scholarly journals Csr1/Zap1 Maintains Zinc Homeostasis and Influences Virulence in Candida dubliniensis but Is Not Coupled to Morphogenesis

2015 ◽  
Vol 14 (7) ◽  
pp. 661-670 ◽  
Author(s):  
Bettina Böttcher ◽  
Katja Palige ◽  
Ilse D. Jacobsen ◽  
Bernhard Hube ◽  
Sascha Brunke
Keyword(s):  
Living Organism ◽  
Tube Formation ◽  
Infection Process ◽  
Candida Dubliniensis ◽  
Zinc Homeostasis ◽  
Growth Defect ◽  
Infection Model ◽  
Content Type ◽  
Restricted Environment ◽  
Embryonated Chicken

ABSTRACTThe supply and intracellular homeostasis of trace metals are essential for every living organism. Therefore, the struggle for micronutrients between a pathogen and its host is an important determinant in the infection process. In this work, we focus on the acquisition of zinc byCandida dubliniensis, an emerging pathogen closely related toCandida albicans. We show that the transcription factor Csr1 is essential forC. dubliniensisto regulate zinc uptake mechanisms under zinc limitation: it governs the expression of the zinc transporter genesZRT1,ZRT2, andZRT3and of the zincophore genePRA1. Exclusively, artificial overexpression ofZRT2partially rescued the growth defect of acsr1Δ/Δ mutant in a zinc-restricted environment. Importantly, we found that, in contrast to what is seen inC. albicans,Csr1(also calledZap1) is not a major regulator of dimorphism inC. dubliniensis. However, although acsr1Δ/Δ strain showed normal germ tube formation, we detected a clear attenuation in virulence using an embryonated chicken egg infection model. We conclude that, unlike inC. albicans, Csr1 seems to be a virulence factor ofC. dubliniensisthat is not coupled to filamentation but is strongly linked to zinc acquisition during pathogenesis.

scholarly journals The Streptococcus iniae Transcriptional Regulator CpsY Is Required for Protection from Neutrophil-Mediated Killing and Proper GrowthInVitro

2011 ◽  
Vol 79 (11) ◽  
pp. 4638-4648 ◽  
Author(s):  
Jonathan P. Allen ◽  
Melody N. Neely
Keyword(s):  
Whole Blood ◽  
Local Environment ◽  
Growth Defect ◽  
Infection Model ◽  
Streptococcus Iniae ◽  
Virulence Determinants ◽  
Wild Type ◽  
Content Type ◽  
Proteose Peptone ◽  
Lysr Family

ABSTRACTThe ability of a pathogen to metabolically adapt to the local environment for optimal expression of virulence determinants is a continued area of research. Orthologs of theStreptococcus iniaeLysR family regulator CpsY have been shown to regulate methionine biosynthesis and uptake pathways but appear to influence expression of several virulence genes as well. AnS. iniaemutant with an in-frame deletion ofcpsY(ΔcpsYmutant) is highly attenuated in a zebrafish infection model. The ΔcpsYmutant displays a methionine-independent growth defect in serum, which differs from the methionine-dependent defect observed for orthologous mutants ofStreptococcus mutansandStreptococcus agalactiae. On the contrary, the ΔcpsYmutant can grow in excess of the wild type (WT) when supplemented with proteose peptone, suggesting an inability to properly regulate growth. CpsY is critical for protection ofS. iniaefrom clearance by neutrophils in whole blood but is dispensable for intracellular survival in macrophages. Susceptibility of the ΔcpsYmutant to killing in whole blood is not due to a growth defect, because inhibition of neutrophil phagocytosis rescues the mutant to WT levels. Thus, CpsY appears to have a pleiotropic regulatory role forS. iniae, integrating metabolism and virulence. Furthermore,S. iniaeprovides a unique model to investigate the paradigm of CpsY-dependent regulation during systemic streptococcal infection.

scholarly journals In VitroandIn VivoActivities of Pterostilbene against Candida albicans Biofilms

2014 ◽  
Vol 58 (4) ◽  
pp. 2344-2355 ◽  
Author(s):  
De-Dong Li ◽  
Lan-Xue Zhao ◽  
Eleftherios Mylonakis ◽  
Gan-Hai Hu ◽  
Yong Zou ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Growth Defect ◽  
Ergosterol Biosynthesis ◽  
Infection Model ◽  
Content Type ◽  
Camp Pathway

ABSTRACTPterostilbene (PTE) is a stilbene-derived phytoalexin that originates from several natural plant sources. In this study, we evaluated the activity of PTE againstCandida albicansbiofilms and explored the underlying mechanisms. In 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assays, biofilm biomass measurement, confocal laser scanning microscopy, and scanning electron microscopy, we found that ≤16 μg/ml PTE had a significant effect againstC. albicansbiofilmsin vitro, while it had no fungicidal effect on planktonicC. albicanscells, which suggested a unique antibiofilm effect of PTE. Then we found that PTE could inhibit biofilm formation and destroy the maintenance of mature biofilms. At 4 μg/ml, PTE decreased cellular surface hydrophobicity (CSH) and suppressed hyphal formation. Gene expression microarrays and real-time reverse transcription-PCR showed that exposure ofC. albicansto 16 μg/ml PTE altered the expression of genes that function in morphological transition, ergosterol biosynthesis, oxidoreductase activity, and cell surface and protein unfolding processes (heat shock proteins). Filamentation-related genes, especially those regulated by the Ras/cyclic AMP (cAMP) pathway, includingECE1,ALS3,HWP1,HGC1, andRAS1itself, were downregulated upon PTE treatment, indicating that the antibiofilm effect of PTE was related to the Ras/cAMP pathway. Then, we found that the addition of exogenous cAMP reverted the PTE-induced filamentous growth defect. Finally, with a rat central venous catheter infection model, we confirmed thein vivoactivity of PTE againstC. albicansbiofilms. Collectively, PTE had strong activities againstC. albicansbiofilms bothin vitroandin vivo, and these activities were associated with the Ras/cAMP pathway.

scholarly journals Efflux Transporter of Siderophore Staphyloferrin A in Staphylococcus aureus Contributes to Bacterial Fitness in Abscesses and Epithelial Cells

2017 ◽  
Vol 85 (8) ◽  
Author(s):  
Hidemasa Nakaminami ◽  
Chunhui Chen ◽  
Que Chi Truong-Bolduc ◽  
Eu Suk Kim ◽  
Yin Wang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Epithelial Cells ◽  
Iron Acquisition ◽  
A549 Cells ◽  
Growth Defect ◽  
Efflux Transporter ◽  
Content Type ◽  
Lung Adenocarcinoma Cell Line ◽  
Restricted Environment ◽  
Bacterial Fitness

ABSTRACT The siderophores staphyloferrin A (SA) and staphyloferrin B (SB) of Staphylococcus aureus are essential for iron acquisition in the iron-restricted environment of the host, such as in subcutaneous abscesses. SA and SB are secreted by SfaA and SbnD transporters, respectively. To assess the further function of SfaA and SbnD in S. aureus fitness, we tested its effect on murine abscess models and intracellular replication in epithelial cells. Bacterial fitness in abscesses and in epithelial cells was studied, by comparing the parental strains RN6390 and MW2 and their ΔsfaA and ΔsbnD mutants using competition assays in a murine abscess model and invasion and replication assays with human lung adenocarcinoma cell line A549. In the murine abscess model using equal inocula of a ΔsfaA or ΔsbnD mutant and the wild-type RN6390 strain, the ΔsfaA mutant exhibited growth defects of 2.2-fold. Additionally, replication of the ΔsfaA mutant within A549 cells was decreased 3.0-fold. In complementation experiments, the ΔsfaA mutant carrying plasmid-borne sfaA restored the growth fitness in abscesses and epithelial cells. The ΔsbnD mutant, in contrast, showed no growth defect in either abscesses or epithelial cells. Our findings demonstrate that the efflux transporter of the siderophore SA contributes to the ability of S. aureus to replicate in abscesses and epithelial cells. Furthermore, fitness of S. aureus in these sites of replication is not compromised by the absence of transporter SbnD.

scholarly journals A ReplicativeIn VitroAssay for Drug Discovery against Leishmania donovani

2016 ◽  
Vol 60 (6) ◽  
pp. 3524-3532 ◽  
Author(s):  
Diana Tegazzini ◽  
Rosario Díaz ◽  
Fernando Aguilar ◽  
Imanol Peña ◽  
Jesús L. Presa ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Leishmania Donovani ◽  
Horse Serum ◽  
Protozoan Parasite ◽  
Infection Process ◽  
Infection Model ◽  
Content Type ◽  
Fetal Bovine

The protozoan parasiteLeishmania donovaniis the causative agent of visceral leishmaniasis, a disease potentially fatal if not treated. Current available treatments have major limitations, and new and safer drugs are urgently needed. In recent years, advances in high-throughput screening technologies have enabled the screening of millions of compounds to identify new antileishmanial agents. However, most of the compounds identifiedin vitrodid not translate their activities when tested inin vivomodels, highlighting the need to develop more predictivein vitroassays. In the present work, we describe the development of a robust replicative, high-content,in vitrointracellularL. donovaniassay. Horse serum was included in the assay media to replace standard fetal bovine serum, to completely eliminate the extracellular parasites derived from the infection process. A novel phenotypicin vitroinfection model has been developed, complemented with the identification of the proliferation of intracellular amastigotes measured by EdU incorporation.In vitroandin vivoresults for miltefosine, amphotericin B, and the selected compound 1 have been included to validate the assay.

scholarly journals Comparative Analyses of a Cystic Fibrosis Isolate of Bordetella bronchiseptica Reveal Differences in Important Pathogenic Phenotypes

2014 ◽  
Vol 82 (4) ◽  
pp. 1627-1637 ◽  
Author(s):  
Neelima Sukumar ◽  
Tracy L. Nicholson ◽  
Matt S. Conover ◽  
Tridib Ganguly ◽  
Rajendar Deora
Keyword(s):  
Cystic Fibrosis ◽  
Gene Expression Pattern ◽  
Infection Process ◽  
Bordetella Bronchiseptica ◽  
Zoonotic Transmission ◽  
Infection Model ◽  
Phenotypic Traits ◽  
Content Type ◽  
Cystic Fibrosis Isolate

ABSTRACTBordetella bronchisepticais a Gram-negative bacterium that infects and causes disease in a wide variety of animals.B. bronchisepticaalso infects humans, thereby demonstrating zoonotic transmission. An extensive characterization of humanB. bronchisepticaisolates is needed to better understand the distinct genetic and phenotypic traits associated with these zoonotic transmission events. Using whole-genome transcriptome and CGH analysis, we report that aB. bronchisepticacystic fibrosis isolate, T44625, contains a distinct genomic content of virulence-associated genes and differentially expresses these genes compared to the sequenced model laboratory strain RB50, a rabbit isolate. The differential gene expression pattern correlated with unique phenotypes exhibited by T44625, which included lower motility, increased aggregation, hyperbiofilm formation, and an increasedin vitrocapacity to adhere to respiratory epithelial cells. Using a mouse intranasal infection model, we found that although defective in establishing high bacterial burdens early during the infection process, T44625 persisted efficiently in the mouse nose. By documenting the unique genomic and phenotypic attributes of T44625, this report provides a blueprint for understanding the successful zoonotic potential ofB. bronchisepticaand other zoonotic bacteria.

scholarly journals Dual Zinc Transporter Systems in Vibrio cholerae Promote Competitive Advantages over Gut Microbiome

2015 ◽  
Vol 83 (10) ◽  
pp. 3902-3908 ◽  
Author(s):  
Ying Sheng ◽  
Fenxia Fan ◽  
Owen Jensen ◽  
Zengtao Zhong ◽  
Biao Kan ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Gene Clusters ◽  
Bioinformatic Analysis ◽  
Zinc Transporter ◽  
Zinc Homeostasis ◽  
Transport Systems ◽  
Growth Defect ◽  
Dependent Manner ◽  
Content Type ◽  
Transporter Systems

Zinc is an essential trace metal required for numerous cellular processes in all forms of life. In order to maintain zinc homeostasis, bacteria have developed several transport systems to regulate its uptake. In this study, we investigated zinc transport systems in the enteric pathogenVibrio cholerae, the causative agent of cholera. Bioinformatic analysis predicts that two gene clusters, VC2081 to VC2083 (annotated as zinc utilization genesznuABC) and VC2551 to VC2555 (annotated aszinc-regulatedgeneszrgABCDE), are regulated by the putative zinc uptake regulator Zur. Using promoter reporter and biochemical assays, we confirmed that Zur repressesznuABCandzrgABCDEpromoters in a Zn2+-dependent manner. Under Zn2+-limiting conditions, we found that mutations in either theznuABCorzrgABCDEgene cluster affect bacterial growth, withznuABCmutants displaying a more severe growth defect, suggesting that both ZnuABC and ZrgABCDE are involved in Zn2+uptake and that ZnuABC plays the predominant role. Furthermore, we reveal that ZnuABC and ZrgABCDE are important forV. choleraecolonization in both infant and adult mouse models, particularly in the presence of other intestinal microbiota. Collectively, our studies indicate that these two zinc transporter systems play vital roles in maintaining zinc homeostasis duringV. choleraegrowth and pathogenesis.

scholarly journals Identification of Staphylococcus aureus Factors Required for Pathogenicity and Growth in Human Blood

2017 ◽  
Vol 85 (11) ◽  
Author(s):  
John Connolly ◽  
Emma Boldock ◽  
Lynne R. Prince ◽  
Stephen A. Renshaw ◽  
Moira K. Whyte ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Human Blood ◽  
Parental Strain ◽  
Zebrafish Embryo ◽  
Opportunistic Pathogen ◽  
Growth Defect ◽  
Infection Model ◽  
Content Type ◽  
Pyrimidine Salvage ◽  
Horse Blood

ABSTRACT Staphylococcus aureus is a human commensal but also has devastating potential as an opportunistic pathogen. S. aureus bacteremia is often associated with an adverse outcome. To identify potential targets for novel control approaches, we have identified S. aureus components that are required for growth in human blood. An ordered transposon mutant library was screened, and 9 genes involved specifically in hemolysis or growth on human blood agar were identified by comparing the mutants to the parental strain. Three genes (purA, purB, and pabA) were subsequently found to be required for pathogenesis in the zebrafish embryo infection model. The pabA growth defect was specific to the red blood cell component of human blood, showing no difference from the parental strain in growth in human serum, human plasma, or sheep or horse blood. PabA is required in the tetrahydrofolate (THF) biosynthesis pathway. The pabA growth defect was found to be due to a combination of loss of THF-dependent dTMP production by the ThyA enzyme and increased demand for pyrimidines in human blood. Our work highlights pabA and the pyrimidine salvage pathway as potential targets for novel therapeutics and suggests a previously undefined role for a human blood factor in the activity of sulfonamide antibiotics.

scholarly journals Comparative Transcript Profiling of Candida albicans and Candida dubliniensis Identifies SFL2, a C. albicans Gene Required for Virulence in a Reconstituted Epithelial Infection Model

2009 ◽  
Vol 9 (2) ◽  
pp. 251-265 ◽  
Author(s):  
Martin J. Spiering ◽  
Gary P. Moran ◽  
Murielle Chauvel ◽  
Donna M. MacCallum ◽  
Judy Higgins ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Virulence Genes ◽  
Systemic Infection ◽  
Global Gene Expression ◽  
Candida Dubliniensis ◽  
Yeast Cells ◽  
Infection Model ◽  
Oral Epithelium ◽  
Content Type ◽  
Rapid Induction

ABSTRACT Candida albicans and Candida dubliniensis are closely related species displaying differences in virulence and genome content, therefore providing potential opportunities to identify novel C. albicans virulence genes. C. albicans gene arrays were used for comparative analysis of global gene expression in the two species in reconstituted human oral epithelium (RHE). C. albicans (SC5314) showed upregulation of hypha-specific and virulence genes within 30 min postinoculation, coinciding with rapid induction of filamentation and increased RHE damage. C. dubliniensis (CD36) showed no detectable upregulation of hypha-specific genes, grew as yeast, and caused limited RHE damage. Several genes absent or highly divergent in C. dubliniensis were upregulated in C. albicans. One such gene, SFL2 (orf19.3969), encoding a putative heat shock factor, was deleted in C. albicans. ΔΔsfl2 cells failed to filament under a range of hypha-inducing conditions and exhibited greatly reduced RHE damage, reversed by reintroduction of SFL2 into the ΔΔsfl2 strain. Moreover, SFL2 overexpression in C. albicans triggered hyphal morphogenesis. Although SFL2 deletion had no apparent effect on host survival in the murine model of systemic infection, ΔΔsfl2 strain-infected kidney tissues contained only yeast cells. These results suggest a role for SFL2 in morphogenesis and an indirect role in C. albicans pathogenesis in epithelial tissues.

scholarly journals Functional Features of TonB Energy Transduction Systems of Acinetobacter baumannii

2013 ◽  
Vol 81 (9) ◽  
pp. 3382-3394 ◽  
Author(s):  
Daniel L. Zimbler ◽  
Brock A. Arivett ◽  
Amber C. Beckett ◽  
Sharon M. Menke ◽  
Luis A. Actis
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Iron Acquisition ◽  
A549 Cells ◽  
Energy Transduction ◽  
Receptor Protein ◽  
Growth Defect ◽  
Infection Model ◽  
Content Type ◽  
Functional Features

ABSTRACTAcinetobacter baumanniiis an opportunistic pathogen that causes severe nosocomial infections. Strain ATCC 19606Tutilizes the siderophore acinetobactin to acquire iron under iron-limiting conditions encountered in the host. Accordingly, the genome of this strain has threetonBgenes encoding proteins for energy transduction functions needed for the active transport of nutrients, including iron, through the outer membrane. Phylogenetic analysis indicates that thesetonBgenes, which are present in the genomes of all sequencedA. baumanniistrains, were acquired from different sources. Two of these genes occur as components oftonB-exbB-exbDoperons and one as a monocistronic copy; all are actively transcribed in ATCC 19606T. The abilities of components of these TonB systems to complement the growth defect ofEscherichia coliW3110 mutants KP1344 (tonB) and RA1051 (exbBD) under iron-chelated conditions further support the roles of these TonB systems in iron acquisition. Mutagenesis analysis of ATCC 19606TtonB1(subscripted numbers represent different copies of genes or proteins) andtonB2supports this hypothesis: their inactivation results in growth defects in iron-chelated media, without affecting acinetobactin biosynthesis or the production of the acinetobactin outer membrane receptor protein BauA.In vivoassays usingGalleria mellonellashow that each TonB protein is involved in, but not essential for, bacterial virulence in this infection model. Furthermore, we observed that TonB2plays a role in the ability of bacteria to bind to fibronectin and to adhere to A549 cells by uncharacterized mechanisms. Taken together, these results indicate thatA. baumanniiATCC 19606Tproduces three independent TonB proteins, which appear to provide the energy-transducing functions needed for iron acquisition and cellular processes that play a role in the virulence of this pathogen.

scholarly journals Broad and Effective Protection against Staphylococcus aureus Is Elicited by a Multivalent Vaccine Formulated with Novel Antigens

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Jian Deng ◽  
Xiaolei Wang ◽  
Bao-Zhong Zhang ◽  
Peng Gao ◽  
Qiubin Lin ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
T Cells ◽  
Γδ T Cells ◽  
Infection Process ◽  
Effective Vaccine ◽  
Infection Model ◽  
Content Type ◽  
Multivalent Vaccine ◽  
Protein Components ◽  
Combined Vaccine

ABSTRACT The demand for a prophylactic vaccine against methicillin-resistant Staphylococcus aureus (MRSA) has motivated numerous dedicated research groups to design and develop such a vaccine. In this study, we have developed a multivalent vaccine, Sta-V5, composed of five conserved antigens involved in three important virulence mechanisms. This prototype vaccine conferred up to 100% protection against multiple epidemiologically relevant S. aureus isolates in five different murine disease models. The vaccine not only elicits functional antibodies that mediate opsonophagocytic killing of S. aureus but also mounts robust antigen-specific T-cell responses. In addition, our data implied that γδ T cells contribute to the protection induced by Sta-V5 in a murine skin infection model. IMPORTANCE Staphylococcus aureus infections, especially MRSA infections, are becoming a major global health issue and are resulting in mortality rates that are increasing every year. However, an effective vaccine is lacking due to the complexity of the infection process of S. aureus. In this study, we found that the addition of two novel protein components to three well-studied vaccine candidates significantly improved the efficacy of the combined vaccine. Furthermore, the five-component vaccine not only elicits a robust antibody response but also induces cytokine secretion by T cells, making it a promising vaccine candidate to fill the void.

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