Pathogenic Role of SEF14, SEF17, and SEF21 Fimbriae in Salmonella enterica Serovar Enteritidis Infection of Chickens

ABSTRACT Very little is known about the contribution of surface appendages of Salmonella enterica serovar Enteritidis to pathogenesis in chickens. This study was designed to clarify the role of SEF14, SEF17, and SEF21 fimbriae in serovar Enteritidis pathogenesis. Stable, single, defined sefA (SEF14), agfA (SEF17), andfimA (SEF21) insertionally inactivated fimbrial gene mutants of serovar Enteritidis were constructed. All mutant strains invaded Caco-2 and HT-29 enterocytes at levels similar to that of the wild type. Both mutant and wild-type strains were ingested equally well by chicken macrophage cell lines HD11 and MQ-NCSU. There were no significant differences in the abilities of these strains to colonize chicken ceca. The SEF14− strain was isolated in lower numbers from the livers of infected chickens and was cleared from the spleens faster than other strains. No significant differences in fecal shedding of these strains were observed.

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Salmonella enterica Serovar Enteritidis Pathogenicity Island 1 Is Not Essential for but Facilitates Rapid Systemic Spread in Chickens

Infection and Immunity ◽

10.1128/iai.00039-09 ◽

2009 ◽

Vol 77 (7) ◽

pp. 2866-2875 ◽

Cited By ~ 35

Author(s):

Taseen S. Desin ◽

Po-King S. Lam ◽

Birgit Koch ◽

Claudia Mickael ◽

Emil Berberov ◽

...

Keyword(s):

Salmonella Enterica ◽

Systemic Infection ◽

Poultry Meat ◽

Wild Type ◽

Secretion Systems ◽

Salmonella Enterica Serovar Enteritidis ◽

Systemic Spread ◽

Mutant Strains ◽

Vitro Analysis

ABSTRACT 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 ΔSPI-1 and ΔinvG 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 ΔSPI-1 mutant strains. Oral challenge of 1-week-old chicken with the wild-type or ΔSPI-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 ΔSPI-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.

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Distinct Antifungal Mechanisms: β-Defensins Require Candida albicans Ssa1 Protein, while Trk1p Mediates Activity of Cysteine-Free Cationic Peptides

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.50.1.324-331.2006 ◽

2006 ◽

Vol 50 (1) ◽

pp. 324-331 ◽

Cited By ~ 62

Author(s):

Slavena Vylkova ◽

Xuewei S. Li ◽

Jennifer C. Berner ◽

Mira Edgerton

Keyword(s):

Candida Albicans ◽

Membrane Permeability ◽

Fungicidal Activity ◽

Wild Type ◽

Histatin 5 ◽

Antifungal Peptides ◽

Mutant Strains ◽

Multistep Process ◽

Type Strains

ABSTRACT Salivary histatin 5 (Hst 5) kills the fungal pathogen Candida albicans via a multistep process which includes binding to Ssa1/2 proteins on the cell surface and requires the TRK1 potassium transporter. Hst 5-induced membrane permeability to propidium iodide (PI) was nearly abolished in strain CaTK1 (TRK1/trk1), suggesting that Hst 5-induced influx of PI is via Trk1p. To explore the functional role of Trk1p in the mechanism of other antifungal peptides, we evaluated candidacidal activity and PI uptake in wild-type strain CaTK2 (TRK1/TRK1) and strain CaTK1 following treatment with lactoferricin 11 (LFcn 11), bactenecin 16 (BN 16), and virion-associated protein VPR 12. Strain CaTK1 was resistant to killing with these peptides (VPR 12 > LFcn 11 > BN 16), showing the requirement of Trk1p for fungicidal activity. In contrast, human neutrophil defensin 1 (HNP-1), human β-defensin 2 (hBD-2), and hBD-3 effects on viability of and membrane permeability to PI were not different between mutant and wild-type strains, clearly showing that their candidacidal mechanism does not involve Trk1p as a functional effector. To test whether defensins require binding to Candida surface Ssa1/2 proteins for their activity, we measured the killing effectiveness in SSA1/2 mutant strains. Both hBD-2 and hBD-3, but not HNP-1, exhibited reduced killing of ssa1Δ and ssa2Δ strains compared to the wild type, showing that Ssa1 and Ssa2 proteins are required for their fungicidal activity. These results demonstrate that (i) Trk1p mediates candidacidal activities of cysteine-free peptides, but not of defensins, and (ii) hBD-2 and hBD-3, but not HNP-1, require Ssa1/2p for antifungal activity.

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Characterization of the Role of the FluG Protein in Asexual Development of Aspergillus nidulans

Genetics ◽

10.1093/genetics/158.3.1027 ◽

2001 ◽

Vol 158 (3) ◽

pp. 1027-1036 ◽

Cited By ~ 2

Author(s):

Cletus A D'Souza ◽

Bee Na Lee ◽

Thomas H Adams

Keyword(s):

Aspergillus Nidulans ◽

Negative Influence ◽

Asexual Development ◽

Wild Type ◽

Significant Similarity ◽

Developmental Defects ◽

Asexual Sporulation ◽

Type Strains

Abstract We showed previously that a ΔfluG mutation results in a block in Aspergillus nidulans asexual sporulation and that overexpression of fluG activates sporulation in liquid-submerged culture, a condition that does not normally support sporulation of wild-type strains. Here we demonstrate that the entire N-terminal region of FluG (∼400 amino acids) can be deleted without affecting sporulation, indicating that FluG activity resides in the C-terminal half of the protein, which bears significant similarity with GSI-type glutamine synthetases. While FluG has no apparent role in glutamine biosynthesis, we propose that it has an enzymatic role in sporulation factor production. We also describe the isolation of dominant suppressors of ΔfluG(dsg) that should identify components acting downstream of FluG and thereby define the function of FluG in sporulation. The dsgA1 mutation also suppresses the developmental defects resulting from ΔflbA and dominant activating fadA mutations, which both cause constitutive induction of the mycelial proliferation pathway. However, dsgA1 does not suppress the negative influence of these mutations on production of the aflatoxin precursor, sterigmatocystin, indicating that dsgA1 is specific for asexual development. Taken together, our studies define dsgA as a novel component of the asexual sporulation pathway.

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Virulence and Metabolic Characteristics of Salmonella enterica Serovar Enteritidis Strains with DifferentsefDVariants in Hens

Applied and Environmental Microbiology ◽

10.1128/aem.00852-12 ◽

2012 ◽

Vol 78 (18) ◽

pp. 6405-6412 ◽

Cited By ~ 6

Author(s):

Cesar A. Morales ◽

Jean Guard ◽

Roxana Sanchez-Ingunza ◽

Devendra H. Shah ◽

Mark Harrison

Keyword(s):

Salmonella Enterica ◽

Egg Production ◽

The Body ◽

Wild Type ◽

Salmonella Enterica Serovar Enteritidis ◽

Blood Calcium ◽

Content Type ◽

Metabolic Characteristics ◽

Wide Range ◽

Metabolic Properties

ABSTRACTSalmonella entericaserovar Enteritidis is one of a fewSalmonella entericaserotypes that has SEF14 fimbriae encoded by thesefoperon, which consists of 4 cotranscribed genes,sefABCD, regulated bysefR. A parental strain was used to construct asefDmutant and its complement, and all 3 strains were compared for gene expression, metabolic properties, and virulence characteristics in hens. Transcription ofsefDby wild type was suppressed at 42°C and absent for the mutant under conditions where the complemented mutant had 103times higher transcription. Growth of the complemented mutant was restricted in comparison to that of the mutant and wild type. Hens infected with the wild type and mutant showed decreased blood calcium and egg production, but infection with the complemented mutant did not. Thus, the absence ofsefDcorrelated with increased metabolic capacity and enhanced virulence of the pathogen. These results suggest that any contribution thatsefDmakes to egg contamination is either unknown or would be limited to early transmission from the environment to the host. Absence ofsefD, either through mutation or by suppression of transcription at the body temperature of the host, may contribute to the virulence ofSalmonella entericaby facilitating growth on a wide range of metabolites.

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Pneumococcal Surface Protein C Contributes to Sepsis Caused by Streptococcus pneumoniae in Mice

Infection and Immunity ◽

10.1128/iai.72.5.3077-3080.2004 ◽

2004 ◽

Vol 72 (5) ◽

pp. 3077-3080 ◽

Cited By ~ 47

Author(s):

Francesco Iannelli ◽

Damiana Chiavolini ◽

Susanna Ricci ◽

Marco Rinaldo Oggioni ◽

Gianni Pozzi

Keyword(s):

Streptococcus Pneumoniae ◽

Protein C ◽

Lethal Dose ◽

Surface Protein ◽

Infection Model ◽

Wild Type ◽

Mutant Strains ◽

Type 3

ABSTRACT The role of pneumococcal surface protein C (PspC; also called SpsA, CbpA, and Hic) in sepsis by Streptococcus pneumoniae was investigated in a murine infection model. The pspC gene was deleted in strains D39 (type 2) and A66 (type 3), and the mutants were tested by being injected intravenously into mice. The animals infected with the mutant strains showed a significant increase in survival, with the 50% lethal dose up to 250-fold higher than that for the wild type. Our findings indicate that PspC affords a decisive contribution to sepsis development.

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Expression of Mycobacterium smegmatisPyrazinamidase in Mycobacterium tuberculosis Confers Hypersensitivity to Pyrazinamide and Related Amides

Journal of Bacteriology ◽

10.1128/jb.182.19.5479-5485.2000 ◽

2000 ◽

Vol 182 (19) ◽

pp. 5479-5485 ◽

Cited By ~ 34

Author(s):

Helena I. M. Boshoff ◽

Valerie Mizrahi

Keyword(s):

Mycobacterium Tuberculosis ◽

Mycobacterium Smegmatis ◽

Intracellular Localization ◽

Wild Type ◽

Gene Encoding ◽

Allelic Exchange ◽

Mutant Strains ◽

Established Role ◽

Amidase Gene

ABSTRACT A pyrazinamidase (PZase)-deficient pncA mutant ofMycobacterium tuberculosis, constructed by allelic exchange, was used to investigate the effects of heterologous amidase gene expression on the susceptibility of this organism to pyrazinamide (PZA) and related amides. The mutant was highly resistant to PZA (MIC, >2,000 μg/ml), in accordance with the well-established role ofpncA in the PZA susceptibility of M. tuberculosis (A. Scorpio and Y. Zhang, Nat. Med. 2:662–667, 1996). Integration of the pzaA gene encoding the major PZase/nicotinamidase from Mycobacterium smegmatis (H. I. M. Boshoff and V. Mizrahi, J. Bacteriol. 180:5809–5814, 1998) or the M. tuberculosis pncA gene into the pncAmutant complemented its PZase/nicotinamidase defect. In bothpzaA- and pncA-complemented mutant strains, the PZase activity was detected exclusively in the cytoplasm, suggesting an intracellular localization for PzaA and PncA. ThepzaA-complemented strain was hypersensitive to PZA (MIC, ≤10 μg/ml) and nicotinamide (MIC, ≥20 μg/ml) and was also sensitive to benzamide (MIC, 20 μg/ml), unlike the wild-type andpncA-complemented mutant strains, which were highly resistant to this amide (MIC, >500 μg/ml). This finding was consistent with the observation that benzamide is hydrolyzed by PzaA but not by PncA. Overexpression of PzaA also conferred sensitivity to PZA, nicotinamide, and benzamide on M. smegmatis (MIC, 150 μg/ml in all cases) and rendered Escherichia colihypersensitive for growth at low pH.

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Lactic Acid Bacteria Isolated From Korean Kimchi Activate the Vitamin D Receptor–autophagy Signaling Pathways

Inflammatory Bowel Diseases ◽

10.1093/ibd/izaa049 ◽

2020 ◽

Vol 26 (8) ◽

pp. 1199-1211 ◽

Cited By ~ 2

Author(s):

Rong Lu ◽

Mei Shang ◽

Yong-Guo Zhang ◽

Yang Jiao ◽

Yinglin Xia ◽

...

Keyword(s):

Vitamin D ◽

Lactic Acid ◽

Lactic Acid Bacteria ◽

Vitamin D Receptor ◽

Salmonella Enterica ◽

Conditional Knockout ◽

Control Group ◽

Salmonella Enterica Serovar Enteritidis ◽

Anti Inflammation

Abstract Background Probiotic lactic acid bacteria (LAB) have been used in the anti-inflammation and anti-infection process of various diseases, including inflammatory bowel disease (IBD). Vitamin D receptor (VDR) plays an essential role in pathogenesis of IBD and infectious diseases. Previous studies have demonstrated that the human VDR gene is a key host factor to shape gut microbiome. Furthermore, intestinal epithelial VDR conditional knockout (VDRΔIEC) leads to dysbiosis. Low expressions of VDR is associated with impaired autophagy, accompanied by a reduction of ATG16L1 and LC3B. The purpose of this study is to investigate probiotic effects and mechanism in modulating the VDR-autophagy pathways. Methods Five LAB strains were isolated from Korean kimchi. Conditional medium (CM) from these strains was used to treat a human cell line HCT116 or intestinal organoids to measure the expression of VDR and autophagy. Mouse embryonic fibroblast (MEF) cells with or without VDR were used to investigate the dependence on the VDR signaling. To test the role of LAB in anti-inflammation, VDR+/+ organoids were treated with 121-CM before infection with Salmonella enterica serovar Enteritidis. In vivo, the role of LAB in regulating VDR-autophagy signaling was examined using LAB 121-CM orally administrated to VDRLoxp and VDRΔIEC mice. Results The LAB-CM-treated groups showed higher mRNA expression of VDR and its target genes cathelicidin compared with the control group. LAB treatment also enhanced expressions of Beclin-1 and ATG16L1 and changed the ratio of LC3B I and II, indicating the activation of autophagic responses. Furthermore, 121-CM treatment before Salmonella enterica serovar Enteritidis infection dramatically increased VDR and ATG16L1 and inhibited the inflammation. Administration of 121-CM to VDRLoxp and VDRΔIEC mice for 12 and 24 hours resulted in an increase of VDR and LC3B II:I ratio. Furthermore, we identified that probiotic proteins P40 and P75 in the LAB-CM contributed to the anti-inflammatory function by increasing VDR. Conclusions Probiotic LAB exert anti-inflammation activity and induces autophagy. These effects depend on the VDR expression. Our data highlight the beneficial effects of these 5 LAB strains isolated from food in anti-infection and anti-inflammation.

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Role of CpALS4790 and CpALS0660 in Candida parapsilosis Virulence: Evidence from a Murine Model of Vaginal Candidiasis

Journal of Fungi ◽

10.3390/jof6020086 ◽

2020 ◽

Vol 6 (2) ◽

pp. 86

Author(s):

Marina Zoppo ◽

Fabrizio Fiorentini ◽

Cosmeri Rizzato ◽

Mariagrazia Di Luca ◽

Antonella Lupetti ◽

...

Keyword(s):

Cell Wall ◽

Murine Model ◽

Type Strain ◽

Wild Type Strain ◽

Candida Parapsilosis ◽

Vaginal Candidiasis ◽

Phenotypic Characterization ◽

Wild Type ◽

Mutant Strains

The Candida parapsilosis genome encodes for five agglutinin-like sequence (Als) cell-wall glycoproteins involved in adhesion to biotic and abiotic surfaces. The work presented here is aimed at analyzing the role of the two still uncharacterized ALS genes in C. parapsilosis, CpALS4790 and CpALS0660, by the generation and characterization of CpALS4790 and CpALS066 single mutant strains. Phenotypic characterization showed that both mutant strains behaved as the parental wild type strain regarding growth rate in liquid/solid media supplemented with cell-wall perturbing agents, and in the ability to produce pseudohyphae. Interestingly, the ability of the CpALS0660 null mutant to adhere to human buccal epithelial cells (HBECs) was not altered when compared with the wild-type strain, whereas deletion of CpALS4790 led to a significant loss of the adhesion capability. RT-qPCR analysis performed on the mutant strains in co-incubation with HBECs did not highlight significant changes in the expression levels of others ALS genes. In vivo experiments in a murine model of vaginal candidiasis indicated a significant reduction in CFUs recovered from BALB/C mice infected with each mutant strain in comparison to those infected with the wild type strain, confirming the involvement of CpAls4790 and CpAls5600 proteins in C. parapsilosis vaginal candidiasis in mice.

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The Entner-Doudoroff Pathway Has Little Effect on Helicobacter pylori Colonization of Mice

Infection and Immunity ◽

10.1128/iai.71.5.2920-2923.2003 ◽

2003 ◽

Vol 71 (5) ◽

pp. 2920-2923 ◽

Cited By ~ 10

Author(s):

Amy E. Wanken ◽

Tyrrell Conway ◽

Kathryn A. Eaton

Keyword(s):

Helicobacter Pylori ◽

Wild Type ◽

Mutant Strains ◽

H Pylori ◽

Type Strains

ABSTRACT Helicobacter pylori mutants deficient in 6-phosphogluconate dehydratase (6PGD) were constructed. Colonization densities were lower and minimum infectious doses were higher for mutant strains than for wild-type strains. In spite of better colonization, however, wild-type strains did not displace the mutant in cocolonization experiments. Loss of 6PGD diminishes the fitness of H. pylori in vivo, but the pathway is nonessential for colonization.

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Role of FAD-I in Fusobacterial Interspecies Interaction and Biofilm Formation

Microorganisms ◽

10.3390/microorganisms8010070 ◽

2020 ◽

Vol 8 (1) ◽

pp. 70 ◽

Cited By ~ 1

Author(s):

Bhumika Shokeen ◽

Jane Park ◽

Emily Duong ◽

Sonam Rambhia ◽

Manash Paul ◽

...

Keyword(s):

Biofilm Formation ◽

Fusobacterium Nucleatum ◽

Interspecies Interaction ◽

Wild Type ◽

Oral Epithelial Cells ◽

Small Proteins ◽

Mutant Strains ◽

Oral Epithelial ◽

Wild Type Parent

RadD, a major adhesin of oral fusobacteria, is part of a four-gene operon encoding the small lipoprotein FAD-I and two currently uncharacterized small proteins encoded by the rapA and rapB genes. Previously, we described a role for FAD-I in the induction of human B-defensin 2 (hBD2) upon contact with oral epithelial cells. Here, we investigated potential roles for fad-I, rapA, and rapB in interspecies interaction and biofilm formation. Gene inactivation mutants were generated for each of these genes in the nucleatum and polymorphum subspecies of Fusobacterium nucleatum and characterized for their adherence to partner species, biofilm formation, and operon transcription. Binding to Streptococcus gordonii was increased in all mutant strains with Δfad-I having the most significant effect. This increased adherence was directly proportional to elevated radD transcript levels and resulted in significantly different architecture and height of the biofilms formed by Δfad-I and S. gordonii compared to the wild-type parent. In conclusion, FAD-I is important for fusobacterial interspecies interaction as its lack leads to increased production of the RadD adhesin suggesting a role of FAD-I in its regulation. This regulatory effect does not require the presence of functional RadD.

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