Role of the toxR Gene from Fish Pathogen Vibiro alginolyticus in the Physiology and Virulence

In this study, an in-frame deletion of the luxS gene was constructed to reveal the role of LuxS in the physiology and virulence of V. harveyi. The statistical analysis showed no significant differences in the growth ability, biofilm formation, antibiotic susceptibility, virulence by intraperitoneal injection, and the ability of V. harveyi to colonize the spleen and liver of the pearl gentian grouper between the wild-type (WT) and the luxS mutant. However, the deletion of luxS decreased the secretion of extracellular protease, while increased the ability of swimming and swarming. Simultaneously, a luxS-deleted mutant showed overproduction of lateral flagella, and an intact luxS complemented the defect. Since motility is flagella dependent, 16 of V. harveyi flagella biogenesis related genes were selected for further analysis. Based on quantitative real-time reverse transcription-PCR (qRT-PCR), the expression levels of these genes, including the polar flagella genes flaB, flhA, flhF, flhB, flhF, fliS, and flrA and the lateral flagella genes flgA, flgB, fliE, fliF, lafA, lafK, and motY, were significantly up-regulated in the ΔluxS: pMMB207 (ΔluxS+) strain as compared with the V. harveyi 345: pMMB207 (WT+) and C-ΔluxS strains during the early, mid-exponential, and stationary growth phase.

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Prophages and Past Prophage-Host Interactions Revealed by CRISPR Spacer Content in a Fish Pathogen

Microorganisms ◽

10.3390/microorganisms8121919 ◽

2020 ◽

Vol 8 (12) ◽

pp. 1919

Author(s):

Elina Laanto ◽

Janne J. Ravantti ◽

Lotta-Riina Sundberg

Keyword(s):

Flavobacterium Columnare ◽

Strain Atcc ◽

Human Pathogens ◽

Fish Pathogen ◽

Bacterial Strains ◽

Host Interactions ◽

Different Strains ◽

Gene Orthologs ◽

Similar Genome Organization

The role of prophages in the evolution, diversification, or virulence of the fish pathogen Flavobacterium columnare has not been studied thus far. Here, we describe a functional spontaneously inducing prophage fF4 from the F. columnare type strain ATCC 23463, which is not detectable with commonly used prophage search methods. We show that this prophage type has a global distribution and is present in strains isolated from Finland, Thailand, Japan, and North America. The virions of fF4 are myoviruses with contractile tails and infect only bacterial strains originating from Northern Finland. The fF4 resembles transposable phages by similar genome organization and several gene orthologs. Additional bioinformatic analyses reveal several species in the phylum Bacteroidetes that host a similar type of putative prophage, including bacteria that are important animal and human pathogens. Furthermore, a survey of F. columnare Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) spacers indicate a shared evolutionary history between F. columnare strains and the fF4 phage, and another putative prophage in the F. columnare strain ATCC 49512, named p49512. First, CRISPR spacer content from the two CRISPR loci (types II-C and VI-B) of the fF4 lysogen F. columnare ATCC 23463 revealed a phage terminase protein-matching spacer in the VI-B locus. This spacer is also present in two Chinese F. columnare strains. Second, CRISPR analysis revealed four F. columnare strains that contain unique spacers targeting different regions of the putative prophage p49512 in the F. columnare strain ATCC 49512, despite the geographical distance or genomovar of the different strains. This suggests a common ancestry for the F. columnare prophages and different host strains.

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Transmission models for the fish pathogen Ichthyophonus: synthesis of field observations and empirical studies

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2018-0166 ◽

2019 ◽

Vol 76 (4) ◽

pp. 636-642 ◽

Cited By ~ 2

Author(s):

Richard M. Kocan

Keyword(s):

Empirical Studies ◽

Large Fish ◽

Fish Pathogen ◽

Free Living ◽

Saltwater Fish ◽

Mode Of Transmission ◽

Infected Prey ◽

Transmission Models ◽

Inshore Migration

Empirical studies have demonstrated that Ichthyophonus is transmitted among piscivores via consumption of infected prey; however, this unidirectional mode of transmission from small to large fish cannot sustain Ichthyophonus within a population. To circumvent this problem, Ichthyophonus evolved an infective waterborne cell that has been shown to infect both fresh- and saltwater fish. Successful transmission of Ichthyophonus via a waterborne stage is linked to the proximity of infected and susceptible individuals, a condition met when the two groups occupy the same habitat. It is posited that this occurs during annual inshore migrations when herring (Clupea spp.) enter areas occupied by infected demersal predators. A plausible transmission scenario is that during inshore excursions, planktivores are exposed to infective waterborne cells shed by demersal piscivores. Once planktivores are infected, the parasite is recycled when consumed by predators. This model is supported by reports of ichthyophoniasis increasing in herring populations at the time of inshore migration. The possible role of an intermediate host for Ichthyophonus, as well as evidence for a free-living stage in its life cycle, is presented.

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The role of reactive oxygen species in the killing of the bacterial fish pathogen Aeromonas salmonicida by rainbow trout macrophages

Fish & Shellfish Immunology ◽

10.1006/fsim.1993.1013 ◽

1993 ◽

Vol 3 (2) ◽

pp. 119-129 ◽

Cited By ~ 134

Author(s):

G.J.E. Sharp ◽

C.J. Secombes

Keyword(s):

Reactive Oxygen Species ◽

Rainbow Trout ◽

Reactive Oxygen ◽

Aeromonas Salmonicida ◽

Oxygen Species ◽

Fish Pathogen

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Characterization and pathogenic role of outer membrane vesicles produced by the fish pathogen Piscirickettsia salmonis under in vitro conditions

Veterinary Microbiology ◽

10.1016/j.vetmic.2015.09.012 ◽

2016 ◽

Vol 184 ◽

pp. 94-101 ◽

Cited By ~ 18

Author(s):

Cristian Oliver ◽

Karla Valenzuela ◽

Mauricio Hernández ◽

Rodrigo Sandoval ◽

Ronie E. Haro ◽

...

Keyword(s):

Outer Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Fish Pathogen ◽

Pathogenic Role ◽

Piscirickettsia Salmonis

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Role of the pJM1 plasmid-encoded transport proteins FatB, C and D in ferric anguibactin uptake in the fish pathogen Vibrio anguillarum

Environmental Microbiology Reports ◽

10.1111/j.1758-2229.2009.00110.x ◽

2009 ◽

Vol 2 (1) ◽

pp. 104-111 ◽

Cited By ~ 12

Author(s):

Hiroaki Naka ◽

Claudia S. López ◽

Jorge H. Crosa

Keyword(s):

Vibrio Anguillarum ◽

Transport Proteins ◽

Fish Pathogen

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Influences of temperature, salinity and starvation on the motility and chemotactic response of Vibrio anguillarum

Microbiology ◽

10.1099/mic.0.26379-0 ◽

2004 ◽

Vol 150 (5) ◽

pp. 1283-1290 ◽

Cited By ~ 39

Author(s):

Marianne H. Larsen ◽

Nicholas Blackburn ◽

Jens L. Larsen ◽

John E. Olsen

Keyword(s):

Growth Factors ◽

Rainbow Trout ◽

Swimming Speed ◽

Vibrio Anguillarum ◽

Specific Inhibitor ◽

Chemotactic Response ◽

Fish Pathogen ◽

Motile Cells ◽

Bath Challenge

The role of growth factors for the motility and chemotaxis of the fish pathogen Vibrio anguillarum was determined. Cells of V. anguillarum were chemotactic to serine in the temperature range 5–25 °C and in 0·8–2·7 % NaCl. The chemotactic response was significantly higher at 25 °C than at 5 or 15 °C. Growth in medium with 1·5 % NaCl gave a higher response than growth with 3 % NaCl; when the salinity of the chemotaxis buffer was raised, the chemotactic response was reduced. The role of starvation was also studied; V. anguillarum showed a high chemotactic response after starvation for 2 and 8 days. Motility and chemotaxis are important virulence factors for this bacterium. Not only was the ability to perform chemotactic motility maintained after starvation, but also it was shown that starvation does not interfere with the ability of the organism to cause infection in rainbow trout after a bath challenge. The swimming speed was reduced at lower temperatures. Within the range of salinity and starvation studied, the motile cells swam with the same velocity, indicating that V. anguillarum under all the examined conditions has a functional flagellum and rotates it with constant speed. Phenamil, a specific inhibitor of Na+-driven flagella, reduced the motility of both starved and non-starved cells of V. anguillarum indicating that, in both cases, a Na+ motive force drives the flagellum.

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