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Haruo Watanabe

Publications and source records attributed to Haruo Watanabe.

At least 19 recordsLinked to original sources
PubMed2003

Effects of lysogeny of Shiga toxin 2-encoding bacteriophages on pulsed-field gel electrophoresis fragment pattern of Escherichia coli K-12.

Escherichia coli K-12 lysogens of three different Shiga toxin 2 (Stx2)-encoding bacteriophages were examined for variability in their pulsed-field gel electrophoresis (PFGE) fragment patterns. The PFGE fragment patterns could be classified into three types (i.e., PFGE types B, C, and D). For the PFGE type D, a 255-kbp fragment present in the original K-12 strain was apparently shifted by the size of Stx 2-encoding phage genomic DNA (ca. 65 kbp) to the position at 320 kbp. In contrast, the types B and C showed the above fragment shift plus further 6- and 10-fragment differences, respectively, from the original K-12 strain. The evidence suggests that even a single genetic event like lysogeny can cause marked genotypic modification of the host strain.

Bacteriophages↗
PubMed2003

IpaC of Shigella binds to the C-terminal domain of beta-catenin.

IpaC of Shigella is essential for initial bacterial entry into epithelial cells. We report here that IpaC interacts with beta-catenin and destabilizes the cadherin-mediated cell adhesion complex. Using a yeast two-hybrid system, we identified beta-catenin as a binding partner of IpaC within the host cell after cell entry, but not in the initial entry. Co-immunoprecipitation, confocal microscopy, and GST pull-down experiments confirmed the intracellular and cell-free interactions between these two proteins. The interaction sites were mapped to the ninth armadillo repeat of beta-catenin and to the C-terminus of IpaC. IpaC-associated beta-catenin was phosphorylated at tyrosine residues. This phosphorylation led to the destabilization of the functional cadherin-catenin complex, which could be a mechanism whereby the epithelial cell-cell tight adhesion is disrupted. These events may facilitate the further basolateral invasion of bacteria through the disrupted space and/or modulate the cell-to-cell spread of Shigella.

Antigens, Bacterial↗
PubMed2003

Evidence for widespread infection of hepatitis E virus among wild rats in Japan.

Sporadic cases of hepatitis E have been reported in industrialized countries, including Japan. The source of hepatitis E virus (HEV) in these patients is unknown, although zoonotic transmission has been suggested. To investigate whether or not rodents might be a reservoir of HEV, we conducted an epidemiological survey for the antibody to a recombinant capsid protein of HEV using serum samples from wild rodents in Japan. One hundred and fourteen of 362 (31.5%) Norway rats (Rattus norvegicus) and 12 of 90 (13.3%) black rats (Rattus rattus) were positive for anti-HEV IgG. In contrast, all of the sera from 55 mice were negative for anti-HEV IgG. The rate of antibody positivity increased with weight among Norway rats. Seropositive rats were found in all five districts surveyed in this study, but the prevalence of anti-HEV IgG in wild rats differed among these prefectures. Despite the fact that Japan is a non-endemic country of hepatitis E, widespread infection of HEV was observed among wild rats in Japan. Our results suggested that HEV or a closely related virus is circulating among wild rats in Japan.

Journal Article↗
PubMed2003

Identification of a novel antigen of pathogenic Leptospira spp. that reacted with convalescent mice sera.

The virulence of leptospires isolated from human patients against C3H/HeJ mice was investigated. Infection with clinical isolates from patients with severe leptospirosis was lethal to C3H/HeJ mice, suggesting that C3H/HeJ mice are suitable as an acute lethal model of severe leptospirosis. Using this model, a novel antigen of pathogenic Leptospira spp. (named LAg42), which reacted with convalescent mice sera, was identified. LAg42 is a 42 kDa inner-membrane protein and its immunogenic region is located in the C-terminal region. The gene for LAg42 is conserved among pathogenic leptospires but not among non-pathogenic leptospires, which suggests its involvement in virulence.

Animals↗
PubMed2003

Screening method for Salmonella enterica serovar Typhi and serovar Paratyphi A with reduced susceptibility to fluoroquinolones by PCR-restriction fragment length polymorphism.

Salmonella enterica serovar Typhi and serovar Paratyphi A with reduced susceptibility to fluoroquinolones (MICs of ciprofloxacin, 0.25 to 2 microg/ml) have a mutation at codon either Ser-83 or Asp-87 of gyrA gene. A screening method by PCR-restriction fragment length polymorphism (PCR-RFLP) was designed to screen the mutations at codon Ser-83 and Asp-87 of the gyrA gene of S. enterica serovar Typhi and serovar Paratyphi A clinical isolates. This method successfully screened the gyrA mutations of S. enterica serovar Typhi and serovar Paratyphi A with reduced susceptibility to fluoroquinolones.

Anti-Infective Agents↗
PubMed2003

Probable laboratory contamination of clinical specimens with Leptospira meyeri.

Leptospira meyeri were isolated from the blood or the pleural effusion cultures of four patients at a commercial clinical laboratory. All isolates were identical in their 16S rDNA sequences and NotI or SfiI restriction profiles of the chromosome DNA on pulsed-field gel electrophoresis. However, intraperitoneal inoculation of the isolate (NIID1) failed to kill hamsters and none of the patients' sera reacted with L. meyeri strains isolated, indicating leptospiral contamination occurred during laboratory investigation.

Animals↗
PubMed2003

Determination of the InvE binding site required for expression of IpaB of the Shigella sonnei virulence plasmid: involvement of a ParB boxA-like sequence.

The InvE protein positively regulates the expression of virulence genes ipaBCD in Shigella sonnei. The InvE has significant homology with ParB of plasmid P1, which is known as a plasmid partitioning factor with DNA binding ability. Although the DNA binding activity of InvE has been predicted, it is not known whether the DNA binding activity is necessary for type III secretion system-associated gene expression. In this study, we determined the transcription start site of the icsB-ipaBCD operon (ipa operon) and constructed a series of deletions of the icsB promoter region in the Escherichia coli K-12 background. The deletion study revealed that an 86-bp region upstream of the icsB transcription start site was essential for expression of the ipa operon, where the ParB binding motif (ParB BoxA-like sequence) was observed. Purified glutathione S-transferase-InvE fusion protein bound directly to the -93 to -54 region (designating the icsB transcription start site as nucleotide +1) containing the ParB BoxA-like sequence. These results indicated that InvE bound directly to the promoter region.

Bacterial Proteins↗
PubMed2003

Life-threatening infantile diarrhea from fluoroquinolone-resistant Salmonella enterica typhimurium with mutations in both gyrA and parC.

Salmonella Typhimurium DT12, isolated from a 35-day-old infant with diarrhea, was highly resistant to ampicillin, tetracycline, chloramphenicol, streptomycin, gentamycin, sulfamethoxazole/trimethoprim, nalidixic acid, and fluoroquinolones. The patient responded to antibiotic therapy with fosfomycin. Multidrug-resistance may become prevalent in Salmonella infections in Japan, as shown in this first case of a patient infected with fluoroquinolone-resistant Salmonella.

Anti-Infective Agents↗
PubMed2002

Genomic diversity of enterohemorrhagic Escherichia coli O157 revealed by whole genome PCR scanning.

Enterohemorrhagic Escherichia coli O157 is one of the leading worldwide public health concerns, causing large outbreaks of hemorrhagic colitis as well as numerous small outbreaks and sporadic cases. The variability of restriction enzyme-digestion patterns of O157 genomes, which is widely used to distinguish strains in the molecular epidemiology of O157 infections, suggests the presence of some genomic diversity among the strains. Based on the complete genome sequence of O157 Sakai, we analyzed the whole genome structures of eight O157 strains displaying diverse XbaI-digestion patterns by a systematic PCR analysis that we have named whole genome PCR scanning. This analysis identified not only the O157-specific sequences that are highly conserved among the strains, but also revealed an unexpectedly high degree of genomic diversity. In particular, prophages, including Shiga toxin-transducing phages, exhibited extensive structural and positional diversity, implying that variation of bacteriophages is a major factor in generating genomic diversity among the O157 lineage.

Chromosomes, Bacterial↗
PubMed2002

Critical role of myeloperoxidase and nicotinamide adenine dinucleotide phosphate-oxidase in high-burden systemic infection of mice with Candida albicans.

Oxygen metabolites generated by myeloperoxidase (MPO) and nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase contribute to microbial killing by phagocytes. To compare the importance of the 2 enzymes for host defense, MPO-deficient (MPO(-/-)) mice and NADPH-oxidase-deficient mice with chronic granulomatous disease (CGD mice) were intraperitoneally infected with 3 different doses of Candida albicans, and their infection severity was analyzed. CGD mice had increased mortality and exhibited increased tissue fungal burden in a dose-dependent manner, whereas normal mice showed no symptoms. Of interest, at the highest dose, the mortality of MPO(-/-) mice was comparable to that of CGD mice, but at the lowest dose, it was the same as that of normal mice. At the middle dose, the number of fungi disseminated into various organs of the MPO(-/-) mice was comparable to that of the CGD mice at day 6 of infection, but it was significantly lower at day 14. These results suggest that MPO and NADPH-oxidase are equally important for early host defense against a large inoculum of Candida.

Animals↗
PubMed2002

Clonal association of Staphylococcus aureus causing bullous impetigo and the emergence of new methicillin-resistant clonal groups in Kansai district in Japan.

A molecular epidemiological analysis was performed to reveal the clonal association of Staphylococcus aureus strains isolated from patients with bullous impetigo. Pulsed-field gel electrophoresis with cluster analysis, genetic and phenotypic characterizations, and antimicrobial susceptibility profiling of 88 S. aureus strains isolated from outpatients at 4 hospitals in the Kansai district in Japan were undertaken. Three distinct clonal groups were identified: 2 of them carried the exfoliative toxin (ET) A gene (eta), and the other carried the ETB gene (etb). The former groups represent 2 eta-positive clonal groups that have not been described previously. All the strains in the more dominant eta-positive clonal group and some of the strains in the etb-positive clonal group were methicillin-resistant S. aureus (MRSA) showing borderline-to-moderate resistance to beta-lactams. These MRSA strains appear to be emerging clonal groups that have not been considered in previous epidemiological studies of ET-producing S. aureus in Japan and thus pose a significant threat for future treatment of patients with bullous impetigo and/or staphylococcal scalded-skin syndrome.

Blister↗
PubMed2002

Silkworm larvae as an animal model of bacterial infection pathogenic to humans.

Silkworm larvae, Bombyx mori, were examined as an animal model of human infection with pathogenic bacteria. When 3 x 10(7) cells of Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa, or Vibrio cholerae were injected into the blood of fifth instar silkworm larvae, over 90% of the larvae died within 2 days, whereas over 90% survived for 5 days after injection of the same amount of Escherichia coli. Growth of S. aureus was observed in larvae blood and tissues. Immunostaining analysis revealed that S. aureus proliferated at the surface of the midgut. Infection of silkworm larvae by methicillin-sensitive S. aureus was cured by ampicillin, oxacillin, and vancomycin, whereas infection by methicillin-resistant S. aureus was not cured by ampicillin or oxacillin, although vancomycin was effective. Disinfectants were not effective because of toxicity against the larvae. Thus, silkworm larvae are useful for evaluating antibiotics for pathogenic bacterial infection in humans.

Animals↗