Virulence genes and pathogenicity islands in environmental<i>Vibrio</i>strains nonpathogenic to humans

Gennari, Micol; Ghidini, Valentina; Caburlotto, Greta; Lleò, Maria M.

doi:10.1111/j.1574-6941.2012.01427.x

Cited by 69 publications

(51 citation statements)

References 38 publications

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“…Many of the algal exudate-enriched OTUs identified here by 16S amplicon sequencing were related to cultured isolates identified as known pathogens, but closely related species and strains within bacterial generic-level clades can exhibit very different hostpathogen dynamics depending on conditions or how cellular machinery is used (Coenye and Vandamme, 2003;Jani and Cotter, 2010;Gennari et al, 2012). The evidence presented here should be interpreted as hypothesis-generating rather than definitive proof that algal exudates select for coral pathogens.…”

Section: Ecological Implicationsmentioning

confidence: 68%

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages

et al. 2013

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Increasing algal cover on tropical reefs worldwide may be maintained through feedbacks whereby algae outcompete coral by altering microbial activity. We hypothesized that algae and coral release compositionally distinct exudates that differentially alter bacterioplankton growth and community structure. We collected exudates from the dominant hermatypic coral holobiont Porites spp. and three dominant macroalgae (one each Ochrophyta, Rhodophyta and Chlorophyta) from reefs of Mo'orea, French Polynesia. We characterized exudates by measuring dissolved organic carbon (DOC) and fractional dissolved combined neutral sugars (DCNSs) and subsequently tracked bacterioplankton responses to each exudate over 48 h, assessing cellular growth, DOC/DCNS utilization and changes in taxonomic composition (via 16S rRNA amplicon pyrosequencing). Fleshy macroalgal exudates were enriched in the DCNS components fucose (Ochrophyta) and galactose (Rhodophyta); coral and calcareous algal exudates were enriched in total DCNS but in the same component proportions as ambient seawater. Rates of bacterioplankton growth and DOC utilization were significantly higher in algal exudate treatments than in coral exudate and control incubations with each community selectively removing different DCNS components. Coral exudates engendered the smallest shift in overall bacterioplankton community structure, maintained high diversity and enriched taxa from Alphaproteobacteria lineages containing cultured representatives with relatively few virulence factors (VFs) (Hyphomonadaceae and Erythrobacteraceae). In contrast, macroalgal exudates selected for less diverse communities heavily enriched in copiotrophic Gammaproteobacteria lineages containing cultured pathogens with increased VFs (Vibrionaceae and Pseudoalteromonadaceae). Our results demonstrate that algal exudates are enriched in DCNS components, foster rapid growth of bacterioplankton and select for bacterial populations with more potential VFs than coral exudates.

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Section: Ecological Implicationsmentioning

confidence: 68%

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages

et al. 2013

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“…Among these, V. anguillarum behaves as a major pathogen for a variety of aquatic organisms (fishes, eels, crustaceans, marine mammals, and corals). Although the environmental isolates are usually lacking the virulence-associated genes found in the clinical ones, some recent studies showed that they can also carry such genes, or homologues thereof, acquired through horizontal transfer events (Kirkup et al 2010;Gennari et al 2012). Both the persistence and abundance of vibrios are related to several parameters, whose influence can differ according to the geographic region .…”

Section: Introductionmentioning

confidence: 98%

Species diversity, spatial distribution, and virulence associated genes of culturable vibrios in a brackish coastal Mediterranean environment

et al. 2015

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The Vibrio genus is widespread in marine and brackish environments, and several species are human and animal pathogens of global importance. Vibrios adapt rapidly to many environmental stresses, so that brackish environments can be both a suitable niche and a possible reservoir for them. To test the occurrence of culturable vibrios and their\ud possible correlation with environmental factors in a temperate brackish environment, a 1year sampling study was performed in three brackish ponds located along the Central Thyrrenian coast in the Macchiatonda Nature Reserve (Santa Marinella, district of Rome, Italy). Molecular methods were used to detect Vibrio cholerae, Vibrio arahaemolyticus,\ud and Vibrio vulnificus pathogenicity associated genes among the Vibrio isolates. Out of 130 Vibrio isolates identified by sequencing a recA fragment, 70 harbored virulence associated genes including ctx, ace, tcpA, tdh, trh, vvhA, vllY, and toxRS, so confirming the spread of virulence determinants across the environmental isolates. Ecological analysis showed that, although the water temperature is known to be a strong predictor of abundance and distribution of vibrios, its influence accounts for 27 % of the observed variance in the Macchiatonda samples, increasing to 40 % when combined with salinity

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“…Sporadic reports of V. parahaemolyticus-like virulence genes in other species have appeared in the literature (33)(34)(35)(36)(37)(38)(39), but little is known regarding the distributions of these genes among Vibrionaceae. In particular, the occurrence of these genes in environmental strains has received very little attention.…”

mentioning

confidence: 99%

Genes Similar to the Vibrio parahaemolyticus Virulence-Related Genes tdh , tlh , and vscC2 Occur in Other Vibrionaceae Species Isolated from a Pristine Estuary

Klein

West

Mejia

et al. 2014

Appl Environ Microbiol

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Detection of the human pathogen Vibrio parahaemolyticus often relies on molecular biological analysis of species-specific virulence factor genes. These genes have been employed in determinations of V. parahaemolyticus population numbers and the prevalence of pathogenic V. parahaemolyticus strains. Strains of the Vibrionaceae species Photobacterium damselae, Vibrio diabolicus, Vibrio harveyi, and Vibrio natriegens, as well as strains similar to Vibrio tubiashii, were isolated from a pristine salt marsh estuary. These strains were examined for the V. parahaemolyticus hemolysin genes tdh, trh, and tlh and for the V. parahaemolyticus type III secretion system 2␣ gene vscC2 using established PCR primers and protocols. Virulence-related genes occurred at high frequencies in non-V. parahaemolyticus Vibrionaceae species. V. diabolicus was of particular interest, as several strains were recovered, and the large majority (>83%) contained virulence-related genes. It is clear that detection of these genes does not ensure correct identification of virulent V. parahaemolyticus. Further, the occurrence of V. parahaemolyticus-like virulence factors in other vibrios potentially complicates tracking of outbreaks of V. parahaemolyticus infections. Vibrio parahaemolyticus is the leading cause of seafood-associated gastroenteritis in the United States and the world (1). The U.S. Food and Drug Administration (1) estimates that 4,500 reported cases of V. parahaemolyticus gastroenteritis occur every year, and outbreaks of V. parahaemolyticus infections are increasing in frequency and expanding in geographic range (2, 3). This organism is ubiquitous in nearshore marine waters, and cell numbers are typically highest in surficial sediments (4) and in turbid waters bearing high loads of resuspended sediment (5, 6). Filterfeeding bivalve mollusks, such as oysters and mussels, can concentrate V. parahaemolyticus and other pathogenic vibrios (for examples, see references 7 and 8), resulting in levels in the mollusks capable of producing infection in a person that ingests them (9). Virulent V. parahaemolyticus strains are clearly a concern for seafood safety, and their detection is important anywhere that elevated levels of this organism are found.Detection of V. parahaemolyticus in shellfish and environmental samples is typically based on molecular biological analysis of specific genes, particularly genes exclusive to this species and those strongly correlated with pathogenicity. The gene encoding the thermolabile hemolysin (TLH), designated tlh, encodes a phospholipase A2 (10). While its contribution to V. parahaemolyticus pathogenicity is unknown, expression of this gene is upregulated under conditions mimicking the human intestine (11,12). tlh is considered to be a species-specific marker for V. parahaemolyticus (13,14) and is frequently employed to identify this species (1,13,(15)(16)(17)(18). Genes encoding the thermostable direct hemolysin (TDH) and the homologous thermostable direct hemolysin-related hemolysin (TRH), tdh and trh, respe...

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Virulence genes and pathogenicity islands in environmentalVibriostrains nonpathogenic to humans

Cited by 69 publications

References 38 publications

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages

Species diversity, spatial distribution, and virulence associated genes of culturable vibrios in a brackish coastal Mediterranean environment

Genes Similar to the Vibrio parahaemolyticus Virulence-Related Genes tdh , tlh , and vscC2 Occur in Other Vibrionaceae Species Isolated from a Pristine Estuary

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