Publications

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antibacterial activities of a new brominated diterpene from borneon laurencia spp.in our continuous interest to study the diversity of halogenated metabolites of malaysian species of the red algal genus laurencia, we examined the chemical composition of five populations of unrecorded laurencia sp. a new brominated diterpene, 10-acetoxyangasiol (1), and four other known metabolites, aplysidiol (2), cupalaurenol (3), 1-methyl-2,3,5-tribromoindole (4), and chamigrane epoxide (5), were isolated and identified. isolated metabolites exhibited potent antibacterial activities against ...201020631866
an experimental study of the mechanism of action of vibrio cholerae on the intestinal mucous membrane. 1953. 201020635557
ultrasensitive detection of vibrio cholerae o1 using microcantilever-based biosensor with dynamic force microscopy.this work presents the first demonstration of a cantilever based cholerae sensor. dynamic force microscopy within atomic force microscope (afm) is applied to measure the cantilever's resonance frequency shift due to mass of cell bound on microcantilever surface. the vibrio cholerae o1, a food and waterborne pathogen that caused cholera disease in human, is a target bacterium cell of interest. commercial gold-coated afm microcantilevers are immobilized with monoclonal antibody (anti-v. cholerae o ...201020637589
assessment of factors influencing antimicrobial activity of carvacrol and cymene against vibrio cholerae in food.carvacrol and cymene, phenolic compounds naturally present in the essential oil of oregano and thyme, were examined for their antimicrobial activity against vibrio cholerae (atcc 14033, vc1, and vc7) inoculated in carrot juice. carvacrol exhibited a dose dependent inhibitory effect on the bacteria. although cymene did not have antimicrobial activity against the bacteria, it enhanced the inhibitory ability of carvacrol. at 25 °c, the lowest concentrations of carvacrol and cymene required for zero ...201020638331
presence of bacteroidales as a predictor of pathogens in surface waters of the central california coast.the value of bacteroidales genetic markers and fecal indicator bacteria (fib) to predict the occurrence of waterborne pathogens was evaluated in ambient waters along the central california coast. bacteroidales host-specific quantitative pcr (qpcr) was used to quantify fecal bacteria in water and provide insights into contributing host fecal sources. over 140 surface water samples from 10 major rivers and estuaries within the monterey bay region were tested over 14 months with four bacteroidales- ...201020639358
vibrio cholerae hemolysin is required for lethality, developmental delay, and intestinal vacuolation in caenorhabditis elegans.cholera toxin (ct) and toxin-co-regulated pili (tcp) are the major virulence factors of vibrio cholerae o1 and o139 strains that contribute to the pathogenesis of disease during devastating cholera pandemics. however, ct and tcp negative v. cholerae strains are still able to cause severe diarrheal disease in humans through mechanisms that are not well understood.201020644623
evaluation of the antibacterial activity of the methylene chloride extract of miconia ligustroides, isolated triterpene acids, and ursolic acid derivatives.the methylene chloride extract of miconia ligustroides (dc.) naudin (melastomataceae), the isolated compounds ursolic and oleanolic acids and a mixture of these acids, and ursolic acid derivatives were evaluated against the following microorganisms: bacillus cereus (atcc 14579), vibrio cholerae (atcc 9458), salmonella choleraesuis (atcc 10708), klebsiella pneumoniae (atcc 10031), and streptococcus pneumoniae (atcc 6305). the microdilution method was used for determination of the minimum inhibito ...201020645834
[toll-like receptor 4 expression in macrophages in endotoxin-induced uveitis in wistar rats].to investigate the dynamics and distribution of toll-like receptor 4 (tlr4) in uvea-resident tissue macrophages during endotoxin-induced uveitis (eiu) in wistar rats.201020654065
evaluation of a rapid immunochromatographic dipstick kit for diagnosis of cholera emphasizes its outbreak utility.we evaluated the crystal vc, a commercially produced dipstick, for the rapid detection of vibrio cholerae serotypes o1 and o139 directly from the stool samples of hospitalized diarrheal patients using the conventional bacteriological method as gold standard. the sensitivity and specificity of the dipsticks were about 92 and 73%, respectively. introduction of the pcr-based method along with the classical bacteriological method as the gold standard for the evaluation of a kit may improve the sensi ...201020657061
antibacterial activity of psidium guajava leaf and bark against multidrug-resistant vibrio cholerae: implication for cholera control.in clinical cholera, a 3-day course of antibiotic complements extensive rehydration therapy by reducing stool volume, shortening the illness, and averting death. however, antibiotic therapy, which has lifesaving implications for cholera, is often hindered due to multidrug resistance in vibrio cholerae, the cause of cholera. crude aqueous mixture and water soluble methanol extract from leaf and bark of psidium guajava, a tropical fruit guava of the family myrtaceae, showed strong antibacterial ac ...201020657067
phob regulates both environmental and virulence gene expression in vibrio cholerae.vibrio cholerae is a facultative pathogen that thrives in two nutritionally disparate environments, aquatic and human small intestine. phosphate (p(i) ) is an essential nutrient that is limited in aquatic ecosystems and of unknown availability in the small intestine. here, we show that the p(i) (pho) regulon, which is controlled by the p(i)-specific transporter (pst) and two-component system phobr, is required for v. cholerae survival in both environments, though for differing reasons. while ind ...201020659293
a highly sensitive and specific multiplex pcr assay for simultaneous detection of vibrio cholerae, vibrio parahaemolyticus and vibrio vulnificus.to develop an effective multiplex pcr for simultaneous and rapid detection of vibrio cholerae, vibrio vulnificus and vibrio parahaemolyticus, the three most important vibrio species that can cause devastating health hazards among human.201020666989
cholera between 1991 and 1997 in mexico was associated with infection by classical, el tor, and el tor variants of vibrio cholerae.vibrio cholerae o1 biotype el tor (et), the cause of the current 7th pandemic, has recently been replaced in asia and africa by an altered et biotype possessing cholera toxin (ctx) of the classical (cl) biotype that originally caused the first six pandemics before becoming extinct in the 1980s. until recently, the et prototype was the biotype circulating in peru; a detailed understanding of the evolutionary trend of v. cholerae causing endemic cholera in latin america is lacking. the present ret ...201020668130
multiple-locus variable-number tandem repeat analysis of vibrio cholerae in comparison with pulsed field gel electrophoresis and virulotyping.molecular analysis of malaysian vibrio cholerae was carried out using a multiple-locus variable-number tandem repeat analysis (mlva) assay based on 7 loci of v. cholerae. the discriminatory ability of the assay was compared with pulsed-field gel electrophoresis (pfge) using 43 malaysian v. cholerae isolated from various sources. in addition, the virulotypes of the strains were determined. based on mlva, 38 allelic profiles were obtained (f = 0.63) while pfge generated 35 pulsotypes (f = 0.71). s ...201020671932
attenuation of bacterial virulence by quorum sensing-regulated lysis.genetically attenuated pathogenic bacteria have been extensively considered as vaccine candidates. however, insufficient attenuation has been a frequent limitation of this approach. many pathogens use quorum sensing to escape host defense mechanism. here, we hypothesized that quorum sensing can be manipulated to diminish pathogenesis. to test this hypothesis, we modified the quorum sensing circuitry of a live cholera vaccine strain to add a second layer of attenuation. attenuation resulted from ...201020673838
mucosal immunization with vibrio cholerae outer membrane vesicles provides maternal protection mediated by antilipopolysaccharide antibodies that inhibit bacterial motility.vibrio cholerae is the causative agent of cholera, a severe diarrheal disease that remains endemic in many parts of the world and can cause outbreaks wherever sanitation and clean water systems break down. prevention of disease could be achieved through improved sanitation and clean water provision supported by vaccination. v. cholerae serogroup o1 is the major cause of cholera; o1 serotypes inaba and ogawa have similar disease burdens, while o139 is the only non-o1 serogroup to cause epidemics. ...201020679439
identification of the tcpp-binding site in the toxt promoter of vibrio cholerae and the role of toxr in tcpp-mediated activation.toxr-dependent recruitment of tcpp to the toxt promoter facilitates toxt transcription in vibrio cholerae, initiating a regulatory cascade that culminates in cholera toxin expression and secretion. although tcpp usually requires toxr to activate the toxt promoter, tcpp overexpression can circumvent the requirement for toxr in this process. to define nucleotides critical for tcpp-dependent promoter recognition and activation, a series of toxt promoter derivatives with single-base-pair transversio ...201020679441
does water hyacinth on east african lakes promote cholera outbreaks?cholera outbreaks continue to occur regularly in africa. cholera has been associated with proximity to lakes in east africa, and vibrio cholerae has been found experimentally to concentrate on the floating aquatic plant, water hyacinth, which is periodically widespread in east african lakes since the late 1980s. from 1994 to 2008, nyanza province, which is the kenyan province bordering lake victoria, accounted for a larger proportion of cholera cases than expected by its population size (38.7% o ...201020682884
detection and differentiation of vibrio spp. in seafood and fish samples with cultural and molecular methods.vibrio spp. as natural inhabitants of sea- and brackwater of both tropical and temperate regions of the world are commonly found in different kinds of seafood. even among the three main human pathogenic species vibrio parahaemolyticus, vibrio cholerae and vibrio vulnificus most of the isolates from seafood do not carry the different virulence factors responsible for foodborne infections. therefore, the risk assessment of vibrio spp. in seafood is currently based mainly on the knowledge of the ge ...201020688407
a toxr-dependent role for the putative phosphoporin vca1008 in bile salt resistance in vibrio cholerae el tor n16961.the putative phosphoporin encoded by vca1008 of vibrio cholerae o1 is expressed in vivo during infection and is essential for the intestinal colonization of infant mice. in vitro, its expression is induced under inorganic phosphate (p(i)) limitation in a phob/r-dependent manner. in this work we demonstrated that vca1008 has a strain-specific role in the physiology and pathogenicity of v. cholerae o1. disruption of vca1008 led to a growth defect, an inability to colonize and a high susceptibility ...201020688821
the cyclic dipeptide cyclo(phe-pro) inhibits cholera toxin and toxin-coregulated pilus production in o1 el tor vibrio cholerae.cyclo(phe-pro) is a cyclic dipeptide produced by multiple vibrio species. in this work, we present evidence that cyclo(phe-pro) inhibits the production of the virulence factors cholera toxin (ct) and toxin-coregulated pilus (tcp) in o1 el tor vibrio cholerae strain n16961 during growth under virulence gene-inducing conditions. the cyclo(phe-pro) inhibition of ct and tcp production correlated with reduced transcription of the virulence regulator tcpph and was alleviated by overexpression of tcpph ...201020453095
acid stress response in enteropathogenic gammaproteobacteria: an aptitude for survival.enteric bacteria such as escherichia coli have acquired a wide array of acid stress response systems to counteract the extreme acidity encountered when invading the host's digestive or urinary tracts. these acid stress response systems are both enzyme and chaperone based. the 3 main enzyme-based acid resistance pathways are glutamate-, arginine-, and lysine-decarboxylase pathways. they are under a complex regulatory network allowing the bacteria to fine tune its response to the external environm ...201020453931
interaction between vibrio mimicus and acanthamoeba castellanii.vibrio mimicus is a gram-negative bacterium, which causes gastroenteritis and is closely related to vibrio cholerae. the environmental reservoir of this bacterium is far from defined. acanthamoeba as well as vibrio species are found in diverse aquatic environments. the present study was aimed to investigate the ability of a. castellanii to host v. mimicus, the role of bacterial protease on interaction with a. castellanii and to disclose the ability of cysts to protect intracellular v. mimicus. c ...201020454692
pro-autophagic signal induction by bacterial pore-forming toxins.pore-forming toxins (pft) comprise a large, structurally heterogeneous group of bacterial protein toxins. nucleated target cells mount complex responses which allow them to survive moderate membrane damage by pft. autophagy has recently been implicated in responses to various pft, but how this process is triggered is not known, and the significance of the phenomenon is not understood. here, we show that s. aureus α-toxin, vibrio cholerae cytolysin, streptolysin o and e. coli haemolysin activate ...201020454906
an ogawa cholera outbreak 6 months after the inaba cholera outbreaks in india, 2006.cholera has been reported in the state of orissa, india during the last decades. an explosive outbreak of diarrhea occurred in central cuttack ward 22 of orissa (population approximately 10,621), between march 12-23, 2006. this outbreak was investigated by a team from the regional medical research centre of bhubaneswar to identify the causative agents and to determine the antimicrobial susceptibility pattern and associated virulent genes.201020457430
heat-labile enterotoxins as adjuvants or anti-inflammatory agents.escherichia coli and vibrio cholerae produce structurally related ab5-type heat-labile enterotoxins, which are classified into two major types. the type i subfamily includes cholera toxin and e. coli lt-i, whereas the type ii subfamily comprises lt-iia and lt-iib. in addition to their roles in microbial pathogenesis, the enterotoxins are widely and intensively studied for their exceptionally strong adjuvant and immunomodulatory activities, which are not necessarily dependent upon their abilities ...201020461887
dna adenine methylation is required to replicate both vibrio cholerae chromosomes once per cell cycle.dna adenine methylation is widely used to control many dna transactions, including replication. in escherichia coli, methylation serves to silence newly synthesized (hemimethylated) sister origins. seqa, a protein that binds to hemimethylated dna, mediates the silencing, and this is necessary to restrict replication to once per cell cycle. the methylation, however, is not essential for replication initiation per se but appeared so when the origins (orii and oriii) of the two vibrio cholerae chro ...201020463886
role of vibrio polysaccharide (vps) genes in vps production, biofilm formation and vibrio cholerae pathogenesis.biofilm formation enhances the survival and persistence of the facultative human pathogen vibrio cholerae in natural ecosystems and its transmission during seasonal cholera outbreaks. a major component of the v. cholerae biofilm matrix is the vibrio polysaccharide (vps), which is essential for development of three-dimensional biofilm structures. the vps genes are clustered in two regions, the vps-i cluster (vpsu, vpsa-k, vc0916-27) and the vps-ii cluster (vpsl-q, vc0934-39), separated by an inte ...201020466768
[serotyping and genotypic characteristic of vibrio cholerae non-o1/non-o139 serogroups isolated from water of surface basins and sewages of rostov-on-don city in 2003 - 2008].determination of serogroup and pcr-genotyping of vibrio cholerae non-o1/non-o139 strains isolated from surface basins and sewages of rostov-on-don city in 2003 - 2008.201020468095
the cyclic amp (camp)-camp receptor protein signaling system mediates resistance of vibrio cholerae o1 strains to multiple environmental bacteriophages.toxigenic vibrio cholerae, the causative agent of the epidemic diarrheal disease cholera, interacts with diverse environmental bacteriophages. these interactions promote genetic diversity or cause selective enrichment of phage-resistant bacterial clones. to identify bacterial genes involved in mediating the phage-resistant phenotype, we screened a transposon insertion library of v. cholerae o1 el tor biotype strain c6706 to identify mutants showing altered susceptibility to a panel of phages iso ...201020472740
evaluation of vca vntr as a strain-typing and phylogeny study method of vibrio cholerae strains.this study attempted to examine the relatedness between rapd-pcr, pfge and vca vntr results with those of conventional phage typing of v. cholerae strains and to evaluate vca vntr as an indispensable molecular-typing tool that accomplishes the urgent need for effective epidemiological surveillance. all the o1 el tor strains were predominantly clustered into phage type t27 with the new phage-typing scheme. using rapd-pcr, a total of 69 o1 el tor strains were grouped under 16 different electrophor ...201020202282
structure, biological functions and applications of the ab5 toxins.ab(5) toxins are important virulence factors for several major bacterial pathogens, including bordetella pertussis, vibrio cholerae, shigella dysenteriae and at least two distinct pathotypes of escherichia coli. the ab(5) toxins are so named because they comprise a catalytic a-subunit, which is responsible for disruption of essential host functions, and a pentameric b-subunit that binds to specific glycan receptors on the target cell surface. the molecular mechanisms by which the ab(5) toxins ca ...201020202851
modeling optimal intervention strategies for cholera.while cholera has been a recognized disease for two centuries, there is no strategy for its effective control. we formulate a mathematical model to include essential components such as a hyperinfectious, short-lived bacterial state, a separate class for mild human infections, and waning disease immunity. a new result quantifies contributions to the basic reproductive number from multiple infectious classes. using optimal control theory, parameter sensitivity analysis, and numerical simulations, ...201020204710
evidence that the c-terminus of oprm is involved in the assembly of the vceab-oprm efflux pump.although the architecture of tripartite multiple drug resistance (mdr) efflux pumps of gram-negative bacteria has been well characterized, the means by which the components recognize each other and assemble into a functional pump remains obscure. in this study we present evidence that the c-terminal domain of the pseudomonas aeruginosa oprm and the alpha-helical hairpin domain of vibrio cholerae vcea play an important role in the recognition/specificity/recruitment step in the assembly of a func ...201020206171
identification of a conserved membrane localization domain within numerous large bacterial protein toxins.vibrio cholerae is the causative agent of the diarrheal disease cholera. many virulence factors contribute to intestinal colonization and disease including the multifunctional autoprocessing rtx toxin (martx(vc)). the rho-inactivation domain (rid) of martx(vc) is responsible for inactivating the rho-family of small gtpases, which leads to depolymerization of the actin cytoskeleton. based on a deletion analysis of rid to determine the minimal functional domain, we have identified a subdomain at t ...201020212166
probing bacterial transmembrane histidine kinase receptor-ligand interactions with natural and synthetic molecules.bacterial histidine kinases transduce extracellular signals into the cytoplasm. most stimuli are chemically undefined; therefore, despite intensive study, signal recognition mechanisms remain mysterious. we exploit the fact that quorum-sensing signals are known molecules to identify mutants in the vibrio cholerae quorum-sensing receptor cqss that display altered responses to natural and synthetic ligands. using this chemical-genetics approach, we assign particular amino acids of the cqss sensor ...201020212168
cholesterol specificity of some heptameric beta-barrel pore-forming bacterial toxins: structural and functional aspects.apart from the thiol-specific/cholesterol-dependent cytolysin family of toxins (see chapter 20) there are a number of other unrelated bacterial toxins that also have an affinity for plasma membrane cholesterol. emphasis is given here on the vibrio cholerae cytolysin (vcc) and the cytolysins from related vibrio species. the inhibition of the cytolytic activity of these toxins by prior incubation with extracellular cholesterol or low density lipoprotein emerges as a unifying feature, as does plasm ...201020213559
[role of galactose-specific receptor--lectin in bactericidal activity of hemolysin of vibrio cholerae non o1/o139].to study the role lectin galactose-specific receptor of vibrio cholerae hemolysin in receptor mechanisms of bacterial cells lysis.201020218337
pilot study of whole-blood gamma interferon response to the vibrio cholerae toxin b subunit and resistance to enterotoxigenic escherichia coli-associated diarrhea.enterotoxigenic escherichia coli (etec), which produces heat-labile toxin (lt), is a common cause of travelers' diarrhea (td). the b subunit of etec lt is immunologically related to the b subunit of vibrio cholerae toxin (ct). in this pilot study we evaluated the whole-blood gamma interferon response to ct b in 17 u.s. adults traveling to mexico. only one of nine subjects who demonstrated a cellular immune response as determined by whole-blood gamma interferon production to ct b on arrival to me ...201020219880
emergence and genetic diversity of el tor vibrio cholerae o1 that possess classical biotype ctxb among travel-associated cases of cholera in japan.vibrio cholerae o1 are classified into two biotypes, classical and el tor, each encoding a biotype-specific cholera toxin. however, el tor strains have recently emerged with a classical cholera-toxin genotype (el tor variant). we characterized el tor strains of v. cholerae o1 from travel-associated cases of cholera in japan isolated from 1991 to 2006 by cholera toxin b subunit gene (ctxb) typing and by molecular epidemiological methods. ctxb in the biotype el tor shifted from the el tor-specific ...201020223896
in vitro susceptibility to antimicrobial agents and ultrastructural characteristics related to swimming motility and drug action in campylobacter jejuni and c. coli.campylobacter jejuni has recently been noted as the most common cause of bacterial food-borne diseases in japan. in this study, we examined in vitro susceptibility to 36 antimicrobial agents of 109 strains of c. jejuni and c. coli isolated from chickens and patients with enteritis or guillain-barré syndrome from 1996 to 2009. among these agents, carbapenems (imipenem, meropenem, panipenem, and biapenem) showed the greatest activity [minimal inhibitory concentration (mic)(90), 0.03-0.125 microg/m ...201020225076
the longus type iv pilus of enterotoxigenic escherichia coli (etec) mediates bacterial self-aggregation and protection from antimicrobial agents.enterotoxigenic escherichia coli (etec) strains are leading causes of childhood diarrhea in developing countries. etec pili and non-pili adherence factors designated colonization surface antigens (csa) are believed to be important in the pathogenesis of diarrhea. longus, a type iv pilus identified as the csa(21), is expressed in up to one-third of etec strains, and share similarities to the toxin-coregulated pilus of vibrio cholerae, and the bundle-forming pilus of enteropathogenic e. coli. to i ...201020227481
comparison between a taqman polymerase chain reaction assay and a culture method for ctx-positive vibrio cholerae detection.the main objective of the present work was to evaluate a real-time polymerase chain reaction (pcr) method to detect toxigenic vibrio cholerae in pangasius hypophthalmus, a freshwater fish cultured mainly in south east asia. a fda traditional culture method and a real-time pcr method of the ctx gene were used for detection of v. cholerae in spiked samples of pangasius fish. after an overnight enrichment of samples at 37 degrees c in alkaline peptone water, 2 cfu/25 g of fish was detected with bot ...201020229998
dissecting electrostatic screening, specific ion binding, and ligand binding in an energetic model for glycine riboswitch folding.riboswitches are gene-regulating rnas that are usually found in the 5'-untranslated regions of messenger rna. as the sugar-phosphate backbone of rna is highly negatively charged, the folding and ligand-binding interactions of riboswitches are strongly dependent on the presence of cations. using small angle x-ray scattering (saxs) and hydroxyl radical footprinting, we examined the cation dependence of the different folding stages of the glycine-binding riboswitch from vibrio cholerae. we found th ...201020194520
efficiency and specificity of ctxphi chromosomal integration: dif makes all the difference. 201020197438
effects of bovine milk lactoperoxidase system on some bacteria.bovine lactoperoxidase (lpo) was purified from skimmed milk using amberlite cg-50-h+ resin, cm sephadex c-50 ion-exchange chromatography, and sephadex g-100 gel filtration chromatography. lactoperoxidase was purified 20.45-fold with a yield of 28.8%. purity of enzyme checked by sodium dodecyl sulphate-polyacrylamide gel electrophoresis method and a single band was observed. km was 0.25 mm at 20 degrees c, vmax value was 7.95 micromol/ml min at 20 degrees c (ph 6.0). antibacterial study was done ...201020198919
halo384: a halo-based potency prediction algorithm for high-throughput detection of antimicrobial agents.a high-throughput (ht) agar-based halo assay is described, which allows for rapid screening of chemical libraries for bioactivity in microorganisms such as yeast and bacteria. a pattern recognition algorithm was developed to identify halo-like shapes in plate reader optical density (od) measurements. the authors find that the total growth inhibition within a detected halo provides an accurate estimate of a compound's potency measured in terms of its ec(50). the new halo recognition method perfor ...201020086209
derivation of escherichia coli o157:h7 from its o55:h7 precursor.there are 29 e. coli genome sequences available, mostly related to studies of species diversity or mode of pathogenicity, including two genomes of the well-known o157:h7 clone. however, there have been no genome studies of closely related clones aimed at exposing the details of evolutionary change. here we sequenced the genome of an o55:h7 strain, closely related to the major pathogenic o157:h7 clone, with published genome sequences, and undertook comparative genomic and proteomic analysis. we w ...201020090843
genetic analysis of ctx prophages with special reference to ctxb and rstr alleles of vibrio cholerae o139 strains isolated from kolkata over a decade.chronological analysis of 125 vibrio cholerae o139 strains isolated during 1993-2005 in kolkata revealed the prevalence of two new genotypes of cholera toxin (ct) and novel combinations of ctxb and rstr alleles resulting in variant ctx prophages. one of the new genotypes of ctxb, which first appeared in 1996 with the re-emerged v. cholerae o139 strains that had ctx calcutta phage, was designated as genotype 4. in 1998, another new genotype, designated as genotype 5, was detected that prevailed m ...201020030720
characterization of an sxt variant vibrio cholerae o1 ogawa isolated from a patient in trivandrum, india.the emerging multiple drug resistance in bacterial pathogens is complicating the treatment of diseases and hence is a major public health concern. in the present study, vibrio cholerae o1 el tor ogawa isolated from a patient was examined for antibiotic susceptibility pattern, presence of sxt and its transmissibility, associated drug resistance genes and variation in the int gene and the attp attachment site of sxt. the strain showed resistance to ampicillin, polymixin b, co-trimoxazole, trimetho ...201020030727
mechanism and inhibition of the fabv enoyl-acp reductase from burkholderia mallei.enoyl-acp reductases catalyze the final step in the elongation cycle of the bacterial fatty acid biosynthesis (fas-ii) pathway. at present, four distinct enoyl-acp reductases have been identified, which are the products of the fabi, fabl, fabk, and fabv genes. the fabv enoyl-acp reductase is the most recent member of this enzyme class and was originally identified in vibrio cholerae by cronan and co-workers [massengo-tiasse, r. p., and cronan, j. e. (2008) vibrio cholerae fabv defines a new clas ...201020055482
rapid identification and characterization of vibrio species using whole-cell maldi-tof mass spectrometry.vibrio identification by means of traditional microbiological methods is time consuming because of the many biochemical tests that have to be performed to distinguish closely related species. this work aimed at evaluating the use of maldi-tof mass spectrometry for the rapid identification of vibrio (v.) spp. as an advantageous application to rapidly discriminate the most important vibrio spp. and distinguish vibrio spp. from closely related bacterial species like photobacterium damselae and grim ...201020059616
fish as reservoirs and vectors of vibrio cholerae.vibrio cholerae, the etiologic agent of cholera, is autochthonous to various aquatic environments, but despite intensive efforts its ecology remains an enigma. recently, it was suggested that copepods and chironomids, both considered as natural reservoirs of v. cholerae, are dispersed by migratory waterbirds, thus possibly distributing the bacteria between water bodies within and between continents. although fish have been implicated in the scientific literature with cholera cases, as far as we ...201020066040
development of simple and rapid pcr-fingerprinting methods for vibrio cholerae on the basis of genetic diversity of the superintegron.to develop simple and rapid pcr-fingerprinting methods for vibrio cholerae o1 (el tor and classical biotypes) and o139 serogroup strains which cause major cholera epidemics, on the basis of the diversity of superintegron (si) carried by these strains.201020070445
statistical assessment of dna extraction reagent lot variability in real-time quantitative pcr.the aim of this study was to evaluate the variability in lots of a dna extraction kit using real-time pcr assays for bacillus anthracis, francisella tularensis and vibrio cholerae.201020070509
the major outer membrane protein ompu of vibrio splendidus contributes to host antimicrobial peptide resistance and is required for virulence in the oyster crassostrea gigas.vibrio splendidus, strain lgp32, is an oyster pathogen associated with the summer mortalities affecting the production of crassostrea gigas oysters worldwide. vibrio splendidus lgp32 was shown to resist to up to 10 microm cg-def defensin and cg-bpi bactericidal permeability increasing protein, two antimicrobial peptides/proteins (amps) involved in c. gigas immunity. the resistance to both oyster cg-def and cg-bpi and standard amps (polymyxin b, protegrin, human bpi) was dependent on the ompu gen ...201020074236
quorum-regulated biofilms enhance the development of conditionally viable, environmental vibrio cholerae.the factors that enhance the waterborne spread of bacterial epidemics and sustain the pathogens in nature are unclear. the epidemic diarrheal disease cholera caused by vibrio cholerae spreads through water contaminated with the pathogen. however, the bacteria exist in water mostly as clumps of cells, which resist cultivation by standard techniques but revive into fully virulent form in the intestinal milieu. these conditionally viable environmental cells (cvec), alternatively called viable but n ...201020080633
genetic heterogeneity of non-o1 and non-o139 vibrio cholerae isolates from shrimp aquaculture system: a comparison of rs-, rep- and eric-pcr fingerprinting approaches.the genetic diversity of vibrio cholerae isolated from black tiger shrimp (penaeus monodon) aquaculture farms was determined using three pcr typing methods based on enterobacterial repetitive intergenic consensus (eric) sequences, ribosomal gene spacer (rs) sequence and repetitive extragenic palindromic (rep) sequences.201020477960
cholera incidence among patients with diarrhea visiting national public health laboratory, nepal.the major objective of this study was to deliver vital statistics related to cholera to health authorities so as to aid in their attempt to prioritize communicable diseases in nepal. a laboratory-based surveillance was conducted from mid-june 2008 to mid-january 2009 at the national public health laboratory, nepal. diarrheal samples alone were processed for vibrio cholerae. isolation and identification of the organisms were carried out as per standard protocol. antimicrobial susceptibility tests ...201020495270
a cholera epidemic in sekong province, lao people's democratic republic, december 2007-january 2008.recent large-scale outbreaks in the lao people's democratic republic (lao pdr) were reported in 1993 and 1994 and from 2000 to 2002. on december 23, 2007, a drastic increase in acute watery diarrhea patients at a health center in sekong province was reported to the provincial health office. an outbreak investigation was initiated to understand the magnitude of the outbreak, identify new cases, identify the suspected causal agent, implement control measures, and prevent new cases. through active ...201020495276
molecular characterization of vibrio cholerae outbreak strains with altered el tor biotype from southern india.forty-four vibrio cholerae isolates collected over a 7-month period in chennai, india in 2004 were characterized for gene traits, antimicrobial susceptibility and genomic fingerprints. all 44 isolates were identified as o1 el tor ogawa, positive for various toxigenic and pathogenic genes viz. ace, ctxb, hlya, ompu, ompw, rfbo1, rtx, tcpa, toxr and zot. nucleotide sequencing revealed the presence of cholera toxin b of classical biotype in all the el tor isolates, suggesting infection of isolates ...201020495624
natural transformation of vibrio cholerae as a tool--optimizing the procedure.vibrio cholerae gains natural competence upon growth on chitin. this allows the organism to take up free dna from the environment and to incorporate it into its genome by homologous recombination.201020509862
replication of vibrio cholerae chromosome i in escherichia coli: dependence on dam methylation.we successfully substituted escherichia coli's origin of replication oric with the origin region of vibrio cholerae chromosome i (orici(vc)). replication from orici(vc) initiated at a similar or slightly reduced cell mass compared to that of normal e. coli oric. with respect to sequestration-dependent synchrony of initiation and stimulation of initiation by the loss of hda activity, replication initiation from oric and orici(vc) were similar. since hda is involved in the conversion of dnaa(atp) ...201020511501
growth in a biofilm induces a hyperinfectious phenotype in vibrio cholerae.biofilm formation plays a multifaceted role in the life cycles of a wide variety of microorganisms. in the case of pathogenic vibrio cholerae, biofilm formation in its native aquatic habitats is thought to aid in persistence during interepidemic seasons and to enhance infectivity upon oral ingestion. the structure of v. cholerae biofilms has been hypothesized to protect the bacteria during passage through the stomach. here, we directly test the role of biofilm architecture in the infectivity of ...201020515927
[rapid detection of vibrio cholerae by loop mediated isothermal amplification (lamp) method].vibrio cholerae is an important foodborne pathogen, mainly causes acute intestinal infectious disease. the development of rapid method for detecting vibrio cholerae is critical for early diagnosis of its infection. in this study, two pairs of specific primers were designed according to housekeeping gene mdh of vibrio cholerae. following optimization of the reaction, dna loop-mediated isothermal amplification (lamp) for rapidly detecting vibrio cholerae was successfully established. the optimal r ...201020518355
emerging trends in the etiology of enteric pathogens as evidenced from an active surveillance of hospitalized diarrhoeal patients in kolkata, india.abstract:201020525383
immunogenicity and protective efficacy of vibrio cholerae outer membrane vesicles in rabbit model.we show here that oral immunization with purified outer membrane vesicles (omvs) of vibrio cholerae induces a prolonged high rise in the protective antibody titre. rabbit immune sera were vibriocidal against the homologous and against several heterologous v. cholerae strains in vitro. in addition, omv immunization conferred significant protective immunity against subsequent bacterial challenges. thirty omv-immunized rabbits were challenged with different v. cholerae strains; each challenged grou ...201020528929
discovery of novel vibrio cholerae vsp-ii genomic islands using comparative genomic analysis.this report describes vibrio seventh pandemic island ii (vsp-ii) and three novel variants revealed by comparative genomics of 23 vibrio cholerae strains and their presence among a large and diverse collection of v. cholerae isolates. three vsp-ii variants were reported previously and our results demonstrate the presence of three novel vsp-ii in clinical and environmental v. cholerae marked by major deletions and genetic rearrangements. a new vsp-ii cluster was found in the seventh pandemic v. ch ...201020528940
sialidase enhances recovery from spinal cord contusion injury.axons fail to regenerate in the injured spinal cord, limiting motor and autonomic recovery and contributing to long-term morbidity. endogenous inhibitors, including those on residual myelin, contribute to regeneration failure. one inhibitor, myelin-associated glycoprotein (mag), binds to sialoglycans and other receptors on axons. mag inhibition of axon outgrowth in some neurons is reversed by treatment with sialidase, an enzyme that hydrolyzes sialic acids and eliminates mag-sialoglycan binding. ...201020534525
engineered bacterial communication prevents vibrio cholerae virulence in an infant mouse model.to investigate the possibility of using commensal bacteria as signal mediators for inhibiting the disease cholera, we stably transformed escherichia coli nissle 1917 (nissle) to express the autoinducer molecule cholera autoinducer 1 (cai-1) (shown previously to prevent virulence when present with another signaling molecule, autoinducer 2, at high concentrations) and determined the effect on vibrio cholerae virulence gene expression and colonization in an infant mouse model. we found that pretrea ...201020534565
toxigenic vibrio cholerae from environmental sources associated with the cholera outbreak after 'aila' cyclone in west bengal, india.west bengal experienced a devastating storm named 'aila' in its coastal and southern districts. we attempted to understand the transmission dynamics emphasizing on potable water to detect the presence of toxigenic strains of vibrio cholerae, followed by the natural devastation.201020536711
vibrio cholerae o1 bacteremia in pakistan: analysis of eight cases.bacteremia caused by vibrio cholerae o1 has been a rare phenomenon. we report on eight cases of v. cholerae o1 bacteremia from pakistan which occurred during 1992-2008. six of the cases were seen in children (two neonates and four infants) and seven of the eight patients were female. urogenital malignancy, hepatitis b virus-associated end-stage liver disease, concurrent campylobacter enteritis and prematurity were the underlying conditions in four patients. two of the eight patients died and one ...201020538311
an experimental study of the population and evolutionary dynamics of vibrio cholerae o1 and the bacteriophage jsf4.studies of vibrio cholerae in the environment and infected patients suggest that the waning of cholera outbreaks is associated with rise in the density of lytic bacteriophage. in accordance with mathematical models, there are seemingly realistic conditions where phage predation could be responsible for declines in the incidence of cholera. here, we present the results of experiments with the el tor strain of v. cholerae (n16961) and a naturally occurring lytic phage (jsf4), exploring the validit ...201020538647
structure-function relations in oxaloacetate decarboxylase complex. fluorescence and infrared approaches to monitor oxomalonate and na(+) binding effect.oxaloacetate decarboxylase (oad) is a member of the na(+) transport decarboxylase enzyme family found exclusively in anaerobic bacteria. oad of vibrio cholerae catalyses a key step in citrate fermentation, converting the chemical energy of the decarboxylation reaction into an electrochemical gradient of na(+) ions across the membrane, which drives endergonic membrane reactions such as atp synthesis, transport and motility. oad is a membrane-bound enzyme composed of alpha, beta and gamma subunits ...201020543879
natural transformation of vibrio fischeri requires tfox and tfoy.summary recent evidence has indicated that natural genetic transformation occurs in vibrio cholerae, and that it requires both induction by chitin oligosaccharides, like chitohexaose, and expression of a putative regulatory gene designated tfox. using sequence and phylogenetic analyses we have found two tfox paralogues in all sequenced genomes of the genus vibrio. like v. cholerae, when grown in chitohexaose, cells of v. fischeri are able to take up and incorporate exogenous dna. chitohexaose-in ...201020545740
vibrio cholerae el tor tcpa crystal structure and mechanism for pilus-mediated microcolony formation.type iv pili (t4p) are critical to virulence for vibrio cholerae and other bacterial pathogens. among their diverse functions, t4p mediate microcolony formation, which protects the bacteria from host defences and concentrates secreted toxins. the t4p of the two v. cholerae o1 disease biotypes, classical and el tor, share 81% identity in their tcpa subunits, yet these filaments differ in their interaction patterns as assessed by electron microscopy. to understand the molecular basis for pilus-med ...201020545841
detection of vibrio cholerae and vibrio parahaemolyticus by molecular and culture based methods from source water to household container-stored water at the point-of-use in south african rural communities.detection methods for vibrio cholerae and vibrio parahaemolyticus which included the culture based approach with polymerase chain reaction (pcr) confirmation, pcr detection without enrichment and pcr with a pre-enrichment were developed and their performance evaluated. pcr assays targeted the sodb (v. cholerae species), flae (v. parahaemolyticus species), 16s rrna (vibrio and enterobacteriacea species) genes (multiplex 1) and v. cholerae o1 and v. cholerae o139 rfb genes, ctxa (cholera toxin) ge ...201020555205
construction and characterization of an auxotrophic ctxa mutant of o139 vibrio cholerae.cholera caused by the o139 serogroup still remains a public health concern in certain regions of the world and the existing o1 vaccines do not cross-protect cholera caused by this serogroup. an aminolevulinic acid (ala) auxotroph vaccine candidate against the o139 serogroup, designated as vcusm2, was recently developed. it was found to be immunogenic in animal model studies but showed mild reactogenic effects due to the presence of two intact copies of vibrio cholerae toxin (ctx) genetic element ...201020558271
localization and function of the membrane-bound riboflavin in the na+-translocating nadh:quinone oxidoreductase (na+-nqr) from vibrio cholerae.the sodium ion-translocating nadh:quinone oxidoreductase (na(+)-nqr) from the human pathogen vibrio cholerae is a respiratory membrane protein complex that couples the oxidation of nadh to the transport of na(+) across the bacterial membrane. the na(+)-nqr comprises the six subunits nqrabcdef, but the stoichiometry and arrangement of these subunits are unknown. redox-active cofactors are fad and a 2fe-2s cluster on nqrf, covalently attached fmns on nqrb and nqrc, and riboflavin and ubiquinone-8 ...201020558724
the phosphoenolpyruvate phosphotransferase system: as important for biofilm formation by vibrio cholerae as it is for metabolism in escherichia coli. 201020562301
the lysr-type virulence activator aphb regulates the expression of genes in vibrio cholerae in response to low ph and anaerobiosis.aphb is a lysr-type activator that initiates the expression of the virulence cascade in vibrio cholerae by cooperating with the quorum-sensing-regulated activator apha at the tcpph promoter on the vibrio pathogenicity island (vpi). to identify the ancestral chromosomal genes in v. cholerae regulated by aphb, we carried out a microarray analysis and show here that aphb influences the expression of a number of genes that are not associated with the vpi. one gene strongly activated by aphb is cadc, ...201020562308
chromosomally encoded blacmy-2 located on a novel sxt/r391-related integrating conjugative element in a proteus mirabilis clinical isolate.integrating conjugative elements (ices) are mobile genetic elements that can transfer from the chromosome of a host to the chromosome of a new host through the process of excision, conjugation, and integration. although sxt/r391-related ices, originally demonstrated in vibrio cholerae o139 isolates, have become prevalent among v. cholerae isolates in asia, the prevalence of the ices among gram-negative bacteria other than vibrio spp. remains unknown. in addition, sxt/r391-related ices carrying g ...201020566768
helicobacter pylori apo-fur regulation appears unconserved across species.the ferric uptake regulator (fur) is a transcriptional regulator that is conserved across a broad number of bacterial species and has been shown to regulate expression of iron uptake and storage genes. additionally, fur has been shown to be an important colonization factor of the gastric pathogen helicobacter pylori. in h. pylori, fur-dependent regulation appears to be unique in that fur is able to act as a transcriptional repressor when bound to iron as well as in its iron free (apo) form. to d ...201020571957
development and characterization of a new epithelial cell line psf from caudal fin of green chromide, etroplus suratensis (bloch, 1790).a new cell line [pearlspot fin (psf)] has been developed from caudal fin of etroplus suratensis, a brackish/freshwater fish cultivated in india. the cell line was maintained in leibovitz's l-15 supplemented with 10% fetal bovine serum (fbs). the psf cell line consisted predominantly of epithelial-like cells. the cells were able to grow at temperatures between 25 degrees c and 32 degrees c with optimum temperature of 28 degrees c. the growth rate of psf cells increased as the fbs proportion incre ...201020577829
pulsed field gel electrophoresis analysis of vibrio cholerae isolates in southern thailand.forty isolates of v. cholorae o1, o139 and non-o1/non-o139 collected from outbreaks in songkhla and phuket provinces of southern thailand during 1999-2001 and sporadic cases from different regions of thailand during 1993-2002 were characterized using pulsed field gel electrophoresis (pfge). digestion of chromosomal dna of the v cholerae isolates with restriction endonuclease noti, followed by pfge, generated 10 distinct restriction endonuclease analysis patterns consisting of 8 to 13 bands, rang ...201020578525
detection of vibrio cholerae o1 and o139 in environmental water samples by an immunofluorescent-aggregation assay.environmental waters are an important reservoir for vibrio cholerae, and effective surveillance of the pathogen can help to warn of and prevent infection with this potentially fatal pathogen. an immunofluorescent-aggregation (ifag) assay to detect v. cholerae o1 and o139 was established and evaluated with estuarine water samples. the practical application of this assay was compared with the conventional culture method and real-time pcr. the ifag method had a sensitivity of 10(3) cfu/ml for detec ...201020581193
newer insights into the mechanism of action of psidium guajava l. leaves in infectious diarrhoea.psidium guajava l., myrtaceae, is used widely in traditional medicine for the treatment of diarrhoea, dysentery, gastroenteritis, stomachaches, and indigestion. however, the effect of the leaf extract of p. guajava on the pathogenesis of infectious diarrhoea has not been studied. the present study evaluates the effect of a hot aqueous extract (decoction) of dried leaves of p. guajava on parameters associated with pathogenicity of infectious diarrhoea. the aim was to understand its possible mecha ...201020584265
relatedness of vibrio cholerae o1/o139 isolates from patients and their household contacts, determined by multilocus variable-number tandem-repeat analysis.the genetic relatedness of vibrio cholerae o1/o139 isolates obtained from 100 patients and 146 of their household contacts in dhaka, bangladesh, between 2002 and 2005 was assessed by multilocus variable-number tandem-repeat analysis. isolate genotypes were analyzed at five loci containing tandem repeats. across the population, as well as within households, isolates with identical genotypes were clustered in time. isolates from individuals within the same household were more likely to have simila ...201020585059
evolution of seventh cholera pandemic and origin of 1991 epidemic, latin america.thirty single-nucleotide polymorphisms were used to track the spread of the seventh pandemic caused by vibrio cholerae. isolates from the 1991 epidemic in latin america shared a profile with 1970s isolates from africa, suggesting a possible origin in africa. data also showed that the observed genotypes spread easily and widely.201020587187
vrra mediates hfq-dependent regulation of ompt synthesis in vibrio cholerae.ompt, an outer membrane porin of vibrio cholerae, is tightly regulated by the organism in response to different environments. two transcriptional regulators, camp receptor protein (crp) and toxr, compete at the ompt promoter region. crp activates ompt transcription by a loop-forming mechanism, while toxr functions as an antiactivator and repressor, depending on its interplay with crp. vrra, a 140-nt small noncoding rna in v. cholerae, is controlled by the alternative sigma factor sigma(e). we ha ...201020595045
passive oral immunization by egg yolk immunoglobulin (igy) to vibrio cholerae effectively prevents cholera.in an attempt to prepare egg yolk immunoglobulin (igy) to treat and prevent cholera, hens were immunized by a mixture of heat- or formalin-killed vibrio cholerae o1 and o139 organisms, or by the recombinant cholera toxin b subunit (ctb). the igys were partially purified from egg yolk and orally administered to suckling mice before or after challenge with live o1 or o139 cells. the anti-o1 and o139 igys and the mixture of either igy with anti-ctb igy significantly protected the occurrence of chol ...201020596127
a systems biology approach to modeling vibrio cholerae gene expression under virulence-inducing conditions.vibrio cholerae is a gram-negative bacillus that is the causative agent of cholera. pathogenesis in vivo occurs through a series of spatiotemporally controlled events under the control of a gene cascade termed the toxr regulon. major genes in the toxr regulon include the master regulators toxrs and tcpph, the downstream regulator toxt, and virulence factors, the ctxab and tcpa operons. our current understanding of the dynamics of virulence gene expression is limited to microarray analyses of exp ...201020601467
antibacterial effect (in vitro) of moringa oleifera and annona muricata against gram positive and gram negative bacteria.antibacterial effects of aqueous and ethanolic extracts of seeds of moringa (moringa oleifera) and pods of soursop (annona muricata) in the concentration of 1:5 and 1:10 in volumes 50, 100, 150 and 200 microl were examined against staphylococcus aureus, vibrio cholerae, escherichia coli (isolated from the organism and the aquatic environment) and salmonella enteritidis. antibacterial activity (inhibition halo > 13 mm) against s. aureus, v. cholerae and e. coli isolated from the whiteleg shrimp, ...201020602021
vibrio cholerae phosphoenolpyruvate phosphotransferase system control of carbohydrate transport, biofilm formation, and colonization of the germfree mouse intestine.the bacterial phosphoenolpyruvate phosphotransferase system (pts) is a highly conserved phosphotransfer cascade whose components modulate many cellular functions in response to carbohydrate availability. here, we further elucidate pts control of vibrio cholerae carbohydrate transport and activation of biofilm formation on abiotic surfaces. we then define the role of the pts in v. cholerae colonization of the adult germfree mouse intestine. we report that v. cholerae colonizes both the small and ...201020123708
structure of uracil-dna n-glycosylase (ung) from vibrio cholerae: mapping temperature adaptation through structural and mutational analysis.the crystal structure of vibrio cholerae uracil-dna n-glycosylase (vcung) has been determined to 1.5 a resolution. based on this structure, a homology model of aliivibrio salmonicida uracil-dna n-glycosylase (asung) was built. a previous study demonstrated that asung possesses typical cold-adapted features compared with vcung, such as a higher catalytic efficiency owing to increased substrate affinity. specific amino-acid substitutions in asung were suggested to be responsible for the increased ...201020124707
classification of hybrid and altered vibrio cholerae strains by ctx prophage and rs1 element structure.analysis of the ctx prophage and rs1 element in hybrid and altered vibrio cholera o1 strains showed two classifiable groups. group i strains contain a tandem repeat of classical ctx prophage on the small chromosome. strains in this group either contain no element(s) or an additional ctx prophage or rs1 element(s) on the large chromosome. group ii strains harbor rs1 and ctx prophage, which has an e1 tor type rstr and classical ctxb on the large chromosome.201020127474
structure of vibrio cholerae toxt reveals a mechanism for fatty acid regulation of virulence genes.cholera is an acute intestinal infection caused by the bacterium vibrio cholerae. in order for v. cholerae to cause disease, it must produce two virulence factors, the toxin-coregulated pilus (tcp) and cholera toxin (ct), whose expression is controlled by a transcriptional cascade culminating with the expression of the arac-family regulator, toxt. we have solved the 1.9 a resolution crystal structure of toxt, which reveals folds in the n- and c-terminal domains that share a number of features in ...201020133655
molecular keys of the tropism of integration of the cholera toxin phage.cholera toxin is encoded in the genome of ctxvarphi, a lysogenic filamentous phage of vibrio cholerae. ctxvarphi variants contribute to the genetic diversity of cholera epidemic strains. it has been shown that the el tor variant of ctxvarphi hijacks xerc and xerd, two host-encoded tyrosine recombinases that normally function to resolve chromosome dimers, to integrate at dif1, the dimer resolution site of the larger of the two v. cholerae chromosomes. however, the exact mechanism of integration o ...201020133778
prevalence of cholera in pediatric patients with acute dehydrating diarrhea.to estimate the prevalence of culture-confirmed cholera in patients with acute dehydrating diarrhea, at a tertiary care center in north india, during a 6-month period from march to august, 2006.201020135270
occurrence of the vibrio cholerae seventh pandemic vsp-i island and a new variant.using comparative genomics, we identified a new variant of the vibrio seventh pandemic island-i (vsp-i). results of polymerase chain reaction (pcr) screening for both known vsp-i variants indicate that the novel variant is present only in non-o1/non-o139 strains of v. cholerae and vibrio mimicus. comparative genomics revealed little sequence divergence in the seventh pandemic vsp-i; however, a second insertion site located on the smaller chromosome was identified. although the seventh pandemic v ...201020141327
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