Green fluorescent protein-tagged Edwardsiella tarda reveals portal of entry in fish

Edwardsiella tarda causes haemorrhagic septicaemia in fish and gastro-and extra-intestinal infections in animals including humans. Resistance to phagocyte-mediated killing is one of the virulence factors of Ed. tarda. The authors' previous studies using TnphoA transposon mutagenesis indicated that katB mutants derived from the strain PPD130/91 are at least 1?6 log higher in LD 50 values than the wild-type strain. These findings suggest the involvement of catalase (KatB) in Ed. tarda pathogenesis. In this study, experiments were conducted to characterize the contribution of KatB to Ed. tarda infection. Zymographic analyses indicated that the 22 Ed. tarda strains examined expressed three different types of catalase-peroxidases (Kat1-3) based on their mobility in non-denaturing polyacrylamide gels. KatB (Kat1), the major catalase enzyme, was expressed in eight out of 22 Ed. tarda strains, and was commonly found in virulent strains except AL9379. AL9379 has a mutated katB, which has a base substitution and a deletion that translate into stop codons in the catalase gene. KatB produced by PPD130/91 was located in both periplasmic and cytoplasmic fractions and was constitutively expressed in various growth phases. Kinetics studies indicated that the catalase provided resistance to H 2 O 2 -and phagocyte-mediated killing. Infection kinetics studies of katB mutant 34 in gourami fish demonstrated its inability to survive and replicate in phagocyte-rich organs and this prevented the dissemination of infections when compared to the wild-type. Complementation of catalase mutants restored the production of catalase, and led to an increase in the resistance to H 2 O 2 -and phagocyte-mediated killing, and a decrease in LD 50 values. This study has identified and characterized a major catalase gene (katB) that is required for resistance to H 2 O 2 -and phagocyte-mediated killing in Ed. tarda. The results also suggest that catalase may play a role as a virulence factor in Ed. tarda pathogenesis.

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“…of Ed. tarda PPD130/91 (Ling et al, 2001) or mutant 34. A control group of fish was injected with 0?1 ml PBS.…”

Section: Methodsmentioning

confidence: 99%

A major catalase (KatB) that is required for resistance to H2O2 and phagocyte-mediated killing in Edwardsiella tarda

2003

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“…The present study revealed that the adherence, as well as the HA, of E. tarda strains FK1051 and KG8401 to HEp-2 cells was markedly inhibited by NANA. It was reported that virulent strains of E. tarda had the ability to adhere to the body mucus of blue gourami Trichogaster trichopterus (Ling et al, 2001). Since NANA is one of the most abundant carbohydrates in the fish mucus (Asakawa, 1983;Wolfe et al, 1998), NANA or related sugar moiety might be a receptor for E. tarda adhesin on the host cells.…”

Section: Discussionmentioning

confidence: 99%

“…E. tarda has the ability to adhere to gill and body surface of fish (Ling et al, 2001). Fimbriae (pili) or hemagglutinins are essential adherence factors usually found in pathogenic bacteria (Finlay and Falkow, 1997;Abraham et al, 1998).…”

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confidence: 99%

Sodium chloride-enhanced adherence of Edwardsiella tarda to HEp-2 cells

2006

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ABSTRACT-The adherence of Edwardsiella tarda strains to HEp-2 cells was studied by the viable cell count and direct microscopic count methods. Three selected E. tarda strains having different hemagglutination activities against guinea pig erythrocytes were cultured in a peptone-yeast extract broth supplemented with 3% NaCl (3%-NaCl culture) or without NaCl (0%-NaCl culture). Strain FK1051 showed significantly higher adherence in the 3%-NaCl culture than in the 0%-NaCl culture. A similar adherence pattern was observed in strain KG8401, though the adherence of the 0%-NaCl culture was higher than that of FK1051. In contrast, both cultures of strain SU166 were low in the adherence. These adherence patterns to the HEp-2 cells correlated well with the previously reported hemagglutinating activities of the strains. N-acetylneuraminic acid markedly inhibited the adherence as well as the hemagglutination. This NaCl-enhanced adherence may be involved in pathogenesis of E. tarda infection particularly in marine fish.

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“…In spite of increasing research efforts, relatively little is known about the complex interactions among the coral host, the marine environment, and invading pathogens that lead to disease (Work and Meteyer 2014). The development of tools to effectively visualize pathogens in situ has provided critical insights into complex and highly dynamic host-pathogen interactions in a wide range of disease systems (Valdivia et al 1996;Ling et al 2001;Sawabe et al 2006) and could lead to similar advances in the field of coral disease research.…”

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confidence: 99%

“…Insertion of green fluorescent protein (GFP) genes into the genomes of microorganisms of interest provides a useful experimental tool to track the behavior of specific microbes as they interact with host tissues and cells (Prasher et al 1992;Chalfie et al 1994;Valdivia et al 1996;Ling et al 2001;Dunn et al 2006). GFPs are nontoxic; therefore, they do not interfere with cell function.…”

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confidence: 99%

Visualization of coral host–pathogen interactions using a stable GFP-labeled Vibrio coralliilyticus strain

et al. 2015

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The bacterium Vibrio coralliilyticus has been implicated as the causative agent of coral tissue loss diseases (collectively known as white syndromes) at sites across the Indo-Pacific and represents an emerging model pathogen for understanding the mechanisms linking bacterial infection and coral disease. In this study, we used a mini-Tn7 transposon delivery system to chromosomally label a strain of V. coralliilyticus isolated from a white syndrome disease lesion with a green fluorescent protein gene (GFP). We then tested the utility of this modified strain as a research tool for studies of coral host-pathogen interactions. A suite of biochemical assays and experimental infection trials in a range of model organisms confirmed that insertion of the GFP gene did not interfere with the labeled strain's virulence. Using epifluorescence video microscopy, the GFP-labeled strain could be reliably distinguished from non-labeled bacteria present in the coral holobiont, and the pathogen's interactions with the coral host could be visualized in real time. This study demonstrates that chromosomal GFP labeling is a useful technique for visualization and tracking of coral pathogens and provides a novel tool to investigate the role of V. coralliilyticus in coral disease pathogenesis.

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Green fluorescent protein-tagged Edwardsiella tarda reveals portal of entry in fish

Cited by 42 publications

References 15 publications

A major catalase (KatB) that is required for resistance to H2O2 and phagocyte-mediated killing in Edwardsiella tarda

A major catalase (KatB) that is required for resistance to H2O2 and phagocyte-mediated killing in Edwardsiella tarda

Sodium chloride-enhanced adherence of Edwardsiella tarda to HEp-2 cells

Visualization of coral host–pathogen interactions using a stable GFP-labeled Vibrio coralliilyticus strain

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