3SS-1 and T3SS-2, respectively). Recently, we reported that S.

Development of Novel EE/Alginate Polyelectrolyte Complex Nanoparticles for Lysozyme Delivery: Physicochemical Properties and In Vitro Safety.

The number of biologic drugs has increased in the pharmaceutical industry due to their high therapeutic efficacy and selectivity. As such, safe and biocompatible delivery systems to improve their stability and efficacy are needed. Here, we developed novel cationic polymethacrylate-alginate (EE-alginate) pNPs for the biologic drug model lysozyme (Lys).

Static Immersion and Injection Methods for Live Cell Imaging of Foodborne Pathogen Infections in Zebrafish Larvae.

Important features of host-pathogen interactions have been discovered using nonmammalian hosts. Therefore, model organisms such as the nematode Caenorhabditis elegans, the social amoeba Dictyostelium discoideum, and zebrafish ( Danio rerio ) have been increasingly used for studying bacterial pathogenesis in vivo. These host models are amenable for live cell imaging studies, which can also benefit from online resources and databases ( Dictybase.

Contribution of the Twin-Arginine Translocation System to the Intracellular Survival of Typhimurium in .

The twin-arginine translocation (Tat) system is a specialized secretion pathway required for bacteria to export fully folded proteins through the cytoplasmic membrane. This system is crucial during infection of animal hosts. In this study, we show that serovar Typhimurium (.

Fnr and ArcA Regulate Lipid A Hydroxylation in Enteritidis by Controlling Expression in Response to Oxygen Availability.

Lipid A is the bioactive component of lipopolysaccharide, and presents a dynamic structure that undergoes modifications in response to environmental signals. Many of these structural modifications influence virulence. This is the case of lipid A hydroxylation, a modification catalyzed by the dioxygenase LpxO.

Evaluating Different Virulence Traits of Using and Zebrafish Larvae as Host Models.

Multiresistant and invasive hypervirulent strains have become one of the most urgent bacterial pathogen threats. Recent analyses revealed a high genomic plasticity of this species, harboring a variety of mobile genetic elements associated with virulent strains, encoding proteins of unknown function whose possible role in pathogenesis have not been addressed. virulence has been studied mainly in animal models such as mice and pigs, however, practical, financial, ethical and methodological issues limit the use of mammal hosts.

Inorganic Polyphosphate Is Essential for Typhimurium Virulence and Survival in .

Inorganic polyphosphate (polyP) deficiency in enteric bacterial pathogens reduces their ability to invade and establish systemic infections in different hosts. For instance, inactivation of the polyP kinase gene () encoding the enzyme responsible for polyP biosynthesis reduces invasiveness and intracellular survival of serovar Typhimurium (. Typhimurium) in epithelial cells and macrophages .

Salmonella Typhimurium induces cloacitis-like symptomsin zebrafish larvae.

Pathogenic Salmonella strains have a set of virulence factors allowing them to generate systemic infections and damage in a variety of hosts. Among these factors, bacterial proteins secreted by specialized systems are used to penetrate the host's intestinal mucosa, through the invasion and destruction of specialized epithelial M cells in the intestine. On the other hand, numerous studies have demonstrated that humans, as well as experimental animal hosts, respond to Salmonella infection by activating both innate and adaptive immune responses.

Differential roles for pathogenicity islands SPI-13 and SPI-8 in the interaction of Salmonella Enteritidis and Salmonella Typhi with murine and human macrophages.

Background: Salmonella pathogenicity island (SPI)-13 is conserved in many serovars of S. enterica, including S. Enteritidis, S.

Live-cell imaging of Salmonella Typhimurium interaction with zebrafish larvae after injection and immersion delivery methods.

The zebrafish model has been used to determine the role of vertebrate innate immunity during bacterial infections. Here, we compare the in vivo immune response induced by GFP-tagged Salmonella Typhimurium inoculated by immersion and microinjection in transgenic zebrafish larvae. Our novel infection protocols in zebrafish allow live-cell imaging of Salmonella colonization.

Relevant Genes Linked to Virulence Are Required for Salmonella Typhimurium to Survive Intracellularly in the Social Amoeba Dictyostelium discoideum.

The social amoeba Dictyostelium discoideum has proven to be a useful model for studying relevant aspects of the host-pathogen interaction. In this work, D. discoideum was used as a model to study the ability of Salmonella Typhimurium to survive in amoebae and to evaluate the contribution of selected genes in this process.

O-antigen chain-length distribution in Salmonella enterica serovar Enteritidis is regulated by oxygen availability.

Lipopolysaccharide (LPS) consists of three covalently linked domains: the lipid A, the core region and the O antigen (OAg), consisting of repeats of an oligosaccharide. Salmonella enterica serovar Enteritidis (S. Enteritidis) produces a LPS with two OAg preferred chain lengths: a long (L)-OAg controlled by WzzSE and a very long (VL)-OAg controlled by WzzfepE.

SPI-9 of Salmonella enterica serovar Typhi is constituted by an operon positively regulated by RpoS and contributes to adherence to epithelial cells in culture.

The genomic island 9 (SPI-9) from Salmonella enterica serovar Typhi (S. Typhi) carries three ORFs (STY2876, STY2877, STY2878) presenting 98 % identity with a type 1 secretory apparatus (T1SS), and a single ORF (STY2875) similar to a large RTX-like protein exhibiting repeated Ig domains. BapA, the Salmonella enterica serovar Enteritidis orthologous to S.

Solid tumors provide niche-specific conditions that lead to preferential growth of Salmonella.

Therapeutic attenuated strains of Salmonella Typhimurium target and eradicate tumors in mouse models. However, the mechanism of S. Typhimurium for tumor targeting is still poorly understood.

Analysis of Two Complementary Single-Gene Deletion Mutant Libraries of Salmonella Typhimurium in Intraperitoneal Infection of BALB/c Mice.

Two pools of individual single gene deletion (SGD) mutants of S. Typhimurium 14028s encompassing deletions of 3,923 annotated non-essential ORFs and sRNAs were screened by intraperitoneal (IP) injection in BALB/c mice followed by recovery from spleen and liver 2 days post infection. The relative abundance of each mutant was measured by microarray hybridization.

Exposure to sub-inhibitory concentrations of cefotaxime enhances the systemic colonization of Salmonella Typhimurium in BALB/c mice.

It has been proposed that sub-inhibitory concentrations of antibiotics play a role in virulence modulation. In this study, we evaluated the ability of Salmonella enterica serovar Typhimurium (hereafter S. Typhimurium) to colonize systemically BALB/c mice after exposure to a sub-inhibitory concentration of cefotaxime (CTX).

Participation of the Salmonella OmpD porin in the infection of RAW264.7 macrophages and BALB/c mice.

Salmonella Typhimurium is the etiological agent of gastroenteritis in humans and enteric fever in mice. Inside these hosts, Salmonella must overcome hostile conditions to develop a successful infection, a process in which the levels of porins may be critical. Herein, the role of the Salmonella Typhimurium porin OmpD in the infection process was assessed for adherence, invasion and proliferation in RAW264.