Nucleotide sequence of the vmhA gene encoding hemolysin from Vibrio mimicus

Kim, Gu-Taek; Lee, Jong‐Young; Huh, Sung‐Hoi; Yu, Ju-Hyun; Kong, In‐Soo

doi:10.1016/s0925-4439(97)00008-2

Cited by 23 publications

(17 citation statements)

References 12 publications

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“…Initially four pairs of degenerate primers, designed to anneal to conserved sequences in 10 hemolysin genes from Vibrio and Aeromonas species, were used in an attempt to amplify DNA from V. harveyi by PCR, but no products were obtained (data not shown). Instead, probes specific for the V. mimicus vmhA hemolysin gene (12) and the V. parahaemolyticus tl hemolysin gene (35), were used to analyze DNA from V. harveyi by Southern blotting and hybridization. The vmhA gene was selected because it showed strong homology with six other hemolysin genes (data not shown), whereas the tl gene of V. parahaemolyticus was selected because this species is the most closely related to V. harveyi (25).…”

Section: Discussionmentioning

confidence: 99%

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Duplication of Hemolysin Genes in a Virulent Isolate of Vibrio harveyi

Zhang¹,

Meaden²,

Austin³

2001

Appl Environ Microbiol

103

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Vibrio harveyi VIB 645, which is very pathogenic towards salmonids and produces extracellular product with a high titer of hemolytic activity towards fish erythrocytes, was found to contain two closely related hemolysin genes (designated vhhA and vhhB), whereas the majority of strains examined (11 of 13) carried only a single hemolysin gene. Both genes from VIB 645 were cloned and sequenced. The open reading frames (ORFs) of vhhA and vhhB shared a high level of identity (98.8%) and were predicted to encode identical polypeptides comprising 418 amino acid residues. The VHH protein shows homology to the lecithinase of V. mimicus and V. cholerae. Transformants of Escherichia coli containing the ORF of either vhhA or vhhB displayed weak hemolytic activity in rainbow trout blood agar. The hemolytic activity was very high when the ORF of vhhB was cloned in E. coli together with the native promoter. Surprisingly, the level of vhh-specific RNA transcript produced by VIB 645 was found to be very low. We conclude that the hemolytic phenotype of VIB 645 is not due to increased expression of one or both copies of the vhh gene.Vibrio harveyi is a gram-negative, luminous bacterium which is widely distributed in the marine environment (28,29). Recently, this organism has emerged as a serious pathogen of marine animals. For example, the organism has been reported as a primary pathogen of cultured penaeid shrimp, especially in South America and Asia (1,10,18,26,33,36). Additionally, V. harveyi has been associated with diseases in finfish (1,8,9,15,30) and pearl oysters (24). However, little is known about the pathogenicity mechanisms of V. harveyi. Liu et al. (19) considered that proteases, phospholipases, or hemolysins might be important for pathogenicity; cysteine protease has been reported as the major exotoxin to penaeid shrimp (16,17,20). Montero and Austin (21) suggested that the lipopolysaccharide might constitute the lethal toxin of V. harveyi E2 to penaeid shrimp. We have previously examined a large number of well-characterized V. harveyi cultures and found that the hemolysin activity in the extracellular product was involved in pathogenesis in salmonids. V. harveyi VIB 645, which was the most pathogenic isolate, produced extracellular product with the highest titer of hemolytic activity towards Atlantic salmon (1:256) and rainbow trout erythrocytes (1:32) (40).In general, bacterial hemolysins have been suggested to be important factors of pathogenic vibrios by causing hemorrhagic septicemia and diarrhea in the host. Many of these hemolysins are well characterized, and genes encoding them have been cloned from V. parahaemolyticus (22, 35), V. cholerae (3, 27), V. hollisae (38), V. mimicus (12), V. vulnificus (38), and V. anguillarum (7).In this study, we describe the cloning and characterization of the hemolysin gene of V. harveyi as a first step towards assessing the role of V. harveyi hemolysin in fish disease. MATERIALS AND METHODSBacterial strains and plasmids. Thirteen V. harveyi isolates from a diverse range of h...

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Section: Discussionmentioning

confidence: 99%

“…Many of these hemolysins are well characterized, and genes encoding them have been cloned from V. parahaemolyticus (22,35), V. cholerae (3,27), V. hollisae (38), V. mimicus (12), V. vulnificus (38), and V. anguillarum (7).…”

mentioning

confidence: 99%

Duplication of Hemolysin Genes in a Virulent Isolate of Vibrio harveyi

Zhang¹,

Meaden²,

Austin³

2001

Appl Environ Microbiol

103

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“…The thermostable hemolysin from V. parahaemolyticus exhibited enterotoxic effects on human and rat cell monolayers [73,74]. To date, Vibrio hemolysin genes have been isolated from V. cholerae [75], V. parahaemolyticus [76], V. anguillarum [77] and V. mimicus [78]. However, the role and biological properties of hemolysin from V. fluvialis have been studied by Han et al [79].…”

Section: Pathogenesis Of Diseasementioning

confidence: 99%

Vibrio Fluvialis: An Unusual Enteric Pathogen of Increasing Public Health Concern

Igbinosa

Okoh

2010

IJERPH

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In developing countries, the fraction of treated wastewater effluents being discharged into watersheds have increased over the period of time, which have led to the deteriorations of the qualities of major rivers in developing nations. Consequently, high densities of disease causing bacteria in the watersheds are regularly reported including incidences of emerging Vibrio fluvialis. Vibrio fluvialis infection remains among those infectious diseases posing a potentially serious threat to public health. This paper addresses the epidemiology of this pathogen; pathogenesis of its disease; and its clinical manifestations in humans.

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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%

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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Nucleotide sequence of the vmhA gene encoding hemolysin from Vibrio mimicus

Cited by 23 publications

References 12 publications

Duplication of Hemolysin Genes in a Virulent Isolate of Vibrio harveyi

Duplication of Hemolysin Genes in a Virulent Isolate of Vibrio harveyi

Vibrio Fluvialis: An Unusual Enteric Pathogen of Increasing Public Health Concern

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

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