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Zeitschriftenartikel zum Thema "Sous-type H3N8 du virus de la grippe A"
Bancej, Christina, Abbas Rahal, Liza Lee, Steven Buckrell, Kara Schmidt und Nathalie Bastien. „Rapport national de mi-saison d’ÉpiGrippe, 2021–2022 : activité grippale sporadique de retour“. Relevé des maladies transmissibles au Canada 48, Nr. 1 (26.01.2022): 43–50. http://dx.doi.org/10.14745/ccdr.v48i01a06f.
Der volle Inhalt der QuelleSidibé, Souleymane, Z. Bocoum, C. F. Simbé, K. Tounkara, Mohamed, Mostafa Bakkali und M. Kané. „Grippe équine au Mali : résultats d’une enquête séroépidémiologique“. Revue d’élevage et de médecine vétérinaire des pays tropicaux 55, Nr. 2 (01.02.2002): 89. http://dx.doi.org/10.19182/remvt.9837.
Der volle Inhalt der QuelleDissertationen zum Thema "Sous-type H3N8 du virus de la grippe A"
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
Barthélémy, Adeline. „Rôle des cellules T natural killer invariants (iNKT) dans la surinfection bactérienne post-grippale“. Thesis, Lille 2, 2016. http://www.theses.fr/2016LIL2S002/document.
Der volle Inhalt der QuelleXDurant l’infection par le virus Influenza A (IAV), les changements physiques et immunologiques du poumon prédisposent l’hôte aux surinfections bactériennes. Les cellules T Natural Killer invariantes (iNKT) sont des lymphocytes T innés pouvant avoir des rôles bénéfiques ou délétères durant l’infection. Nos objectifs ont visé à (i) étudier le rôle naturel des cellules iNKT et (ii) à rechercher l’effet d’une activation exogène des cellules iNKT dans la surinfection bactérienne post-influenza.Lors de mon arrivée, le laboratoire venait de décrire, pour la première fois en contexte infectieux, que les cellules iNKT étaient capables de produire de l’IL-22 au cours de l’infection grippale. Cette cytokine joue un rôle majeur dans les processus de maintien et de réparation des épithéliums. L’une desDuring the infection by the virus Influenza A ( IAV), the physical and immunological changes of the lung predispose the host to the bacterial secondary infections. The invariant cells(units) T Natural Killer iNKT ) are lymphocytes T innate being able to have beneficial or noxious roles during the infection. Our objectives aimed at i) to study the natural role of cells(units) iNKT and ii) to look for the effect of an exogenous activation of cells(units) iNKT in the bacterial secondary infection post-influenza. During my arrival, the laboratory had just described, for the first time in infectious context, that cells(units) iNKT were capable of producing of IL-22 during the flu-like infection. This cytokine plays a major role in the processes of preservation and repair of epitheliums [...]
Rameix-Welti, Marie-Anne. „Neuraminidase des virus influenza A : Sensibilité aux antiviraux et interaction avec Neisseria meningitidis“. Paris 7, 2008. http://www.theses.fr/2008PA077037.
Der volle Inhalt der QuelleNeuraminidase is a major surface glycoprotein of influenza A viruses, which possesses critical enzymatic activity allowing elution of progeny virus particles from infected cells. Neuraminidase inhibitors : zanamivir and oseltamivir (OC), are the major drugs available against influenza viruses. We studied the sensitivity to NA inhibitors of influenza H5N1 and H1N1 viruses. Our data show that sensitivity to OC of the NA of H5N1 viruses isolated in 2004-05, when determined by IC50 and Ki calculation, is about 10-fold higher as compared to earlier H5N1 viruses or to currently circulating H1N1 viruses. During 2007-08 winter surveillance of the antiviral susceptibility of influenza viruses in Europe revealed thé émergence of H1N1 viruses naturally resistant to OC. When compared to previously circulating H1N1 viruses, OC sensitive H1N1 viruses from the 2007-08 season were found to have significantly reduced Km value for the substrate. Thus, affinity for the substrate of the H275Y mutated N1 is comparable to that of previously circulating sensitive viruses, which may contribute to their overall fitness and transmissibility. These observations on H5N1 or H1N1 viruses underline the natural variability of NA enzymatic properties and its potential consequences in terms of antiviral sensitivity. Epidemiological and clinical data repeatedly report a coincidence between influenza infections and secondary meningococcal disease. Our data suggest that partial hydrolysis of neisserial capsule favour bacterial adhesion on epithelial cells in vitro, and could promote nasopharyngeal tract colonisation in vivo leading in some case to invasive infection
Hervé, Pierre-Louis. „Evaluation de nouvelles stratégies vaccinales contre les virus grippaux H5N1 hautement pathogènes“. Paris 7, 2011. http://www.theses.fr/2011PA077090.
Der volle Inhalt der QuelleHuman transmission of avian, highly pathogenic, H5N1 influenza viruses is currently inefficient. However, the recent geographic spread throughout the world and the increasing number of sporadic human cases increase the likelihood of virus adaptation to humans and the risk of a pandemic episode. The development of vaccines candidate against H5N1 influenza virus remains a global public health priority. This is made particularly complex because of the evolution of H5N1 viruses within multiple phylogenetic clades and subclades. Thus, the core challenge of developing a pre-pandemic H5N1 vaccine resides in defining an immunogenic composition able to induce a cross-protective immunity against ail avian strains, which are susceptible to emerge in humans. An approach based on the development of a bivalent vaccine composed of H5 and NI, which would target two essential functions in the virus, the binding of the virus to its receptor (driven by the HA) and sialidase activity involved in the production of new particles (driven by NA). Taken together, our data demonstrate the value of a vaccine approach based on the induction of anti-Nl immunity, for the broadening of the vaccine effïcacy spectrum against a large number of highly pathogenic H5N1 viruses' clades or sub-clades. They also highlight the limitations of vaccine approaches based solely on the induction of anti-H5 immunity, and propose to focus on a bivalent strategy, targeting two essential functions of the influenza virus carried by the H5 and the NI
Sawoo, Louis Olivier. „Identification des déterminants moléculaires impliqués dans la stabilité des virus grippaux de type A dans l'environnement“. Paris 7, 2014. http://www.theses.fr/2014PA077173.
Der volle Inhalt der QuelleInfluenza A viruses cause thousands of deaths, each year during seasonal outbreaks and at irregular intervals the threat of enduring pandemics. The last one to date was caused by a novel influenza A (H1N1) reassortant which arose in 2009. The fear of pandemics, in particular a potential ine caused by avian H5N1 viruses has stimulated many studies on the mechanisms of transmission of these viruses. However, the knowledge about how environmental factors may influence the survival of the virus outside their host remains limited. Studying the virus survival is crucial to better understand the ecology of influenza viruses and could help authorities to establish and adapt individual hygiene and protection measures during the emergence of a new pandemic virus example. The main goal of this work is to better characterize and understand the mechanisms involved in the survival of influenza viruses outside their hosts. Despite the presence of an envelope, influenza viruses can survive outside the host for an extended period of time (higher than expected). Nevertheless, the stability of these viruses was highly affected by increasing temperatures in air, on surfaces and in water and by increasing salinities in water. Using two strains of H1N1 and H5N1 viruses, it has been shown that the origin of the viral envelope was involved in virus survival as the viral suspensions produced in mammalian cells (MDCK) remained infectious for longer period of time than those grown on avian cells. These results could mainly be explained by differences in lipid composition of the newly formed virions (QT6). Indeed, changes in lipid composition, particularly in cholesterol, directly impressed on the survival of the virus outside the host. Viruses containing a lesser extent of cholesterol in their envelope persisted for shorter periods. In parallel, it was shown that the loss of infectivity, observed when influenza viruses were exposed to the environment with various physical and chemical, was not due to the degradation of their genome. Indeed, it was also shown at the end of survival kinetics, that the viral genome was still protected by an intact viral envelope. Based on these observations, we have, thus, focused our studies on the extemal structures of the virion, in particular the hemagglutinin (HA) whose alterations by physical factors such as temperature could have a direct negative impact on viral survival. Lentiviral particles bearing influenza HA were used to test this hypothesis. In this study, pseudotypes based on the 2009 H1N1 pandemic strain and a seasonal strain of influenza A (H1N1) from 1999 were generated and subjected to different environmental conditions over time. The ability of H1 pseudotypes to infect MDCK cells was then evaluated at various time points of the survival kinetic. It has been shown that an increase in temperature and salinity had a direct negative effect on the survival of influenza pseudotypes. A higher impact was observed for H1 pseudotypes from 1999, in agreement with the experimental results obtained with the corresponding wild type influenza viruses. Moreover, pseudotypes carrying selected single point mutations in the HA were also generated and tested in survival kinetics in a liquid medium. Following these experiments, several key mutations have been identified to either increase or decrease survival time. These same mutations have subsequently been investigated using rescued influenza viruses by reverse genetics. For a more global perspective, other subtypes, such as H3N2 and highly pathogenic H5N1 viruses were included in the study. Taken together, these results suggest a pivotai role of the HA and the lipid composition of the viral envelope in the survival of influenza A viruses outside their hosts
Dublineau, Amélie. „Contribution à l'étude des bases moléculaires des virus grippaux à potentiel pandémique dans l'environnement“. Paris 7, 2012. http://www.theses.fr/2012PA077236.
Der volle Inhalt der QuelleKnowledge of influenza A virus survival in different environmental conditions is a key element to a better understanding of virus transmission and viral ecology. This study could allow anticipating emergences on the one hand and helping health authorities implementating of hygiene and personal protection measures on the other hand. Virus survival outside the host varies from one viral subtype to the other one and also within a subtype. So, viral infectivity was studied over time for five viruses: 2 of H1N1 subtype, 1 of H3N2 subtype and 2 of highly pathogenic (HP) H5N1 subtype. Viruses were subjected to various environmental parameters over time and tested for infectivity using a microtitre endpoint titration or 50% Tissue Culture Infective Dose (TCID50). In water, up to three temperatures were tested: 4, 25 and 35°C, combined or not with four concentrations of sodium chloride (0, 5, 35, 270 part per thousand (ppt)). For H1N1 strains, viral survival was also studied on smooth surface, using watch glasses, at 4, 25 and 35°C. In water, at 4°C and without sodium chloride, viruses were infectious at least 800 days. Increasing environmental temperature and salinity level had a strong negative effect on the survival of viruses which retained their infectivity no more than 1 day at 35°C and 270 ppt of salt. On smooth surface, H1N1 viruses were infectious at least 7 days at 35°C and up to 66 days at 4°C. The viruses have the ability to persist in water and on glass surface for extended periods of time, even at 35°C. The viral genome quantification by quantitative RT-PCR in real time and the detection of the whole M segment by two steps endpoint RT-PCR suggest that external viral structures in direct contact with the environment are mostly involved in virus loss of infectivity. These observational data are in agreement with previously published studies. Until now, only one study focused on the molecular determinants of the résistance of influenza viruses in natural reservoirs and Systems. The study of molecular determinants was performed using a model of lentiviral pseudotypes in order to avoid the work in Biosafety Level 3 (BSL-3) laboratory and the large production of viruses mutated by reverse genetic. Lentiviral pseudotypes produced expressed the HA and the NA glycoproteins at their surface and were used to perform survival kinetics in water. The implementation of this lentiviral System required some experimental improvements and was developed for A(H5N1) viruses. The HA and NA sequences came from the A/Thailand/1 (Kan-1)72004 (H5N1) strain. The potential role of the N-glycosylation of the HA was studied performing mutations in the potential sites of N-glycosylation. Lentiviral pseudotypes mutated for only one glycosylation site were produced. Unsuccessful glycosylation occured changing asparagine (Asn) by glutamine (Gin) in the motif of glycosylation. The preliminary results suggest the involvement of N-glycosylation in the observed persistence of influenza A virus. Plasmids mutated for two or three glycosylation sites and also plasmids mutated for some residues found in the interface of the two HA subunits (HA1/HA2 et HA2/HA2) were produced. Nevertheless, the involvement of these molecular determinants needs further experiments
Buchy, Philippe. „Le virus HSN1 au Cambodge“. Paris 7, 2008. http://www.theses.fr/2008PA077125.
Der volle Inhalt der QuelleH5N1 virus was firstly discovered in Cambodia in December 2003. A study of human infections shows that the virus is responsible for systemic infections and can be recovered in blood and rectum. There are no tissue adaptation mutations on HA protein. Only few mutations associated with higher virulence or human adaptation were found. Cambodian strains are more sensitive to neuraminidase-inhibitors than H5N1 viruses that were circulating previously in Asia but are resistant to ion channel inhibitors in relation with a double mutation on M2 protein. We developed a high-throughput serological test using H5 pseudotyped lentiviral particles and we discovered that 0 to 2% of the villagers (living in places were avian flu outbreaks occurred) have been asymptomatically infected. Bathing and swimming in ponds was associated with a higher risk of being contaminated, We identified H5N1 RNA in ponds and soil in farm settings. Phylogenetic analyses suggest that H5N1 was introduced in Cambodia from Vietnam during several waves and became endemic since 2006 in the South Indochina peninsula. H5N1 virus evolved with the time and a significant antigenic drift was observed. Commercial poultry exchanges play a major role in virus introduction and circulation
Leymarie, Olivier. „Etude du facteur de virulence PB1-F2 dans les interactions hôtes/virus influenza A“. Paris 7, 2013. http://www.theses.fr/2013PA077278.
Der volle Inhalt der QuelleSince 1997, highly pathogenic avian influenza A viruses (HPAIV) H5N1 have been transmitted occasionally to human with a high mortality rate reaching 60%. Although HPAIV H5N1 transmission among people remains a rare event, adaptation cr such strains to human may constitute a danger to public health. PB1-F2, a viral protein identified in 2001, was defined as an influenza A virus virulence factor but its contribution in HPAIV H5N1 pathogenesis in avian and mammalian host species is poorly described. This thesis work focused on better characterization of the PB1-F2 function during HPAIV H5N1 infection in these different host species. For that purpose, we performed comparative transcriptome analysis between an H5N1 HPAIV strain and its PB1-F2- deficient mutant infected mice or chickens. Our work shows in mice that PB1-F2 expression delays the immune response activation but leads to an exacerbation of the inflammatory response accompanied with significant lung damages at the late stage of the infection. On the contrary, PB1-F2 expression down-regulates inflammatory response and reduces mortality rate during chicken infection. In parallel to this work, an in vitro study helped us to identify a novel interacting protein of PB1-F2: Calcoco2. Functional analysis in alveolar cell line A549 demonstrates that the interaction between thesi two proteins leads to increase the type I interferon response by potentiating the MAVS signaling pathway activation
Desdouits, Marion. „Myopathies virales : étude des interactions entre les cellules musculaires et les virus HTLV-1 et Influenza A“. Paris 7, 2011. http://www.theses.fr/2011PA077181.
Der volle Inhalt der QuelleThis thesis aimed at deciphering the pathogenesis of myopathies associated with human viral infections and study the interactions between muscle cells and these viruses, namely HTLV-1 and Influenza A. HTLV-1 associated inflammatory myopathies (HAIM) present similarities with idiopathic inflammatory myopathies (IIM) and with tropical spastic paraparesis or HTLV-1 associated myelopathy (TSP/HAM). Using a series of blood and muscle samples from 13 patients with HAIM, we showed that the pro viral load of these patients is low, similar to that of asymptomatic HTLV-1 carriers, whereas an elevated proviral load is a known risk factor for TSP/HAM. Other experiments allowed us to highlight the possible role of IFNγ in the disease, as well as the presence of autoantibodies in HTLV-1 infected individuals, with or without HAIM. Thèse results shed a new light on the pathogenesis of HAIM, suggesting that it may differ from that of TSP/HAM and be more similar to that of IIM. Besides, we modelized in vitro the effect of HTLV-1 on muscle reneration using a coculture of infected lymphocytes and primary human muscle cells. The expression of Tax by infected lymphocytes inhibited the differentiation of muscle cells, a mechanism that could worsen the muscle symptoms during HAIM. Eventually, using field isolates of Influenza A (H1N1) and human muscle cells in primary culture, we showed that differenciated muscle cells can be productively infected by Influenza A, which leads to their lysis. This could explain the development of acute myopathies with rhabdomyolysis after Influenza infection
Salez, Nicolas. „Contribution à l'étude séro-épidémiologique de la grippe“. Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM5005/document.
Der volle Inhalt der QuelleIn late April 2009, news swine-origin A/H1N1 influenza virus cases were confirmed in Mexico and the United States. Quickly, it was spread worldwide causing the first flu pandemic of the 21st century. Different works presented in this thesis describe the means used to obtain information to estimate the actual attack rate of this new virus, and information on risk populations. During the first months, we have established a serology platform including a reception-processing samples laboratory for implementing our hémagglutination Inhibition technique (IHA). Processing of 40,000 sera from several parts of the world: France, Bolivia, Djibouti, Mali, Reunion and Laos, has allowed the analysis of serological data and their comparison. Our serological studies of influenza A(H1N1) pdm09 show that 10% to 40% of people tested were infected with this new virus after the first wave in 2009. The highest attack rates were observed in children and young adults, while the elderly were relatively spared because they were already protected again antigenic close viruses that circulated before 1957 (pandemic and / or seasonal). The analysis of serological data were also used to try to identify the risk factors for A(H1N1)pdm09 infection. It appears that infection with influenza A(H1N1)pdm09 was ubiquitous on the French territory, whatever the socio-demographic factors, and the Flu virus transmission can probably conditioned by the environmental and hygienic conditions in household