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 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.

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 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 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 Identification of Genetic Loci Required for Capsular Expression in Vibrio vulnificus

2003 ◽  
Vol 71 (3) ◽  
pp. 1091-1097 ◽  
Author(s):  
Amy B. Smith ◽  
Ronald J. Siebeling
Keyword(s):  
Unknown Function ◽  
Gene Locus ◽  
Insertion Sequence ◽  
Capsular Polysaccharide ◽  
Vibrio Vulnificus ◽  
Virulent Strain ◽  
Gene Cassette ◽  
Open Reading Frames ◽  
Genetic Loci ◽  
Reading Frames

ABSTRACT Transposon mutagenesis of an encapsulated, virulent strain of Vibrio vulnificus 1003(O) led to the identification of four genetic regions that are essential to capsular polysaccharide (CPS) expression and virulence. Of the four regions, three are believed to be part of a capsule gene locus comprised of biosynthesis, polymerization, and transport genes clustered on a single chromosomal fragment. Genes indicating a Wzy-dependent system of polymerization and transmembrane export are present, suggesting that the CPS of V. vulnificus is lipid linked. The fourth region, while it contains a gene essential for CPS expression, is characteristic of an integron-gene cassette region, similar to the super integron of V. cholerae. It is not believed to be part of a CPS gene locus and is located in a region of the chromosome separate from the putative CPS loci. It is comprised of open reading frames (ORFs) carrying genes of unknown function surrounded by direct repeats. This region also contains IS492, an insertion sequence located numerous times throughout a region of the genome, demonstrating a restriction fragment length polymorphism among an encapsulated and nonencapsulated morphotype of V. vulnificus. Collectively, 22 ORFs were recognized: 13 capsule synthesis genes, 4 insertion sequences, 1 truncated biosynthesis gene, and 4 genes of unknown function. This study has led to the identification of previously unrecognized genetic loci that may help to increase the understanding of capsular genetics and antigenic diversity among V. vulnificus strains.

scholarly journals Characterization of a New Plasmid-Like Prophage in a Pandemic Vibrio parahaemolyticus O3:K6 Strain

2009 ◽  
Vol 75 (9) ◽  
pp. 2659-2667 ◽  
Author(s):  
Shih-Feng Lan ◽  
Chung-Ho Huang ◽  
Chuan-Hsiung Chang ◽  
Wei-Chao Liao ◽  
I-Hsuan Lin ◽  
...  
Keyword(s):  
Vibrio Parahaemolyticus ◽  
Vibrio Vulnificus ◽  
Open Reading Frames ◽  
Host Chromosome ◽  
Food Borne ◽  
Dna Adenine Methylase ◽  
Related Group ◽  
Bacterial Genes

ABSTRACT Vibrio parahaemolyticus is a common food-borne pathogen that is normally associated with seafood. In 1996, a pandemic O3:K6 strain abruptly appeared and caused the first pandemic of this pathogen to spread throughout many Asian countries, America, Europe, and Africa. The role of temperate bacteriophages in the evolution of this pathogen is of great interest. In this work, a new temperate phage, VP882, from a pandemic O3:K6 strain of V. parahaemolyticus was purified and characterized after mitomycin C induction. VP882 was a Myoviridae bacteriophage with a polyhedral head and a long rigid tail with a sheath-like structure. It infected and lysed high proportions of V. parahaemolyticus, Vibrio vulnificus, and Vibrio cholerae strains. The genome of phage VP882 was sequenced and was 38,197 bp long, and 71 putative open reading frames were identified, of which 27 were putative functional phage or bacterial genes. VP882 had a linear plasmid-like genome with a putative protelomerase gene and cohesive ends. The genome does not integrate into the host chromosome but was maintained as a plasmid in the lysogen. Analysis of the reaction sites of the protelomerases in different plasmid-like phages revealed that VP882 and ΦHAP-1 were highly similar, while N15, ΦKO2, and PY54 made up another closely related group. The presence of DNA adenine methylase and quorum-sensing transcriptional regulators in VP882 may play a specific role in this phage or regulate physiological or virulence-associated traits of the hosts. These genes may also be remnants from the bacterial chromosome following transduction.

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.

Calcium promotes exopolysaccharide phase variation and biofilm formation of the resulting phase variants in the human pathogen Vibrio vulnificus

2010 ◽  
Vol 13 (3) ◽  
pp. 643-654 ◽  
Author(s):  
Katherine L. Garrison-Schilling ◽  
Brenda L. Grau ◽  
Kevin S. McCarter ◽  
Brett J. Olivier ◽  
Nicole E. Comeaux ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Vibrio Vulnificus ◽  
Phase Variation ◽  
Human Pathogen ◽  
Phase Variants

scholarly journals Eikenella corrodens Phase Variation Involves a Posttranslational Event in Pilus Formation

1999 ◽  
Vol 181 (14) ◽  
pp. 4154-4160 ◽  
Author(s):  
Maria T. Villar ◽  
Jennifer T. Helber ◽  
Becky Hood ◽  
Michael R. Schaefer ◽  
Rona L. Hirschberg
Keyword(s):  
Sequence Analysis ◽  
Phase Variation ◽  
S Phase ◽  
Open Reading Frames ◽  
Major Type ◽  
Eikenella Corrodens ◽  
Dichelobacter Nodosus ◽  
Type Iv ◽  
Type Iv Pilin ◽  
Phase Variants

ABSTRACT The human pathogen Eikenella corrodens synthesizes type IV pili and exhibits a phase variation involving the irreversible transition from piliated to nonpiliated variants. On solid medium, piliated variants form small (S-phase), corroding colonies whereas nonpiliated variants form large (L-phase), noncorroding colonies. We are studying the molecular basis of this phase variation in the clinical isolate E. corrodens VA1. A genomic fragment encoding the major type IV pilin was cloned from the S-phase variant of strain VA1. Sequence analysis of the fragment revealed four tandemly arranged potential open reading frames (ORFs), designatedpilA1, pilA2, pilB, andhagA. Both pilA1 and pilA2 predict a type IV pilin. The protein predicted by pilB shares sequence identity with the Dichelobacter nodosus FimB fimbrial assembly protein. The protein predicted by hagAresembles a hemagglutinin. The region containing these four ORFs was designated the pilA locus. DNA hybridization and sequence analysis showed that the pilA locus of an L-phase variant of strain VA1 was identical to that of the S-phase variant. An abundantpilA1 transcript initiating upstream of pilA1and terminating at a predicted hairpin structure betweenpilA1 and pilA2 was detected by several assays, as was a less abundant read-through transcript encompassingpilA1, pilA2, and pilB. Transcription from the pilA locus was nearly indistinguishable between S- and L-phase variants. Electron microscopy and immunochemical analysis showed that S-phase variants synthesize, export, and assemble pilin into pili. In contrast, L-phase variants synthesize pilin but do not export and assemble it into pili. These data suggest that a posttranslational event, possibly involving an alteration in pilin export and assembly, is responsible for phase variation in E. corrodens.

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