Vibrio neptunius Produces Piscibactin and Amphibactin and Both Siderophores Contribute Significantly to Virulence for Clams.

Vibrio neptunius is an inhabitant of mollusc microbiota and an opportunistic pathogen causing disease outbreaks in marine bivalve mollusc species including oysters and clams. Virulence of mollusc pathogenic vibrios is mainly associated with the production of extracellular products. However, siderophore production is a common feature in pathogenic marine bacteria but its role in fitness and virulence of mollusc pathogens remains unknown. We previously found that V. neptunius produces amphibactin, one of the most abundant siderophores in marine microbes. In this work, synthesis of the siderophore piscibactin was identified as the second siderophore produced by V. neptunius. Single and double mutants in biosynthetic genes of each siderophore system, piscibactin and amphibactin, were constructed in V. neptunius and their role in growth ability and virulence was characterized. Although the High Pathogenicity Island encoding piscibactin is a major virulence factor in vibrios pathogenic for fish, the V. neptunius wild type did not cause mortality in turbot. The results showed that amphibactin contributes more than piscibactin to bacterial fitness in vitro. However, infection challenges showed that each siderophore system contributes equally to virulence for molluscs. The V. neptunius strain unable to produce any siderophore was severely impaired to cause vibriosis in clams. Although the inactivation of one of the two siderophore systems (either amphibactin or piscibactin) significantly reduced virulence compared to the wild type strain, the ability to produce both siderophores simultaneously maximised the degree of virulence. Evaluation of the gene expression pattern of each siderophore system showed that they are simultaneously expressed when V. neptunius is cultivated under low iron availability in vitro and ex vivo. Finally, the analysis of the distribution of siderophore systems in genomes of Vibrio spp. pathogenic for molluscs showed that the gene clusters encoding amphibactin and piscibactin are widespread in the Coralliilyticus clade. Thus, siderophore production would constitute a key virulence factor for bivalve molluscs pathogenic vibrios.

The Vibriolysin-Like Protease VnpA and the Collagenase ColA Are Required for Full Virulence of the Bivalve Mollusks Pathogen Vibrio neptunius.

Vibrio neptunius is an important pathogen of bivalve mollusks worldwide. Several metalloproteases have been described as virulence factors in species of Vibrio that are pathogenic to bivalves, but little is known about the contribution of these potential virulence factors to Vibrio neptunius pathogenesis. In silico analysis of the genome of V. neptunius strain PP-145.98 led to the identification of two hitherto uncharacterized chromosomal loci encoding a probable vibriolysin-like metalloprotease and a putative collagenase, which were designated VnpA and ColA, respectively. Single defective mutants of each gene were obtained in V. neptunius PP-145.98, and the phospholipase, esterase and collagenase activities were studied and compared with those of the wild-type strain. The results showed that the single inactivation of vnpA resulted in a 3-fold reduction in phospholipase/esterase activity. Inactivation of colA reduced the collagenase activity by 50%. Finally, infection challenges performed in oyster larvae showed that ΔvnpA and ΔcolA-single mutant strains of V. neptunius-are between 2-3-fold less virulent than the wild-type strain. Thus, the present work demonstrates that the production of both VnpA and ColA is required for the full virulence of the bivalve pathogen V. neptunius.

Draft Genome Sequences of Five Vibrio neptunius Strains Isolated from Hatcheries of Bivalve Mollusks.

Vibrio neptunius is a Gram-negative bacterium that has been shown to cause disease in marine bivalve mollusk larvae. Here, we report the draft genome sequences and annotations of five V. neptunius strains isolated from larvae of European oyster (Ostrea edulis) and Manila clam (Ruditapes philippinarum) at hatcheries in Galicia, northwest Spain.

The marine bivalve molluscs pathogen Vibrio neptunius produces the siderophore amphibactin, which is widespread in molluscs microbiota.

Amphiphilic siderophores, including amphibactins, are the most abundant siderophores in oceans. Genes putatively encoding the amphibactin system were proposed in some bacteria and homologues of these genes are particularly abundant in multiple bacterial lineages inhabitant of low-iron seawater. However, since no defective mutant strains in any of these genes were studied to date, their role in amphibactin synthesis or uptake was not demonstrated. In this work, an in silico analysis of the genome of the mollusc pathogen Vibrio neptunius leads us to identify a gene cluster (denoted absABDEF) that is predicted to encode an amphibactin-like siderophore and several mutant strains unable to synthesize or use siderophores were constructed. The results showed that genes absABDEF are required for amphibactin synthesis. A comparative chemical analysis of V. neptunius wild type and biosynthesis mutants allowed us to identify a mixture of nine amphibactin forms produced by this bacterium. In addition, the gene abtA is predicted to encode the ferri-amphibactin outer membrane transporter. The prevalence of the amphibactin system in bivalve hemolymph microbiota was also studied. We found that the amphibactin system is widespread in hemolymph microbiota including both commensal and pathogenic bacterial species. Thus, its contribution to bacterial fitness must be more related to environmental persistence than to pathogenicity.

Draft Genome Sequence of Vibrio ostreicida Strain PP-203, the Type Strain of a Pathogen That Infects Bivalve Larvae.

Vibrio ostreicida is a Gram-negative gammaproteobacterium that has been shown to cause disease in bivalve larvae. Presented here is the draft genome of the type strain Vibrio ostreicida strain PP-203, which was isolated from the inner surface of an Ostrea edulis (European flat oyster) spat container with recorded deaths at a hatchery in Galicia, Spain.

Polimorfismos en los genes MTHFR e IL-10 y factores de riesgo en pacientes con cáncer gástrico del municipio de San José de Cúcuta, Colombia / Polymorphisms in MTHFR and IL-10 Genes and Risk Factors in Patients with Gastric Cancer in the Municipality of San José de Cúcuta, Colombia

Introducción: el cáncer gástrico es una de las neoplasias de mayor interés en el mundo por su incidencia y mortalidad asociada. Se consideran tres factores relacionados con la ocurrencia del carcinoma gástrico: infección por Helicobacter pylori, susceptibilidad genética del huésped y factores ambientales. Objetivo: evaluar los polimorfismos C677T, A592C y T819C y factores de riesgo en pacientes con cáncer gástrico del municipio San José de Cúcuta. Métodos: aplicación de encuestas para detectar factores de riesgo, determinación de infección por Helicobacter pylori, genotipificación de polimorfismos mediante PCR-RFLP y análisis estadístico. Resultados: el análisis de factores de riesgo en los pacientes del grupo de casos mostró un consumo de tabaco, alcohol, y sal en el 68,8%, e infección por Helicobacter pylori de 75%; se determinó que el 68,8% tenían antecedentes familiares de cáncer y el 75% enfermedades gástricas preexistentes. El grupo control presentó un consumo de alcohol y tabaco inferior al de los pacientes del grupo de casos, alto consumo de verduras (64%) y valor similar de infección por Helicobacter pylori (80%). El análisis del polimorfismo C677T mostró mayor frecuencia en los pacientes del grupo de casos y grupo control para el alelo salvaje; los polimorfismos A592C y T819C presentaron mayor frecuencia del alelo mutado en los pacientes del grupo de casos y grupo control. El polimorfismo C677T no evidenció asociación significativa con la probabilidad de cáncer gástrico. Los polimorfismos A592C y T819C no registraron diferencias significativas entre los pacientes del grupo de casos y grupo control. Conclusión: aunque no se observaron diferencias significativas en las variantes genéticas, al evaluar los factores ambientales se detectaron distintos patrones entre los pacientes del grupo de casos y grupo control, lo cual probablemente explicaría la ausencia de la enfermedad en individuos sanos.

Introduction: gastric cancer is one of more concern neoplasms around the world due to its incidence and associated mortality. Helicobacter pylori infection, host genetic susceptibility and environmental factors are considered the causes of gastric carcinoma occurrence. Objective: to evaluate the C677T, A592C and T819C polymorphisms and risk factors in patients with gastric cancer in the municipality of San José de Cúcuta. Methods: application of surveys for determining risk factors, detection of serologic response to H. pylori infection, genotyping of polymorphisms using PCR-RFLP and statistical analysis. Results: the analysis of risk factors in the cases showed consumption of tobacco, alcohol, and salt in 68.8% and H. pylori infection in 75% of cases; 68.8% had a family history of cancer and 75% had preexisting gastric disease. The control population had lower consumption of alcohol and tobacco comparing to the cases group, high consumption of vegetables (64%) and similar value of H. pylori infection (80%). Analysis of the C677T polymorphism revealed predominance of the wild-type allele in both cases and controls with no evidence of association with the developing of gastric cancer; the polymorphisms A592C and T819C presented higher frequency of the mutated allele in both groups, with no significant differences between cases and controls. Conclusions: although no significant differences were observed in the genetic variants, different patterns were detected between cases and controls regarding the evaluation of environmental factors, which would probably explain the absence of the disease in healthy individuals.

Polimorfismos en los genes MTHFR e IL-10 y factores de riesgo en pacientes con cáncer gástrico del municipio de San José de Cúcuta, Colombia / Polymorphisms in MTHFR and IL-10 Genes and Risk Factors in Patients with Gastric Cancer in the Municipality of San José de Cúcuta, Colombia

Introducción: el cáncer gástrico es una de las neoplasias de mayor interés en el mundo por su incidencia y mortalidad asociada. Se consideran tres factores relacionados con la ocurrencia del carcinoma gástrico: infección por Helicobacter pylori, susceptibilidad genética del huésped y factores ambientales.Objetivo: evaluar los polimorfismos C677T, A592C y T819C y factores de riesgo en pacientes con cáncer gástrico del municipio San José de Cúcuta.Métodos: aplicación de encuestas para detectar factores de riesgo, determinación de infección por Helicobacter pylori, genotipificación de polimorfismos mediante PCR-RFLP y análisis estadístico.Resultados: el análisis de factores de riesgo en los pacientes del grupo de casos mostró un consumo de tabaco, alcohol, y sal en el 68,8 por ciento, e infección por Helicobacter pylori de 75 por ciento; se determinó que el 68,8 por ciento tenían antecedentes familiares de cáncer y el 75 por ciento enfermedades gástricas preexistentes. El grupo control presentó un consumo de alcohol y tabaco inferior al de los pacientes del grupo de casos, alto consumo de verduras (64 por ciento) y valor similar de infección por Helicobacter pylori (80 por ciento). El análisis del polimorfismo C677T mostró mayor frecuencia en los pacientes del grupo de casos y grupo control para el alelo salvaje; los polimorfismos A592C y T819C presentaron mayor frecuencia del alelo mutado en los pacientes del grupo de casos y grupo control. El polimorfismo C677T no evidenció asociación significativa con la probabilidad de cáncer gástrico. Los polimorfismos A592C y T819C no registraron diferencias significativas entre los pacientes del grupo de casos y grupo control.Conclusión: aunque no se observaron diferencias significativas en las variantes genéticas, al evaluar los factores ambientales se detectaron distintos patrones entre los pacientes del grupo de casos y grupo control, lo cual probablemente explicaría la ausencia de la enfermedad en individuos sanos.(AU)

Introduction: gastric cancer is one of more concern neoplasms around the world due to its incidence and associated mortality. Helicobacter pylori infection, host genetic susceptibility and environmental factors are considered the causes of gastric carcinoma occurrence.Objective: to evaluate the C677T, A592C and T819C polymorphisms and risk factors in patients with gastric cancer in the municipality of San José de Cúcuta.Methods: application of surveys for determining risk factors, detection of serologic response to H. pylori infection, genotyping of polymorphisms using PCR-RFLP and statistical analysis.Results: the analysis of risk factors in the cases showed consumption of tobacco, alcohol, and salt in 68.8 percent and H. pylori infection in 75 percent of cases; 68.8 percent had a family history of cancer and 75 percent had preexisting gastric disease. The control population had lower consumption of alcohol and tobacco comparing to the cases group, high consumption of vegetables (64 percent) and similar value of H. pylori infection (80 percent). Analysis of the C677T polymorphism revealed predominance of the wild-type allele in both cases and controls with no evidence of association with the developing of gastric cancer; the polymorphisms A592C and T819C presented higher frequency of the mutated allele in both groups, with no significant differences between cases and controls.Conclusions: although no significant differences were observed in the genetic variants, different patterns were detected between cases and controls regarding the evaluation of environmental factors, which would probably explain the absence of the disease in healthy individuals.(AU)