A
            <i>Vibrio</i>
            T6SS-Mediated Lethality in an Aquatic Animal Model

Cohen, Hadar; Fridman, Chaya Mushka; Gerlic, Motti; Salomon, Dor

doi:10.1128/spectrum.01093-23

Cited by 6 publications

(5 citation statements)

References 13 publications

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“…Whereas most T6SSs investigated to date mediate interbacterial competitions by delivering antibacterial effectors, a few T6SSs have been shown to target eukaryotes and mediate virulence [33,35,36]. In accordance, although most Vibrio T6SSs play a role in interbacterial competitions [24][25][26][27][28][37][38][39], we and others recently revealed Vibrio T6SSs and effectors that target eukaryotes, and we postulated that they play a role in virulence [22,[40][41][42][43].…”

Section: Introductionsupporting

confidence: 61%

“…Based on the above results, we hypothesized that T6SS2 mediates anti-eukaryotic activities. To investigate whether T6SS2 plays a role in bacterial virulence, we employed the saline lake-dwelling brine shrimp, Artemia salina , as an aquatic animal model [41,48,49]. Wild-type Vcor OCN008 was lethal to Artemia nauplii (larvae), with a median survival of 53 hours.…”

Section: Resultsmentioning

confidence: 99%

“…Artemia infection assays: Artemia infection assays were performed as previously reported [41], with minor modifications. Artemia salina eggs (Artemio Pur; JBL) were incubated in deionized distilled water containing chloramphenicol (10 μg/ml), kanamycin (100 μg/ml), and ampicillin (100 μg/ml) at 28°C with continuous rotation for an hour.…”

Section: Construction Of Deletion Strainsmentioning

confidence: 99%

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A T6SS in the coral pathogenVibrio coralliilyticussecretes an arsenal of anti-eukaryotic effectors and contributes to virulence

Mass,

Cohen,

Gerlic

et al. 2024

Preprint

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Vibrio coralliilyticus(Vcor) is a pathogen of coral and shellfish, leading to devastating economic and ecological consequences worldwide. Although rising ocean temperatures correlate with increasedVcorpathogenicity, the specific molecular mechanisms and determinants contributing to virulence remain poorly understood. Here, we systematically analyzed the type VI secretion system (T6SS), a contact-dependent toxin delivery apparatus, inVcor. We identified two omnipresent T6SSs that are activated at temperatures in whichVcorbecomes virulent; T6SS1 is an antibacterial system mediating interbacterial competition, whereas T6SS2 mediates anti-eukaryotic toxicity and contributes to mortality during infection of an aquatic model organism,Artemia salina. Using comparative proteomics, we identified the T6SS1 and T6SS2 toxin arsenals of threeVcorstrains. Remarkably, T6SS2 secretes at least nine novel anti-eukaryotic toxins comprising core and accessory repertoires. We propose that T6SSs differently contribute toVcor's virulence: T6SS2 plays a direct role by targeting the host, while T6SS1 plays an indirect role by eliminating competitors.

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Section: Introductionsupporting

confidence: 61%

Section: Resultsmentioning

confidence: 99%

Section: Construction Of Deletion Strainsmentioning

confidence: 99%

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A T6SS in the coral pathogenVibrio coralliilyticussecretes an arsenal of anti-eukaryotic effectors and contributes to virulence

Mass,

Cohen,

Gerlic

et al. 2024

Preprint

Self Cite

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“…This includes T6SS systems that have been suggested to sometimes be involved in host virulence as well as interbacterial competition [71]. In this respect, all of the salmon strains possess a T6SS system, except the S2MY1 group, and also possess multiple associated effectors (i.e., hcp, vgrG) [72,73]. Strains A9 and A21 possess both hcp and S-type pyocin-like [74] homologs on a contig that is likely a large plasmid.…”

Section: Genome Annotation Data Provides Indications Of Colonisation ...mentioning

confidence: 99%

Active colonisers of the gastrointestinal tract of Atlantic salmon farmed in a warm water region

Hall,

Reid,

Tan

et al. 2024

Preprint

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Background. Atlantic salmon (Salmo salar) farmed in seawater in Tasmania (lutruwita) can experience temper-atures close to their thermotolerance limit during summer and Vibrionaceae are a major component of their gut microbiome. This study focuses on understanding the microbiome of the Atlantic salmon gastrointestinal tract via the taxonomy, population dynamics, and traits of the main colonists. Results. Multiyear survey and co-occurrence network analyses confirmed novel members of Aliivibrio reliably colonise the gut microbiome in Atlantic salmon farmed in marine pens in Tasmania when the confounding influences of DNA and bacteria from feed and water was considered. Aliivibrio and Mycoplasma were the main taxa found to colonise the gut mucosal layers. Warm water temperature(19°C) experiments performed in seawater tanks indicated Aliivibrio and Vibrio rapidly become predominant in the digesta of Atlantic salmon that had reduced feeding and high faecal cast production while Mycoplasma were found to be mostly absent. Salmon-associated Aliivibrio isolates were found to share many genes required for host colonisation with that of the faunal mutualist Aliivibrio fischeri. Though most salmon digesta isolates seem to lack obvious virulence factors, strains of two abundant novel colonising Aliivibriostrain groups possessed the genes for cytolethal distending toxin (CDT). Conclusions. Multiyear surveys confirm Atlantic salmon farmed in the relatively warm conditions of Tasmania are persistently colonised by the same, largely novel, Aliivibrio species and a restricted range of other Vibrionaceae. Some of these species were found to be particularly adept at colonising salmon in warm water conditions. Though some Aliivibrio coloniser strains possessed CDT-genes it is yet unknown whether CDT-gene-positive Aliivibrio negatively impact Atlantic salmon . Since the strains studies possess a range of different colonization enabling mechanisms, interactions between Vibrionaceae in the gut of Atlantic salmon could be important for overall fish health, especially when they are exposed to stressful conditions, such as elevated sea surface temperatures.

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“…The type VI secretion system (T6SS) is a contact-dependent mechanism that allows inhibitor cells to deliver effector proteins directly into target cells through a syringe-like apparatus. T6SSs are prevalent in free-living, symbiotic, and pathogenic species (3,4) and are active in animal microbiomes (5)(6)(7)(8)(9)(10).…”

Section: Introductionmentioning

confidence: 99%

Flagella are required to coordinately activate competition and host colonization factors in response to a mechanical signal

Speare,

Zhao,

Pavelsky

et al. 2024

Preprint

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Bacteria employ antagonistic strategies to eliminate competitors of an ecological niche. Contact-dependent mechanisms, such as the type VI secretion system (T6SS), are prevalent in host-associated bacteria, yet we know relatively little about how T6SS+ strains make contact with competitors in highly viscous environments, such as host mucus. To better understand how cells respond to and contact one another in such environments, we performed a genome-wide transposon mutant screen of the T6SS-wielding beneficial bacterial symbiont, Vibrio fischeri, and identified two sets of genes that are conditionally required for killing. LPS/capsule and flagellar-associated genes do not affect T6SS directly and are therefore not required for interbacterial killing when cell contact is forced yet are necessary for killing in high-viscosity liquid (hydrogel) where cell-cell contact must be biologically mediated. Quantitative transcriptomics revealed that V. fischeri significantly increases expression of both T6SS genes and cell surface modification factors upon transition from low- to high-viscosity media. Consistent with coincubation and fluorescence microscopy data, flagella are not required for T6SS expression in hydrogel. However, flagella play a key role in responding to the physical environment by promoting expression of the surface modification genes identified in our screen, as well as additional functional pathways important for host colonization including uptake of host-relevant iron and carbon sources, and nitric oxide detoxification enzymes. Our findings suggest that flagella may act as a mechanosensor for V. fischeri to coordinately activate competitive strategies and host colonization factors, underscoring the significance of the physical environment in directing complex bacterial behaviors.

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A Vibrio T6SS-Mediated Lethality in an Aquatic Animal Model

Cited by 6 publications

References 13 publications

A T6SS in the coral pathogenVibrio coralliilyticussecretes an arsenal of anti-eukaryotic effectors and contributes to virulence

A T6SS in the coral pathogenVibrio coralliilyticussecretes an arsenal of anti-eukaryotic effectors and contributes to virulence

Active colonisers of the gastrointestinal tract of Atlantic salmon farmed in a warm water region

Flagella are required to coordinately activate competition and host colonization factors in response to a mechanical signal

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