Auswahl der wissenschaftlichen Literatur zum Thema „Déterminant de virulence“
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Zeitschriftenartikel zum Thema "Déterminant de virulence"
Sansonetti, P. „Déterminants de virulence chez les bacilles à Gram negatif“. médecine/sciences 3, Nr. 2 (1987): 68. http://dx.doi.org/10.4267/10608/3624.
Der volle Inhalt der QuelleAudet, René. „Lieux et pragmatique de la monstruosité dans la prose narrative d’Éric Chevillard“. Tangence, Nr. 91 (28.10.2010): 11–27. http://dx.doi.org/10.7202/044807ar.
Der volle Inhalt der QuelleBleibtreu, A. „Déterminants de la virulence extra-intestinale de Escherichia coli : de la microbiologie à la clinique“. Journal des Anti-infectieux 18, Nr. 2 (Juni 2016): 45–51. http://dx.doi.org/10.1016/j.antinf.2016.01.008.
Der volle Inhalt der QuelleMatejka, Ladislav. „Jakobson's Response to Saussure's Cours“. Cahiers du Centre de Linguistique et des Sciences du Langage, Nr. 9 (09.04.2022): 177–84. http://dx.doi.org/10.26034/la.cdclsl.1997.1892.
Der volle Inhalt der QuelleBROCHARD, M., K. DUHEN und D. BOICHARD. „Dossier "PhénoFinlait : Phénotypage et génotypage pour la compréhension et la maîtrise de la composition fine du lait"“. INRAE Productions Animales 27, Nr. 4 (21.10.2014): 251–54. http://dx.doi.org/10.20870/productions-animales.2014.27.4.3071.
Der volle Inhalt der QuelleDissertationen zum Thema "Déterminant de virulence"
Razafimanantsoa, ép Dubail Iharilalao. „Identification et étude du rôle du gène Imo2537 déterminant une UDP-N-acetylglucosamine épimérase dans la virulence de Listéria monocytogenes“. Paris 5, 2006. http://www.theses.fr/2006PA05T053.
Der volle Inhalt der QuelleListeria monocytogenes is an opportunistic pathogenic bacterium. It is responsible for meningitidi and septicemia in humans. In pregnant women, infection is responsible for abortion, premature de ivrance or infection of the new-born with heavy neurological sequels. Virulence of the genetically modified strains may be measured « in vivo » in a murine model. In our studies, we wanted to identify the bacteria promoters specifically induced during « in vivo « infection by L. Monocytogenes. For that purpose, we used the IVET (in vivo expression technology) strategy. We used the hly gene as reporter gene. Our library of recombinant p asmids was transferred by electroporation in a listeria strain deleted in My Only the non-hemolytic bac ena were mixed and injected intraveneously in mice. Therefore, only mice with an active « in vivo » promoter n bacteria were analyzed and sequenced. This method allowed us to identify nine loci induced « in vivo >>. Among these loci, we found genes coding for phosphatidylinositol phospholipase C, already known o be induced «in vivo » and a JV-acetylglucosamine epimerase involved m teichoic acid synthesis. We could demonstrate that this enzyme allows the synthesis of a pillar element, which untoj teichoic acids to the peptidoglycane. We constructed and characterized a conditional mutant of Imo2537 gene. Our results demonstrate that expression of this gene affects survival and intracellular multiplication of bacteria reflecting importance of teichoic acids in L. Monocytogenes pathogenesis
Kleij, Lena. „Identification and validation of the virulence determinants of circulating equine influenza viruses“. Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASL136.
Der volle Inhalt der QuelleInfluenza viruses are enveloped, their genome being segmented into 8 negative RNA segments. They are classified in the Orthomyxoviridae family. They are the etiological agents of the flu, a respiratory disease that affects many mammalian and avian species. Equine influenza is caused by the H3N8 and H7N7 subtypes of the type A influenza virus, the latter being extinct since the 1970s. Despite the existence of a vaccine, France has experienced several H3N8 epidemics since the 2000s. To reduce the significant economic impact of these epidemics for the equine industry, it is necessary to establish rapid, robust, and on-terrain applicable diagnostic tests to limit the circulation of the virus as much as possible and identify its virulence determinants as well as characterize antigenic drift.We studied the potential of the so-called “long read” sequencing technique developed by Oxford Nanopore Technologies. We carried out a characterization of the complete genome of two equine H3N8 viruses that circulated in France in 2009 and 2018 (A/equine/Paris/1/2018 and A/equine/Beuvron-en-Auge/2/2009, two viruses of clade 1 Florida) as well as the two strains of the vaccine commonly used in France.Our results demonstrated the reliability of this sequencing technique using amplicons of the eight genomic segments of the four viruses analyzed as well as the ability to produce reliable readings from direct sequencing of viral RNA (results presented in the first part). Analysis of the amino acid sequence of hemagglutinin HA of circulating strains demonstrated a very slight antigenic drift compared to vaccine strains with specific substitutions such as T161I in A/equine/Paris/1/2018 and N188T in the post-2015 strains, two substitutions located in the antigenic site B. The antigenic site E also shows modifications in the post-2018 strains, with the N63D substitution.Genomic segment 2 encodes one of the three subunits of the viral RNA polymerase, PB1, as well as an accessory protein, PB1-F2, of an alternative reading frame. PB1-F2 is recognized as a virulence determinant. While the A/equine/Paris/1/2018 strain encodes a variant 90 amino acids long, many strains, including A/equine/Beuvron-en-Auge/2/2009, encode a variant only 81 residues. Biological and biochemical tests were carried out to characterize the properties of each of these two forms of PB1-F2. In an assay where the long form of PB1-F2 is expressed in eukaryotic cells without other viral constituents, it abolishes the membrane potential of the cellular mitochondria. Placed in the presence of synthetic vesicles mimicking the mitochondrial outer membrane, the long form of PB1-F2 permeabilizes them more effectively than the short form. Amino acid sequence analyzes of the viral proteins (mainly HA and PB1-F2) are presented in a second part.In order to validate the impact of PB1-F2 on virulence in an infectious context, we sought to establish a reverse genetics system for the A/equine/Paris/1/2018 virus (third part). To do this, the 8 genomic segments were cloned into the pRF483 plasmid to ensure the synthesis of genomic RNA strands and the expression of viral proteins. The sequence of the inserts of each of the plasmids was validated. To validate the functioning of the replicative complex encoded by 4 of the 8 viral segments cloned in pRF483 (PA, PB1, PB2 and NP), these plasmids were transfected with a plasmid coding for the NA genomic segment in which its reading frame was substituted. by a reporter gene, luciferase. Under these experimental conditions, activity of the RNA-polymerase complex was detected. These tests will be extended for the production of recombinant viruses by transfection of the 8 constructed plasmids
Dufour, Delphine. „Recherche de déterminants génétiques permettant l'adaptation d'une souche Escherichia coli à la mamelle bovine“. Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL050N/document.
Der volle Inhalt der QuelleThe objective of this work was to characterize the MPEC Escherichia coli P4 strain. A phylogenetic study showed that it belongs to the phylogenetic group A of the E. coli species and that its core genome is similar to the one of the commensal non-pathogenic E. coli K12 MG1655 strain which also belongs to the group A. A search in its genome of different genes encoding virulence factors known among other pathotypes of the E. coli species was done and only the traT gene, encoding a serum resistance factor, was detected. A screening of fifteen tRNA loci known for frequently hosting genomic islands, made in its genome, revealed for seven of them the presence of such structures. The partial or complete sequencing of the regions downstream from these seven loci showed the systematic presence of nucleotide sequences different from those present in E. coli K12 MG1655. If the content analysis of these islands does not yet explain the virulence of E. coli P4, their highlighting is the first of this kind in the pathotype MPEC and suggests the discovery of other genomic regions specific to this pathotype, which may explain its tropism and its nature. In addition, to assessing the role of E. coli P4 in milk caseinolysis observed during bovine mastitis, a constitutive secretion of four extracellular proteases was highlighted by casein zymography. However, the caseinolytic activity of these enzymes does not seem significant. This fact may suggest a role in virulence of the strain
Bahuon, Céline. „Construction d’un clone infectieux d’une souche méditerranéenne du Virus West Nile, validation de ses propriétés biologiques et développement de nouveaux modèles d’évaluation de la virulence“. Thesis, Paris 11, 2012. http://www.theses.fr/2012PA114828/document.
Der volle Inhalt der QuelleWest Nile virus (WNV) is a neurotropic virus mainly transmitted through mosquito bites. Wild birds represent the main reservoir hosts. Strains circulating in Europe belong to four lineages and have caused numerous but limited epidemics over the last few years. In 1998, an important outbreak associated to huge bird fatalities caused by a highly neuroinvasive strain (IS-98-ST1) took place in Israel. We aimed at producing a new infectious clone, based on the lineage 1a IS-98-ST1 WNV strain, for the characterization of its neuroinvasion properties as well as the molecular determinants of European WNV virulence. The growth kinetics of recombinant and parental WNV were similar in Vero cells. Moreover, the phenotypes of recombinant and parental WNV were indistinguishable in terms of viremia, viral load in the brain and mortality in susceptible and resistant mice. Finally, the pathobiology of the infectious clone was examined in embryonated chicken eggs, proposed as a new model for the evaluation of WNV virulence. The potential of human neuroblastoma cells (SK-N-SH) to discriminate between highly and mildly virulent WNV strains was assayed. In conclusion: a new molecular tool that is useful for the study of molecular determinants of WNV virulence has been generated. We take advantage of the high genetic stability of our one-piece infectious WNV cDNA clone to produce mutant viruses through the insertion of point mutations or the exchange of genetic fragments between WNV strains into the backbone of the IS-98-ST1 infectious clone
Morel, Arry. „Etude du rôle lors de l'infection et sur la défense des plantes hôtes des effecteurs de type III RipH1,2,3 et RipAX2 de Ralstonia pseudosolanacearum“. Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0134.
Der volle Inhalt der QuelleOne of the major virulence determinants of plant pathogenic Ralstonia species is the type III secretion system that enables it to inject proteins (also called “Ralstonia Injected Proteins” or Rip) into the host cells. The RipH1,2,3 type III effectors are conserved in different strains of the Ralstonia solanacearum species complex. The role of these effectors during infection has been studied, taking as an entry point the tomato proteins they interact with. Using yeast-two-hybrid screenings we have identified 19 tomato targets of these three RipH. Reverse genetics methods have then been used to study the role of orthologous genes of these targets in other model plants. Virus induced gene silencing in Nicotiana benthamiana showed that the orthologous genes of TOM3 were involved in plant response to Ralstonia pseudosolanacearum, as the bacterial multiplication was diminished in plants silenced for these genes. In Arabidopsis thaliana, mutants of the TOM9 orthologous gene which is described as involved in chromatin remodelisation were more tolerant to infection. In a second chapter corresponding to a published article, the role of RipAX2 has been studied. This effector triggers specific resistance in AG9125 eggplant which carry the major resistance locus EBWR9. This eggplant accession AG9125 is resistant to the wild type R. pseudosolanacearum strain GMI1000, while a ripAX2 defective mutant of this strain can cause wilt. The addition of ripAX2 from GMI1000 to the naturally pathogenic strain PSS4 suppresses its pathogenicity, demonstrating that RipAX2 causes AG9125 resistance. Moreover, a zinc binding motif described as necessary to induce defenses on the eggplant wild relative Solanum torvum upon RipAX2 recognition is not necessary for AG91-25 resistance. The conservation of RipAX2 has been studied in the different strains of the bacteria in order to determine the potential of this resistance source against various strains for breeding
Gardette, Marion. „Virulence des Escherichia coli entérohémmoragiques : rôle central du monoxyde d'azote dans le devenir de l'infection et identification de nouveaux déterminants impliqués dans l'adaptation du pathogène à l'envirronement digestif“. Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC075.
Der volle Inhalt der QuelleEnterohemorrhagic Escherichia coli (EHEC) are a major public health concern. Indeed, these pathogens are responsible for thousands of food-borne illness cases worldwide every year and can lead to serious complications, including kidney damages in young children and brain damages in the elderly. Currently, the main issue is the limited number of available therapeutic treatments since antibiotic therapy can promote the development of infection-related complications. Therefore, it appears essential and topical to identify bacterial factors associated with EHEC virulence and to understand the interactions occurring between the pathogen and the host, in order to develop new anti-infective strategies. The first objective of this thesis was to identify new bacterial factors potentially involved in the infectious process. Application of the RIVET technology to the reference strain O157:H7 EDL933 revealed 31 genes specifically induced during mouse infection. Characterization of these genes showed that some of them encode niche factors potentially involved in the adaptation of EHEC to the intestinal environment, therefore contributing to virulence. The second aim of this thesis was to characterize in vivo the response of EHEC to nitric oxide (NO), a mediator of the host’s immune response, and thus assess the protective role of NO against EHEC infection in a mouse model. By using a NO-sensing reporter EHEC strain, we demonstrated that NO is produced by the host at the early stages of infection and this NO limits adhesion of the pathogen to the colonic mucosa. On the other hand, we also showed that NO is detrimental to the host since it promotes the production of Shigatoxins (Stx), which is the major EHEC virulence factor, and leads to the development of renal dysfunction. Finally, we showed that the NO reductase NorVW is important for the virulence of some, but not all, EHEC strains. Inactivation of the norVW operon in strain O157:H7 620 reduces the ability of the pathogen to efficiently colonize the digestive tract and to produce Stx. However, this observation is strain-specific and this suggests that EHEC response to nitrosative stress during infection is complex and probably multifactorial. This work contributes to a better understanding of the EHEC infectious process, an essential step for the development of future anti-infective strategies
Gauriat, Marie-Anne. „Connaissance des facteurs déterminants dans la conduite d'un procédé pour la production de toxine par Corynebacterium diphteriae utilisée dans la formulation de vaccins“. Thesis, Toulouse, INSA, 2012. http://www.theses.fr/2012ISAT0041/document.
Der volle Inhalt der QuelleFaced with an important variability in production yields of vaccines against diphtheria, a dynamic systemic approach, including central and iron metabolism and transcriptome analysis, led to an improved knowledge of Corynebacterium diphtheriae physiology, notably as regards the connection of central metabolism and virulence. Gene expression analysis coupled to metabolic characterization enabled a correlation between maltose consumption and virulence to be established. Because of the typical human diet, maltose is present in the human oropharynx where it may serve as a key nutrient source for C. diphtheriae. Maltose consumption during stationary phase, coupled with toxin production, seems to be linked to maintenance and secondary metabolites rather than growth. Several genes, including uptake and catabolism of maltose, are related to diphtheria toxin production. However, mechanisms of regulation are complex and may involve several transcriptional regulators. Bacterial iron requirements and its relation to pathogenicity were considered. Indeed, diphtheria toxin gene is regulated by Fe2+ activated DtxR. These studies revealed that C. diphtheriae is able to store an important quantity of intracellular iron within ferritin-like proteins visualized by NanoSIMS microscopy and the definition of an intracellular threshold concentration provoking expression of toxin production. Finally, genome-wide gene expression analysis of C.diphtheriae in iron starvation and iron excess conditions provided information on relations between central and iron metabolism, virulence establishment and oxidative stress. The resulting knowledge was exploited to suggest process optimization strategies to enhance toxin production, currently being assessed by the industrial partner. Adjusting some key physico-chemical parameters (targeting oxygenation and better maltose metabolization) enabled significant gains in toxin production (2.5 fold increase). Specific productivity could be increased by 2.2 thanks to a novel biomass dilution and recycling step at the end of the culture
Mazigh, Daniel. „Etude des déterminants moléculaires de la virulence de Yersinia enterocolitica et de leurs rôles dans l'induction d'une immunogénicité croisée contre Yersinia pestis“. Paris 7, 1985. http://www.theses.fr/1985PA077065.
Der volle Inhalt der QuelleCoulibaly, Fasséli. „Etude structurale des birnavirus : identification des déterminants d'antigénicité, de virulence et d'assemblage : mise en évidence d'un lien évolutif entre virus à ARN(+) et à ARN double brin“. Paris 11, 2003. http://www.theses.fr/2003PA112236.
Der volle Inhalt der QuelleBirnaviruses appear to be atypical among icosahedral RNA viruses. Their genomic and structural organization lead to comparisons with members of the Reoviridae family. However, birnaviruses seem to bear more functional similarities to positive-strand RNA viruses such as Nodaviridae or Picornaviridae. We have determined the structures of T=l icosahedral subviral particles of two birnaviruses. Twenty copies of the attachment protein VP2 trimers make up these 260A-wide particles. VP2 folds as two orthogonal jelly rolls on top of a helical domain. The radial jelly roll is the trimeric spike (domain P) projecting outward of a continuous icosahedral shell formed by the other jelly roll (domain S). Domain P is the major site of virus-host interactions as it bears all the neutralizing epitopes as well as the determinants of viral tropism and virulence. Helical domain B coats the inner surface of the particle providing a domain of interaction to other viral constituents such as RNA or VP3. In particular, this domain forms a helical barrel at five fold axes which might be involved in viral RNA exit. Our structural comparison of VP2 structure to other capsid proteins points to an evolutionary link between RNA(+) (Nodaviridae and Tetraviridae) and double-stranded RNA (Reoviridae) viruses embodied by Birnaviruses. Finally, a fit of VP2 in the viral particle requires a major conformational change. We propose a model for morphogenesis in which VP3 binding to VP2 would act as a molecular switch triggering assembly thereafter driven by VP2 self association capacities
Bahuon, Céline. „Construction d'un clone infectieux d'une souche méditerranéenne du Virus West Nile, validation de ses propriétés biologiques et développement de nouveaux modèles d'évaluation de la virulence“. Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00747842.
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