High prevalence of thermostable direct hemolysin (TDH)-like toxin in<i>Vibrio mimicus</i>strains isolated from diarrhoeal patients

Uchimura, Masako; Koiwai, Kenji; Tsuruoka, Yoshihisa; Tanaka, Hiroyuki

doi:10.1017/s0950268800056661

Cited by 10 publications

(6 citation statements)

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“…Although it was previously recognized as a biotype of V. cholerae , it has now been reclassified as an independent species because of differences in a number of biochemical characteristics; e.g., V. mimicus is negative for sucrose fermentation, Voges-Proskauer, lipase (corn oil) activity, and Jordan tartrate reactions [2] . However, in terms of pathogenesis, V. mimicus and V. cholerae are similar due to sharing virulence factors, such as enterotoxins or hemolysins [3] , [4] , [5] , [6] , [7] . Although V. mimicus has not yet been reported to produce a severe epidemic of diarrhea, it is often isolated from sporadic diarrheal patients, sea water and food, indicating that it may be a potential source of the emergence of a new pathogen, as increasing numbers of genetic elements and virulence factors are exchanged by acquisition of foreign DNA from V. cholerae or other bacteria [8] .…”

Section: Introductionmentioning

confidence: 99%

“…V. mimicus hemolysin (VMH) is heat labile and immunologically similar to V. cholerae El Tor hemolysin [5] . Vm-TDH is a heat stable hemolysin that is closely related to the thermostable direct hemolysin (TDH) produced by V. parahaemolyticus [6] . Finally, V. mimicus produces a novel hemolysin, designated HLX, but little is known regarding its function [11] .…”

Section: Introductionmentioning

confidence: 99%

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Genome Sequencing Reveals Unique Mutations in Characteristic Metabolic Pathways and the Transfer of Virulence Genes between V. mimicus and V. cholerae

Wang

Zhou

et al. 2011

PLoS ONE

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Vibrio mimicus, the species most similar to V. cholerae, is a microbe present in the natural environmental and sometimes causes diarrhea and internal infections in humans. It shows similar phenotypes to V. cholerae but differs in some biochemical characteristics. The molecular mechanisms underlying the differences in biochemical metabolism between V. mimicus and V. cholerae are currently unclear. Several V. mimicus isolates have been found that carry cholera toxin genes (ctxAB) and cause cholera-like diarrhea in humans. Here, the genome of the V. mimicus isolate SX-4, which carries an intact CTX element, was sequenced and annotated. Analysis of its genome, together with those of other Vibrio species, revealed extensive differences within the Vibrionaceae. Common mutations in gene clusters involved in three biochemical metabolism pathways that are used for discrimination between V. mimicus and V. cholerae were found in V. mimicus strains. We also constructed detailed genomic structures and evolution maps for the general types of genomic drift associated with pathogenic characters in polysaccharides, CTX elements and toxin co-regulated pilus (TCP) gene clusters. Overall, the whole-genome sequencing of the V. mimicus strain carrying the cholera toxin gene provides detailed information for understanding genomic differences among Vibrio spp. V. mimicus has a large number of diverse gene and nucleotide differences from its nearest neighbor, V. cholerae. The observed mutations in the characteristic metabolism pathways may indicate different adaptations to different niches for these species and may be caused by ancient events in evolution before the divergence of V. cholerae and V. mimicus. Horizontal transfers of virulence-related genes from an uncommon clone of V. cholerae, rather than the seventh pandemic strains, have generated the pathogenic V. mimicus strain carrying cholera toxin genes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Genome Sequencing Reveals Unique Mutations in Characteristic Metabolic Pathways and the Transfer of Virulence Genes between V. mimicus and V. cholerae

Wang

Zhou

et al. 2011

PLoS ONE

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“…In addition, both species may also share important virulence factors, such as ct and tcp genes (Boyd et al, 2000;O'Shea et al, 2004). V. mimicus has only been associated with small outbreaks or isolated cases of diarrhoea (Campos et al, 1996;Uchimura et al, 1993).Amplified Fragment Length Polymorphism (AFLP) has proved to be the most powerful taxonomic tool for discriminating species and strains of vibrios (Thompson et al, 2003(Thompson et al, , 2004. However, AFLP is not easily adaptable for use in an online electronic taxonomy (Thompson et al, 2005(Thompson et al, , 2007Thompson & Swings, 2006).…”

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confidence: 99%

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confidence: 99%

Identification of Vibrio cholerae and Vibrio mimicus by multilocus sequence analysis (MLSA)

Thompson

Vicente

2008

INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLO

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Vibrio cholerae and Vibrio mimicus have similar phenotypes and genomes making rapid differentiation of these two species difficult. The first standard multilocus sequence analysis (MLSA) scheme for the identification of these species is described. A collection of 45 representative isolates from different geographical regions and hosts was examined using segments of the housekeeping genes pyrH, recA and rpoA. Overall, the closest phylogenetic neighbours of these species were Vibrio furnissii and Vibrio fluvialis. V. cholerae and V. mimicus formed separate species clusters on the basis of each gene, suggesting that these genes are useful as identification markers. These species clusters arose by the accumulation of point mutations. The pyrH gene showed the highest resolution for differentiating V. cholerae and V. mimicus. The maximum interspecies pyrH gene sequence similarity was 91 %. Clearly, V. mimicus strains were more heterogeneous than V. cholerae strains at the three loci. It is suggested that vibrio species may be defined on the basis of MLSA data. A vibrio species was defined as a group of strains forming a monophyletic group on the basis of these loci and with an intraspecific sequence similarity of at least 95 %. V. cholerae and V. mimicus isolates can be readily identified through the open database resource 'The Taxonomy of Vibrios' (http://www.taxvibrio.lncc.br/).Vibrio cholerae, the causative agent of cholera, is a major pathogen worldwide, particularly in the developing world. Cholera killed at least 5000 people in 2006 in Angola and neighbouring countries (http://www.who.int/en/). V. cholerae can be classified into more than 200 serogroups, but only serogroups O1 and O139 have been responsible for epidemics of cholera (Hunter, 1997;Kay et al., 1994). The species Vibrio mimicus was first proposed to encompass biochemically atypical non-O1 V. cholerae isolates that were unable to utilize sucrose (Davis et al., 1981). Phenotypically, most of the features of V. mimicus are identical to those found in V. cholerae (Davis et al., 1981). A sucrose-negative strain of V. cholerae was identified during cholera epidemics (Desmarchelier & Reichelt, 1984;Ramos et al., 1997), making it difficult to differentiate these two species on this basis. Because V. cholerae and V. mimicus share nearly 100 % 16S rRNA gene sequence similarity and show around 80 % DNA-DNA relatedness, discriminating between these species remains a difficult task for taxonomists and clinicians (Thompson et al., 2003). In addition, both species may also share important virulence factors, such as ct and tcp genes (Boyd et al., 2000;O'Shea et al., 2004). V. mimicus has only been associated with small outbreaks or isolated cases of diarrhoea (Campos et al., 1996;Uchimura et al., 1993).Amplified Fragment Length Polymorphism (AFLP) has proved to be the most powerful taxonomic tool for discriminating species and strains of vibrios (Thompson et al., 2003(Thompson et al., , 2004. However, AFLP is not easily adaptable for use in an online electronic tax...

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“…It has been demonstrated that cyclic AMP can stimulate the CFTR (a Cl Ϫ channel) of intestinal cells. The stimulation of CFTR results in diarrhea (21). From these data, we thought that the action of ALH to stimulate the intestinal cell to produce ATP was involved in the onset of diarrhea by ALH (7).…”

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confidence: 99%

A Hemolysin of Vibrio mimicus (VMH) Stimulates Cells to Produce ATP and Cyclic AMP Which Appear to Be Secretory Mediators

Okamoto

Takahashi

et al. 2005

Microbiology and Immunology

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Vibrio mimicus is a causative agent of human gastroenteritis. Various clinical symptoms are induced by infections of the pathogenic strains of V. mimicus including watery to dysentery-like diarrhea (11). As the virulent factors inducing diarrhea, three kinds of toxins, an enterotoxin similar to cholera toxin (CT-like toxin) (18), a heat-stable enterotoxin (ST-like toxin) (9), and hemolysin (2) have been reported. Further analysis of the hemolysin showed that two types are produced from V. mimicus. One is heat-labile and immunologically similar to the El Tor hemolysin produced by V. cholerae, while the other is heat-stable and closely related to the thermostable direct hemolysin produced by V. parahaemolyticus (1,12,20).Miyoshi et al. purified the hemolysin (VMH) which is heat-labile and immunologically similar to El Tor hemolysin from a culture filtrate of V. mimicus and showed that VMH possesses two types of biological activity, hemolytic and enterotoxic (14). Subsequent studies on the mechanism of action showed that VMH is a pore-forming toxin and that the hemolytic activity of VMH is attributable to the ability to make pores in the cell membrane (14, 17). However, the mechanism by which VMH induces diarrhea has remained unclear.Such properties of VMH, i.e., pore-forming ability and hemolytic as well as enterotoxic activity, are retained by the aerolysin-like hemolysin (ALH) produced by Aeromonas sobria (5,7,15). Previously, we found that ALH induces diarrhea without causing cellular damage to intestinal epithelial cells (5). This indicates that some signals to trigger diarrhea are sent from the intestinal cells immediately after ALHs act in the intestine. To identify the signals, we examined the action of ALH in T84 cells (a human colon carcinoma cell line) and found that the amount of ATP in the culture medium increased on incubation with ALH (7). The extracellular ATPs are decomposed into adenosines which induce an elevation in cyclic AMP levels by Abstract: The hemolysin of Vibrio mimicus (VMH) is a pore-forming toxin with both enterotoxic and hemolytic activity. The hemolysis by VMH is induced by creation of pores in the membrane of erythrocyte; however, the mechanism for the enterotoxic action of VMH has remained unclear. In order to clarify the mechanism, we incubated T84 cells (a human colon carcinoma cell line) with VMH and found that the levels of ATP and cyclic AMP of culture medium increased after exposure of the cells to VMH. Subsequently, we found that the fluid accumulating activity of VMH in a mouse internal loop assay was reduced by administration of glibenclamide, an inhibitor of cyclic AMP-dependent chloride channels, into the intestinal loop. These results suggest that the stimulation of cells to produce nucleotides by VMH is linked to the enterotoxic activity of the toxin. A Hemolysin of Vibrio mimicus (VMH) Stimulates

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High prevalence of thermostable direct hemolysin (TDH)-like toxin inVibrio mimicusstrains isolated from diarrhoeal patients

Cited by 10 publications

References 17 publications

Genome Sequencing Reveals Unique Mutations in Characteristic Metabolic Pathways and the Transfer of Virulence Genes between V. mimicus and V. cholerae

Genome Sequencing Reveals Unique Mutations in Characteristic Metabolic Pathways and the Transfer of Virulence Genes between V. mimicus and V. cholerae

Identification of Vibrio cholerae and Vibrio mimicus by multilocus sequence analysis (MLSA)

A Hemolysin of Vibrio mimicus (VMH) Stimulates Cells to Produce ATP and Cyclic AMP Which Appear to Be Secretory Mediators

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