scholarly journals Cyclic-di-GMP Regulates Extracellular Polysaccharide Production, Biofilm Formation, and Rugose Colony Development by Vibrio vulnificus

2008 ◽  
Vol 74 (13) ◽  
pp. 4199-4209 ◽  
Author(s):  
Alina Nakhamchik ◽  
Caroline Wilde ◽  
Dean A. Rowe-Magnus
Keyword(s):  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Genomic Library ◽  
Extracellular Polysaccharide ◽  
Invasive Disease ◽  
Colony Development ◽  
Independent Manner ◽  
Disease Agent ◽  
And Control

ABSTRACT Vibrio vulnificus is a human and animal pathogen that carries the highest death rate of any food-borne disease agent. It colonizes shellfish and forms biofilms on the surfaces of plankton, algae, fish, and eels. Greater understanding of biofilm formation by the organism could provide insight into approaches to decrease its load in filter feeders and on biotic surfaces and control the occurrence of invasive disease. The capsular polysaccharide (CPS), although essential for virulence, is not required for biofilm formation under the conditions used here. In other bacteria, increased biofilm formation often correlates with increased exopolysaccharide (EPS) production. We exploited the translucent phenotype of acapsular mutants to screen a V. vulnificus genomic library and identify genes that imparted an opaque phenotype to both CPS biosynthesis and transport mutants. One of these encoded a diguanylate cyclase (DGC), an enzyme that synthesizes bis-(3′-5′)-cyclic-di-GMP (c-di-GMP). This prompted us to use this DGC, DcpA, to examine the effect of elevated c-di-GMP levels on several developmental pathways in V. vulnificus. Increased c-di-GMP levels induced the production of an EPS that was distinct from the CPS and dramatically enhanced biofilm formation and rugosity in a CPS-independent manner. However, the EPS could not compensate for the loss of CPS production that is required for virulence. In contrast to V. cholerae, motility and virulence appeared unaffected by elevated levels of c-di-GMP.

scholarly journals Cryptococcus neoformans Biofilm Formation Depends on Surface Support and Carbon Source and Reduces Fungal Cell Susceptibility to Heat, Cold, and UV Light

2007 ◽  
Vol 73 (14) ◽  
pp. 4592-4601 ◽  
Author(s):  
Luis R. Martinez ◽  
Arturo Casadevall
Keyword(s):  
Cryptococcus Neoformans ◽  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Uv Light ◽  
Surface Characteristics ◽  
Extracellular Polysaccharide ◽  
Microtiter Plate ◽  
Support Surface ◽  
Fungal Cell ◽  
Biofilm Development

ABSTRACT The fungus Cryptococcus neoformans possesses a polysaccharide capsule and can form biofilms on medical devices. We describe the characteristics of C. neoformans biofilm development using a microtiter plate model, microscopic examinations, and a colorimetric 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium-hydroxide (XTT) reduction assay to observe the metabolic activity of cryptococci within a biofilm. A strong correlation between XTT and CFU assays was demonstrated. Chemical analysis of the exopolymeric material revealed sugar composition consisting predominantly of xylose, mannose, and glucose, indicating the presence of other polysaccharides in addition to glucurunoxylomannan. Biofilm formation was affected by surface support differences, conditioning films on the surface, characteristics of the medium, and properties of the microbial cell. A specific antibody to the capsular polysaccharide of this fungus was used to stain the extracellular polysaccharide matrix of the fungal biofilms using light and confocal microscopy. Additionally, the susceptibility of C. neoformans biofilms and planktonic cells to environmental stress was investigated using XTT reduction and CFU assays. Biofilms were less susceptible to heat, cold, and UV light exposition than their planktonic counterparts. Our findings demonstrate that fungal biofilm formation is dependent on support surface characteristics and that growth in the biofilm state makes fungal cells less susceptible to potential environmental stresses.

scholarly journals Further Characterization of Vibrio vulnificus Rugose Variants and Identification of a Capsular and Rugose Exopolysaccharide Gene Cluster

2008 ◽  
Vol 76 (4) ◽  
pp. 1485-1497 ◽  
Author(s):  
Brenda L. Grau ◽  
Margaret C. Henk ◽  
Katherine L. Garrison ◽  
Brett J. Olivier ◽  
Randall M. Schulz ◽  
...  
Keyword(s):  
Mouse Model ◽  
Gene Cluster ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Three Dimensional ◽  
Extracellular Polysaccharide ◽  
Colony Morphology ◽  
Colony Type ◽  
Major Virulence Factor

ABSTRACT Capsular polysaccharide (CPS) is a major virulence factor in Vibrio vulnificus, and encapsulated strains have an opaque, smooth (OpS) colony morphology, while nonencapsulated strains have a translucent, smooth (TrS) colony morphology. Previously, we showed that OpS and TrS parental strains can yield a third colony type, rugose (R), and that the resulting strains, with the OpR and TrR phenotypes, respectively, form copious biofilms. Here we show that while OpR and TrR strains both produce three-dimensional biofilm structures that are indicative of rugose extracellular polysaccharide (rEPS) production, OpR strains also retain expression of CPS and are virulent in an iron-supplemented mouse model, while TrR strains lack CPS and are avirulent. Chlorine resistance assays further distinguished OpR and TrR isolates as exposure to 3 μg/ml NaOCl eradicated both OpS and OpR strains, while both TrS and TrR strains survived, but at rates which were significantly different from one another. Taken together, these results further emphasize the importance of CPS for virulence of V. vulnificus and establish a correlation between CPS expression and chlorine sensitivity in this organism. Using reverse transcriptase PCR, we also identified a nine-gene cluster associated with both CPS and rEPS expression in V. vulnificus, designated the wcr (capsular and rugose polysaccharide) locus, with expression occurring primarily in R variants. The latter results set the stage for characterization of functional determinants which individually or collectively contribute to expression of multiple EPS forms in this pathogen.

scholarly journals Expression of Vibrio vulnificus Capsular Polysaccharide Inhibits Biofilm Formation

2004 ◽  
Vol 186 (3) ◽  
pp. 889-893 ◽  
Author(s):  
Lavin A. Joseph ◽  
Anita C. Wright
Keyword(s):  
Virulence Factor ◽  
Related Species ◽  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Human Pathogen ◽  
Multiple Strains ◽  
Phase Variants

ABSTRACT Vibrio vulnificus is a human pathogen that produces lethal septicemia in susceptible persons, and the primary virulence factor for this organism is capsular polysaccharide (CPS). The role of the capsule in V. vulnificus biofilms was examined under a variety of conditions, by using either defined CPS mutants or spontaneous CPS expression phase variants derived from multiple strains. CPS expression was shown to inhibit attachment and biofilm formation, which contrasted with other studies describing polysaccharides as integral to biofilms in related species.

scholarly journals Role of Anaerobiosis in Capsule Production and Biofilm Formation in Vibrio vulnificus

2014 ◽  
Vol 83 (2) ◽  
pp. 551-559 ◽  
Author(s):  
Britney L. Phippen ◽  
James D. Oliver
Keyword(s):  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Human Infection ◽  
Content Type ◽  
Type Iv ◽  
Virulence Potential ◽  
Capsule Production ◽  
Type Iv Pilin ◽  
Effect Of Oxygen

Vibrio vulnificus, a pervasive human pathogen, can cause potentially fatal septicemia after consumption of undercooked seafood. Biotype 1 strains ofV. vulnificusare most commonly associated with human infection and are separated into two genotypes, clinical (C) and environmental (E), based on the virulence-correlated gene. For ingestion-based vibriosis to occur, this bacterium must be able to withstand multiple conditions as it traverses the gastrointestinal tract and ultimately gains entry into the bloodstream. One such condition, anoxia, has yet to be extensively researched inV. vulnificus. We investigated the effect of oxygen availability on capsular polysaccharide (CPS) production and biofilm formation in this bacterium, both of which are thought to be important for disease progression. We found that lack of oxygen elicits a reduction in both CPS and biofilm formation in both genotypes. This is further supported by the finding thatpilA,pilD, andmshAgenes, all of which encode type IV pilin proteins that aid in attachment to surfaces, were downregulated during anaerobiosis. Surprisingly, E-genotypes exhibited distinct differences in gene expression levels of capsule and attachment genes compared to C-genotypes, both aerobically and anaerobically. The importance of understanding these disparities may give insight into the observed differences in environmental occurrence and virulence potential between these two genotypes ofV. vulnificus.

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 10. Kinetics of Post-Vaccination Seroprotection to S. Pneumonia for the Immune-Compromised and Vaccine-Naïve Populations

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S27-S28
Author(s):  
Jeffrey Gruenglas ◽  
James Mond ◽  
Micaela Scobie ◽  
Cynthia Tolman ◽  
Joseph Martinez
Keyword(s):  
Capsular Polysaccharide ◽  
The Elderly ◽  
Community Acquired Pneumonia ◽  
Prior History ◽  
Antibody Activity ◽  
Vaccine Response ◽  
Serum Samples ◽  
Opsonic Activity ◽  
And Control

Abstract Background S. pneumonia infection presents a significant challenge, accounting for 20–38% of hospital-acquired pneumonia, and the leading cause of community-acquired pneumonia despite availability of effective vaccines. Incidence is highest in children under 2 years, the immunocompromised, and elderly. CDC has reported the emergence of antibiotic resistance in ~30% of cases, adding to risk of morbidity and mortality. Fewer than half of the elderly are vaccinated and vulnerable to infection on admission. Passive immunotherapy as an adjunct to vaccines may improve outcomes in such populations. The objective of this study was to evaluate whether seroprotective response induced with a pneumococcal conjugate vaccine could rapidly yield protective opsonic levels of antibody within anticipated duration of hospitalization. Methods Healthy donors (n=30) were immunized with Prevnar. Blood was drawn on days 0, 3, 7, 10, 14, 21, and 28. Samples were pooled and tested for presence of functional opsonic antibodies recognizing capsular polysaccharides. Clearance mechanism of S. pneumonia was based on antibody recognition to pneumococcal capsular polysaccharide and opsonic titers used as an in vitro surrogate to evaluate the efficacy of vaccine. Results There was little to no opsonic activity against most serotypes on day 0, except for low antibody activity with serotypes 1, 3, 4, and 5. Titers increased, with protective levels achieved by day 10 for most serotypes (except 14 and 18C), peaking at day 14 or after across serotypes (Figures 1 and 2). Average titers rose from log2 titer 2 on day 0 to log2 titer 8 on days 21 and 28. Titers against most serotypes reached log2 10 (titer 1024) or higher. Patients remained susceptible to nosocomial infection for at least 10 days post admission until protective titers are reached. OPK titers (log2 scale) for serum samples on day 0 (pre), day 3, 7, 10, 14, 21, 28, and control for S. pneumoniae serotypes 1, 3, 4, 5, 6A, 6B, 7F, 9V. N=2. OPK titers (log2 scale) for serum samples on day 0 (pre), day 3, 7, 10, 14, 21, 28, and control for S. pneumoniae serotypes 14, 18C, 19A, 19F, and 23F. N=2. Conclusion Patients with no prior history of vaccination (or inability to mount response) with Prevnar or pneumovax remain vulnerable to S. pneumonia infection even if vaccinated on entry, due to delayed kinetics in reaching protective titers. These patients may require prophylactic intervention of hyperimmune Ig with high opsonic titers to S. pneumonia, providing protection until vaccine response elicits protective antibodies. Disclosures All Authors: No reported disclosures

scholarly journals Role of DegQ in differential stability of flagellin subunits in Vibrio vulnificus

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
You-Chul Jung ◽  
Mi-Ae Lee ◽  
Han-Shin Kim ◽  
Kyu-Ho Lee
Keyword(s):  
Life Cycle ◽  
Biofilm Formation ◽  
Vibrio Vulnificus ◽  
Differential Regulation ◽  
Specific Manner ◽  
Associated Proteins ◽  
Differential Stability ◽  
Methionine Residues

AbstractBiofilm formation of Vibrio vulnificus is initiated by adherence of flagellated cells to surfaces, and then flagellum-driven motility is not necessary during biofilm maturation. Once matured biofilms are constructed, cells become flagellated and swim to disperse from biofilms. As a consequence, timely regulations of the flagellar components’ expression are crucial to complete a biofilm life-cycle. In this study, we demonstrated that flagellins’ production is regulated in a biofilm stage-specific manner, via activities of a protease DegQ and a chaperone FlaJ. Among four flagellin subunits for V. vulnificus filament, FlaC had the highest affinities to hook-associated proteins, and is critical for maturating flagellum, showed the least susceptibility to DegQ due to the presence of methionine residues in its DegQ-sensitive domains, ND1 and CD0. Therefore, differential regulation by DegQ and FlaJ controls the cytoplasmic stability of flagellins, which further determines the motility-dependent, stage-specific development of biofilms.

scholarly journals Severe acute respiratory syndrome (SARS) related coronavirus in bats

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Rong Geng ◽  
Peng Zhou
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Current Knowledge ◽  
Disease Outbreaks ◽  
First Century ◽  
Intermediate Hosts ◽  
Human Coronavirus ◽  
Transmission Potential ◽  
Disease Agent ◽  
And Control ◽  
Genomic Similarity

AbstractThree major human coronavirus disease outbreaks, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and 2019 coronavirus disease (COVID-19), occurred in the twenty-first century and were caused by different coronaviruses (CoVs). All these viruses are considered to have originated from bats and transmitted to humans through intermediate hosts. SARS-CoV-1 and SARS-CoV-2, disease agent of COVID-19, shared around 80% genomic similarity, and thus belong to SARS-related CoVs. As a natural reservoir of viruses, bats harbor numerous other SARS-related CoVs that could potentially infect humans around the world, causing SARS or COVID-19 like outbreaks in the future. In this review, we summarized the current knowledge of CoVs on geographical distribution, genetic diversity, cross-species transmission potential and possible pathogenesis in humans, aiming for a better understanding of bat SARS-related CoVs in the context of prevention and control.

scholarly journals Risk factors and biofilm formation analyses of hospital-acquired infection of Candida pelliculosa in a neonatal intensive care unit

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Zhijie Zhang ◽  
Yu Cao ◽  
Yanjian Li ◽  
Xufang Chen ◽  
Chen Ding ◽  
...  
Keyword(s):  
Risk Factors ◽  
Intensive Care Unit ◽  
Biofilm Formation ◽  
Prevention And Control ◽  
Neonatal Intensive Care ◽  
Infection Prevention ◽  
Infection Prevention And Control ◽  
Anti Fungal ◽  
Hospital Acquired ◽  
And Control

Abstract Background Candida pelliculosa is an ecological fungal species that can cause infections in immunocompromised individuals. Numerous studies globally have shown that C. pelliculosa infects neonates. An outbreak recently occurred in our neonatal intensive care unit; therefore, we aimed to evaluate the risk factors in this hospital-acquired fungal infection. Methods We performed a case-control study, analysing the potential risk factors for neonatal infections of C. pelliculosa so that infection prevention and control could be implemented in our units. Isolated strains were tested for drug resistance and biofilm formation, important factors for fungal transmission that give rise to hospital-acquired infections. Results The use of three or more broad-spectrum antimicrobials or long hospital stays were associated with higher likelihoods of infection with C. pelliculosa. The fungus was not identified on the hands of healthcare workers or in the environment. All fungal isolates were susceptible to anti-fungal medications, and after anti-fungal treatment, all infected patients recovered. Strict infection prevention and control procedures efficiently suppressed infection transmission. Intact adhesin-encoding genes, shown by genome analysis, indicated possible routes for fungal transmission. Conclusions The use of three or more broad-spectrum antimicrobials or a lengthy hospital stay is theoretically associated with the risk of infection with C. pelliculosa. Strains that we isolated are susceptible to anti-fungal medications, and these were eliminated by treating all patients with an antifungal. Transmission is likely via adhesion to the cell surface and biofilm formation.

scholarly journals Specific Control of Pseudomonas aeruginosa Surface-Associated Behaviors by Two c-di-GMP Diguanylate Cyclases

mBio ◽  
2010 ◽  
Vol 1 (4) ◽  
Author(s):  
Judith H. Merritt ◽  
Dae-Gon Ha ◽  
Kimberly N. Cowles ◽  
Wenyun Lu ◽  
Diana K. Morales ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Extracellular Polysaccharide ◽  
Diguanylate Cyclase ◽  
Flagellar Motility ◽  
Critical Question ◽  
Cyclic Diguanylate ◽  
Critical Signal ◽  
Content Type ◽  
Wide Range

ABSTRACT The signaling nucleotide cyclic diguanylate (c-di-GMP) regulates the transition between motile and sessile growth in a wide range of bacteria. Understanding how microbes control c-di-GMP metabolism to activate specific pathways is complicated by the apparent multifold redundancy of enzymes that synthesize and degrade this dinucleotide, and several models have been proposed to explain how bacteria coordinate the actions of these many enzymes. Here we report the identification of a diguanylate cyclase (DGC), RoeA, of Pseudomonas aeruginosa that promotes the production of extracellular polysaccharide (EPS) and contributes to biofilm formation, that is, the transition from planktonic to surface-dwelling cells. Our studies reveal that RoeA and the previously described DGC SadC make distinct contributions to biofilm formation, controlling polysaccharide production and flagellar motility, respectively. Measurement of total cellular levels of c-di-GMP in ∆roeA and ∆sadC mutants in two different genetic backgrounds revealed no correlation between levels of c-di-GMP and the observed phenotypic output with regard to swarming motility and EPS production. Our data strongly argue against a model wherein changes in total levels of c-di-GMP can account for the specific surface-related phenotypes of P. aeruginosa. IMPORTANCE A critical question in the study of cyclic diguanylate (c-di-GMP) signaling is how the bacterial cell integrates contributions of multiple c-di-GMP-metabolizing enzymes to mediate its cognate functional outputs. One leading model suggests that the effects of c-di-GMP must, in part, be localized subcellularly. The data presented here show that the phenotypes controlled by two different diguanylate cyclase (DGC) enzymes have discrete outputs despite the same total level of c-di-GMP. These data support and extend the model in which localized c-di-GMP signaling likely contributes to coordination of the action of the multiple proteins involved in the synthesis, degradation, and/or binding of this critical signal.

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