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1.
Infect Immun ; 86(11)2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30150258

RESUMO

The fhuACDB operon, present in a number of Enterobacteriaceae, encodes components essential for the uptake of ferric hydroxamate type siderophores. FhuA acts not only as a transporter for physiologically important chelated ferric iron but also as a receptor for various bacteriophages, toxins, and antibiotics, which are pathogenic to bacterial cells. In this research, fhuA gene distribution and sequence diversity were investigated in Enterobacteriaceae, especially Salmonella and Escherichia Comparative sequence analysis resulted in a fhuA phylogenetic tree that did not match the expected phylogeny of species or trees of the fhuCDB genes. The fhuA sequences showed a unique mosaic clustering pattern. On the other hand, the gene sequences showed high conservation for strains from the same serovar or serotype. In total, six clusters were identified from FhuA proteins in Salmonella and Escherichia, among which typical peptide fragment variations could be defined. Six fragmental insertions/deletions and two substitution fragments were discovered, for which the combination of polymorphism patterns could well classify the different clusters. Structural modeling demonstrated that all the six featured insertions/deletions and one substitution fragment are located at the apexes of the long loops present as part of the FhuA external pocket. These frequently mutated regions are likely under high selection pressure, with bacterial strains balancing escape from phage infection or toxin/antibiotics attack via fhuA gene mutations while maintaining the siderophore uptake activity essential for bacterial survival. The unusual fhuA clustering suggests that high-frequency exchange of fhuA genes has occurred between enterobacterial strains after distinctive species were established.


Assuntos
Proteínas da Membrana Bacteriana Externa/genética , Proteínas de Escherichia coli/genética , Escherichia/genética , Evolução Molecular , Variação Genética , Salmonella/genética , Proteínas da Membrana Bacteriana Externa/química , Análise por Conglomerados , Proteínas de Escherichia coli/química , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/genética , Modelos Moleculares , Filogenia , Receptores Virais/química , Receptores Virais/genética , Análise de Sequência de DNA , Homologia de Sequência
2.
Environ Microbiol ; 19(10): 3879-3895, 2017 10.
Artigo em Inglês | MEDLINE | ID: mdl-28401683

RESUMO

The type III secretion system (T3SS) is an important genetic determinant that mediates interactions between Gram-negative bacteria and their eukaryotic hosts. Our understanding of the T3SS continues to expand, yet the availability of new bacterial genomes prompts questions about its diversity, distribution and evolution. Through a comprehensive survey of ∼20 000 bacterial genomes, we identified 174 non-redundant T3SSs from 109 genera and 5 phyla. Many of the bacteria are environmental strains that have not been reported to interact with eukaryotic hosts, while several species groups carry multiple T3SSs. Four ultra-conserved Microsynteny Blocks (MSBs) were defined within the T3SSs, facilitating comprehensive clustering of the T3SSs into 13 major categories, and establishing the largest diversity of T3SSs to date. We subsequently extended our search to identify type III effectors, resulting in 8740 candidate effectors. Lastly, an analysis of the key transcriptional regulators and circuits for the T3SS families revealed that low-level T3SS regulators were more conserved than higher-level regulators. This comprehensive analysis of the T3SSs and their protein effectors provides new insight into the diversity of systems used to facilitate host-bacterial interactions.


Assuntos
Bactérias Gram-Negativas/metabolismo , Proteobactérias/metabolismo , Sistemas de Secreção Tipo III/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Genoma Bacteriano/genética , Bactérias Gram-Negativas/genética , Interações Hospedeiro-Patógeno/fisiologia , Proteobactérias/genética , Sistemas de Secreção Tipo III/genética
3.
Infect Immun ; 83(6): 2312-26, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25824832

RESUMO

Pathogenic bacteria often need to survive in the host and the environment, and it is not well understood how cells transition between these equally challenging situations. For the human and animal pathogen Salmonella enterica serovar Typhimurium, biofilm formation is correlated with persistence outside a host, but the connection to virulence is unknown. In this study, we analyzed multicellular-aggregate and planktonic-cell subpopulations that coexist when S. Typhimurium is grown under biofilm-inducing conditions. These cell types arise due to bistable expression of CsgD, the central biofilm regulator. Despite being exposed to the same stresses, the two cell subpopulations had 1,856 genes that were differentially expressed, as determined by transcriptome sequencing (RNA-seq). Aggregated cells displayed the characteristic gene expression of biofilms, whereas planktonic cells had enhanced expression of numerous virulence genes. Increased type three secretion synthesis in planktonic cells correlated with enhanced invasion of a human intestinal cell line and significantly increased virulence in mice compared to the aggregates. However, when the same groups of cells were exposed to desiccation, the aggregates survived better, and the competitive advantage of planktonic cells was lost. We hypothesize that CsgD-based differentiation is a form of bet hedging, with single cells primed for host cell invasion and aggregated cells adapted for persistence in the environment. This allows S. Typhimurium to spread the risks of transmission and ensures a smooth transition between the host and the environment.


Assuntos
Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Salmonella typhimurium/metabolismo , Salmonella typhimurium/patogenicidade , Transativadores/metabolismo , Animais , Proteínas de Bactérias/genética , Células CACO-2 , GMP Cíclico/análogos & derivados , Humanos , Camundongos , Transporte Proteico , Salmonella typhimurium/genética , Transcrição Gênica , Virulência
4.
Vaccine ; 42(20): 125980, 2024 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-38769033

RESUMO

The emergence and ongoing evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has highlighted the need for rapid vaccine development platforms that can be updated to counteract emerging variants of currently circulating and future emerging coronaviruses. Here we report the development of a "train model" subunit vaccine platform that contains a SARS-CoV-2 Wuhan S1 protein (the "engine") linked to a series of flexible receptor binding domains (RBDs; the "cars") derived from SARS-CoV-2 variants of concern (VOCs). We demonstrate that these linked subunit vaccines when combined with Sepivac SWE™, a squalene in water emulsion (SWE) adjuvant, are immunogenic in Syrian hamsters and subsequently provide protection from infection with SARS-CoV-2 VOCs Omicron (BA.1), Delta, and Beta. Importantly, the bivalent and trivalent vaccine candidates offered protection against some heterologous SARS-CoV-2 VOCs that were not included in the vaccine design, demonstrating the potential for broad protection against a range of different VOCs. Furthermore, these formulated vaccine candidates were stable at 2-8 °C for up to 13 months post-formulation, highlighting their utility in low-resource settings. Indeed, our vaccine platform will enable the development of safe and broadly protective vaccines against emerging betacoronaviruses that pose a significant health risk for humans and agricultural animals.


Assuntos
Vacinas contra COVID-19 , COVID-19 , Mesocricetus , SARS-CoV-2 , Vacinas de Subunidades Antigênicas , Animais , Vacinas contra COVID-19/imunologia , SARS-CoV-2/imunologia , SARS-CoV-2/genética , Vacinas de Subunidades Antigênicas/imunologia , COVID-19/prevenção & controle , COVID-19/imunologia , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/sangue , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/sangue , Glicoproteína da Espícula de Coronavírus/imunologia , Glicoproteína da Espícula de Coronavírus/genética , Cricetinae , Humanos , Adjuvantes Imunológicos/administração & dosagem , Feminino , Eficácia de Vacinas
5.
Avian Dis ; 57(1): 116-22, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23678739

RESUMO

Campylobacter jejuni, a gram-negative motile bacterium commonly found in the chicken gastrointestinal tract, is one of the leading causes of bacterial gastroenteritis in humans worldwide. An intact and functional flagellum is important for C. jejuni virulence and colonization. To understand the role of C. jejuni motility in adherence and internalization in polarized Caco-2 cells and in cecal colonization of chickens we constructed a C. jejuni NCTC11168 V1 deltamotAB mutant. The motAB genes code for the flagellar motor, which enables the rotation of the flagellum. The nonmotile deltamotAB mutant expressed a full-length flagellum, which allowed us to differentiate between the roles of full-length flagella and motility in the ability of C. jejuni to colonize. To study the adherence and invasion abilities of the C. jejuni deltamotAB mutant we chose to use polarized Caco-2 cells, which are thought to be more representative of in vivo intestinal cell architecture and function. Although the C. jejuni deltamotAB mutant adhered significantly better than the wild type to the Caco-2 cells, we observed a significant reduction in the ability to invade the cells. In this study we obtained evidence that the flagellar rotation triggers C. jejuni invasion into polarized Caco-2 cells and we believe that C. jejuni is propelled into the cell with a drill-like rotation. The deltamotAB mutant was also tested for its colonization potential in a 1-day-old chicken model. The nonmotile C. jejuni deltamotAB mutant was not able to colonize any birds at days 3 and 7, suggesting that motility is essential for C. jejuni colonization.


Assuntos
Proteínas de Bactérias/metabolismo , Infecções por Campylobacter/veterinária , Campylobacter jejuni/fisiologia , Galinhas , Flagelos/genética , Doenças das Aves Domésticas/microbiologia , Animais , Aderência Bacteriana , Proteínas de Bactérias/genética , Células CACO-2 , Infecções por Campylobacter/microbiologia , Campylobacter jejuni/genética , Ceco/microbiologia , Flagelos/metabolismo , Humanos , Mutação
6.
Front Microbiol ; 13: 824052, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35308377

RESUMO

The roles of TonB mediated Fe3+ (ferric iron) uptake via enterobactin (involving biosynthesis genes entABCDEF) and Fe2+ (ferrous iron) uptake through the FeoABC transporter are poorly defined in the context of chicken-Salmonella interactions. Both uptake systems are believed to be the major contributors of iron supply in the Salmonella life cycle. Current evidence suggests that these iron uptake systems play a major role in pathogenesis in mammals and as such, they represent promising antibacterial targets with therapeutic potential. We investigated the role of these iron uptake mechanisms regarding the ability of Salmonella Enteritidis (SEn) strains to colonize in a chicken infection model. Further we constructed a bioluminescent reporter to sense iron limitation during gastrointestinal colonization of Salmonella in chicken via ex vivo imaging. Our data indicated that there is some redundancy between the ferric and ferrous iron uptake mechanisms regarding iron acquisition during SEn pathogenesis in chicken. We believe that this redundancy of iron acquisition in the host reservoir may be the consequence of adaptation to unique avian environments, and thus warrants further investigation. To our knowledge, this the first report providing direct evidence that both enterobactin synthesis and FeoABC mediated iron uptake contribute to the virulence of SEn in chickens.

7.
Front Vet Sci ; 9: 948448, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35982923

RESUMO

The light emitting module lux operon (luxCDABE) of Photorhabdus luminescens can be integrated into a "dark" bacterium for expression under a suitable promoter. The technique has been used to monitor kinetics of infection, e.g., by studying gene expression in Salmonella using mouse models in vivo and ex vivo. Here, we applied the bioluminescence imaging (BLI) technique to track Salmonella Enteritidis (SEn) strains carrying the lux operon expressed under a constitutive promoter sequence (sigma 70) in chicken after oral challenge. Detectable photon signals were localized in the crop, small intestine, cecum, and yolk sac in orally gavaged birds. The level of colonization was determined by quantification of signal intensity and SEn prevalence in the cecum and yolk sac. Furthermore, an isogenic SEn mutant strain tagged with the lux operon allowed for us to assess virulence determinants regarding their role in colonization of the cecum and yolk sac. Interestingly, mutations of SPI-1(Salmonella Pathogenicity Island 1) and fur (ferric uptake regulator) showed significantly decreased colonization in yolk sac that was correlated with the BLI data. A similar trend was detected in a ΔtonB strain by analyzing enrichment culture data. The inherently low quantum yield, light scattering, and absorption by tissues did not facilitate detection of signals from live birds. However, the detection limit of lux operon has the potential to be improved by resonance energy transfer to a secondary molecule. As a proof-of-concept, we were able to show that sensitization of a fluorescent-bound molecule known as the lumazine protein (LumP) improved the limit of detection to a certain extent.

8.
Vet Sci ; 9(5)2022 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-35622731

RESUMO

Innate immune stimulants, especially toll-like receptor (TLR) ligands and agonists, are the main players in the initiation of innate immunity and have been widely studied as alternatives to antibiotics to control infection. In the present study, we characterized the dosage levels of various innate immune stimulants, including unmethylated cytosine-phosphate-guanosine dinucleotide -containing oligodeoxynucleotides (CpG ODN), polyinosinic-polycytidylic acid (poly I:C), cyclic polyphosphazene 75B (CPZ75B), avian beta-defensin 2 (ABD2), and combinations of these reagents given in ovo. Data derived from a series of animal experiments demonstrated that the in ovo administration of 10-50 µg CpG ODN/embryo (on embryonic day 18) is an effective formulation for control of yolk sac infection (YSI) due to avian pathogenic Escherichia coli (E. coli) in young chicks. Amongst the different combinations of innate immune stimulants, the in ovo administration of CpG ODN 10 µg in combination with 15 µg of poly I:C was the most effective combination, offering 100% protection from YSI. It is expected that the introduction of these reagents to management practices at the hatchery level may serve as a potential replacement for antibiotics for the reduction of early chick mortality (ECM) due to YSI/colibacillosis.

9.
Poult Sci ; 101(11): 102119, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36087444

RESUMO

This study was conducted to characterize and compare the protective effects of various innate immune stimulants against yolk sac infection (YSI) caused by an avian pathogenic Escherichia coli in young chicks. The immune stimulants were administered alone or in various combinations of unmethylated CpG oligodeoxynucleotides (CpG), polyinosinic:polycytidylic acid (Poly I:C), and avian antimicrobial peptides (AMPs). Routes included in ovo or in ovo followed by a subcutaneous (S/C) injection. CpG alone and in combination with Poly I:C, truncated avian cathelicidin (CATH)-1(6-26), avian beta defensin (AvBD)1, and CATH-1(6-26) + AvBD1, were administered in ovo to 18-day-old embryonated eggs for gene expression and challenge studies. Next, CpG alone and the potentially effective formulation of CpG + Poly I:C, were administrated via the in ovo route using 40 embryonated eggs. At 1 day post-hatch, half of each group also received their respective treatments via the S/C route. Four hours later, all chicks were challenged using E. coli strain EC317 and mortalities were recorded for 14 d. The first challenge study revealed that amongst the single use and combinations of CpG with different innate immune stimulants, a higher protection and a lower clinical score were offered by the combination of CpG + Poly I:C. The second challenge study showed that this combination (CpG + Poly I:C) provides an even higher level of protection when a second dose is administered via the S/C route at 1 day post-hatch. The current research highlights the efficacy of a combination of CpG + Poly I:C administered either in ovo or in ovo along with a S/C injection and its potential use as an alternative to antibiotics against yolk sac infection in young chicks.


Assuntos
Galinhas , Doenças das Aves Domésticas , Animais , Doenças das Aves Domésticas/prevenção & controle , Adjuvantes Imunológicos/farmacologia , Saco Vitelino , Escherichia coli , Óvulo , Poli I-C/farmacologia
10.
Sci Rep ; 11(1): 2132, 2021 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-33483611

RESUMO

Increasing antibiotic resistance is a matter of grave concern for consumers, public health authorities, farmers, and researchers. Antimicrobial peptides (AMPs) are emerging as novel and effective non-antibiotic tools to combat infectious diseases in poultry. In this study, we evaluated six avian AMPs including 2 truncated cathelicidins, [CATH-1(6-26) and CATH-2(1-15)], and 4 avian ß-defensins (ABD1, 2, 6 and 9) for their bactericidal and immunomodulatory activities. Our findings have shown CATH-1(6-26) and ABD1 being the two most potent avian AMPs effective against Gram-positive and Gram-negative bacteria investigated in these studies. Moreover, CATH-1(6-26) inhibited LPS-induced NO production and exhibited dose-dependent cytotoxicity to HD11 cells. While, ABD1 blocked LPS-induced IL-1ß gene induction and was non-toxic to HD11 cells. Importantly, in ovo administration of these AMPs demonstrated that ABD1 can offer significant protection from early chick mortality (44% less mortality in ABD1 treated group versus the control group) due to the experimental yolk sac infection caused by avian pathogenic Escherichia coli. Our data suggest that in ovo administration of ABD1 has immunomodulatory and anti-infection activity comparable with CpG ODN. Thus, ABD1 can be a significant addition to potential alternatives to antibiotics for the control of bacterial infections in young chicks.


Assuntos
Peptídeos Catiônicos Antimicrobianos/farmacologia , Testes de Sensibilidade Microbiana/métodos , Doenças das Aves Domésticas/prevenção & controle , Saco Vitelino/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Peptídeos Catiônicos Antimicrobianos/síntese química , Peptídeos Catiônicos Antimicrobianos/química , Catelicidinas/síntese química , Catelicidinas/química , Catelicidinas/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Células Cultivadas , Galinhas , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Expressão Gênica/efeitos dos fármacos , Macrófagos/citologia , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Doenças das Aves Domésticas/microbiologia , Conformação Proteica , Salmonella/efeitos dos fármacos , Salmonella/crescimento & desenvolvimento , Saco Vitelino/microbiologia , beta-Defensinas/síntese química , beta-Defensinas/química , beta-Defensinas/farmacologia
11.
Infect Immun ; 78(8): 3493-505, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20498258

RESUMO

Salmonella enterica subsp. enterica serovar Enteritidis is a leading causative agent of gastroenteritis in humans. This pathogen also colonizes the intestinal tracts of poultry and can spread systemically in chickens. Transfer to humans usually occurs through undercooked or improperly handled poultry meat or eggs. The bacterial twin-arginine transport (Tat) pathway is responsible for the translocation of folded proteins across the cytoplasmic membrane. In order to study the role of the Tat system in the infection and colonization of chickens by Salmonella Enteritidis, we constructed chromosomal deletion mutants of the tatB and tatC genes, which are essential components of the Tat translocon. We observed that the tat mutations affected bacterial cell morphology, motility, and sensitivity to albomycin, sodium dodecyl sulfate (SDS), and EDTA. In addition, the mutant strains showed reduced invasion of polarized Caco-2 cells. The wild-type phenotype was restored in all our Salmonella Enteritidis tat mutants by introducing episomal copies of the tatABC genes. When tested in chickens by use of a Salmonella Enteritidis Delta tatB strain, the Tat system inactivation did not substantially affect cecal colonization, but it delayed systemic infection. Taken together, our data demonstrated that the Tat system plays a role in Salmonella Enteritidis pathogenesis.


Assuntos
Proteínas de Bactérias/fisiologia , Células Epiteliais/microbiologia , Doenças das Aves Domésticas/microbiologia , Salmonelose Animal/microbiologia , Salmonella enteritidis/patogenicidade , Fatores de Virulência/fisiologia , Animais , Antibacterianos/toxicidade , Proteínas de Bactérias/genética , Células CACO-2 , Galinhas , Ácido Edético/toxicidade , Ferricromo/análogos & derivados , Ferricromo/toxicidade , Deleção de Genes , Teste de Complementação Genética , Humanos , Locomoção , Salmonella enteritidis/citologia , Salmonella enteritidis/efeitos dos fármacos , Salmonella enteritidis/fisiologia , Dodecilsulfato de Sódio/toxicidade , Virulência , Fatores de Virulência/genética
12.
Microbiology (Reading) ; 156(Pt 9): 2770-2781, 2010 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-20488876

RESUMO

Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) has been identified as a significant cause of salmonellosis in humans. Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) each encode a specialized type III secretion system (T3SS) that enables Salmonella to manipulate host cells at various stages of the invasion/infection process. For the purposes of our studies we used a chicken isolate of S. Enteritidis (Sal18). In one study, we orally co-challenged 35-day-old specific pathogen-free (SPF) chickens with two bacterial strains per group. The control group received two versions of the wild-type strain Sal18: Sal18 attTn7 : : tet and Sal18 attTn7 : : cat, while the other two groups received the wild-type strain (Sal18 attTn7 : : tet) and one of two mutant strains. From this study, we concluded that S. Enteritidis strains deficient in the SPI-1 and SPI-2 systems were outcompeted by the wild-type strain. In a second study, groups of SPF chickens were challenged at 1 week of age with four different strains: the wild-type strain, and three other strains lacking either one or both of the SPI-1 and SPI-2 regions. On days 1 and 2 post-challenge, we observed a reduced systemic spread of the SPI-2 mutants, but by day 3, the systemic distribution levels of the mutants matched that of the wild-type strain. Based on these two studies, we conclude that the S. Enteritidis SPI-2 T3SS facilitates invasion and systemic spread in chickens, although alternative mechanisms for these processes appear to exist.


Assuntos
Galinhas , Ilhas Genômicas , Intestinos/microbiologia , Doenças das Aves Domésticas/microbiologia , Salmonelose Animal/microbiologia , Salmonella enteritidis/patogenicidade , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Galinhas/microbiologia , Humanos , Salmonella enteritidis/genética , Salmonella enteritidis/metabolismo , Organismos Livres de Patógenos Específicos , Virulência
13.
Can J Microbiol ; 56(6): 522-6, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20657623

RESUMO

Salmonella enterica serovar Enteritidis (Salmonella Enteritidis) is one of the major causes of bacterial food-borne illness in humans. During the course of infection, Salmonella Enteritidis uses 2 type III secretion systems (T3SS), one of which is encoded on Salmonella pathogenicity island 1 (SPI-1). SPI-1 plays a major role in the invasion process. In the present study, we evaluated the effect of sera against the SPI-1 T3SS components on invasion in vitro using polarized human intestinal epithelial cells (Caco-2). Antisera to SipD protected Caco-2 cells against entry of wild-type Salmonella Enteritidis. On the other hand, sera against InvG, PrgI, SipA, SipC, SopB, SopE, and SopE2 did not affect Salmonella Enteritidis entry. To illustrate the specificity of anti-SipD mediated inhibition, SipD-specific antibodies were depleted from the serum. Antiserum depleted of SipD-specific antibodies lost its capacity to inhibit Salmonella Enteritidis entry. Thus, we demonstrate for the first time that antibodies against the SPI-1 needle tip protein (SipD) inhibit Salmonella Enteritidis invasion and that the SipD protein may be an important target in blocking SPI-1 mediated virulence of Salmonella Enteritidis.


Assuntos
Anticorpos Antibacterianos/imunologia , Proteínas de Bactérias/antagonistas & inibidores , Células Epiteliais/microbiologia , Proteínas de Membrana Transportadoras/imunologia , Infecções por Salmonella/prevenção & controle , Salmonella enteritidis/imunologia , Fatores de Virulência/antagonistas & inibidores , Animais , Proteínas de Bactérias/imunologia , Linhagem Celular , Humanos , Coelhos , Fatores de Virulência/imunologia
14.
Microorganisms ; 8(8)2020 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-32784620

RESUMO

Iron is an essential micronutrient for most bacteria. Salmonella enterica strains, representing human and animal pathogens, have adopted several mechanisms to sequester iron from the environment depending on availability and source. Chickens act as a major reservoir for Salmonella enterica strains which can lead to outbreaks of human salmonellosis. In this review article we summarize the current understanding of the contribution of iron-uptake systems to the virulence of non-typhoidal S. enterica strains in colonizing chickens. We aim to address the gap in knowledge in this field, to help understand and define the interactions between S. enterica and these important hosts, in comparison to mammalian models.

15.
Infect Immun ; 77(7): 2866-75, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19364835

RESUMO

Salmonella enterica subsp. enterica serovar Enteritidis is a leading cause of human food-borne illness that is mainly associated with the consumption of contaminated poultry meat and eggs. To cause infection, S. Enteritidis is known to use two type III secretion systems, which are encoded on two salmonella pathogenicity islands, SPI-1 and SPI-2, the first of which is thought to play a major role in invasion and bacterial uptake. In order to study the role of SPI-1 in the colonization of chicken, we constructed deletion mutants affecting the complete SPI-1 region (40 kb) and the invG gene. Both DeltaSPI-1 and DeltainvG mutant strains were impaired in the secretion of SipD, a SPI-1 effector protein. In vitro analysis using polarized human intestinal epithelial cells (Caco-2) revealed that both mutant strains were less invasive than the wild-type strain. A similar observation was made when chicken cecal and small intestinal explants were coinfected with the wild-type and DeltaSPI-1 mutant strains. Oral challenge of 1-week-old chicken with the wild-type or DeltaSPI-1 strains demonstrated that there was no difference in chicken cecal colonization. However, systemic infection of the liver and spleen was delayed in birds that were challenged with the DeltaSPI-1 strain. These data demonstrate that SPI-1 facilitates systemic infection but is not essential for invasion and systemic spread of the organism in chickens.


Assuntos
Ilhas Genômicas , Doenças das Aves Domésticas/microbiologia , Salmonelose Animal/microbiologia , Salmonella enteritidis/patogenicidade , Fatores de Virulência/fisiologia , Animais , Células CACO-2 , Ceco/microbiologia , Galinhas , DNA Bacteriano/genética , Células Epiteliais , Humanos , Mucosa Intestinal , Intestino Delgado/microbiologia , Fígado/microbiologia , Técnicas de Cultura de Órgãos , Salmonella enteritidis/genética , Deleção de Sequência , Baço/microbiologia
16.
Artigo em Inglês | MEDLINE | ID: mdl-31214517

RESUMO

Non-typhoidal Salmonella (NTS) strains are Gram negative bacterial pathogens that are associated with foodborne illness worldwide. During the process of infection, Salmonella uses two molecular injectisomes known as Type 3 Secretion Systems (T3SS) to secrete virulence factors that are encoded by Salmonella Pathogenicity Island-1 (SPI-1) and SPI-2 into host cells. These secretion systems play a major role in virulence, as shown in various animal models, but little is known about their role in human infections. In Saudi Arabia, NTS strains frequently cause human infections but data regarding these pathogenic strains is fairly limited. The aim of this study was to characterize Salmonella human clinical isolates in Riyadh, Saudi Arabia, by determining their serotype, testing for the presence of SPI-1 and SPI-2 genes and to determine the antibiotic resistance profiles of these strains. Using the rapid Check and Trace Salmonella™ (CTS) system our results demonstrate that S. Enteritidis and S. Typhimurium were the predominant serovars, followed by S. Livingstone, S. Kentucky and S. Poona among a list of 36 serovars reported for the first time in the country. In addition, SPI-1 genes were detected in 99% of the isolates, while the sifA gene (SPI-2) was not detected in 13.5% of the isolates. These results suggest that both the SPI-1 and SPI-2 virulence determinants are important for human infection. Moreover, we report the presence of a Multi-Drug (MDR) carbapenem resistant S. Kentucky isolate harboring the blaOXA-48 gene not reported previously in Saudi Arabia.


Assuntos
Proteínas de Bactérias/isolamento & purificação , Proteínas de Membrana/isolamento & purificação , Salmonella enteritidis/isolamento & purificação , Salmonella typhimurium/isolamento & purificação , Sorogrupo , Febre Tifoide/microbiologia , Fatores de Virulência/genética , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Carbapenêmicos/farmacologia , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla , Genoma Bacteriano , Genótipo , Humanos , Proteínas de Membrana/genética , Salmonella enteritidis/classificação , Salmonella enteritidis/efeitos dos fármacos , Salmonella enteritidis/genética , Salmonella typhimurium/classificação , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Arábia Saudita/epidemiologia , Sorotipagem , Sistemas de Secreção Tipo III/genética , Sistemas de Secreção Tipo III/isolamento & purificação , Virulência , beta-Lactamases/genética
17.
Avian Dis ; 62(3): 316-321, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30339510

RESUMO

Omphalitis or yolk sac infection (YSI) and colibacillosis are the most common infectious diseases that lead to high rates of early chick mortalities (ECMs) in young chicks. Out of numerous microbial causes, avian pathogenic Escherichia coli (APEC) or extraintestinal pathogenic E. coli infections are considered the most common cause of these conditions. YSI causes deterioration and decomposition of yolk, leading to deficiency of necessary nutrients and maternal antibodies, retarded growth, poor carcass quality, and increased susceptibility to other infections, including omphalitis, colibacillosis, and respiratory tract infection. Presently, in ovo injection of antibiotics, heavy culling, or after hatch use of antibiotics is practiced to manage ECM. However, increased antibiotic resistance and emergence of "super bugs" associated with use or misuse of antibiotics in the animal industry have raised serious concerns. These concerns urgently require a focus on host-driven nonantibiotic approaches for stimulation of protective antimicrobial immunity. Using an experimental YSI model in newborn chicks, we evaluated the prophylactic potential of three in ovo-administered innate immune stimulants and immune adjuvants for protection from ECM due to YSI. Our data have shown >80%, 65%, and 60% survival with in ovo use of cytosine-phosphodiester-guanine (CpG) oligodeoxynucleotides (ODN), polyinosinic:polycytidylic acid, and polyphosphazene, respectively. In conclusion, data from these studies suggest that in ovo administration of CpG ODN may serve as a potential candidate for replacement of antibiotics for the prevention and control of ECM due to YSI in young chicks.


Assuntos
Adjuvantes Imunológicos/administração & dosagem , Galinhas/imunologia , Infecções por Escherichia coli/veterinária , Óvulo/imunologia , Doenças das Aves Domésticas/prevenção & controle , Animais , Animais Recém-Nascidos , Escherichia coli/efeitos dos fármacos , Infecções por Escherichia coli/prevenção & controle , Imunidade Inata/efeitos dos fármacos , Injeções/veterinária , Oligodesoxirribonucleotídeos/administração & dosagem , Compostos Organofosforados/administração & dosagem , Poli I-C/administração & dosagem , Polímeros/administração & dosagem , Saco Vitelino/imunologia
18.
mSphere ; 3(6)2018 11 28.
Artigo em Inglês | MEDLINE | ID: mdl-30487154

RESUMO

Central venous access devices (CVADs) are an essential component of modern health care. However, their prolonged use commonly results in microbial colonization, which carries the potential risk of hospital-acquired bloodstream infections. These infections complicate the treatment of already sick individuals and cost the existing health care systems around the world millions of dollars. The microbes that colonize CVADs typically form multicellular biofilms that are difficult to dislodge and are resistant to antimicrobial treatments. Clinicians are searching for better ways to extend the working life span of implanted CVADs, by preventing colonization and reducing the risk of bloodstream infections. In this study, we analyzed 210 bacterial and fungal isolates from colonized CVADs or human bloodstream infections from two hospitals geographically separated in the east and west of Canada and screened the isolates for biofilm formation in vitro Twenty isolates, representing 12 common, biofilm-forming species, were exposed to 4% tetrasodium EDTA, an antimicrobial lock solution that was recently approved in Canada for use as a medical device. The EDTA solution was effective at eradicating surface-attached biofilms from each microbial species, indicating that it could likely be used to prevent biofilm growth within CVADs and to eliminate established biofilms. This new lock solution fits with antibiotic stewardship programs worldwide by sparing the use of important antibiotic agents, targeting prevention rather than the expensive treatment of hospital-acquired infections.IMPORTANCE The colonization of catheters by microorganisms often precludes their long-term use, which can be a problem for human patients that have few body sites available for new catheters. The colonizing organisms often form biofilms, and increasingly these organisms are resistant to multiple antibiotics, making them difficult to treat. In this article, we have taken microorganisms that are associated with biofilm formation in catheters from two Canadian hospitals and tested them with tetrasodium EDTA, a new antimicrobial catheter lock solution. Tetrasodium EDTA was effective at eliminating Gram-positive, Gram-negative, and fungal species and represents a promising alternative to antibiotic treatment with less chance of the organisms developing resistance. We expect that our results will be of interest to researchers and clinicians and will lead to improved patient care.


Assuntos
Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Quelantes de Cálcio/farmacologia , Cateteres Venosos Centrais/microbiologia , Ácido Edético/farmacologia , Fungos/efeitos dos fármacos , Bactérias/isolamento & purificação , Canadá , Fungos/isolamento & purificação , Fungos/fisiologia , Hospitais , Humanos
19.
Front Vet Sci ; 4: 138, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29159172

RESUMO

Salmonella are important pathogens worldwide and a predominant number of human infections are zoonotic in nature. The ability of strains to form biofilms, which is a multicellular behavior characterized by the aggregation of cells, is predicted to be a conserved strategy for increased persistence and survival. It may also contribute to the increasing number of infections caused by ingestion of contaminated fruits and vegetables. There is a correlation between biofilm formation and the ability of strains to colonize and replicate within the intestines of multiple host species. These strains predominantly cause localized gastroenteritis infections in humans. In contrast, there are salmonellae that cause systemic, disseminated infections in a select few host species; these "invasive" strains have a narrowed host range, and most are unable to form biofilms. This includes host-restricted Salmonella serovar Typhi, which are only able to infect humans, and atypical gastroenteritis strains associated with the opportunistic infection of immunocompromised patients. From the perspective of transmission, biofilm formation is advantageous for ensuring pathogen survival in the environment. However, from an infection point of view, biofilm formation may be an anti-virulence trait. We do not know if the capacity to form biofilms prevents a strain from accessing the systemic compartments within the host or if loss of the biofilm phenotype reflects a change in a strain's interaction with the host. In this review, we examine the connections between biofilm formation, Salmonella disease states, degrees of host adaptation, and how this might relate to different transmission patterns. A better understanding of the dynamic lifecycle of Salmonella will allow us to reduce the burden of livestock and human infections caused by these important pathogens.

20.
Front Biosci ; 10: 462-77, 2005 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-15574383

RESUMO

Iron is a vital nutrient for the vast majority of organisms. Gram-positive bacteria, Gram-negative bacteria and archaea established different strategies to utilize iron from various sources. This article concentrates on the cytoplasmic membrane-associated uptake systems involved in the acquisition of iron. Genetic, biochemical and structural data as well as computational analyses were taken into consideration. Besides divalent metal transporters of the Nramp type and ferrous iron transport proteins of the Feo type, four distinct families of ABC transporters related to iron uptake are known. Their components mediate the transfer of iron, siderophores, heme and vitamin B12 into the cytosol of prokaryotes.


Assuntos
Proteínas da Membrana Bacteriana Externa/metabolismo , Membrana Celular/metabolismo , Citoplasma/metabolismo , Ferro/química , Proteínas de Membrana Transportadoras/química , Transportadores de Cassetes de Ligação de ATP/metabolismo , Trifosfato de Adenosina/metabolismo , Transporte Biológico , Citosol/metabolismo , Proteínas de Escherichia coli/metabolismo , Heme/química , Ferro/metabolismo , Ferro/farmacocinética , Modelos Biológicos , Mycobacterium/metabolismo , Ligação Proteica , Vitamina B 12/metabolismo
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