Mélanie Gay
Anses, Food Safety Laboratory, Adjunct
Deliverable D-IA.2.2.OH-Harmony-Cap.4.3 - Technical Report: Designing and Implementation of Harmonised Protocols for the Detection and Typing of Shiga toxin-producing Escherichia coli (STEC), Enterotoxigenic Escherichia coli (ETEC), Cryptosporidium and antimicrobial resistance (AMR) in Salmonella...more
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Polyphasic analysis of four new Vibrio isolates originating from the haemolymph of diseased cultured oysters is described. The new isolates were closely related to Vibrio splendidus, having 98 % 16S rRNA gene sequence similarity.... more
Polyphasic analysis of four new Vibrio isolates originating from the haemolymph of diseased cultured oysters is described. The new isolates were closely related to Vibrio splendidus, having 98 % 16S rRNA gene sequence similarity. Phylogenetic analysis based on DNA gyrase subunit B (gyrB), RNA polymerase σ 70 factor (rpoD), replication origin-binding protein (rctB) and transmembrane regulatory protein (toxR) genes, fluorescent amplified fragment length polymorphism and DNA–DNA hybridization experiments clearly showed that the new isolates form a tight genomic group that is different from the currently known Vibrio species. It is proposed that these new isolates should be accommodated in a novel species, Vibrio gigantis sp. nov. Phenotypic features that differentiate V. gigantis from other known Vibrio species include arginine dihydrolase, gelatinase and β-galactosidase activities, NO2 production, growth at 35 °C, and utilization of sucrose, melibiose, amygdalin, glycerol, galactose, ...
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Fish are often speckled with “black spots” caused by metacercarial trematode infection, inducing a host response. Cryptocotyle spp. (Opisthorchiidae) are among the parasites responsible for this phenomenon. So far, the impact on human... more
Fish are often speckled with “black spots” caused by metacercarial trematode infection, inducing a host response. Cryptocotyle spp. (Opisthorchiidae) are among the parasites responsible for this phenomenon. So far, the impact on human health is still unknown. In addition, few publications dealing with black spot recovery, identification, distribution and diversity among commercially important fish are available. Moreover, “black spots” have been observed by fishermen on marine fish, revealing an appreciable but unquantified presence in consumed fish. An epidemiological survey of 1,586 fish from seven commercial species (herring, sprat, whiting, pout, dab, flounder, and plaice) was conducted in the Eastern English Channel and the North Sea in January 2019 and 2020. Encysted metacercariae were found in 325 out of 1,586 fish, with a total prevalence of 20.5%. Intensity of infection varied from 1 to 1,104 parasites. The recorded encysted metacercariae were identified either by microscop...
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Parasites play a key but overlooked role in the functioning of marine systems. Understanding the drivers of parasites infection in fish is thus crucial. Anisakis levels in the Atlantic horse mackerel Trachurus trachurus resulted from both... more
Parasites play a key but overlooked role in the functioning of marine systems. Understanding the drivers of parasites infection in fish is thus crucial. Anisakis levels in the Atlantic horse mackerel Trachurus trachurus resulted from both biotic and environmental drivers. Ontogenic variation of the diet was the first driver of Anisakis level. Nonlinear pattern confirmed that the variation of parasitism was related to ontogenetic dietary shifts. The impact of depth on diet also explained the effect of depth on parasites. In deeper areas, fish only access pelagic preys, where Anisakis presence is high, consistently with the pelagic nature of the parasite. Finally, relative proportions of parasitic burden by tissue appeared to be driven by lipid content. In lipid-rich species like T. trachurus, Anisakis can find favorable conditions in the body cavity and in muscle and avoid liver. Parasitism levels in fish are thus the result of patterns at play at different levels and that these fact...
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Seafood safety: new findings and innovation challenges, Brussels, 25-26 January 2017Atlantic cod (Gadus morhua) is among the commercially most important fish species on the world market. It is marketed fresh, frozen or processed.... more
Seafood safety: new findings and innovation challenges, Brussels, 25-26 January 2017Atlantic cod (Gadus morhua) is among the commercially most important fish species on the world market. It is marketed fresh, frozen or processed. Infection of the edible parts (fillets and liver) with ascaridoid nematodes has long been knownPeer reviewe
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Different methods were evaluated to extract DNA from pooled nematodes belonging to Anisakis, Contracaecum, Pseudoterranova and Hysterothylacium genera isolated from edible fish. Pooled DNA extraction is the first and compulsory step to... more
Different methods were evaluated to extract DNA from pooled nematodes belonging to Anisakis, Contracaecum, Pseudoterranova and Hysterothylacium genera isolated from edible fish. Pooled DNA extraction is the first and compulsory step to allow the identification of a large number of samples through high-throughput DNA sequencing with drastic time and cost reductions.
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Research Interests: Immune response, Ecotoxicology, Flow Cytometry, Aquatic Toxicology, Biology, and 15 moreAquaculture, Medicine, Gene expression, Biological Sciences, Environmental Sciences, Animals, Bacteria, CHEMICAL SCIENCES, In Vivo, Hemocytes, Crassostrea gigas, Enzyme activity, Cell Survival, Mortality rate, and Pacific oyster
Introduction et objectifs Les vibrions, bactéries de la famille des Vibrionaceae, sont présents naturellement dans les eaux côtières et estuariennes du monde entier et chez de nombreuses espèces de coquillages et de crustacés fréquemment... more
Introduction et objectifs Les vibrions, bactéries de la famille des Vibrionaceae, sont présents naturellement dans les eaux côtières et estuariennes du monde entier et chez de nombreuses espèces de coquillages et de crustacés fréquemment consommés en France. Certaines espèces (Vibrio parahaemolyticus, Vibrio vulnificus et Vibrio cholerae nonO1/non-O139) peuvent induire des phénomènes pathologiques chez l’Homme suite à la consommation de produits de la mer crus, insuffisamment cuits ou contaminés après cuisson. Le plan exploratoire mis en œuvre en 2019 par la Direction générale de l’Alimentation du ministère de l’Agriculture et de l’Alimentation avait pour objectif d’estimer la contamination de produits de la mer prélevés au stade de la distribution en France par ces trois espèces de Vibrio potentiellement entéropathogènes et par conséquent l’exposition potentielle des consommateurs. Matériels et méthodes Des prélèvements de mollusques bivalves vivants et de produits de la pêche ont ...
Polyphasic analysis of five new Vibrio isolates originating from the haemolymph of diseased cultured oysters is described. The new isolates were closely related to Vibrio splendidus, having 98 % 16S rRNA gene sequence similarity. gyrB... more
Polyphasic analysis of five new Vibrio isolates originating from the haemolymph of diseased cultured oysters is described. The new isolates were closely related to Vibrio splendidus, having 98 % 16S rRNA gene sequence similarity. gyrB phylogenetic analysis, fluorescent amplified-fragment length polymorphism (FAFLP) fingerprinting and DNA–DNA hybridization experiments clearly showed that the new isolates form a tight genomic group that is different from the currently known Vibrio species. It is proposed to accommodate these isolates in a novel species, Vibrio crassostreae sp. nov. (type strain LGP 7T=LMG 22240T=CIP 108327T). Phenotypic and chemotaxonomic features that differentiate V. crassostreae from other known Vibrio species include arginine dihydrolase, utilization and fermentation of various carbon sources, β-galactosidase activity, NO2 production and the presence of the fatty acids 14 : 0 iso and 16 : 0 iso.
Research Interests: Evolutionary Biology, Microbiology, Medical Microbiology, Phylogeny, Identification, and 13 moreFatty acids, Animals, Nucleic acid hybridization, DNA fingerprinting, Vibrio, Dna Gyrase, Systematic, Hemolymph, Crassostrea gigas, Ribosomal DNA, Nitrogen Dioxide, Glycosyl Hydrolases, and Molecular Sequence Data
Trematode larvae (metacercariae) causing black spot disease occur frequently in gills, fins, skin and the superficial muscle layers of marine fish. Species within the genus Cryptocotyle Lühe, 1899 are frequently associated with this... more
Trematode larvae (metacercariae) causing black spot disease occur frequently in gills, fins, skin and the superficial muscle layers of marine fish. Species within the genus Cryptocotyle Lühe, 1899 are frequently associated with this disease. Descriptions of the metacercarial stage are relatively limited and none has hitherto been reported from fish from the English Channel. The present study reports the morphological and molecular identifications of encysted black spot-inducing parasites from whiting (Merlangius merlangus) and Atlantic cod (Gadus morhua) caught respectively from the north coast of France (English Channel) and from Danish sea waters. Metacercariae were characterised morphologically based on microscopic observations and molecularly using Sanger sequencing of fragments of the mitochondrial cox1 gene and rDNA ITS region. Morphological data were compared with available data in the literature. Phylogenetic trees including reference sequences were built to confirm morpholo...
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ABSTRACT: Different strains related to Vibrio splendidus have been associated with infection of aquatic animals. An epidemiological study of V. splendidus strains associated with Crassostrea gigas mortalities demonstrated genetic... more
ABSTRACT: Different strains related to Vibrio splendidus have been associated with infection of aquatic animals. An epidemiological study of V. splendidus strains associated with Crassostrea gigas mortalities demonstrated genetic diversity within this group and suggested its polyphyletic nature. Recently 4 species, V. lentus, V. chagasii, V. pomeroyi and V. kanaloae, phenotypically related to V. splendidus, have been described, although biochemical methods do not clearly discriminate species within this group. Here, we propose a polyphasic approach to investigate their taxonomic relationships. Phylogenetic analysis of V. splendidus-related strains was carried out using the nucleotide sequences of 16S ribosomal DNA (16S rDNA) and gyrase B subunit (gyrB) genes. Species delineation based on 16S rDNA-sequencing is limited because of divergence between cistrons, roughly equivalent to divergence between strains. Despite a high level of sequence similarity, strains were separated into 2 cl...
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Trematode larvae (metacercariae) causing black spot disease occur frequently in gills, fins, skin and the superficial muscle layers of marine fish. Species within the genus Cryptocotyle Lühe, 1899 are frequently associated with this... more
Trematode larvae (metacercariae) causing black spot disease occur frequently in gills, fins, skin and the superficial muscle layers of marine fish. Species within the genus Cryptocotyle Lühe, 1899 are frequently associated with this disease. Descriptions of the metacercarial stage are relatively limited and none has hitherto been reported from fish from the English Channel. The present study reports the morphological and molecular identifications of encysted black spot-inducing parasites from whiting (Merlangius merlangus) and Atlantic cod (Gadus morhua) caught respectively from the north coast of France (English Channel) and from Danish sea waters. Metacercariae were characterised morphologically based on microscopic observations and molecularly using Sanger sequencing of fragments of the mitochondrial cox1 gene and rDNA ITS region. Morphological data were compared with available data in the literature. Phylogenetic trees including reference sequences were built to confirm morpholo...
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Blastocystis is frequently identified in humans and animal hosts and exhibits a large genetic diversity with the identification of 17 subtypes (STs). Despite its zoonotic potential, its prevalence and ST distribution in edible marine fish... more
Blastocystis is frequently identified in humans and animal hosts and exhibits a large genetic diversity with the identification of 17 subtypes (STs). Despite its zoonotic potential, its prevalence and ST distribution in edible marine fish and marine mammals remain unknown. A large-scale survey was thus conducted by screening 345 fish caught in Atlantic Northeast and 29 marine mammals stranded on the coasts of northern France for the presence of the parasite using real-time Polymerase Chain Reaction PCR. The prevalence of the parasite was about 3.5% in marine fish. These animals were mostly colonized by poikilotherm-derived isolates not identified in humans and corresponding to potential new STs, indicating that fish are natural hosts of Blastocystis. Marine fishes are also carriers of human STs and represent a likely limited source of zoonotic transmission. 13.8% of the marine mammals tested were colonized and 6 different STs were identified including 3 potential new STs. The risk o...
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Seafood products are widely consumed all around the world and play a significant role on the economic market. Bacteria of the Vibrio genus can contaminate seafood and thus pose a risk to human health. Three main Vibrio species, V.... more
Seafood products are widely consumed all around the world and play a significant role on the economic market. Bacteria of the Vibrio genus can contaminate seafood and thus pose a risk to human health. Three main Vibrio species, V. cholerae, V. parahaemolyticus and V. vulnificus, are potentially pathogenic to humans. These species are responsible for a dramatic increase of seafood-borne infections worldwide. Hence, early detection of total and pathogenic Vibrio is needed and should rely on quick and effective methods. This review aims to present the standard methods FDA-BAM, ISO/TS 21872-1:2007 and TS 21872-2:2007 and compare them to recent molecular biology methods including endpoint PCR, quantitative real-time PCR (qPCR) and PCR-derived methods with a focus on LAMP (loop-mediated isothermal amplification). The available methods presented here are dedicated to the detection and identification of the Vibrio species of interest in seafood.
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Metazoan parasites were studied in 96 Alosa alosa and 78 Alosa fallax from North-East Atlantic coastal waters and connected rivers (among them three sympatric sites) in order to increase knowledge on these anadromous endangered fish and... more
Metazoan parasites were studied in 96 Alosa alosa and 78 Alosa fallax from North-East Atlantic coastal waters and connected rivers (among them three sympatric sites) in order to increase knowledge on these anadromous endangered fish and measure the parasitic impact on host condition. All shads were infected by one to six metazoan parasite taxa among the 12 identified in the whole sampling, with a mean abundance of parasites higher for A. alosa (167 ± 10) than for A. fallax (112 ± 11). Helminths, mostly trophically transmitted, were the best represented (eight taxa, prevalence up to 99%) in contrast with crustaceans and Petromyzontidae that rarely occurred (four taxa, prevalence <6%). Despite some quantitative differences, metazoan parasite communities of A. alosa and A. fallax remained stable in composition whatever the host developmental stage, sex, sample site, and salinity. Among the nine parasite taxa harbored by each Alosa species, six were shared with some differences in di...
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Infectious diseases are a limiting factor to the development and sustainability of aquaculture. For mollusc cultures, only prophylactic measures may be applied, their development usually facilitated by the reproduction of the disease... more
Infectious diseases are a limiting factor to the development and sustainability of aquaculture. For mollusc cultures, only prophylactic measures may be applied, their development usually facilitated by the reproduction of the disease under experimental conditions. To develop an experimental infection in Crassostrea gigas, Vibrio strains were isolated and their virulence was experimentally evaluated. Collaboration phenomena between some strains were observed in infection trial, leading to higher mortality rate when two strains are concomitantly inoculated. Two pathogenic strains, belonging to the polyphyletic group of Vibrio splendidus and named 31 and 32 illustrate this phenomenon. They induce extensive alterations of the adductor muscle in C. gigas. The issue of infection trials with these strains is influenced by intrinsic C. gigas factors. Eventually, strain 32 was used as target strain to select inhibitory strain, potentially usable as a probiotic. Les maladies infectieuses sont...
The French oyster production is mainly based on the pacific oyster, Crassos/rea gigas. However, for several years, C. gigas spat has suffered severe mortality outbreaks. A multifactorial etiology implicating environment, oyster... more
The French oyster production is mainly based on the pacific oyster, Crassos/rea gigas. However, for several years, C. gigas spat has suffered severe mortality outbreaks. A multifactorial etiology implicating environment, oyster physiology, genetics and pathogens is heavily suspected. A herpesvims and bacteria belonging to the Vihrio s\p/endidus polyphyletic group have been isolated From summer mortality outbreaks. Moreover, several strains belonging to the genus Vibrio have been identified as pathogen for different mollusk species. However, few tools are available for the identification of these Vibrios and for the characterization of the virulence of the pathogenic strains.
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Nowadays, cupped oyster, Crassostrea gigas, production is the main shellfish production in France. Spats cultivated on most farms are usually collected in the wild, but hatchery spats are becoming more numerous, and represent around 10%... more
Nowadays, cupped oyster, Crassostrea gigas, production is the main shellfish production in France. Spats cultivated on most farms are usually collected in the wild, but hatchery spats are becoming more numerous, and represent around 10% of today's cultivated spats. During the summer period, when the temperatures are higher, high mortality rates have been regularly observed in cupped in oyster C. gigas (60 to 100%) spats since 1991, both in hatcheries-nurseries and in their natural habitat. Over the last five years, these episodes have become a big concern for all the professionals. La production d'huître creuse, Crassostrea gigas, est aujourd'hui la principale production française de coquillages. Le naissain mis en élevage dans les différents centres de production est généralement obtenu par captage naturel mais l'utilisation de naissain d'écloserie est en constante progression depuis quelques a1U1ées, et représente aujourd'hui près de 10% du naissain mis en ...
Vibrio spp. have emerged as a serious threat to human health worldwide. Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus are of particular concern as they have been linked to gastrointestinal infections and septicemia... more
Vibrio spp. have emerged as a serious threat to human health worldwide. Vibrio parahaemolyticus, Vibrio cholerae and Vibrio vulnificus are of particular concern as they have been linked to gastrointestinal infections and septicemia associated with the consumption of raw or undercooked seafood. We developed hydrolysis probe-based real-time PCR systems with an internal amplification control for the detection of these species. We applied these systems to a total of 167 fresh or frozen crustacean, fish and shellfish samples consumed in France. Of them, 34.7% (n=58) were positive for Vibrio. V. parahaemolyticus was the most common, in 31.1% of samples, followed by V. vulnificus in 12.6% and V. cholerae in 0.6%. Furthermore, V. parahaemolyticus and V. vulnificus were present simultaneously in 9.6% of samples. Virulence genes (tdh and trh sequences) were present in 25% of the V. parahaemolyticus-positive samples. The V. cholerae strain detected was non toxigenic. The densities of V. parahaemolyticus and V. cholerae ranged from &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;10(2) to 10(4)bacteria/g of seafood. All samples positive for V. vulnificus displayed low-level contamination with fewer than 10(2)bacteria/g. Our findings indicate that seafood consumption presents a potential risk to human health in France and highlight the importance of tools for a preventive consumer protection policy.
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The most-probable-number (MPN) method is often time-consuming for the isolation, detection, and quantification of Vibrio parahaemolyticus from natural sources. MPN counting of V. parahaemolyticus bacteria usually involves the isolation of... more
The most-probable-number (MPN) method is often time-consuming for the isolation, detection, and quantification of Vibrio parahaemolyticus from natural sources. MPN counting of V. parahaemolyticus bacteria usually involves the isolation of typical V. parahaemolyticus colonies on selective medium, with subsequent confirmation by biochemical identification. In this study, we evaluated the use of a PCR on MPN enrichment cultures (MPN-PCR) for the direct detection of total and pathogenic V. parahaemolyticus cells in frozen shrimp. This reaction targeted the R72H, tdh, and trh sequences. An internal amplification control was added to the samples before R72H amplification. There was an excellent correlation between the results of the two methods for artificially inoculated and natural shrimp samples. Of 36 natural samples, 28 tested positive for the presence of V. parahaemolyticus, with an MPN value of 2 × 10−1 to 9.2 × 101 per g. No pathogenic V. parahaemolyticus cells were detected. The ...
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Research Interests: Microbiology, Molecular Biology, Crustacea, Industrial Biotechnology, SHRIMP, and 15 moreFood Microbiology, Quantitative analysis, real time PCR, European Commission, Legislation, Animals, Bacteria, Polymerase Chain Reaction, Real Time, Shellfish, Food Sciences, Quantitative Analysis, Sensitivity and Specificity, Penaeidae, and Most Probable Number
Research Interests: Transmission Electron Microscopy, Genetic Diversity, Biological Sciences, Virulence, Phylogeny, and 15 moreMolecular taxonomy, Animals, Nucleic acid hybridization, Cluster Analysis, Muscles, Phenotype, Experimental Infection, Vibrio, Granular Material, Dna Gyrase, Crassostrea gigas, Species Specificity, Base Sequence, Mortality rate, and Molecular Sequence Data
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Research Interests: Genetics, Epidemiology, Aquaculture, Comparative Study, Biological Sciences, and 10 moreVirulence, Environmental Sciences, Bacteria, Polymerase Chain Reaction, DNA hybridization, Comparative Analysis, Natural Environment, Crassostrea gigas, Management of Aquatic Living Resources, and Pathogenic Bacteria
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Research Interests: Immune response, Ecotoxicology, Flow Cytometry, Aquatic Toxicology, Aquaculture, and 18 moreGene expression, Biological Sciences, real time PCR, Environmental Sciences, Pesticide, Pesticides, Animals, Bacteria, CHEMICAL SCIENCES, In Vivo, Hemocytes, Phagocytosis, Vibrio, Crassostrea gigas, Enzyme activity, Cell Survival, Mortality rate, and Random Allocation
Caractérisation des parasites dans les produits de la pêche : développement de méthodes d’identification et prévalence SEESAO Yuwalee 1-2, GAY Mélanie 1, DEI-CAS Eduardo 2, AUDEBERT Christophe 3,8, THEBAULT Anne 4, VERREZ-BAGNIS Véronique... more
Caractérisation des parasites dans les produits de la pêche : développement de méthodes d’identification et prévalence SEESAO Yuwalee 1-2, GAY Mélanie 1, DEI-CAS Eduardo 2, AUDEBERT Christophe 3,8, THEBAULT Anne 4, VERREZ-BAGNIS Véronique 5, LE FUR Bruno 6, VISCOGLIOSI Eric 2, DUPOUY-CAMET Jean 7, ALIOUAT-DENIS 2 Cécile-Marie et les membres du réseau ‘Fish-Parasites’ 1ANSES-Agence Nationale de sécurité Sanitaire de l’alimentation, de l’environnement et du travail, Boulogne-sur-Mer, France; 2IPL-CIIL-BDPEE, Univ Lille Nord de France, Lille, France 3Gènes Diffusion, Douai, France 4ANSES-DER-UMA-MSA, Maisons-Alfort, France 5IFREMER-BRM-EM3B, Nantes, France 6 Plateforme d’innovation Nouvelles Vagues, Boulogne-sur-Mer, France 7Hôpital Cochin, Paris, France 8 PEGASE-Biosciences, Institut Pasteur de Lille, France Yuwalee.seesao@anses.fr , www.anses.fr, www.pasteur-lille.fr Mots clés Anisakidae Séquençage à haut débit Cox2 Extraction d’ADN en pool Poisson De nombreux parasites infestent fré...
Different methods were evaluated to extract DNA from pooled nematodes belonging to Anisakis, Contracaecum, Pseudoterranova and Hysterothylacium genera isolated from edible fish. Pooled DNA extraction is the first and compulsory step to... more
Different methods were evaluated to extract DNA from pooled nematodes belonging to Anisakis, Contracaecum, Pseudoterranova and Hysterothylacium genera isolated from edible fish. Pooled DNA extraction is the first and compulsory step to allow the identification of a large number of samples through high-throughput DNA sequencing with drastic time and cost reductions.