Résumé : As the emergence of new vibriosis in the European Atlantic coasts has been associated with mass mortalities of molluscs cuasing important economic losses, the project obectives are to provide knowledge and operational tools to evaluate the impact of vibriosis on farmed japenese oyster Crassostrea gigas. Facing the diversity of Vibrio species associated to bivalve disease outbreaks, the difficulties of identification and the detemrination of their pathogenic abilities we propose a double approach to correlate phenotype/geneotype of a bacteria with risk of disease : 1) by genotyping we will evaluate if specific strains are associated with disease. 2) by evaluating likely virulence mechanisms implicated in pathogenesis, we will characterise the genes involved. Therefore, new diagnostic test should be used in an epizootiological study to evaluate the importance of these emerging pathogens in farmed bivalves and will be supplied for further exploitation in aquaculture.
Les vibrioses sont les infections bactériennes les plus courantes chez les espèces marines d'intérêt aquacole. Certaines espèces sont pathogènes et ont été associées à d'importantes pertes économiques pour l'industrie aquacole dans le monde. L'objectif principal de mon projet de recherche est de développer des outils diagnostiques pertinents permettant d'évaluer l'impact des vibrioses dans des élevages d'huîtres creuses Crassostrea gigas. Le problème majeur est l'extraordinaire diversité des espèces appartenant à ce genre bactérien, compliquant considérablement leur caractérisation en terme de spéciation et de virulence. Nous développons une double approche pour corréler le phénotype et le génotype de pathogènes potentiels par : 1) une clarification taxonomique des souches de vibrions nous déterminons si certaines espèces sont systématiquement associées à de maladies; 2) une caractérisation des mécanismes de virulence, nous recherchons les gènes supports de la pathogénie. Les marqueurs génétiques ou de virulence mis au point pourront alors être utilisés pour une étude épidémiologique de ces maladies.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2004/these-3699.pdf
http://archimer.ifremer.fr/doc/00000/3699/

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Dairy working increases the prevalence of lower airway respiratory diseases, especially COPD and asthma. Epidemiological studies have reported that chronic inhalation of organic dusts released during specific daily tasks could represent a major risk factor for development of these pathologies in dairy workers. Knowledge on size, nature and biological activity of such organic dusts remain however limited. OBJECTIVE: To compare size distribution, microbial composition and cellular effects of dusts liberated by the spreading of straw bedding in five French dairy farms located in Brittany. RESULTS: Mechanized distribution of straw bedding generated a cloud of inhalable dusts in the five dairy farms' barns. Thoracic particles having a 3-7.5µm size constituted 58.9-68.3% of these dusts. Analyses of thoracic dusts by next generation sequencing showed that the microbial dust composition differed between the five French farms, although Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria represent more than 97.5% of the bacterial phyla detected in each sample. Several bacteria genera comprising of human pathogenic species, such as Pseudomonas, Staphylococcus, Thermoactinomyces or Saccharopolyspora were identified. Cladosporium and Alternaria fungal genera, which are potent environmental determinants of respiratory symptoms, were detected in dusts collected in the five farms and their levels reached 15.5-51.1% and 9-24.7% of assignable fungal sequences in each sample, respectively. Finally, all dust samples significantly and strongly increased the expression of the pro-inflammatory TNF-α, IL-1β, IL-6 and IL-8 cytokines at both mRNA and protein levels in human monocyte-derived macrophages. Their effects were dose-dependent and detectable from 1µg/ml. The intensity of the macrophage responses however differed according to the samples. CONCLUSIONS: Our results strengthen the hypothesis that organic dusts released during the distribution of straw bedding are mainly constituted of thoracic particles which are small enough to deposit on lower bronchial epithelium of dairy farmers and induce inflammation.
Environmental Research

hal-01579610
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01579610
DOI : 10.1016/j.envres.2017.07.025
PUBMED : 28735230

Éditeur(s) : Elsevier
Résumé : In May 1997, some white lesions evoking the white spot syndrome disease were observed in Litopenaeus stylirostris broodstock in New Caledonia. The occurrence of these lesions was neither associated with mortality, nor with histological evidence of white spot syndrome baculovirus (WSBV), The evidence suggests that these lesions result from a form of bacterial disease and are associated with an increased bacterial flora on the outer surface of the cuticle, as well as an increased incidence throughout the molt cycle. A microscopic observation of these lesions allows them to be differentiated from WSBV-associated lesions.
Aquaculture (0044-8486) (Elsevier), 2000-03 , Vol. 183 , N. 1-2 , P. 25-30

Droits : 2000 Elsevier Science B.V. All rights reserved
http://archimer.ifremer.fr/doc/2000/publication-373.pdf
DOI:10.1016/S0044-8486(99)00284-7
http://archimer.ifremer.fr/doc/00000/373/

Éditeur(s) : HAL CCSD
Résumé : International audience
In French Guiana, located on the northeastern coast of South America, bats of different species are very numerous. The infection of bats and their ticks with zoonotic bacteria, especially Rickettsia species, is so far unknown. In order to improve knowledge of these zoonotic pathogens in this French overseas department, the presence and diversity of tick-borne bacteria was investigated with molecular tools in bat ticks. In the beginning of 2013, 32 bats were caught in Saint-Jean-du-Maroni, an area close to the coast of French Guiana, and the ticks of these animals were collected. A total of 354 larvae of Argasidae soft ticks (Ornithodoros hasei) from 12 bats (Noctilio albiventris) were collected and 107 of them were analysed. DNA was extracted from the samples and quantitative real-time PCR was carried out to detect Rickettsia spp., Bartonella spp., Borrelia spp. and Coxiella burnetii. All tested samples were negative for Bartonella spp., Borrelia spp. and Coxiella burnetii. Rickettsia DNA was detected in 31 (28.9%) ticks. An almost entire (1118 base pairs long) sequence of the gltA gene was obtained after the amplification of some positive samples on conventional PCR and sequencing. A Bayesian tree was constructed using concatenated rrs, gltA, ompA, ompB, and gene D sequences. The study of characteristic sequences shows that this Rickettsia species is very close (98.3-99.8%) genetically to R. peacockii. Nevertheless, the comparative analysis of sequences obtained from gltA, ompA, ompB, rrs and gene D fragments demonstrated that this Rickettsia is different from the other members of the spotted fever group. The sequences of this new species were deposited in GenBank as Candidatus Rickettsia wissemanii. This is the first report showing the presence of nucleic acid of Rickettsia in Ornithodoros hasei ticks from South American bats. (C) 2016 Elsevier GmbH. All rights reserved.
TICKS AND TICK-BORNE DISEASES

hal-01459758
https://hal.archives-ouvertes.fr/hal-01459758
DOI : 10.1016/j.ttbdis.2016.09.004

Éditeur(s) : Wiley-blackwell
Résumé : Aims To describe the diversity of the culturable mesophilic and potentially pathogenic vibrios isolated at 22 and 37 degrees C on TCBS medium, in September 2009 from seawater and surface sediments. Methods and Results q-PCR assays previously selected for the identification of bacterial strains isolated at 37 degrees C were used in combination with the partial sequencing of two housekeeping genes, pyrH and toxR, to identify 315 strains isolated at 22 degrees C. The great majority of the 37 degrees C strains was identified by q-PCR assays, (five of the six species) with the predominance of Vibrio alginolyticus (85 center dot 9%) and V.harveyi (10 center dot 7%). The human pathogens V.parahaemolyticus and V.cholerae were rarely detected (two strains each). The 22 degrees C strains were successfully identified by the phylogeny analysis of pyrH and toxR genes, revealing 20 Vibrio species, with the predominance of the clam pathogen V.celticus (36 center dot 8%). The Splendidus and the Harveyi groups represented the main Vibrio group at 22 degrees C (80%) and 37 degrees C (99 center dot 5%), respectively. Conclusions The combination of q-PCR assays and the sequencing of pyrH and toxR genes highlighted two different Vibrio communities at 22 and 37 degrees C both dominated by pathogenic species for marine organisms. Significance and Impact of the Study The sequencing of the pyrH gene revealed to be a valuable tool to identify environmental Vibrio spp. strains isolated at 22 degrees C, as 92 center dot 3% of them were identified in this study.
Journal Of Applied Microbiology (1364-5072) (Wiley-blackwell), 2013-06 , Vol. 114 , N. 6 , P. 1713-1724

Droits : 2013 The Society for Applied Microbiology
http://archimer.ifremer.fr/doc/00144/25502/24832.pdf
DOI:10.1111/jam.12181
http://archimer.ifremer.fr/doc/00144/25502/

Éditeur(s) : Agro Paris Tech
Résumé : P. acidilactici MA 18/5M is a dietary probiotic (BACTOCELL®) which has shown its efficiency on several terrestrial and aquatic species. The present thesis aimed to investigate more fully the effects of this probiotic on cultured penaeid shrimps. For this study, we chose a global approach by replacing the problem studied in a model of interactions between three compartments: the shrimp, its intestinal microflora and the probiotic. Having first defined how the probiotic should be administrated, we studied its effects under controlled laboratory conditions at several levels of Litopenaeus stylirostris biology: (i) Nutritional status and growth, (ii) associated bacterial microflora, and (iii) health status with respect to oxidative stress. Then the probiotic improves the growth of the shrimps and the feed conversion ratio. Our study shows that these effects are partially due to a better use of the feed, particularly of dietary carbohydrates, but also suggest an action on the metabolism, andor on the growth via a contribution of essential nutrients. On the other hand, although the intestinal bacterial communities seems little affected, we show an antagonism effect of the probiotic toward total and vibrionacea intestinal flora, as well as a decrease in the level of infection of shrimps during challenge with pathogenic V. nigripulchritudo. Beside, our works highlight that infection by this pathogen, led to a reduction in antioxidant defences, to a rise in oxidative damages, and to a release of mortalities within 48 hours. This oxidative stress following bacterial infection was better controlled by animals receiving the probiotic diet, and resistance of the shrimps to infection was significant improved. A nutritional hypothesis is proposed to explain such result, hypothesis based on a link between carbohydrate metabolism and antioxidant status. As a conclusion of these works, we can propose a first explanatory scenario for the effects of P. acidilactici on a penaeid shrimp. Finally probiotic's effects were assessed under a pilot scale in a commercial farm from New Caledonia currently affected by the "summer syndrome ". We confirm the improvements brought in term of zootechnical results, with in particular, a better resistance to this syndrome. This work was made possible thanks to a breeding method in floating cages, developed during this thesis, and therefore transferred, as an experimental tool, to the shrimp industry of New Caledonia.
Pediococcus acidilacticii MA18/5M est un probiotique bactérien (BACTOCELL®) qui a démontré son efficacité chez plusieurs espèces d'animaux terrestres et aquatiques. Cette thèse avait pour objectif d'investiguer plus en détails les effets de ce probiotique chez les crevettes pénéides d'élevage. Pour cette étude, nous avons choisi une approche globale replaçant la problématique dans un modèle d'interactions entre trois compartiments : la crevette, sa microflore intestinale et le probiotique. Après avoir défini les modalités d'administration, l'effet de P. acicilactici a été étudié, en conditions de laboratoire, chez la crevette Litopenaeus stylirostris, à différents niveaux: (i) statut nutritionnel et croissance, (ii) microflore bactérienne associée, et (iii) santé de l'animal à travers son statut antioxydant et son niveau de stress oxydant. Ainsi, le probiotique améliore la croissance des crevettes et l'indice de conversion de l'aliment. Notre étude montre que ces effets sont en partie liés à une meilleure utilisation de l'aliment, notamment des carbohydrates alimentaires, mais suggèrent aussi une action sur le métabolisme, et/ou sur la croissance via un apport de nutriments essentiels. D'autre part, bien que les communautés bactériennes intestinales semblent peu affectées, un effet d'antagonisme du probiotique vis-à-vis de la flore intestinale totale et vibrionacée a été montré, ainsi qu'une réduction du niveau d'infection des crevettes au cours de challenge avec le pathogène V. nigripulchritudo. Par ailleurs, nous mettons en évidence que l'infection par ce pathogène, conduit à un abaissement des défenses antioxydantes, à une élévation des dégâts oxydatifs, et au déclenchement de mortalités dans les 48 heures. Le probiotique atténue le niveau de ce stress oxydant, et améliore significativement la résistance des crevettes à l'infection. Une hypothèse nutritionnelle est proposée afin d'expliquer ce résultat, hypothèse reposant sur un lien entre le métabolisme des carbohydrates et le statut antioxydant. A l'issue de ces travaux, nous pouvons alors proposer un premier scénario explicatif des effets de P. acidilactici chez une crevette pénéide. Finalement le probiotique a été éprouvé à l'échelle pilote sur une ferme commerciale de Nouvelle-Calédonie affectée par le « syndrome d'été ». Nous confirmons les améliorations apportées en termes de résultats zootechniques, avec notamment une meilleure résistance au syndrome. Ce travail a été réalisé grâce une méthode d'élevage en cages flottantes, mis au point au cours de cette thèse, et qui a dés lors été transférée, comme outil expérimental, à la filière crevetticole Calédonienne.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2009/these-6814.pdf
http://archimer.ifremer.fr/doc/00000/6814/

Éditeur(s) : Public Library Science
Résumé : Global change and its associated temperature increase has directly or indirectly changed the distributions of hosts and pathogens, and has affected host immunity, pathogen virulence and growth rates. This has resulted in increased disease in natural plant and animal populations worldwide, including scleractinian corals. While the effects of temperature increase on immunity and pathogen virulence have been clearly identified, their interaction, synergy and relative weight during pathogenesis remain poorly documented. We investigated these phenomena in the interaction between the coral Pocillopora damicornis and the bacterium Vibrio coralliilyticus, for which the infection process is temperature-dependent. We developed an experimental model that enabled unraveling the effects of thermal stress, and virulence vs. non-virulence of the bacterium. The physiological impacts of various treatments were quantified at the transcriptome level using a combination of RNA sequencing and targeted approaches. The results showed that thermal stress triggered a general weakening of the coral, making it more prone to infection, non-virulent bacterium induced an 'efficient' immune response, whereas virulent bacterium caused immuno-suppression in its host.
Plos One (1932-6203) (Public Library Science), 2014-09 , Vol. 9 , N. 9 , P. 1-15

Droits : This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.
http://archimer.ifremer.fr/doc/00221/33265/31738.pdf
DOI:10.1371/journal.pone.0107672
http://archimer.ifremer.fr/doc/00221/33265/

Éditeur(s) : Springer
Résumé : Two recurring syndromes threaten the viability of the shrimp industry in New Caledonia, which represents the second largest export business. The "Syndrome 93" is a cold season disease due to Vibrio penaeicida affecting all shrimp farms, while the "Summer Syndrome" is a geographically restricted vibriosis caused by a virulent lineage of Vibrio nigripulchritudo. Microbiological procedures for diagnosis of these diseases are time-consuming and do not have the ability to discriminate the range of virulence potentials of V. nigripulchritudo. In this study, we developed a multiplex PCR method to simultaneously detect these two bacterial species and allow for pathotype discrimination. The detection limits of this assay, that includes an internal amplification control to eliminate any false-negative results, were determined at 10 pg purified DNA and 200 cfu/ml. After confirming the effectiveness of our method using experimentally infected animals, its accuracy was compared to standard biochemical methods during a field survey using 94 samples collected over 3 years from shrimp farms encountering mortality events. The multiplex PCR showed very high specificity for the detection of V. penaeicida and V. nigripulchritudo (inclusivity and exclusivity 100%) and allowed us to detect the spreading of highly pathogenic isolates of V. nigripulchritudo to a farm adjoining the "Summer Syndrome area." This assay represents a simple, rapid, and cost-effective diagnostic tool for implementing timely risk management decisions but also understanding the seasonal and geographical distribution of these pathogens.
Microbial Ecology (0095-3628) (Springer), 2012-01 , Vol. 63 , N. 1 , P. 127-138

Droits : Springer Science+Business Media, LLC 2011
http://archimer.ifremer.fr/doc/00063/17398/15169.pdf
DOI:10.1007/s00248-011-9951-3
http://archimer.ifremer.fr/doc/00063/17398/

Éditeur(s) : Elsevier
Résumé : In a previous study, we demonstrated the existence of an emerging cluster of Vibrio nigripulchritudo that proved to be associated with shrimp mortality events in New Caledonia. Using sequence polymorphisms evidenced in this previous MultiLocus Sequence Typing study, we developed two new quantitative PCR assays permitting the detection and quantification of V. nigripulchritudo at the genospecies level using SYBR Green I chemistry and at the emerging cluster level using Fluorescence Resonance Energy Transfer technology with hybridization probes. The use of this molecular diagnostic tool evidenced the colonization of the shrimp pond ecosystem by the pathogenic cluster at least at the onset of the disease. This new tool will allow better investigation of the dynamics of this bacterial pathogen in the shrimp farm ecosystem. (C) 2007 Elsevier B.V. All rights reserved.
Journal of Microbiological Methods (0167-7012) (Elsevier), 2007-07 , Vol. 70 , N. 1 , P. 30-38

Droits : 2007 Elsevier B.V. All rights reserved
http://archimer.ifremer.fr/doc/2007/publication-2729.pdf
DOI:10.1016/j.mimet.2007.03.007
http://archimer.ifremer.fr/doc/00000/2729/

Éditeur(s) : Colloque IMBC - International Marine Biotechnology Conference
Résumé : Since 1997, a new pathology seasonally occurs in new caledonian shrimp farms during the warm season. Diseased Litopenaeus stylirostris shrimp suffer from a systemic vibriosis which was attributed to highly pathogenic Vibrio nigripulchritudo. At the present time, only two farms among 17 are affected by the so called "summer syndrome". In such a context it appears urgent to develop reliable diagnostic tools to detect V. nigripulchritudo strains and to differentiate highly virulent strains from non virulent ones in order to understand the mechanisms of infection and overcome disease spreading. Multilocus Sequencing Typing (MLST) analysis on 24 bacterial strains isolated in geographically distinct shrimp farms highlighted the existence of a cluster A containing only strains displaying moderate to high virulence. Since experimental infection procedure for virulence status determination is material intensive and time consuming, and MLST method not accurate enough to inform on the virulence status of strains, it appeared of great interest to develop other diagnostic tools. Two phylogenetically closed strains, one highly virulent SFn1 and the other non-virulent SFn118 were selected in order to characterize genes specific of the virulent strain by Substractive Suppression Hybridization (SSH). Firstly, a total of 622 DNA fragments specific of SFn1 were sequenced, characterized and further used as probes in a DNA macroarray. Testing 24 strains, hybridization profiles were found to be strongly correlated with both MLST genotypes and bacterial virulence status. A total of 96 representative probes were secondly selected to validate macroarray results on 34 more additionnal strains, allowing identification of genetic markers of virulence. Most of DNA fragments specific of highly virulent strains associated to summer syndrome were found to be bore by a plasmid successfully isolated in the laboratory. In next future, these results would permit the development of relevant diagnostic tools useful for accurate epidemiological survey of the summer syndrome.

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2007/acte-3398.pdf
http://archimer.ifremer.fr/doc/00000/3398/

Éditeur(s) : HAL CCSD Wiley
Résumé : International audience
Analysis of microbial biodiversity is hampered by a lack of reference genomes from most bacteria, viruses, and algae. This necessitates either the cultivation of a restricted number of species for standard sequencing projects or the analysis of highly complex environmental DNA metagenome data. Single-cell genomics (SCG) offers a solution to this problem by constraining the studied DNA sample to an individual cell and its associated symbionts, prey, and pathogens. We used SCG to study marine heterotrophic amoebae related to Paulinella ovalis (A. Wulff) P.W. Johnson, P.E. Hargraves & J.M. Sieburth (Rhizaria). The genus Paulinella is best known for its photosynthetic members such as P.chromatophora Lauterborn that is the only case of plastid primary endosymbiosis known outside of algae and plants. Here, we studied the phagotrophic sister taxa of P.chromatophora that are related to P.ovalis and found one SCG assembly to contain -cyanobacterial DNA. These cyanobacterial contigs are presumably derived from prey. We also uncovered an associated cyanophage lineage (provisionally named phage PoL_MC2). Phylogenomic analysis of the fragmented genome assembly suggested a minimum genome size of 200Kbp for phage PoL_MC2 that encodes 179 proteins and is most closely related to Synechococcus phage S-SM2. For this phage, gene network analysis demonstrates a highly modular genome structure typical of other cyanophages. Our work demonstrates that SCG is a powerful approach for discovering algal and protist biodiversity and for elucidating biotic interactions in natural samples.
ISSN: 0022-3646

hal-01544797
https://hal.archives-ouvertes.fr/hal-01544797
DOI : 10.1111/jpy.12028

Éditeur(s) : Elsevier Science Bv
Résumé : In New Caledonia, shrimp hatcheries are confronted with mass mortality in the larval stages, a phenomenon poorly understood as no specific causative agent has been identified. This has resulted in an excessive use of prophylactic antibiotics, although their adverse effects in aquaculture are notorious. The present work was thus aimed at selecting potential probiotic strains for penaeid hatcheries. From a pool of more than 400 marine bacterial isolates sampled from the local marine environment seven strains exhibited in vitro antagonistic activity towards Vibrio harveyi. These isolates were characterized both phenotypically and genotypically using a biochemical approach and 16S rDNA sequencing. Six out of these seven strains were found to belong to the genus Pseudoalteromonas, the last one belonging to the Vibrionaceae family and related to the Harveyi clade. Selected probiotic candidates were individually tested for antagonistic activities in vitro using a green fluorescent protein (GFP)-labelled transconjugant of V. harveyi and for inherent pathogenicity towards cultured shrimp larvae at two different developmental stages. This approach enabled rapid processing and selection of candidates to be tested in our experimental hatchery. Four different experiments were conducted to test candidate strains either alone or in combination. Repeated trials showed that postlarval survival was significantly improved by adding the strain NC201 individually to the rearing water compared to unchallenged controls. The analysis of immune-related gene expressions showed that the Litsty PEN3 transcript abundance of larvae was significantly increased after being reared in probiotic-containing water; however no significant difference in lysozyme gene expression was recorded in this study. Together, these results open new insights into the use of these strains as potential substitutes to antibiotherapy in shrimp larval rearing in New Caledonia.
Aquaculture (0044-8486) (Elsevier Science Bv), 2014-08 , Vol. 432 , P. 475-482

Droits : 2014 Elsevier B.V. All rights reserved.
http://archimer.ifremer.fr/doc/00190/30129/28591.pdf
DOI:10.1016/j.aquaculture.2014.04.031
http://archimer.ifremer.fr/doc/00190/30129/

Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd
Résumé : Antioxidant defences and induced oxidative stress tissue damage of the blue shrimp Litopenaeus stylirostris, under challenge with Vibrio nigriputchritudo, were investigated for a 72-h period. For this purpose, L stylirostris were first infected by immersion with pathogenic V. nigripulchritudo strain SFn1 and then antioxidant defences: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (Gpx), Total antioxidant status (TAS), glutathiones and induced tissue damage (MDA and carbonyl proteins) were determined in the digestive gland at 0, 12, 24, 48 and 72 h post-infection (h.p.i.). In the meantime, TAS was also measured in the blood. Infection level of the shrimps during the challenge was followed by determining V. nigripulchritudo prevalence and load in the haemolymph of the shrimps. Changes in all these parameters during the 72-h.p.i. period were recorded for control shrimps and shrimps previously fed for one month with probiotic Pediococcus aciditactici MA18/5M at 10(7) CFU g(-1) of feed. Our results showed that immersion with V nigripulchritudo led to maximal infection level in the haemolymph at 24 h.p.i. preceding the mortality peak recorded at 48 h.p.i. Significant decreases in the antioxidant defences were detected from 24 h.p.i. and beyond that time infection leaded to increases in oxidative stress level and tissue damage.. Compared to control group, shrimps fed the probiotic diet showed lower infection (20% instead of 45% at 24 h.p.i. in the control group) and mortality (25% instead of 41.7% in the control group) levels. Moreover, infected shrimp fed the probiotic compared to uninfected control shrimps exhibited very similar antioxidant status and oxidative stress level. Compared to the infected control group, shrimps fed the probiotic sustained higher antioxidant defences and lower oxidative stress level. This study shows that bacterial infection leads to oxidative stress in L. stylirostris and highlighted a beneficial effect of P. acidilactici, suggesting both a competitive exclusion effect leading to a reduction of the infection level and/or an enhancement of the antioxidant status of the shrimps. (C) 2010 Elsevier Ltd. All rights reserved.
Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2010-04 , Vol. 28 , N. 4 , P. 622-631

Droits : 2010 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00003/11419/7984.pdf
DOI:10.1016/j.fsi.2009.12.024
http://archimer.ifremer.fr/doc/00003/11419/

Résumé : Les bactéries appartenant au genre Vibrio sont largement répandues en milieu côtier tropical et tempéré. Certaines espèces sont pathogènes pour l'homme, comme Vibrio cholerae 01 et 0139 responsables du choléra, ou V. cholerae non-01/non-0139, V. parahaemolyticus et V. vulnificus impliqués dans de nombreuses pathologies (gastro-entérites, des septicémies et autres infections). En France, le risque associé à la présence de vibrions en milieu marin est mal évalué. Ce rapport fait le bilan des données disponibles sur la contamination littorale et les infections à vibrions en France. Une large place a été consacrée aux études écologiques, réalisées sur les sites d'implantation des centrales nucléaires sur le littoral français. Dans la population, le nombre d'infections est restreint car seules les pathologies graves sont recensées. Il s'agit de cas isolés, le plus souvent immuno-déprimés, enregistrés en été et en automne. Le milieu marin (par contact, baignade ou consommation de produits de la mer) est très souvent cité comme source probable de la contamination. Un petit nombre d'espèces de vibrions est concerné (V. alginolyticus, V. vulnificus, V. parahaemolyticus, V. cholerae non-01/non-0139 et V. hollisae). Dans l'environnement marin, l'espèce dominante est V. alginolyticus ; V. vulnificus et V. parahaemolyticus sont détectés sporadiquement. Le suivi, pendant plus de dix ans, des effets d'un réchauffement artificiel des eaux littorales à Gravelines a souligné des modifications sur les populations de Vibrio marins (présence des Vibrio en hiver, augmentation de la densité bactérienne et de la diversité spécifique). Le développement de techniques de biologie moléculaire devrait permettre une meilleure évaluation du risque sanitaire en quantifiant et en caractérisant les vibrions présents en milieu côtier (stade viable non cultivable, maintien du pouvoir pathogène et virulence des souches présentes).

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/00104/21545/19124.pdf
DOI:Ifremer 2002
http://archimer.ifremer.fr/doc/00104/21545/

Éditeur(s) : HAL CCSD Hindawi Publishing Corporation
Résumé : International audience
HLA-G is a nonclassical major histocompatibility complex molecule first described at the maternal-fetal interface, on extravillous cytotrophoblasts. Its expression is restricted to some tissues in normal conditions but increases strongly in pathological conditions. The expression of this molecule has been studied in detail in cancers and is now also beginning to be described in infectious diseases. The relevance of studies on HLA-G expression lies in the well known inhibitory effect of this molecule on all cell types involved in innate and adaptive immunity, favoring escape from immune control. In this review, we summarize the features of HLA-G expression by type of infections (i.e, bacterial, viral, or parasitic) detailing the state of knowledge for each pathogenic agent. The polymorphism, the interference of viral proteins with HLA-G intracellular trafficking, and various cytokines have been described to modulate HLA-G expression during infections. We also discuss the cellular source of HLA-G, according to the type of infection and the potential role of HLA-G. New therapeutic approaches based on synthetic HLA-G-derived proteins or antibodies are emerging in mouse models of cancer or transplantation, and these new therapeutic tools may eventually prove useful for the treatment of infectious diseases.
ISSN: 2314-8861

hal-01063925
https://hal.archives-ouvertes.fr/hal-01063925
https://hal.archives-ouvertes.fr/hal-01063925/document
https://hal.archives-ouvertes.fr/hal-01063925/file/Immunomodulatory%20Properties%20of%20HLA-G.pdf
DOI : 10.1155/2014/298569

Résumé : The New-Caledonian shrimp industry is based on the controlled reproduction of the shrimp Litopenaeus stylirostris, a species which was introduced in the 80s. The major difficulty to which the industry has been faced for 10 years is the occurrence of the "syndrome 93", which corresponds to mortality phases when the temperature falls down in April-May-June. This mortality is associated to the pathogenic bacteria Vibrio penaecida and is expressed at different levels which are variable from year ta year and from pond to pond. No resistance to this pathology has been developed spontaneously. This is likely due to the protocole used to rear spawners, which does not allow to implement an efficient selective pressure at each generation An experimental selection on the criteria of survival after picks of syndrome 93 has been conducted at the Laboratoire Aquacole de Calédonie. The 3rd selected generation demonstrates survival rates improved by 20% during experimental infections with V. penaeicida in comparison with a non selected control population of same genetic origin. The comparison of the correlated responses on the level of expression of 5 genes which are potentially implicated in immunity phenomena (Peneidins, lysozyme, transglutaminase. profiline, annexine) shows that the selected population has a level of expression in lyzozyme twice higher than the control population. This result suggests that the lysozyme could be a genetic marker which could be used in a selective breeding program to he developed in relation with the private hatcheries.
La filière crevette de Nouvelle-Calédonie repose sur la maîtrise de la reproduction contrôlée de la crevette Litopenaeus stylirostris, espèce introduite dans les années 80. La difficulté majeure que rencontre la filière depuis une dizaine d'années est la récurrence du « syndrome 93 », qui correspond à des épisodes de mortalités lors des baisses de température en avril-mai-juin. Ces mortalités sont associées à la bactérie pathogène Vibrio penaeicida et s'expriment à des niveaux d'intensité variable d'une année à l'autre et d'un bassin à l'autre. Aucune résistance vis-à-vis de cette pathologie ne s'est développée spontanément. Ceci est vraisemblablement lié au protocole employé pour l'élevage des géniteurs qui ne permet pas d'exercer une pression de sélection efficace à chaque génération. Une expérience de sélection sur un critère de survie à des épisodes de syndrome 93 a été menée au Laboratoire Aquacole de Calédonie. La 3ème génération sélectionnée montre des survies améliorées de l'ordre de 20% lors d'infections expérimentales à V. penaeicida par rapport à une population témoin non sélectionnée de même origine génétique. La comparaison des réponses corrélées sur le niveau d'expression de 5 gènes potentiellement impliqués dans les phénomènes de défense immunitaire (penaeidine, lysozyme, transglutaminase, profiline, annexine) montre que la population sélectionnée a un niveau d'expression en lysozyme deux fois plus élevé que la population témoin. Ce résultat suggère que le lysozyme pourrait être un marqueur génétique utilisable dans un programme de sélection à développer en relation avec les écloseries de production.

Droits : 2003 Ifremer
http://archimer.ifremer.fr/doc/00109/22020/19643.pdf
http://archimer.ifremer.fr/doc/00109/22020/

Résumé : L’ingénierie agroécologique vise à produire des savoirs actionnables, pour concevoir des systèmes de cultures économiquement et écologiquement performants, par la valorisation de régulations naturelles. Notre problématique est centrée sur la santé des cultures, et plus particulièrement sur la bactérie phytopathogène Ralstonia solanacearum, agent du flétrissement bactérien alors qu’une souche extrêmement agressive menace la production de tomates en plein champ en Martinique. La nécessité d’explorer et de développer des alternatives aux méthodes conventionnelles de protection des plantes (variétés résistantes, pesticides), actuellement inefficaces, invite à la mise en œuvre d’une démarche de conception innovante. Nos travaux montrent que la mobilisation d’une barrière rhizosphérique est une stratégie de régulation biologique alternative. Différents processus y contribuent, telle que la mycorhization, symbiose entre racines et champignons mycorhiziens à arbuscules, présents dans la plupart des sols. Nous montrons que la mobilisation de réseaux de mycorhizes indigènes à partir d’un sol agricole permet une mycorhization précoce de la tomate. De plus, l’association de plantes aux propriétés mycorhizotrophes et assainissantes en conditions contrôlées montre des effets bioprotecteurs partiels et ouvre de nouvelles perspectives de combinaisons entre processus. Ces combinaisons sont mobilisables par des leviers d’actions multi-scalaires. Nous avons produit une grille d’analyse générique de ces leviers d’action pour la conception, par des trajectoires d’innovation multidirectionnelles, de « systèmes de culture bioprotégés ». Dans le contexte agricole martiniquais, une démarche d’apprentissage permet en effet l’émergence d’une dynamique de co-conception de systèmes de cultures recourant aux plantes mycorhizotrophes. Nos travaux proposent des outils pour une exploration collective de nouvelles stratégies de gestion durable de la santé des cultures.
Agroecological engineering aims to produce actionable knowledge to design economically and environmentally efficient cropping systems, based on the exploitation of natural regulation mechanisms. Our issue is centered on crop health, especially on the plant pathogenic bacterium Ralstonia solanacearum (bacterial wilt agent), of which an extremely aggressive strain threatens field tomato production in Martinique. The need to explore and develop alternatives to conventional methods of plant protection (resistant varieties, pesticides), ineffective in our case, calls for the implementation of an innovative design approach. Our work shows that the protection of the roots via the formation of a self-sustaining rhizospheric barrier may be an alternative biological control strategy. Different processes contribute, such as mycorrhizal symbiosis between roots and arbuscular mycorrhizal fungi, which are present in most soils. We show that the mobilization of indigenous mycorrhizal networks from an agricultural soil allows early mycorrhization of tomatoes. In addition, the association of plants with mycorrhizal and sanitizing properties in controlled conditions showed partial bioprotective effects and opens up new prospects for combinations between processes. These combinations may be exploited in various ways. We produced a generic analysis grid of key levers to design "healthy cropping systems " through multi-directional innovation trajectories. In Martinique's agricultural context, a learning process allows the emergence of a dynamic co-design of cropping systems using mycorrhizal plants. Our work thus provides tools for collective exploration of new sustainable management strategies for crop health.

http://www.theses.fr/2015AGUY0828/document

Éditeur(s) : Academic Press Ltd- Elsevier Science Ltd
Résumé : The understanding of reciprocal interactions between Crassostrea gigas and Vibrio sp., whether these be virulent or avirulent, is vital for the development of methods to improve the health status of cultured oysters. We describe an original non-invasive experimental infection technique using cohabitation, designed to explore these interactions. Using real-time PCR techniques we examined the dynamics of virulent and avirulent Vibrio sp. in oyster hemolymph and tank seawater, and made a parallel study of the expression of four genes involved in oyster immune defense: Cg-BPI, Cg-EcSOD, Cg-IκB, Cg-TIMP. No mortality occurred in control animals, but oysters put in cohabitation for 2–48 h with animals previously infected by two Vibrio pathogens suffered mortalities from 2 to 16 days post-cohabitation. Our results show that virulent Vibrio infect healthy individuals after only 2 h of cohabitation, with values ranging from 4.5×102 to 2×104 cells ml−1 hemolymph. Simultaneously, an approximate ten-fold increase of the total Vibrio population was observed in control animals, with a 6.6–78.5-fold up-expression of targeted genes. In contrast, oysters exposed to harmful bacteria had mean expression levels strongly down-regulated by a factor of 9.2–29 (depending on the gene) compared with control animals. Although oysters were still found to be infected by virulent Vibrio after 6–48 h of cohabitation, no significant differences were noted when comparing levels of each transcript in control and infected oysters at the same sampling times during this period: the important differences were noted before 6 h cohabitation. Taken together, our data support (1) the hypothesis that virulent Vibrio disturbs the immune response of this invertebrate host both rapidly and significantly, although this occurs specifically during an early and transient period during the first 6 h of cohabitation challenge, and that (2) expression of targeted genes is not correlated with vibriosis resistance.
Fish & Shellfish Immunology (1050-4648) (Academic Press Ltd- Elsevier Science Ltd), 2011-02 , Vol. 30 , N. 2 , P. 691-699

Droits : 2011 Elsevier Ltd All rights reserved.
http://archimer.ifremer.fr/doc/00025/13604/10681.pdf
DOI:10.1016/j.fsi.2010.12.017
http://archimer.ifremer.fr/doc/00025/13604/

Éditeur(s) : HAL CCSD Wiley
Résumé : Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699
International audience
Potato can be severely affected by various pathogens, including Pectobacterium atrosepticum, the cause of bacterial soft rot on tubers and of blackleg on stems. To date, no complete resistance to P.similar to atrosepticum is available, so that only cultivars exhibiting partial resistance can be found. The mechanistic basis of this type of resistance is still poorly understood. A proteomic approach was thus developed to identify pathways specifically activated during the interaction between potato tubers and P.similar to atrosepticum. Protein profiles on silver-stained gels in the 58 similar to pH range were obtained from healthy and infected tubers from two cultivars differing for resistance level and analyzed by 2-DE and nano-LC-MS/MS. Thirteen proteins were differentially up-regulated in the partially resistant cv. Kerpondy; by contrast, no significant differences in protein profiles of inoculated and control tubers were observed in the susceptible cv. Bintje. Mass spectrometry and database searching showed that these proteins are involved in energetic metabolism (glyceraldehyde-3-phosphate dehydrogenase, 2-phosphoglycerate dehydratase or enolase, fructose biphosphate aldolase and ATPase a subunit), cytoskeleton structure (actin), protein catabolism (cysteine protease inhibitor) and patatins or patatin precursors. Their involvement in defence responses of cv. Kerpondy to P.similar to atrosepticum is discussed. Proteomic appears as an efficient approach to have insight into the mechanisms and pathways leading to potato resistance against P.similar to atrosepticum.
ISSN: 0931-1785

hal-01208654
https://hal.archives-ouvertes.fr/hal-01208654
PRODINRA : 213002
DOI : 10.1111/j.1439-0434.2012.01950.x

Résumé : L'année 2004, année du vingtième anniversaire de sa création, aura été marquée, pour l'Ifremer, par une intense activité. 2004 a en effet été d'abord une année d'investissements et de résultats: de la biodiversité des massifs de coraux froids à la capacité des bactéries à produire des polymères biodégradables, de l'observation des effets de la crue centennale du Rhône sur les sédiments à la variabilité de l'hydrologie dans l'Atlantique Nord, de l'effet de la pluviométrie en hiver sur la mortalité estivale des huîtres à la sensibilisation environnementale des crevettes aux bactéries pathogènes, au lever par Lidar aéroporté de plus de 900 km² d'estrans de Bretagne, les résultats scientifiques ont été nombreux La technologie n'a pas été en reste avec les progrès de la protection contre la corrosion marine, les essais concluants de l'AUV, la mise à l'eau du Pourquoi pas?, ni les activités de surveillance du fait de l'augmentation des apparitions de toxines dans les coquillages. L'institut a en outre mené en 2004, avec ses ministères de tutelle, un important effort de réflexion sur ses missions et ses priorités, dont le contrat quadriennal 2005-2008, approuvéen conseil à' administration, finalisé en fin d'année et signé le 25 mai 2005 en présence de quatre ministres, trace désormais le cadre, en cohérence avec notre plan stratégique. [OCR NON CONTRÔLE]

Droits : info:eu-repo/semantics/openAccess
http://archimer.ifremer.fr/doc/2004/rapport-4830.PDF
http://archimer.ifremer.fr/doc/00000/4830/