scholarly journals Structure, Function, and Regulation of the Essential Virulence Factor Capsular Polysaccharide of Vibrio vulnificus

2020 ◽  
Vol 21 (9) ◽  
pp. 3259 ◽  
Author(s):  
Gregg S. Pettis ◽  
Aheli S. Mukerji
Keyword(s):  
Coastal Waters ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Critical Role ◽  
Phase Variation ◽  
Innate Immune ◽  
Repeat Sequences ◽  
Life Threatening ◽  
Inflammatory Cytokine Response ◽  
Group 1

Vibrio vulnificus populates coastal waters around the world, where it exists freely or becomes concentrated in filter feeding mollusks. It also causes rapid and life-threatening sepsis and wound infections in humans. Of its many virulence factors, it is the V. vulnificus capsule, composed of capsular polysaccharide (CPS), that plays a critical role in evasion of the host innate immune system by conferring antiphagocytic ability and resistance to complement-mediated killing. CPS may also provoke a portion of the host inflammatory cytokine response to this bacterium. CPS production is biochemically and genetically diverse among strains of V. vulnificus, and the carbohydrate diversity of CPS is likely affected by horizontal gene transfer events that result in new combinations of biosynthetic genes. Phase variation between virulent encapsulated opaque colonial variants and attenuated translucent colonial variants, which have little or no CPS, is a common phenotype among strains of this species. One mechanism for generating acapsular variants likely involves homologous recombination between repeat sequences flanking the wzb phosphatase gene within the Group 1 CPS biosynthetic and transport operon. A considerable number of environmental, genetic, and regulatory factors have now been identified that affect CPS gene expression and CPS production in this pathogen.

scholarly journals Identification of a Group 1-Like Capsular Polysaccharide Operon for Vibrio vulnificus

2001 ◽  
Vol 69 (11) ◽  
pp. 6893-6901 ◽  
Author(s):  
Anita C. Wright ◽  
Jan L. Powell ◽  
James B. Kaper ◽  
J. Glenn Morris
Keyword(s):  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Phase Variation ◽  
Surface Expression ◽  
Open Reading Frames ◽  
Biosynthetic Genes ◽  
Virulent Phenotype ◽  
Phase Variants ◽  
Group 1

ABSTRACT Virulence of Vibrio vulnificus correlates with changes in colony morphology that are indicative of a reversible phase variation for expression of capsular polysaccharide (CPS). Encapsulated variants are virulent with opaque colonies, whereas phase variants with reduced CPS expression are attenuated and are translucent. Using TnphoA mutagenesis, we identified a V.vulnificus CPS locus, which included an upstreamops element, a wza gene (wza Vv), and several open reading frames with homology to CPS biosynthetic genes. This genetic organization is characteristic of group 1 CPS operons. The wzagene product is required for transport of CPS to the cell surface inEscherichia coli. Polar transposon mutations inwza Vv eliminated expression of downstream biosynthetic genes, confirming operon structure. On the other hand, nonpolar inactivation of wza Vv was specific for CPS transport, did not alter CPS biosynthesis, and could be complemented in trans. Southern analysis of CPS phase variants revealed deletions or rearrangements at this locus. A survey of environmental isolates indicated a correlation between deletions inwza Vv and loss of virulent phenotype, suggesting a genetic mechanism for CPS phase variation. Full virulence in mice required surface expression of CPS and supported the essential role of capsule in the pathogenesis of V.vulnificus.

scholarly journals Genetic Variation in the Vibrio vulnificus Group 1 Capsular Polysaccharide Operon

2006 ◽  
Vol 188 (5) ◽  
pp. 1987-1998 ◽  
Author(s):  
Maria Chatzidaki-Livanis ◽  
Melissa K. Jones ◽  
Anita C. Wright
Keyword(s):  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Allelic Variation ◽  
Phase Variation ◽  
Phase Variable ◽  
Deletion Mutations ◽  
Underlying Illness ◽  
Dna Elements ◽  
Repetitive Dna Elements ◽  
Group 1

ABSTRACT Vibrio vulnificus produces human disease associated with raw-oyster consumption or wound infections, but fatalities are limited to persons with chronic underlying illness. Capsular polysaccharide (CPS) is required for virulence, and CPS expression correlates with opaque (Op) colonies that show “phase variation” to avirulent translucent (Tr) phenotypes with reduced CPS. The results discussed here confirmed homology of a V. vulnificus CPS locus to the group 1 CPS operon in Escherichia coli. However, two distinct V. vulnificus genotypes or alleles were associated with the operon, and they diverged at sequences encoding hypothetical proteins and also at unique, intergenic repetitive DNA elements. Phase variation was examined under conditions that promoted high-frequency transition of Op to Tr forms. Recovery of Tr isolates in these experiments showed multiple genotypes, which were designated TR1, TR2, and TR3: CPS operons of TR1 isolates were identical to the Op parent, and cells remained phase variable but expressed reduced CPS. TR2 and TR3 showed deletion mutations in one (wzb) or multiple genes, respectively, and deletion mutants were acapsular and locked in the Tr phase. Complementation in trans restored the Op phenotype in strains with the wzb deletion mutation. Allelic variation in repetitive elements determined the locations, rates, and extents of deletion mutations. Thus, different mechanisms are responsible for reversible phase variation in CPS expression versus genetic deletions in the CPS operon of V. vulnificus. Repetitive-element-mediated deletion mutations were highly conserved within the species and are likely to promote survival in estuarine environments.

Role of GacA in virulence of Vibrio vulnificus

Microbiology ◽  
2010 ◽  
Vol 156 (12) ◽  
pp. 3722-3733 ◽  
Author(s):  
Julie D. Gauthier ◽  
Melissa K. Jones ◽  
Patrick Thiaville ◽  
Jennifer L. Joseph ◽  
Rick A. Swain ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Phase Variation ◽  
Dependent Manner ◽  
Wild Type ◽  
Significant Impairment ◽  
Life Threatening ◽  
Two Component Signal Transduction ◽  
Systemic Infections

The GacS/GacA two-component signal transduction system regulates virulence, biofilm formation and symbiosis in Vibrio species. The present study investigated this regulatory pathway in Vibrio vulnificus, a human pathogen that causes life-threatening disease associated with the consumption of raw oysters and wound infections. Small non-coding RNAs (csrB1, csrB2, csrB3 and csrC) commonly regulated by the GacS/GacA pathway were decreased (P<0.0003) in a V. vulnificus CMCP6 ΔgacA : : aph mutant compared with the wild-type parent, and expression was restored by complementation of the gacA deletion mutation in trans. Of the 20 genes examined by RT-PCR, significant reductions in the transcript levels of the mutant in comparison with the wild-type strain were observed only for genes related to motility (flaA), stationary phase (rpoS) and protease (vvpE) (P=0.04, 0.01 and 0.002, respectively). Swimming motility, flagellation and opaque colony morphology indicative of capsular polysaccharide (CPS) were unchanged in the mutant, while cytotoxicity, protease activity, CPS phase variation and the ability to acquire iron were decreased compared with the wild-type (P<0.01). The role of gacA in virulence of V. vulnificus was also demonstrated by significant impairment in the ability of the mutant strain to cause either skin (P<0.0005) or systemic infections (P<0.02) in subcutaneously inoculated, non-iron-treated mice. However, the virulence of the mutant was equivalent to that of the wild-type in iron-treated mice, demonstrating that the GacA pathway in V. vulnificus regulates the virulence of this organism in an iron-dependent manner.

scholarly journals Capsular Polysaccharide Phase Variation in Vibrio vulnificus

2006 ◽  
Vol 72 (11) ◽  
pp. 6986-6993 ◽  
Author(s):  
Tamara Hilton ◽  
Tom Rosche ◽  
Brett Froelich ◽  
Benjamin Smith ◽  
James Oliver
Keyword(s):  
Oxidative Stress ◽  
Quorum Sensing ◽  
Cell Surface ◽  
Serum Iron ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Phase Variation ◽  
Fatality Rate ◽  
Single Colony ◽  
And Oxidative Stress

ABSTRACT Commonly found in raw oysters, Vibrio vulnificus poses a serious health threat to immunocompromised individuals and those with serum iron overload, with a fatality rate of approximately 50%. An essential virulence factor is its capsular polysaccharide (CPS), which is responsible for a significant increase in virulence compared to nonencapsulated strains. However, this bacterium is known to vary the amount of CPS expressed on the cell surface, converting from an opaque (Op) colony phenotype to a translucent (Tr) colony phenotype. In this study, the consistency of CPS conversion was determined for four strains of V. vulnificus. Environmental conditions including variations in aeration, temperature, incubation time, oxidative stress, and media (heart infusion or modified maintenance medium agar) were investigated to determine their influence on CPS conversion. All conditions, with the exception of variations in media and oxidative stress, significantly affected the conversion of the population, with high ranges of CPS expression found even within cells from a single colony. The global quorum-sensing regulators RpoS and AI-2 were also examined. While RpoS was found to significantly mediate phenotypic conversion, quorum sensing was not. Finally, 12 strains that comprise the recently found clinical (C) and environmental (E) genotypes of V. vulnificus were examined to determine their rates of population conversion. C-genotype strains, which are most often associated with infection, had a significantly lower rate of population conversion from Op to Tr phenotypes than did E-genotype strains (ca. 38% versus ca. 14%, respectively). Biofilm capabilities of these strains, however, were not correlated with increased population conversion.

scholarly journals Differential Expression of Vibrio vulnificus Capsular Polysaccharide

1999 ◽  
Vol 67 (5) ◽  
pp. 2250-2257 ◽  
Author(s):  
Anita C. Wright ◽  
Jan L. Powell ◽  
Mike K. Tanner ◽  
Lynne A. Ensor ◽  
Arthur B. Karpas ◽  
...  
Keyword(s):  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Phase Variation ◽  
Surface Expression ◽  
Ruthenium Red ◽  
Cell Surface Expression ◽  
Enzyme Linked Immunosorbent Assay ◽  
Type I ◽  
Transposon Mutants ◽  
Phase Variants

ABSTRACT Vibrio vulnificus is a human pathogen whose virulence has been associated with the expression of capsular polysaccharide (CPS). Multiple CPS types have been described; however, virulence does not appear to correlate with a particular CPS composition. Reversible-phase variation for opaque and translucent colony morphologies is characterized by changes in CPS expression, as suggested by electron microscopy of cells stained nonspecifically with ruthenium red. Isolates with opaque colony morphologies are virulent and appear to be more thickly encapsulated than naturally occurring translucent-phase variants, which have reduced, patchy, or absent CPS. Previously, we have shown that the virulence of translucent-phase variants was intermediate between opaque-phase variants and acapsular transposon mutants, suggesting a correlation between virulence and the amount of CPS expressed. In the present study, CPS expression of phase variants and genetically defined mutants of V. vulnificusM06-24/O was examined by using a CPS-specific monoclonal antibody with an enzyme-linked immunosorbent assay, flow cytometry, and immunoelectron microscopy. Semiquantitative analyses of CPS expression correlated well among these assays, confirming that the translucent-phase variant was intermediate in CPS expression and retained type I CPS-specific epitopes. Cell surface expression of CPS varied with the growth phase, increasing during logarithmic growth and declining in stationary culture. Significantly greater CPS expression (P = 0.026) was observed for cells grown at 30°C than for those at 37°C. These studies confirm that phase variation and virulence in V. vulnificus correlate with the amount of CPS expressed and demonstrate the fluidity of bacterial polysaccharide expression in response to environmental conditions.

Fibrin Polymerization Defect in HIV-infected Patients-Evidence for a Critical Role of Albumin in the Prolongation of Thrombin and Reptilase Clotting Times

1995 ◽  
Vol 73 (03) ◽  
pp. 349-355 ◽  
Author(s):  
Pierre Toulon ◽  
Elyane Frere ◽  
Claude Bachmeyer ◽  
Nathalie Candia ◽  
Philippe Blanche ◽  
...  
Keyword(s):  
Critical Role ◽  
Human Albumin ◽  
Albumin Level ◽  
Final Concentration ◽  
Albumin Concentration ◽  
Clotting Time ◽  
Fibrin Polymerization ◽  
Small Series ◽  
Group 1

SummaryThrombin clotting time (TCT) and reptilase clotting time (RCT) were found significantly prolonged in a series of 72 HIV-infected patients drawn for routine coagulation testing. Both TCT and RCT were highly significantly correlated with albumin (r = -0.64, and r = -0.73 respectively, p<0.0001). TCT and RCT were significantly higher (p<0.0001) in a series of 30 other HIV-infected patients selected on their albumin level below 30.0 g/l (group l) than in 30 HIV-infected patients with albumin level above 40.0 g/l or in 30 HIV-negative controls; the two latter groups were not different. In vitro supplementation of plasma from group 1 patients with purified human albumin up to 45.0 g/l (final concentration) lead to a dramatic shortening effect on both TCT and RCT, which reached normal values. The TCT and RCT of the purified fibrinogen solutions (2.0 g/l final concentration) were not different in the three groups, and normal polymerization curves were obtained in all cases. This further ruled out the presence of any dysfibrinogenemia in the plasma from group 1 patients. Using purified proteins, highly significant correlations were demonstrated between the albumin concentration and the prolongations of both TCT and RCT, which were of the same magnitude order than those found in the patients plasma. These results suggest that hypo-albuminemia is responsible for the acquired fibrin polymerization defect reported in HIV-infected patients. The pathophysiological implication of the low albumin levels was suggested by the finding of decreased albumin levels (associated with prolonged TCT and RCT) in a small series of the eight HIV-infected patients who developed thrombotic complications.

CD34 immunostain increases sensitivity of the diagnosis of fetal vascular malperfusion in placentas from ex-utero intrapartum treatment

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Jerzy Stanek
Keyword(s):  
Statistical Significance ◽  
Treatment Procedure ◽  
Fetal Survival ◽  
Ex Utero Intrapartum Treatment ◽  
Life Threatening ◽  
Group 2 ◽  
Cd34 Immunostain ◽  
The Impact ◽  
Diaphragmatic Hernias ◽  
Group 1

AbstractShort CommunicationsEXIT (ex-utero intrapartum treatment) procedure is a fetal survival-increasing modification of cesarean section. Previously we found an increase incidence of fetal vascular malperfusion (FVM) in placentas from EXIT procedures which indicates the underlying stasis of fetal blood flow in such cases. This retrospective analysis analyzes the impact of the recently introduced CD34 immunostain for the FVM diagnosis in placentas from EXIT procedures.Objectives and MethodsA total of 105 placentas from EXIT procedures (48 to airway, 43 to ECMO and 14 to resection) were studied. In 73 older cases, the placental histological diagnosis of segmental FVM was made on H&E stained placental sections only (segmental villous avascularity) (Group 1), while in 32 most recent cases, the CD34 component of a double E-cadherin/CD34 immunostain slides was also routinely used to detect the early FVM (endothelial fragmentation, villous hypovascularity) (Group 2). 23 clinical and 47 independent placental phenotypes were compared by χ2 or ANOVA, where appropriate.ResultsThere was no statistical significance between the groups in rates of segmental villous avascularity (29 vs. 34%), but performing CD34 immunostain resulted in adding and/or upgrading 12 more cases of segmental FVM in Group 2, thus increasing the sensitivity of placental examination for FVM by 37%. There were no other statistically significantly differences in clinical (except for congenital diaphragmatic hernias statistically significantly more common in Group 2, 34 vs 56%, p=0.03) and placental phenotypes, proving the otherwise comparability of the groups.ConclusionsThe use of CD34 immunostain increases the sensitivity of placental examination for FVM by 1/3, which may improve the neonatal management by revealing the increased likelihood of the potentially life-threatening neonatal complications.

scholarly journals AB0051 SERUM AMYLOID A AND PENTRAXIN 3: INNATE IMMUNE RESPONSE AND DISEASE ACTIVITY IN SYSTEMIC LUPUS ERYTHEMATOSUS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 1328.1-1328
Author(s):  
R. Assandri ◽  
G. Martellosio ◽  
A. Montanelli
Keyword(s):  
Disease Activity ◽  
Lupus Erythematosus ◽  
Serum Amyloid A ◽  
Serum Levels ◽  
Innate Immune ◽  
Pentraxin 3 ◽  
Systemic Lupus ◽  
Amyloid A ◽  
Group 2 ◽  
Group 1

Background:Systemic Lupus Erythematosus (SLE) is an autoimmune disease that involves several molecular patterns with a wide spectrum of clinical manifestations and symptoms. Inflammation and related pathway play a role in SLE pathogenesis. The pentraxin superfamily including long and short pentraxin, C Reactive Protein CRP, Serum amyloid A (SAA), Pentraxin 3 (PTX3) are key components of innate immune system and induce a variety of inflammation associated pathway. However Literature provides several evidences that CRP serum levels not correlated with clinical and immunological manifestations. This situation affected clinical practice and the patient follow up. PTX3 have been identified as a component of inflammatory status in several autoimmune conditions. SAA is an acute phase protein secreted in large quantity during inflammation.Objectives:We want to evaluated SAA, PTX3 and CRP concentrations, their correlation between SLE Disease Activity Index (SLEDAI), that including complement fractions C3, C4.Methods:We enrolled fifty patients that fulfilled the SLE American College of Rheumatology criteria and fifty healthy subjects. The SLE disease activity was classified with the SLEDAI (0 to 12). Patients were divided into two groups according to SLEDAI score: inactive group (Group 1, 25 patients, 50%: SLEDAI < 4) and active group (Group 2, 25 patients, 50%: SLEDAI 5 to 12). PTX3 concentration was measured by a sandwich ELISA kit (Hycult) with 2.8 ng/mL cut-off point. SAA concentration was detected by nephelometry performed on a BN ProSpec System (Siemens, Germany), with assay kit based on polyclonal antibodies (Siemens Healthcare Diagnostics Products, Germany, 6.5 mg/L cut-off point). High sensitive CRP concentrations were determined using the ci8200 platform (Abbott Laboratories Chicago, Illinois).Results:Plasma PTX3 and serum SAA levels was significantly higher in SLE patients than in the healthy subjects (PTX311.5 ± 7.3 ng/mL vs 2.3 ± 1.1; p < 0.001; SAA: 87 ±77 mg/L vs 2.6±2.5; p < 0.001). These differences were not evident in CRP levels (8.5 ± 7.8 mg/L vs 6.2± 2.5). Considering two groups, there were statistical differences in PTX3 level (Group 2: 14.9 ± 12 ng/mL vs Group 1: 2.16 ±0.5 ng/mL, p<0,05) and SAA concentration (Group 2: 114 ± 89 ng/mL vs Group 1: 3.6 ±1.7 ng/mL, p<0,05) but not in CRP concentration (Group 2: 11.5 ± 8.4 mg/L vs Group 1: 9.5 ±3.5). There was a significantly negative correlation between C3, C4 fractions, PTX3 and SSA levels (respectively r = −0.74, p=<0.05, and r = −0.79, p<0.05). No statistical correlation were appeared between C3, C4 fractions and CRP serum levels (r= −0,12., p= 0.82, and r= −0.18, p= 0,21). We noted a positive significant correlation between SLEDAI, PTX3 and SAA concentration (r = 0.79, p < 0.05, 0.83, p < 0.05, respectively) an increase in PTX3 and SAA levels followed the lupus flare and symptoms. No significant correlation appeared between SLEDAI and CRP (r= 0.15, p=0.89)Conclusion:PTX3 and SAA concentration was significantly higher in SLE patients than the healthy control subjects and their levels reflected disease activity. We showed a direct correlation between PTX3 and SAA. In SLE patients PTX3 and SAA concentrations were correlated with SLEDAI. We suggest an integrate viewpoint in witch SAA and PTX3 may play a role as a biomarker of disease activity, with synergic work during SLE events. Evidences suggested that PTX3 and SAA could trigger the same molecular pathway, by TLR4, via NF-kB.References:[1]Assandri R, Monari M Montanelli A. Pentraxin 3 in Systemic Lupus Erithematosus: Questions to be Resolved, Translational Biomedicine (2015)Disclosure of Interests:None declared

scholarly journals Induced Disruption of the Iron-Regulatory Hormone Hepcidin Inhibits Acute Inflammatory Hypoferraemia

2016 ◽  
Vol 8 (5) ◽  
pp. 517-528 ◽  
Author(s):  
Andrew E. Armitage ◽  
Pei Jin Lim ◽  
Joe N. Frost ◽  
Sant-Rayn Pasricha ◽  
Elizabeth J. Soilleux ◽  
...  
Keyword(s):  
Mouse Model ◽  
Transgenic Mouse ◽  
Brucella Abortus ◽  
Serum Iron ◽  
Vibrio Vulnificus ◽  
Iron Status ◽  
Transgenic Mouse Model ◽  
Innate Immune ◽  
Serum Hepcidin

Withdrawal of iron from serum (hypoferraemia) is a conserved innate immune antimicrobial strategy that can withhold this critical nutrient from invading pathogens, impairing their growth. Hepcidin (Hamp1) is the master regulator of iron and its expression is induced by inflammation. Mice lacking Hamp1 from birth rapidly accumulate iron and are susceptible to infection by blood-dwelling siderophilic bacteria such as Vibrio vulnificus. In order to study the innate immune role of hepcidin against a background of normal iron status, we developed a transgenic mouse model of tamoxifen-sensitive conditional Hamp1 deletion (termed iHamp1-KO mice). These mice attain adulthood with an iron status indistinguishable from littermate controls. Hamp1 disruption and the consequent decline of serum hepcidin concentrations occurred within hours of a single tamoxifen dose. We found that the TLR ligands LPS and Pam3CSK4 and heat-killed Brucella abortus caused an equivalent induction of inflammation in control and iHamp1-KO mice. Pam3CSK4 and B. abortus only caused a drop in serum iron in control mice, while hypoferraemia due to LPS was evident but substantially blunted in iHamp1-KO mice. Our results characterise a powerful new model of rapidly inducible hepcidin disruption, and demonstrate the critical contribution of hepcidin to the hypoferraemia of inflammation.

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