21 research outputs found
Increasing importance of Bunyaviridae in public and veterinary health illustrated by hantaviruses, and the Schmallenberg and Rift Valley fever viruses
The virus family of Bunyaviridae is very important in terms of public health and veterinary medicine.
With over 350 viruses identified to date, it includes viruses mainly transmitted by arthropods
(arboviruses) or rodents (roboviruses), infecting mammals and plants for the genus Tospovirus. Humans
can be infected by around 60 bunyaviruses sometime with very serious or even fatal consequences.
The examples of Schmallenberg and Rift Valley fever viruses and hantavirus genus illustrate perfectly
the many questions surrounding the Bunyaviridae family’s capacity to emerge, widely variable pathogenicity
for different hosts, and capacity to persist in different vectors such as arthropods or rodents
and more recently the soricomorph species (insectivores)La famille des Bunyaviridae est très importante en santé publique et vétérinaire. Avec plus de
350 virus identifiés à ce jour, elle regroupe des virus transmis principalement par des arthropodes (arbovirus)
ou des rongeurs (robovirus), responsables d’infections chez les mammifères et chez les plantes
pour le genre Tospovirus. L’homme peut être infecté par une soixantaine de ces Bunyaviridae, parfois
avec des conséquences très graves, voire fatales. Les exemples du virus de Schmallenberg, du virus
de la fièvre de la Vallée du Rift et du genre viral hantavirus illustrent parfaitement les nombreuses
incertitudes concernant cette famille virale quant à leur potentiel d’émergence, leur pouvoir pathogène
très varié pour des hôtes divers, et leur capacité à persister chez différents vecteurs appartenant
aux arthropodes ou aux rongeurs et, plus récemment, aux soricomorphes (insectivores
Etude de la régulation de l'expression des gènes du locus d'effacement des entérocytes par les ARN non codants chez les Escherichia coli entérohémorragiques
TOULOUSE3-BU Santé-Centrale (315552105) / SudocTOULOUSE-EN Vétérinaire (315552301) / SudocSudocFranceF
Role of Spore Coat Proteins in the Resistance of Bacillus subtilis Spores to Caenorhabditis elegans Predationâ–ż
Bacterial spores are resistant to a wide range of chemical and physical insults that are normally lethal for the vegetative form of the bacterium. While the integrity of the protein coat of the spore is crucial for spore survival in vitro, far less is known about how the coat provides protection in vivo against predation by ecologically relevant hosts. In particular, assays had characterized the in vitro resistance of spores to peptidoglycan-hydrolyzing enzymes like lysozyme that are also important effectors of innate immunity in a wide variety of hosts. Here, we use the bacteriovorous nematode Caenorhabditis elegans, a likely predator of Bacillus spores in the wild, to characterize the role of the spore coat in an ecologically relevant spore-host interaction. We found that ingested wild-type Bacillus subtilis spores were resistant to worm digestion, whereas vegetative forms of the bacterium were efficiently digested by the nematode. Using B. subtilis strains carrying mutations in spore coat genes, we observed a correlation between the degree of alteration of the spore coat assembly and the susceptibility to the worm degradation. Surprisingly, we found that the spores that were resistant to lysozyme in vitro can be sensitive to C. elegans digestion depending on the extent of the spore coat structure modifications
Régulation de l expression du Locus d effacement des entérocytes chez les escherichia coli Enterohémorragiques (rôle des ARN non-codants)
TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF
La diphtérie zoonotique à Corynebacterium ulcerans à l'interface des santés humaine et animale
National audienceDiphtheria is a mandatory notofoable bacterial infection in human medicine. Two major etiological agents are responsible for this human disease, including the zoonotic bacterium Corynebacterium ulcerans, which has been responsible for most human cases reported in France in recent years. C. ulcerans can infect domestic carnivores (dogs and cats), sometimes with symptomatic infections. This article discusses the role of veterinarians in teh management of zoonotic diptheria when a human case is investigated or upon clinical management of an animal case.La diphtérie est une maladie bactérienne à déclaration obligatoire en médecine humaine. Deux agents majeurs sont responsables de la maladie humaine, dont la bactérie zoonotique Corynebacterium ulcerans à l'origine de la majorité des cas de diphtérie humaine déclarés en France ces dernières années. C. ulcerans peut infecter les carnivores domestiques (chiens et chats), entraînant occasionnellement des signes cliniques. Cet article traite du rôle des vétérinaires dans la gestion de la diphtérie zoonotique lors d'investigations autour d'un cas humain ou de la prise en charge d'un cas chez l'animal
INCREASING IMPORTANCE OF BUNYAVIRIDAE IN PUBLIC AND VETERINARY HEALTH ILLUSTRATED BY HANTAVIRUSES, AND THE SCHMALLENBERG AND RIFT VALLEY FEVER VIRUSES
National audienceThe virus family of Bunyaviridae is very important in terms of public health and veterinary medicine. With over 350 viruses identified to date, it includes viruses mainly transmitted by arthropods (arboviruses) or rodents (roboviruses), infecting mammals and plants for the genus Tospovirus. Humans can be infected by around 60 bunyaviruses sometime with very serious or even fatal consequences. The examples of Schmallenberg and Rift Valley fever viruses and hantavirus genus illustrate perfectly the many questions surrounding the Bunyaviridae family's capacity to emerge, widely variable pathogenicity for different hosts, and capacity to persist in different vectors such as arthropods or rodents and more recently the soricomorph species (insectivores)
Environmental Free-Living Amoebae Can Predate on Diverse Antibiotic-Resistant Human Pathogens
International audienceHere, we sought to test the resistance of human pathogens to unaltered environmental free-living amoebae. Amoebae are ubiquitous eukaryotic microorganisms and important predators of bacteria. Environmental amoebae have also been proposed to serve as both potential reservoirs and training grounds for human pathogens. However, studies addressing their relationships with human pathogens often rely on a few domesticated amoebae that have been selected to feed on rich medium, thereby possibly overestimating the resistance of pathogens to these predatory phagocytes. From an open-air composting site, we recovered over 100 diverse amoebae that were able to feed on Acinetobacter baumannii and Klebsiella pneumoniae. In a standardized and quantitative assay for predation, the isolated amoebae showed a broad predation spectrum, killing clinical isolates of A. baumannii, K. pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. Interestingly, A. baumannii, which was previously reported to resist predation by laboratory strains of Acanthamoeba, was efficiently consumed by closely related environmental amoebae. The isolated amoebae were capable of feeding on highly virulent carbapenem-resistant or methicillin-resistant clinical isolates. In conclusion, the natural environment is a rich source of amoebae with broad-spectrum bactericidal activities, including against antibiotic-resistant isolates
Interbacterial Transfer of Carbapenem Resistance and Large Antibiotic Resistance Islands by Natural Transformation in Pathogenic Acinetobacter
International audienceAcinetobacter baumannii infection poses a major health threat, with recurrent treatment failure due to antibiotic resistance, notably to carbapenems. While genomic analyses of clinical strains indicate that homologous recombination plays a major role in the acquisition of antibiotic resistance genes, the underlying mechanisms of horizontal gene transfer often remain speculative. Our understanding of the acquisition of antibiotic resistance is hampered by the lack of experimental systems able to reproduce genomic observations. We here report the detection of recombination events occurring spontaneously in mixed bacterial populations and which can result in the acquisition of resistance to carbapenems. We show that natural transformation is the main driver of intrastrain but also interstrain recombination events between A. baumannii clinical isolates and pathogenic species of Acinetobacter. We observed that interbacterial natural transformation in mixed populations is more efficient at promoting the acquisition of large resistance islands (AbaR4 and AbaR1) than when the same bacteria are supplied with large amounts of purified genomic DNA. Importantly, analysis of the genomes of the recombinant progeny revealed large recombination tracts (from 13 to 123 kb) similar to those observed in the genomes of clinical isolates. Moreover, we highlight that transforming DNA availability is a key determinant of the rate of recombinants and results from both spontaneous release and interbacterial predatory behavior. In the light of our results, natural transformation should be considered a leading mechanism of genome recombination and horizontal gene transfer of antibiotic resistance genes in Acinetobacter baumannii
Interbacterial Transfer of Carbapenem Resistance and Large Antibiotic Resistance Islands by Natural Transformation in Pathogenic Acinetobacter
International audienceAcinetobacter baumannii infection poses a major health threat, with recurrent treatment failure due to antibiotic resistance, notably to carbapenems. While genomic analyses of clinical strains indicate that homologous recombination plays a major role in the acquisition of antibiotic resistance genes, the underlying mechanisms of horizontal gene transfer often remain speculative. Our understanding of the acquisition of antibiotic resistance is hampered by the lack of experimental systems able to reproduce genomic observations. We here report the detection of recombination events occurring spontaneously in mixed bacterial populations and which can result in the acquisition of resistance to carbapenems. We show that natural transformation is the main driver of intrastrain but also interstrain recombination events between A. baumannii clinical isolates and pathogenic species of Acinetobacter. We observed that interbacterial natural transformation in mixed populations is more efficient at promoting the acquisition of large resistance islands (AbaR4 and AbaR1) than when the same bacteria are supplied with large amounts of purified genomic DNA. Importantly, analysis of the genomes of the recombinant progeny revealed large recombination tracts (from 13 to 123 kb) similar to those observed in the genomes of clinical isolates. Moreover, we highlight that transforming DNA availability is a key determinant of the rate of recombinants and results from both spontaneous release and interbacterial predatory behavior. In the light of our results, natural transformation should be considered a leading mechanism of genome recombination and horizontal gene transfer of antibiotic resistance genes in Acinetobacter baumannii