Toshio Kodama

Osaka University, Suika, Ōsaka, Japan

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Publications (42)163.92 Total impact

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    ABSTRACT: Clostridium perfringens is a causative agent of foodborne gastroenteritis for which C. perfringens enterotoxin (CPE) has been considered an essential factor. Recently, we experienced two outbreaks of foodborne gastroenteritis in which non-CPE producers of C. perfringens was strongly suspected to be the cause. Here, we report a novel enterotoxin, BEC (binary enterotoxin of C. perfringens), produced by C. perfringens isolates. Culture supernatants of the C. perfringens strains showed fluid accumulating activity in rabbit ileal loop and suckling mouse assays. Purification of the enterotoxic substance in the supernatants and high-throughput sequencing of genomic DNA of the strains revealed a binary toxin BEC composed of BECa and BECb. BECa and BECb displayed limited amino acid sequence similarity to other binary toxin family members, such as the C. perfringens iota toxin. The becAB genes were located on 54.5-kb pCP13-like plasmids. Recombinant BECb (rBECb) alone had fluid accumulating activity in the suckling mouse assay. Although rBECa alone did not show enterotoxic activity, rBECa enhanced the enterotoxicity of rBECb when simultaneously administered in suckling mice. The entertoxicity of the mutant in which becB gene was disrupted was dramatically decreased compared with the parental strain. rBECa showed an ADP-ribosylating activity on purified actin. Although we have not directly evaluated whether BECb delivers BECa into cells, rounding of Vero cells occurred only when cells were treated with both rBECa and rBECb. These results suggest that BEC is a novel enterotoxin of C. perfringens distinct from CPE and that BEC-producing C. perfringens strains can be causative agents of acute gastroenteritis in humans. Additionally, the presence of becAB on nearly identical plasmids in distinct lineages of C. perfringens isolates suggests the involvement of horizontal gene transfer in the acquisition of the toxin genes.
    Infection and immunity 03/2014; · 4.21 Impact Factor
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    ABSTRACT: Vibrio parahaemolyticus is a Gram-negative marine bacterium that causes acute gastroenteritis in humans. The virulence of V. parahaemolyticus is dependent upon a type III secretion system (T3SS2). One effector for T3SS2, VopC, is a homolog of the catalytic domain of cytotoxic necrotizing factor (CNF), and was recently reported to be a Rho family GTPase activator and to be linked to internalization of V. parahaemolyticus by nonphagocytic cultured cells. Here, we provide direct evidence that VopC deamidates Rac1 and CDC42, but not RhoA, in vivo. Our results also suggest that VopC, through its activation of Rac1, contributes to formation of actin stress fibers in infected cells. Invasion of host cells, which occurs at a low frequency, does not seem linked to Rac1 activation, but instead appears to require CDC42. Finally, using an infant rabbit model of V. parahaemolyticus infection, we show that the virulence of V. parahaemolyticus is not dependent upon VopC-mediated invasion. Genetic inactivation of VopC did not impair intestinal colonization nor reduce signs of disease, including fluid accumulation, diarrhea, and tissue destruction. Thus, although VopC can promote host cell invasion, such internalization is not a critical step of the disease process, consistent with the traditional view of V. parahaemolyticus as an extracellular pathogen.
    Cellular Microbiology 12/2013; · 4.81 Impact Factor
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    ABSTRACT: Resistance nodulation cell division (RND)-type efflux transporters play the main role in intrinsic resistance to various antimicrobial agents in many gram-negative bacteria. Here, we estimated 12 RND-type efflux transporter genes in Vibrio parahaemolyticus. Because VmeAB has already been characterized, we cloned the other 11 RND-type efflux transporter genes and characterized them in Escherichia coli KAM33 cells, a drug hypersusceptible strain. KAM33 expressing either VmeCD, VmeEF, or VmeYZ showed increased minimum inhibitory concentrations (MICs) for several antimicrobial agents. Additional four RND-type transporters were functional as efflux pumps only when co-expressed with VpoC, an outer membrane component in V. parahaemolyticus. Furthermore, VmeCD, VmeEF, and VmeYZ co-expressed with VpoC exhibited a broader substrate specificity and conferred higher resistance than that with TolC of E. coli. Deletion mutants of these transporter genes were constructed in V. parahaemolyticus. TM32 (ΔvmeAB and ΔvmeCD) had significantly decreased MICs for many antimicrobial agents and the number of viable cells after exposure to deoxycholate were markedly reduced. Strains in which 12 operons were all disrupted had very low MICs and much lower fluid accumulation in rabbit ileal loops. These results indicate that resistance nodulation cell division-type efflux transporters contribute not only to intrinsic resistance but also to exerting the virulence of V. parahaemolyticus.
    MicrobiologyOpen. 07/2013;
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    ABSTRACT: Twelve Vibrio cholerae isolates with genes for a type III secretion system (T3SS) were detected among 110 environmental and 14 clinical isolates. T3SS-related genes were distributed among the various serogroups and pulsed-field gel electrophoresis of NotI-digested genomes showed genetic diversity in these strains. However, the restriction fragment length polymorphism profiles of the T3SS-related genes had similar patterns. Additionally, naturally competent T3SS-negative V. cholerae incorporated the ca. 47 kb gene cluster of T3SS, which had been integrated into a site on the chromosome by recombination. Therefore, it is suggested that horizontal gene transfer of T3SS-related genes occurs among V. cholerae in natural ecosystems.
    Microbiology and Immunology 05/2013; 57(5):334-9. · 1.55 Impact Factor
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    ABSTRACT: A total of 12 Vibrio cholerae isolates with genes for a type III secretion system (T3SS) were detected from 110 environmental and 14 clinical isolates. T3SS-related genes were distributed among the various serogroups, and these strains showed genetic diversity in the PFGE of NotI-digested genomes. However, the restriction fragment length polymorphism profiles of the T3SS-related genes showed similar patterns. Additionally, natural competent T3SS-negative V. cholerae incorporated the ca. 47kb gene cluster of T3SS, which integrated into a site of the chromosome by recombination. Therefore, it was suggested that the horizontal gene transfer of T3SS-related genes occurred among V. cholerae in the natural ecosystem.
    Microbiology and Immunology 02/2013; · 1.55 Impact Factor
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    ABSTRACT: Bacterial pathogens utilize pore-forming toxins or sophisticated secretion systems to establish infection in hosts. Recognition of these toxins or secretion system by nucleotide-binding oligomerization domain leucine-rich repeat proteins (NLRs) triggers the assembly of inflammasomes, the multiprotein complexes necessary for caspase-1 activation and the maturation of inflammatory cytokines such as IL-1β or IL-18. Here we demonstrate that both the NLRP3 and NLRC4 inflammasomes are activated by thermostable direct hemolysins (TDHs) and type III secretion system 1 (T3SS1) in response to V. parahaemolyticus infection. Furthermore, we identify T3SS1 secreted effector proteins, VopQ and VopS, which induce autophagy and the inactivation of Cdc42, respectively, to prevent mainly NLRC4 inflammasome activation. VopQ and VopS interfere with the assembly of specks in infected macrophages. These data suggest that bacterial effectors interfere with inflammasome activation and contribute to bacterial evasion from the host inflammatory responses.
    PLoS Pathogens 01/2013; 9(1):e1003142. · 8.14 Impact Factor
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    ABSTRACT: The type III secretion system (T3SS) of gram-negative bacteria involves dedicated protein translocation machinery that directly injects proteins into target cells. Pathogenic bacteria already benefit from this unique system. The successful functional cloning of this useful tool into non-pathogenic bacteria would help establish novel clinical and basic biotechnology strategies in areas such as vaccine administration, the development of screening systems for anti-T3SS drugs and the target-specific delivery of bioactive compounds. In this study, we successfully cloned the Vibrio parahaemolyticus T3SS1 genetic locus into a non-pathogenic Escherichia coli K-12 strain. Assays performed here revealed that the T3SS1 cloned into the E. coli K-12 strain has the ability to translocate V. parahaemolyticus T3SS1 secreted proteins. Importantly, we also observed this system to allow the E. coli K-12 strain to inject foreign protein, as well as the V. parahaemolyticus T3SS effector, into cultured cells. These results demonstrate a prospective useful tool with experimental and therapeutic applications.
    Biochemical and Biophysical Research Communications 09/2012; 427(2):242-7. · 2.41 Impact Factor
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    ABSTRACT: Vibrio parahaemolyticus is one of the human pathogenic vibrios. During the infection of mammalian cells, this pathogen exhibits cytotoxicity that is dependent on its type III secretion system (T3SS1). VepA, an effector protein secreted via the T3SS1, plays a major role in the T3SS1-dependent cytotoxicity of V. parahaemolyticus. However, the mechanism by which VepA is involved in T3SS1-dependent cytotoxicity is unknown. Here, we found that protein transfection of VepA into HeLa cells resulted in cell death, indicating that VepA alone is cytotoxic. The ectopic expression of VepA in yeast Saccharomyces cerevisiae interferes with yeast growth, indicating that VepA is also toxic in yeast. A yeast genome-wide screen identified the yeast gene VMA3 as essential for the growth inhibition of yeast by VepA. Although VMA3 encodes subunit c of the vacuolar H(+)-ATPase (V-ATPase), the toxicity of VepA was independent of the function of V-ATPases. In HeLa cells, knockdown of V-ATPase subunit c decreased VepA-mediated cytotoxicity. We also demonstrated that VepA interacted with V-ATPase subunit c, whereas a carboxyl-terminally truncated mutant of VepA (VepAΔC), which does not show toxicity, did not. During infection, lysosomal contents leaked into the cytosol, revealing that lysosomal membrane permeabilization occurred prior to cell lysis. In a cell-free system, VepA was sufficient to induce the release of cathepsin D from isolated lysosomes. Therefore, our data suggest that the bacterial effector VepA targets subunit c of V-ATPase and induces the rupture of host cell lysosomes and subsequent cell death.
    PLoS Pathogens 07/2012; 8(7):e1002803. · 8.14 Impact Factor
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    ABSTRACT: The pathogenesis of the diarrheal disease caused by Vibrio parahaemolyticus, a leading cause of seafood-associated enteritis worldwide, is dependent upon a type III secretion system, T3SS2. This apparatus enables the pathogen to inject bacterial proteins (effectors) into the cytosol of host cells and thereby modulate host processes. T3SS effector proteins transit into the host cell via a membrane pore (translocon) typically formed by 3 bacterial proteins. We have identified the third translocon protein for T3SS2: VopW, which was previously classified as an effector protein for a homologous T3SS in V. cholerae. VopW is a hydrophilic translocon protein; like other such proteins, it is not inserted into the host cell membrane but is required for insertion of the two hydrophobic translocators, VopB2 and VopD2, that constitute the membrane channel. VopW is not required for secretion of T3SS2 effectors into the bacterial culture medium; however, it is essential for transfer of these proteins into the host cell cytoplasm. Consequently, deletion of vopW abrogates the virulence of V. parahaemolyticus in several animal models of diarrheal disease. Unlike previously described hydrophilic translocators, VopW is itself translocated into the host cell cytoplasm, raising the possibility that it functions as both a translocator and an effector.
    Infection and immunity 05/2012; 80(8):2940-7. · 4.21 Impact Factor
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    ABSTRACT: Among three haemolysins identified thus far in Escherichia coli, alpha-haemolysin (HlyA) is encoded on the pathogenicity islands of extraintestinal pathogenic strains, while enterohaemolysin (EhxA) is encoded on the virulence plasmids of enterohaemorrhagic E. coli (EHEC) strains. In contrast, the gene for haemolysin E (HlyE) is located on the E. coli chromosome backbone and is therefore widely distributed among E. coli strains. However, because hlyE gene expression is repressed by the H-NS protein and because the gene has been disrupted in many strains, its haemolytic activity cannot be detected in wild-type strains by routine screening on blood agar plates. In this study, we found that the HlyE-derived haemolytic activity of enteropathogenic E. coli (EPEC) O55 : H7 can be detected after anaerobic cultivation on a washed blood agar plate (EHX plate) that is used to detect the production of EhxA. We also found that the haemolytic activity of EHEC O157 : H7 observed on EHX plates under aerobic and anaerobic growth conditions is derived from EhxA and HlyE, respectively; this differential expression of the two haemolysins occurs at the transcriptional level. Our analysis of 60 E. coli strains of various pathotypes and phylogenies for their repertoires of haemolysin genes, haemolytic phenotypes and hlyE gene sequences revealed that HlyE activity can generally be detected on EHX plates under anaerobic growth conditions if the gene is intact. Furthermore, our results indicate that hlyE gene inactivation occurred in three of the five E. coli lineages (phylogroups A, B1 and B2), which demonstrates phylogroup-specific gene disruption patterns.
    Microbiology 12/2011; 158(Pt 3):746-58. · 3.06 Impact Factor
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    ABSTRACT: The enteropathogen Vibrio parahaemolyticus possesses two sets of type III secretion systems, T3SS1 and T3SS2. Effector proteins secreted by these T3SSs are delivered into host cells, leading to cell death or diarrhea. However, it is not known how specific effectors are secreted through a specific T3SS when both T3SSs are expressed within bacteria. One molecule thought to determine secretion specificity is a T3SS-associated chaperone; however, no T3SS2-specific chaperone has been identified. Therefore, we screened T3SS2 chaperone candidates by a pull-down assay using T3SS2 effectors fused with glutathione-S-transferase. A secretion assay revealed that the newly identified cognate chaperone VocC for the T3SS2-specific effector VopC was required for the efficient secretion of the substrate through T3SS2. Further experiments determined the chaperone-binding domain and the amino-terminal secretion signal of the cognate effector. These findings, in addition to the previously identified T3SS1-specific chaperone, VecA, provide a strategy to clarify the specificity of effector secretion through T3SSs of V. parahaemolyticus.
    FEMS Microbiology Letters 11/2011; 324(2):156-64. · 2.05 Impact Factor
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    ABSTRACT: Vibrio parahaemolyticus, a Gram-negative halophilic bacterium that causes acute gastroenteritis in humans, is characterized by two type III secretion systems (T3SS), namely T3SS1 and T3SS2. T3SS2 is indispensable for enterotoxicity but the effector(s) involved are unknown. Here, we identify VopV as a critical effector that is required to mediate V. parahaemolyticus T3SS2-dependent enterotoxicity. VopV was found to possess multiple F-actin-binding domains and the enterotoxicity caused by VopV correlated with its F-actin-binding activity. Furthermore, a T3SS2-related secretion system and a vopV homologous gene were also involved in the enterotoxicity of a non-O1/non-O139 V. cholerae strain. These results indicate that the F-actin-targeting effector VopV is involved in enterotoxic activity of T3SS2-possessing bacterial pathogens.
    Cell host & microbe 10/2011; 10(4):401-9. · 13.02 Impact Factor
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    ABSTRACT: AexU is a type three secretion system (TTSS) effector of Aeromonas hydrophila which has an in vitro ADP-ribosyltransferase (ART) and GTPase-activating protein (GAP) activities on Rac1, RhoA and Cdc42. Here we show that, AexU of Aeromonas veronii bv. sobria AeG1 strain disrupts actin cytoskeleton of HeLa cells during AeG1 infection, aexU transfection or direct application of AexU protein. Such cellular disruption was rescued by either inactivation of AexU-GAP activity by substitution of arginine residue 143 to alanine or expression of a constitutively active (CA) Rac1 but not CA RhoA or CA Cdc42. On the other hand, AexU was found co-localized with β4-integrin probably through its Arg-Gly-Asp (RGD) integrin binding motif (319-321) residues. Interestingly, direct application of GST-AexU-HA fusion protein caused significant cytotoxic effect on β4-integrin expressing HT-29 cells. In contrast, β4-integrin blockade with a specific antibody reduced such cytotoxicity. Consequently, AexU cytotoxic effect was exaggerated with a greater expression of β4-integrin in Caco-2 and HeLa cells, while it was incompetent on β4-integrin non-expressing CHO cells. As far as we know, this is a novel TTSS effector which specifically inactivates Rac1 to disrupt actin cytoskeleton and has an alternative cytotoxic pathway through β4-integrin mediation.
    Microbial Pathogenesis 09/2011; 51(6):454-65. · 1.97 Impact Factor
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    ABSTRACT: The enteropathogen Vibrio parahaemolyticus possesses two sets of type III secretion systems, T3SS1 and T3SS2. Effector proteins secreted by these T3SSs are delivered into host cells, leading to cell death or diarrhea. However, it is not known how specific effectors are secreted through a specific T3SS when both T3SSs are expressed within bacteria. One molecule thought to determine secretion specificity is a T3SS‐associated chaperone; however, no T3SS2‐specific chaperone has been identified. Therefore, we screened T3SS2 chaperone candidates by a pull‐down assay using T3SS2 effectors fused with glutathione‐S‐transferase. A secretion assay revealed that the newly identified cognate chaperone VocC for the T3SS2‐specific effector VopC was required for the efficient secretion of the substrate through T3SS2. Further experiments determined the chaperone‐binding domain and the amino‐terminal secretion signal of the cognate effector. These findings, in addition to the previously identified T3SS1‐specific chaperone, VecA, provide a strategy to clarify the specificity of effector secretion through T3SSs of V. parahaemolyticus.
    FEMS Microbiology Letters 01/2011; 324(2). · 2.05 Impact Factor
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    ABSTRACT: Vibrio vulnificus secretes a hemolysin/cytolysin (VVH) that induces cytolysis in target cells. A detergent resistant membrane domain (DRM) fraction of the cells after sucrose gradient centrifugation includes cholesterol-rich membrane microdomains which have been called "lipid rafts". It was reported that some pore-forming toxins require association with DRM and/or lipid rafts to exert their cytotoxicity. It has also been thought that cellular cholesterol is involved in VVH cytotoxicity because VVH cytotoxicity was inhibited by pre-incubation with cholesterol. However, both cellular localization and mode of action of VVH cytotoxicity remain unclear. In this study, we investigated the relationship between VVH localization on the cellular membrane and its cytotoxicity. Oligomers of VVH were detected from DRM fractions by sucrose gradient ultracentrifugation but all of these oligomers shifted from DRM fractions to non-DRM fractions after treatment with methyl-beta-cyclodextrin (MβCD), a cholesterol sequestering agent. On the other hand, immunofluorescence analysis showed that VVH did not co-localize with major lipid raft markers on cellular membrane of CHO cells. These data suggested that VVH localized at membrane regions which are relatively abundant in cholesterol but which are not identical with lipid rafts. To determine the linkage between localization and cytotoxicity of VVH, cytotoxicity was evaluated in MβCD-treated CHO cells. The cytotoxicity of VVH was not decreased by the MβCD treatment. In addition, the amount of VVH oligomer did not decrease in MβCD-treated CHO cells. Thus, we found that the amount of oligomer on cellular membrane is important for induction of cytotoxicity, whereas localization to lipid rafts on the cellular membrane was not essential to cytotoxicity.
    PLoS ONE 01/2011; 6(10):e26018. · 3.73 Impact Factor
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    ABSTRACT: Vibrio parahaemolyticus, one of the human pathogenic vibrios, causes gastroenteritis, wound infections and septicemia. Genomic sequencing of this organism revealed that it has two distinct type III secretion systems (T3SS1 and T3SS2). T3SS1 plays a significant role in lethal activity in a murine infection model. It was reported that expression of the T3SS1 gene is controlled by a positive regulator, ExsA, and a negative regulator, ExsD, which share a degree of sequence similarity with Pseudomonas aeruginosa ExsA and ExsD, respectively. However, it is unknown whether T3SS1 is regulated by a mechanism similar to that demonstrated for P. aeruginosa, because functional analysis of VP1701, which is homologous to ExsC, is lacking and there is no ExsE homologue in the T3SS1 region. Here, we demonstrate that vp1701 and vp1702 are functional orthologues of exsC and exsE, respectively, of P. aeruginosa. VP1701 was required for the production of T3SS1-related proteins. VP1702 was a negative regulator for T3SS1-related protein production and was secreted by T3SS1. We also found that H-NS represses T3SS1-related gene expression by suppressing exsA gene expression. These findings indicate that the transcription of V. parahaemolyticus T3SS1 genes is regulated by a dual regulatory system consisting of the ExsACDE regulatory cascade and H-NS.
    FEMS Microbiology Letters 10/2010; 311(1):10-7. · 2.05 Impact Factor
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    ABSTRACT: Cholera and enterotoxigenic Escherichia coli (ETEC) are among the most common causes of acute infantile gastroenteritis globally. We previously developed a rice-based vaccine that expressed cholera toxin B subunit (MucoRice-CTB) and had the advantages of being cold chain-free and providing protection against cholera toxin (CT)-induced diarrhea. To advance the development of MucoRice-CTB for human clinical application, we investigated whether the CTB-specific secretory IgA (SIgA) induced by MucoRice-CTB gives longstanding protection against diarrhea induced by Vibrio cholerae and heat-labile enterotoxin (LT)-producing ETEC (LT-ETEC) in mice. Oral immunization with MucoRice-CTB stored at room temperature for more than 3 y provided effective SIgA-mediated protection against CT- or LT-induced diarrhea, but the protection was impaired in polymeric Ig receptor-deficient mice lacking SIgA. The vaccine gave longstanding protection against CT- or LT-induced diarrhea (for > or = 6 months after primary immunization), and a single booster immunization extended the duration of protective immunity by at least 4 months. Furthermore, MucoRice-CTB vaccination prevented diarrhea in the event of V. cholerae and LT-ETEC challenges. Thus, MucoRice-CTB is an effective long-term cold chain-free oral vaccine that induces CTB-specific SIgA-mediated longstanding protection against V. cholerae- or LT-ETEC-induced diarrhea.
    Proceedings of the National Academy of Sciences 05/2010; 107(19):8794-9. · 9.81 Impact Factor
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    ABSTRACT: Vibrio parahaemolyticus, one of the human-pathogenic vibrios, causes three major types of clinical illness: gastroenteritis, wound infections, and septicemia. Thermostable direct hemolysin (TDH) secreted by this bacterium has been considered a major virulence factor of gastroenteritis because it has biological activities, including cytotoxic and enterotoxic activities. Previous reports revealed that V. parahaemolyticus strain RIMD2210633, which contains tdh, has two sets of type III secretion system (T3SS) genes on chromosomes 1 and 2 (T3SS1 and T3SS2, respectively) and that T3SS1 is responsible for cytotoxicity and T3SS2 is involved in enterotoxicity, as well as in cytotoxic activity. However, the relative importance and contributions of TDH and the two T3SSs to V. parahaemolyticus pathogenicity are not well understood. In this study, we constructed mutant strains with nonfunctional T3SSs from the V. parahaemolyticus strain containing tdh, and then the pathogenicities of the wild-type and mutant strains were evaluated by assessing their cytotoxic activities against HeLa, Caco-2, and RAW 264 cells, their enterotoxic activities in rabbit ileal loops, and their lethality in a murine infection model. We demonstrated that T3SS1 was involved in cytotoxic activities against all cell lines used in this study, while T3SS2 and TDH had cytotoxic effects on a limited number of cell lines. T3SS2 was the major contributor to V. parahaemolyticus-induced enterotoxicity. Interestingly, we found that both T3SS1 and TDH played a significant role in lethal activity in a murine infection model. Our findings provide new indications that these virulence factors contribute to and orchestrate each distinct aspect of the pathogenicity of V. parahaemolyticus.
    Infection and immunity 04/2010; 78(4):1772-80. · 4.21 Impact Factor
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    ABSTRACT: In Aeromonas hydrophila, the gram-negative bacterial fish pathogen, PepO constitutes the thermoregulated outer membrane M13 family zinc endopeptidase, which is expressed maximally at 16 degrees C and is down-regulated above 30 degrees C. Cultivation of A. hydrophila at 16 degrees C enabled it to activate big endothelin (ET), the vasoconstrictor and ulcerogenic peptide naturally secreted from human vascular endothelial cell (HUVEC) culture. Furthermore, A. hydrophila PepO in vitro shows strong enzymatic preference for human big ET-3 rather than big ET-1 and big ET-2. At water temperature of 16+/-1 degrees C, intramuscular infection of goldfish, Carassius auratus, with wild-type A. hydrophila led to development of a pathognomonic big ulcer at the injection site while the PepO deficient mutant strain lost both its big ET endopeptidase activity in vitro as well as its ulcerogenic property in vivo. This is the first report of expression, subcellular localization and functional analysis of PepO metalloendopeptidase in A. hydrophila.
    Veterinary Microbiology 03/2010; 145(1-2):113-21. · 3.13 Impact Factor
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    ABSTRACT: Vibrio parahaemolyticus, a bacterial pathogen, causes human gastroenteritis. A type III secretion system (T3SS2) encoded in pathogenicity island (Vp-PAI) is the main contributor to enterotoxicity and expression of Vp-PAI encoded genes is regulated by two transcriptional regulators, VtrA and VtrB. However, a host-derived inducer for the Vp-PAI genes has not been identified. Here, we demonstrate that bile induces production of T3SS2-related proteins under osmotic conditions equivalent to those in the intestinal lumen. We also show that bile induces vtrA-mediated vtrB transcription. Transcriptome analysis of bile-responsive genes revealed that bile strongly induces expression of Vp-PAI genes in a vtrA-dependent manner. The inducing activity of bile was diminished by treatment with bile acid sequestrant cholestyramine. Finally, we demonstrate an in vivo protective effect of cholestyramine on enterotoxicity and show that similar protection is observed in infection with a different type of V. parahaemolyticus or with non-O1/non-O139 V. cholerae strains of vibrios carrying the same kind of T3SS. In summary, these results provide an insight into how bacteria, through the ingenious action of Vp-PAI genes, can take advantage of an otherwise hostile host environment. The results also reveal a new therapeutic potential for widely used bile acid sequestrants in enteric bacterial infections.
    PLoS ONE 01/2010; 5(10):e13365. · 3.73 Impact Factor

Publication Stats

660 Citations
163.92 Total Impact Points

Institutions

  • 1999–2013
    • Osaka University
      • • International Research Center for Infectious Diseases
      • • Laboratory of Genomic Research on Pathogenic Bacteria
      Suika, Ōsaka, Japan
  • 2012
    • Harvard Medical School
      • Department of Microbiology and Immunobiology
      Boston, Massachusetts, United States
  • 2010
    • Suez Canal University
      • Faculty of Veterinary Medicine
      Ismailia, Muhafazat al Isma`iliyah, Egypt
  • 2007
    • East China University of Science and Technology
      • School of Pharmacy
      Shanghai, Shanghai Shi, China