Dissertations / Theses on the topic 'Glycoprotéines de fusion virales'
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Bär, Séverine. "Rôle de l'ectodomaine des glycoprotéines d'enveloppe transmembranaires virales dans les étapes tardives de la fusion membranaire." Paris 7, 2005. http://www.theses.fr/2005PA077005.
Full textMinoves, Marie. "Etude fonctionnelle et structurale de la glycoprotéine du virus de la Stomatite Vésiculaire et des Lyssavirus." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASL068.
Full textVesicular stomatitis virus (VSV), an enveloped virus, is the prototype species of the genus Vesiculovirus within the family Rhabdoviridae. Its G glycoprotein is responsible for receptor recognition, on the host cell surface, that triggers clathrin-mediated endocytosis of VSV. Then, within the acidic environment of the endosome, VSV G undergoes a fusogenic conformational change from the pre-fusion form of G to its post-fusion form, leading the fusion of both membranes. G is also the target of virus-neutralizing antibodies. Both structures of the pre- and post-fusion forms of the soluble ectodomain of G (i.e. without its transmembrane part) were determined by radiocrystallography. These structures established G as the prototype of class III fusion glycoproteins. However, the organization of the carboxyterminal part of the ectodomain and the transmembrane domain of G, which play an important role during the fusion process, remains unknown. Therefore, we carried out a cryo-electron microscopy study on the complete glycoprotein, directly purified from viral particles, alone or in complex with a monoclonal antibody. This study led to complete the structures of the ectodomain in its pre- and post-fusion conformations. It also revealed that the transmembrane domains are mobile within the membrane. We have also solved two structures of G in complex with a FAb derived from a neutralizing antibody, recognizing both pre- and post-fusion forms of G from several strains of Vesiculovirus. Based on these first structures of a complex between G and an antibody, we could characterize the epitope, identify the key G residues in the interaction and propose a neutralization mechanism. This work significantly increases our knowledge of the structure of G, which is the most widely used glycoprotein in biotechnology for cargo delivery and in gene therapy (by lentivirus pseudotyping).We also initiated a study aimed at characterizing the glycoproteins of Lyssaviruses, a genus also part of the Rhabdoviridae family, and for which rabies virus is the prototype. We produced and purified the ectodomains of several Lyssaviruses, and we were able to obtain a crystallographic structure of the ectodomain of Ikoma virus (IKOV G), which corresponds to a late monomeric intermediate. Several approaches are underway to further characterize this structure. We also carried out a phage display selection of alphaReps directed against IKOV G. Alphareps are artificial proteins binders consisting of helical repeats. 6 out of 11 alphareps are able to bind IKOVG. Complexes of IKOV G with alphareps are currently being characterized. We plan to i) use these tools as crystallization helpers to trap different conformations of G in crystallography or cryo-EM ii) evaluate the potential antiviral activity of these alphareps
Mougin, Bruno. "Immunogénicité des glycoprotéines membranaires du virus de la rougeole : influence du vecteur de présentation de l'antigène sur la réponse immunitaire et sur les interactions avec le macrophage." Lyon 1, 1990. http://www.theses.fr/1990LYO1T048.
Full textCiczora, Yann. "Rôles fonctionnels des domaines transmembranaires des glycoprotéines d'enveloppe E1 et E2 du virus de l'hépatite C." Lille 2, 2006. http://www.theses.fr/2006LIL2S064.
Full textHepatitis C virus (HCV) encodes two envelope glycoproteins, E1 and E2 associated as heterodimers. These proteins are essential for virus infectivity. The two charged residues (Asp728 and Arg 730) of transmembrane domain (TMD) of E2 do not contribute equally in the glycoprotein functions. The two charged residues are required for ER retention, but only the aspartic acid is necessary for heterodimerization. Moreover the mutation of this charged residues affects the entry functions of these proteins. We have done a tryptophane scanning mutagenesis of each residue of these segments. The Asp728 and the two glycine residues (Gly354 and Gly358) are required for the formation of the heterodimer. Moreover other residues (Lys370, Leu726, Ala727, Ala729) are also implicated in these interactions. Finally, our observations indicate that the TMDs are also involved in virus entry. Indeed, some mutants of the TMDs of E1 and E2 affected an early step of the fusion between the viral and cell membrane
Vasiliauskaite, Ieva. "Structural characterization of viral envelope glycoproteins." Electronic Thesis or Diss., Paris 6, 2014. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2014PA066507.pdf.
Full textViral glycoproteins are responsible for the two major steps in entry into host cells by enveloped viruses: 1) attachment to cellular receptor/s and 2) fusion of the viral and cellular membranes. My thesis concentrated first on the structural analysis of the major envelope glycoprotein E2 of two hepaciviruses: GB virus B (GBV-B) and hepatitis C virus (HCV). Crystallization of the GBV-B E2 ectodomain remained unsuccessful, but the characterization of truncated versions of E2 suggested an important role of its C-terminal moiety in receptor binding. In parallel, I co-crystallized a synthetic peptide mimicking HCV E2 with an antibody fragment directed against the major receptor-binding loop of E2 that is targeted by broadly neutralizing antibodies. The structure unexpectedly revealed an α-helical peptide conformation, which is in stark contrast to the extended conformation of this region observed in the structure of an E2 core fragment. Together with further biochemical evidence this suggests an unanticipated structural flexibility within this region in the context of the soluble E2 ectodomain. Secondly, I focused on the structural analysis of the baculovirus glycoprotein F. I determined the crystal structure of the post-fusion trimer of a trypsin-truncated F fragment. This structure confirmed previous predictions that baculovirus F protein adopts a class I fusion protein fold and is homologous to the paramyxovirus F protein. Baculovirus F is therefore the first class I fusion protein encoded by a DNA virus. My results support the hypothesis that F proteins may have a common ancestor and imply interesting evolutionary links between DNA and RNA viruses and their hosts
Vasiliauskaite, Ieva. "Structural characterization of viral envelope glycoproteins." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066507/document.
Full textViral glycoproteins are responsible for the two major steps in entry into host cells by enveloped viruses: 1) attachment to cellular receptor/s and 2) fusion of the viral and cellular membranes. My thesis concentrated first on the structural analysis of the major envelope glycoprotein E2 of two hepaciviruses: GB virus B (GBV-B) and hepatitis C virus (HCV). Crystallization of the GBV-B E2 ectodomain remained unsuccessful, but the characterization of truncated versions of E2 suggested an important role of its C-terminal moiety in receptor binding. In parallel, I co-crystallized a synthetic peptide mimicking HCV E2 with an antibody fragment directed against the major receptor-binding loop of E2 that is targeted by broadly neutralizing antibodies. The structure unexpectedly revealed an α-helical peptide conformation, which is in stark contrast to the extended conformation of this region observed in the structure of an E2 core fragment. Together with further biochemical evidence this suggests an unanticipated structural flexibility within this region in the context of the soluble E2 ectodomain. Secondly, I focused on the structural analysis of the baculovirus glycoprotein F. I determined the crystal structure of the post-fusion trimer of a trypsin-truncated F fragment. This structure confirmed previous predictions that baculovirus F protein adopts a class I fusion protein fold and is homologous to the paramyxovirus F protein. Baculovirus F is therefore the first class I fusion protein encoded by a DNA virus. My results support the hypothesis that F proteins may have a common ancestor and imply interesting evolutionary links between DNA and RNA viruses and their hosts
Voss, James. "Chikungunya envelope glycoprotein structure at neutral PH determined by X-ray crystallography." Paris 7, 2011. http://www.theses.fr/2011PA077021.
Full textChikungunya is an emerging mosquito-bome alphavirus that has caused widespread outbreaks of debilitating human disease in the past five years. CHIKV invasion of susceptible cells is mediated by two viral glycoproteins, E1 and E2, which carry the main antigenic determinants and form an icosahedral shell at the virion surface. Glycoprotein E2, derived from furin cleavage of the p62 precursor to E3 and E2 is responsible for receptor binding and is the major viral antigen. The E1 protein is responsible for inducing the fusion of viral and cellular membranes in the target cell endosome which is required for release of the viral nucleocapsid into the cytoplasm to initiale infection of a cell. While the structure of E1 has been determined, the structure of E2"has remained elusive over the years. This thesis reports the atomic structures of the mature (E3/E2/E1) and immature (P62/E1) envelope glycoprotein complexes from Chikungunya virus determined by X-ray crystallography using a recombinant protein construct. This construct contained the covalently linked ectodomains of p62 and E1. Diffracting crystals of the purified complexes were obtained at neutral pH when the linker joining the ectodomains was cleaved. The glycoprotein structures were fit into reconstructions of the alphavirus virion obtained from cryo-electron microscopy (cryoEM). This analysis resulted in an inferred atomic model of the entire 25MDa surface of the highly conserved alphavirus virion and allowed for the synthesis of a wealth of genetic, biochemical, immunological and electron microscopy data accumulated over the years on alphaviruses in general
Lopez, Sandra. "Rôle du cofacteur cellulaire TIP47 dans l'incorporation de la glycoprotéine d'enveloppe dans les particules virales du VIH-1." Paris 7, 2007. http://www.theses.fr/2007PA077170.
Full textThe formation of new infectious HIV-1 viruses requires the encounter between three major viral components: the envelope glycoprotein (Env), the Gag precursor and the genomic RNA. Env incorporation into the viral Gag particles is a crucial step since it confers to the newly formed virions the capacity to infect new target cells. Yet the mechanisms of Env incorporation are not well known. The first part of my thesis allowed us to identify the first cellular cofactor, TIP47, required for Env incorporation. TIP47 permits the association between Gag and Env by interacting simultaneously with the matrix domain of Gag and with the cytoplasmic domain of the transmembrane subunit TMgp41 of Env. HIV-1 Env incorporation is an active mechanism, in which the interaction between Gag, TIP47 and Env plays a central role. TIP47 is essential for Env incorporation into virions produced by différent target cells of HIV-1, as T CD4+ lymphocytes and primary macrophages. The second part of my thesis allowed the characterization of a new group of partners of the cytoplasmic domain of TMgp41 of HIV-1 Env: transcription factors anchored in the endoplasmic reticulum. Thus, Env can participate in the regulation of different cellular pathways. The interaction between Env and one of these factors, Luman, inhibits its activation. Luman inhibits the transcriptional activity of HIV-1 genes, and Env seems to counteract this inhibition. On the other hand, ATF6 and SREBP, the other factors we identified, are necessary for viral replication and might be activated during HIV-1 infection
Baquero, Salazar Eduard. "Etude structurale de la glycoprotéine G du virus Chandipura : identification d'intermédiaires fonctionnels durant la transition structurale associée à la fusion." Paris 7, 2013. http://www.theses.fr/2013PA077046.
Full textEnveloped viruses enter cells through a membrane fusion reaction driven by conformational changes of viral fusion glycoproteins. Crystal structures have provided static pictures of pre- and post-fusion conformations for several of these glycoproteins but structures of intermediates are unknown. Vesiculovirus glycoproteins (G) form trimeric assemblies both in their pre- and post- fusion conformation. We report here a single crystal structure containing two different states of G which correspond to an early and a late intermediate during the conformational change of the glycoprotein G of Chandipura virus, a vesiculovirus responsible for deadly encephalopathies. In the crystal, the two intermediates are associated to form a fusion loop-exposing flat tetramer with twofold symmetry. Consistent with these data, electron microscopy and tomography show two different intermediates at the viral surface depending on experimental conditions : a flat assembly leading to viral aggregation and a monomeric elongated structure which resembles the late intermediate. All this information and previous rhabdoviruses mutants with so far unexplained phenotypes, allowed us to propose that G dimer or tetramer have a role during membrane fusion. We propose a model for G structural transition that is depicted as a series of events in which, after dissociation of the trimeric prefusion state, the resulting monomers are able to form, on the one hand, a tetrameric assembly in the contact zone with the target membrane, and on the other, outside this contact zone, a helical network of spikes in their post-fusion state. This helical network would be involved in fusion pore enlargement
Vautherot, Jean-François. "Coronavirus entérique bovin : identification des protéines structurales et analyse antigénique des glycoprotéines externes." Lyon 1, 1994. http://www.theses.fr/1994LYO1T273.
Full textMoulard, Maxime. "Caractérisation de la protéase cellulaire responsable de la maturation des glycoprotéines d'enveloppes virales." Aix-Marseille 2, 1992. http://www.theses.fr/1992AIX22066.
Full textVachot, Laurence. "Caractérisation des mécanismes de capture de glycoprotéines d'enveloppe de VIH-1 par le DC-SIGN : application aux glycoprotéines d'isolats primaires de primo-infection." Lyon 1, 2003. http://www.theses.fr/2003LYO10185.
Full textDenesvre, Caroline. "Étude fonctionnelle des glycoprotéines d'enveloppe des rétrovirus HTLV-I et F-MuLV." Lyon 1, 1995. http://www.theses.fr/1995LYO1T200.
Full textBonnafous, Pierre. "Fusion membranaire induite par l'hémagglutinine du virus de la grippe." Toulouse 3, 2000. http://www.theses.fr/2000TOU30196.
Full textBouard, David. "La glycoprotéine d'enveloppe rétrovirale : trafic intracellulaire et recrutement lors de l'assemblage viral." Lyon, École normale supérieure (sciences), 2008. http://www.theses.fr/2008ENSL0471.
Full textAslan, Hamide. "Étude moléculaire des glycoprotéines d'attachement des Henipavirus : identification et caractérisation des domaines responsables de l'interaction avec les récepteurs cellulaires, éphrineB2 et éphrineB3." Lyon 1, 2007. http://www.theses.fr/2007LYO10195.
Full textThe Henipaviruses - Nipah (NiV) and Hendra (HeV) - are recently emergent zoonotic paramyxoviruses, responsible for pathologies in the man and the animals. Their high virulence and the absence of available treatments led to their classification into P4 pathogens. The entry of these viruses in the host cell is under control of two glycoproteins, the attachment glycoprotein (G) and the fusion protein (F). We identified several residues of the attachment glycoprotein of the NiV (NiV-G), potentially participating in receptor-binding, the ephrinB2. Ours results suggest that a receptor-binding site localizes on the top surface of the NiV-G globular head. We also showed that the site responsible for ephrinB2 interaction on the globular head of the HeV attachment glycoprotein (HeV-G) is in an identical location to that predicted for NiV-G. We also tested the attachment glycoprotein residues of the HeV and NiV for ephrinB3 interaction, an alternate receptor of the NiV. Our results indicate that the HeV could use ephrinB3 as receptor
Garnier, Florence. "Contribution à l'étude de la réponse du système immunitaire au virus de la rougeole." Lyon 1, 1993. http://www.theses.fr/1993LYO1T212.
Full textChanel, Vos Chantal. "Etude du rôle de l' acide aminé histidine 230 dans la boucle ij de la protéine E1 du virus de la Forêt de Semliki dans la fusion membranaire virale." Paris 7, 2005. http://www.theses.fr/2005PA077060.
Full textGirerd-Chambaz, Yves. "Approche moléculaire des fonctions de l'enveloppe du virus HTLV-I : régulation du gène env et expression des glycoprotéines virales dans des cellules humaines exprimant le récepteur cellulaire du virus." Lyon 1, 1993. http://www.theses.fr/1993LYO1T297.
Full textBrandler, Samantha. "Etude du mécanisme d'inhibition de la fusion des flavivirus par les anticorps et mise au point d'un candidat vaccin contre la dengue basé sur l'expression d'un antigène d'enveloppe par un vecteur dérivé du vaccin contre la rougeole." Aix-Marseille 1, 2008. http://theses.univ-amu.fr.lama.univ-amu.fr/2008AIX11003.pdf.
Full textDengue fever is a reemerging disease that threatens one third of the world's population, for which no vaccine is available. In this work, we evaluated a new vaccination strategy based on the expression of a combined dengue antigen by a vector derived from the pediatric live attenuated measles vaccine. Understanding the mechanisms of flavivirus neutralization by antibodies is essential for the design of innovative vaccine approaches against dengue. Therefore, as a first step, we studied the mechanism of inhibition of fusion by neutralizing antibodies directed against the three domains of the envelope protein (E). The Tick-borne encephalitis virus (TBEV) was used as a model in in vitro fusion tests, and coflottation assays with lipid membranes. The results showed that the neutralizing antibodies can interfere with the early or late stages of the fusion process. This study also shows that antibodies against domain III of the E protein can block both the viral entry and fusion. As a proof-of-concept of our vaccination strategy, we inserted into measles vector the domain III of the glycoprotein E of dengue virus (EDIII), which contains the putative receptor binding site and serotype-specific neutralizing epitopes. To strengthen its immunogenicity, EDIII was fused with the pro-apoptotic ectodomain of the membrane protein (ectoM) of VDEN-1. Tested in mice susceptible to measles, this vaccine candidate was immunogenic and able to induce long term serotype-specific neutralizing antibodies. The presence of the ectoM proved crucial for the immunogenicity of EDIII. Its adjuvant capacity correlated with its ability to mature dendritic cells and to enhance the secretion of proinflammatory and antiviral cytokines, as well as chemokines involved in the development of adaptive immunity. A tetravalent measles-dengue candidate was then generated in order to induce the same immunity against the 4 serotypes of dengue virus. This vaccination strategy combining measles and dengue might offer an affordable pediatric vaccine particularly attractive to immunize children both against measles and dengue fever in areas of the world where the two diseases co-exist
Roche, Stéphane. "Caractérisation du complexe de fusion des rhabdovirus." Phd thesis, Palaiseau, École polytechnique, 2004. http://www.theses.fr/2004EPXX0050.
Full textRoche, Stéphane. "Caractérisation du complexe de fusion des rhabdovirus." Phd thesis, Palaiseau, Ecole polytechnique, 2004. http://pastel.archives-ouvertes.fr/pastel-00504172/en/.
Full textNominé, Yves. "Caractérisation biophysique de la qualité des protéines de fusion : application à l'étude structurale et fonctionnelle de l'oncoprotéine virale E6." Strasbourg 1, 2002. https://publication-theses.unistra.fr/public/theses_doctorat/2002/NOMINE_Yves_2002.pdf.
Full textE6 is an oncoprotein produced by "high risk" Human Papillomaviruses (HPVs) involved in cervical cancers. E6 participates oncogenesis through different pathways, in particular by degrading the cellular tumor suppressor protein p53. The aim of this thesis was to solve the solution structure of E6 by Nuclear Magnetic Resonance (NMR). The introduction chapter first focuses on the different states (micro- and macroscopic) adopted by globular proteins in solution, including notions such as folding and stability. Then we record the principles, applications and limits of various biophysical techniques for the study of proteins. Finally, we briefly introduce the biological context of E6 protein. At the start of this work, E6 had never been purified although its sequence was known since 1985. In the results section, we first demonstrate that bacterial expression of E6 fused to the C-terminus of MBP (Maltose Binding Protein) generates " soluble inclusion bodies ". These particles, which originate from agregation of misfolded E6 moieties, remain soluble thanks to the high solubility of MBP moities. These observations have allowed us to produce soluble and folded samples of full-length E6 as well as its two zinc-binding domains. Finally, we have managed to solve the NMR structure of the C-terminal zinc-binding domain. On another hand, the optimized quality of our E6 samples have allowed us to demonstrate E6 binding to a particular DNA structural motif found in four-way DNA junctions. The kinetic parameters of this interaction have been determined by BIAcore. This work will provide a better understanding of the molecular pathways of E6 action and opens the way for new therapeutic strategies against cervical cancers. Furthermore, our methods for control and optimization of protein fusion quality can be generalized for future studies of other recalcitrant proteins
D'Arienzo, Valentina. "Caractérisation des glycoprotéines d'enveloppe des variants viraux impliqués dans la transmission du virus de l'hépatite C." Thesis, Tours, 2013. http://www.theses.fr/2013TOUR3803/document.
Full textLittle is known about the transmitted variants responsible for the spread of HCV infection, principally because of the difficulties to recruit patients early enough in infection. To address this issue, we proposed to track the genetic bottleneck event in HCV quasispecies, leading to productive clinical infection in three health care workers accidentally contaminated through needlestick accidents. By using a single genome amplification (SGA) approach we identified genes coding the viral envelope glycoprotein E1E2 which composed these quasispecies. The E1E2 sequences were then directly sequenced and subjected to a phylogenetic analysis. By cloning these full-length E1E2 sequences, we investigated the phenotypic properties of the envelope glycoproteins potentially involved in selective HCV transmission and early stage of infection, a period during which the virus might be most vulnerable to elimination by preventive vaccines or immunotherapies
Rifi, Omar. "Production des polypeptides issus des glycoprotéines d'enveloppe du VIH-1 pour des études biophysique et structurale par RMN et DC." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAF026.
Full textA few stable regions have been discovered on the HIV-1 env gp against which some patients produce neutralizing antibodies. The most promising ones are located in the MPER and are probably exposed transiently during the fusion. Whereas the peptides isolated from this region failed to induce immunogenic response, previous studies suggest the lipid membrane plays a role in antigens structure and in the immunogenic response.That is why we investigate the structure of these épitopes in membrane models. This requires the production of these épitopes by bacterial overexpression, their purification and their reconstitution in liposomes. A CD study shows that they could undergo a conformational change; this will be confirmed by NMR. Also their immunogenicity will be checked by mice immunization. In addition, we find that cholesterol could change the orientation of peptides encompassing a gp41 CRAC motif
Albecka, Anna. "Étude de l’entrée cellulaire du virus de l’hépatite C : rôle du récepteur aux LDL et identification de régions fonctionnelles des protéines de l’enveloppe virale." Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10143/document.
Full textTo initiate its life cycle, hepatitis C virus (HCV) needs to cross the cellular membrane. This process involves the viral envelope proteins and cellular receptor(s). During this thesis, we studied these two aspects. Our objectives were to identify new functional determinants in HCV glycoprotein E2 and to investigate the role of the LDL receptor (LDLR) during the HCV life cycle. With the hypothesis that E1 and E2 glycoproteins have co-evolved within the different genotypes, we identified functional intergenotypic incompatibilities between these two proteins. Based on a structural model, we then constructed several series of intergenotypic E2 chimeras. The functionality of these chimeras was analyzed in an infectious system and with the help of retroviral pseudotypes. This work led us to identify several E2 determinants involved in viral particle assembly as well as a juxtamembrane region taking part in virus entry. This latter has also been characterized at a structural level to better understand its role. Due to the potential interaction between HCV particle and low-density lipoproteins, the LDLR has been proposed as an entry factor for this virus. However, its exact role in HCV entry remains poorly understood. In this thesis, we investigated the role of this receptor in the HCV life cycle by comparing virus entry to the mechanism of lipoprotein uptake. We showed that the viral particle interacts with the LDLR. However, this interaction does not seem to lead to a productive infection. Furthermore, our data are in favour for a role of the LDLR as a lipid providing receptor which modules viral RNA replication
Belot, Laura. "Etude structurale et fonctionnelle de la glycoprotéine des Rhabdovirus Structural basis for the recognition of LDL-receptor family members by VSV glycoprotein Structural and cellular biology of rhabdovirus entry Monomeric Intermediates Formed by Vesiculovirus Glycoprotein during Its Low-pH-induced Structural Transition." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS522.
Full textRhabdoviruses are single stranded RNA enveloped viruses. They own a unique glycoprotein G anchored on the viral membrane. G is involved in the early stages of the viral cycle. At first G binds a cellular receptor, leading to the virus endocytosis. Then G orchestrates the membrane fusion between the viral and endosomal membranes. Membrane fusion allows the release of the viral genome into the cytoplasm of the infected cell.The low-density lipoprotein receptor (LDLR) is the main receptor of VSV. The ectodomain of the LDLR is composed of a large ligand binding domain constituted of cysteine-rich domains (CR1 to CR7).In order to understand the molecular basis of the interaction between G and its receptor, we performed binding test of G with all the CR domains of the LDLR. This revealed that only CR2 and CR3 domains could bind G. When CR2 and CR3 are present in the VSV inoculum, they protect the cells from VSV infection. We crystallized G in complex with each of these CR domains. The structures reveal that CR2 and CR3 binding sites on G are identical, and that the same residues on G are involved in the binding of the two CR domains. HAP-1 cells in which the gene encoding the LDLR has been invalidated are still susceptible to VSV infection. This confirms that VSV can use other receptors than the LDLR itself to enter the cells. However, mutation of G residues that are key in the interaction with the CR domains of the LDLR abolish the infectivity of VSV in mammalian and insect cells. This indicates that the only VSV receptors in these cells are members of the LDLR family and that VSV G has specifically evolved to interact with their CR domains. Moreover, we have shown that G mutated for key residues involved in the interaction with CR domains, are still able to induce fusion. This work shows that receptor recognition and G fusion activities can be decoupled. This paves the way to develop glycoproteins derived from G with modified tropism.In Rhabdoviruses, G is the only target of neutralizing antibodies. There is no structure of a Rhabdovirus G in complex with an antibody. The 8G5F11 antibody neutralizes several genotypes of the genus Vesiculovirus including VSV. We have shown that FAB 8G5F11 prevents infection of cells by VSV Indiana on the one hand and that they recognize the pre- and post-fusion form of VSV G with a 1: 1 G: FAB stoichiometry on the other hand. We have developed the observation conditions of the G-FAB complex in cryo-electron microscopy, which could be useful to obtain the structure of the G-FAB complex.We also started a study to characterize the glycoproteins of other Rhabdoviruses of the Lyssavirus genus. We produced and purified G ectodomains of rabies virus (RABV), Mokola virus (MOKV) and West Caucasian bat virus (WCBV). We characterize these G by electron microscopy at different pHs. The measurements made on G at pH 8 are compatible with those expected for a pre-fusion monomer of G. At pH 6, these ectodomains could correspond to a monomeric late intermediate in the structural transition. Obtaining the crystallographic structure of the G ectodomain of MOKV could validate these results
Dubois, Julia. "Étude de l'infection par le métapneumovirus humain : facteurs de virulence et développement de vaccins vivants atténués." Thesis, Université Laval, 2018. http://www.theses.fr/2018LYSE1018/document.
Full textHuman metapneumovirus (hMPV) is a major pathogen responsible of acute respiratory tract infections, such as bronchiolitis or pneumonia, affecting especially infants, under five years old, elderly individuals and immunocompromised adults. Identified since 2001, this virus and its pathogenesis still remain largely unknown and no licensed vaccines or specific antivirals against hMPV are currently available. In this context, my research project was built over two main subjects: (i) The study of the fusion F glycoprotein which is the major antigenic protein of hMPV and is responsible of viral entry into host cell. By its crucial role for the virus, the F protein has already been characterized in several structural and/or functional studies. Thus, it has been described that the hMPV F protein induces membrane fusion autonomously, resulting in variable cytopathic effects in vitro, in a strain-dependent manner. However, as the determinants of the hMPV fusogenic activity are not well characterized yet, we focused on identification of some of these, located in heptad repeats domains of the protein. (ii) The evaluation of hMPV SH and G gene deletion for viral attenuation. Liveattenuated hMPV vaccine candidates for infants’ immunization has been constructed thank to this deletion approach at the beginning of hMPV vaccine development efforts. Despite encouraging results, these candidates have not been further characterized and the importance of the viral background has not been evaluated
Guinoiseau, Thibault. "Etude des propriétés génétiques et fonctionnelles des variants du virus de l'hépatite C lors d'évènements de transmission." Thesis, Tours, 2018. http://www.theses.fr/2018TOUR3301.
Full textIn infected individuals, HCV circulates as a complex mixture of genetically different, but closely related viral variants named quasispecies. In a transmission event, some viral variants are preferentially transmitted. The genetic and functional properties of these variants are still unknown. The aim of our work was to identify molecular determinants of E1E2 associates with a greater capacity of transmission. We also intend to study the functional properties of transmitted and no transmitted variants, as for example sensibility to autologous neutralization. Studied sera samples were obtained from three women and their child infected by the HCV, who were participating in HIV prevention clinical trial for the prevention of perinatal transmission of HIV in Thailand. Quasispecies were studied with single genome amplification (SGA) followed by deep sequencing (Illumina). A decrease in intra-host diversity (genetic bottleneck) was observed in the viral population of child near birth (week 6) compared with that observed in the mother (just before delivery). For 2 pairs, the major variant observed in the mother was the same as the major one identified in the child. Retroviral pseudotypes (HCVpp), bearing each transmitted and non-transmitted envelope glycoproteins were produced. For each one, the level of infectivity on HuH7 cells was measured as well as the neutralizing activity of the autologous sera. For the first pair, the major variant (transmitted) appears resistant to autologous neutralization. For the second pair, the transmitted minor variant appears slightly resistant to autologous neutralization. A non-transmitted major variant is sensitive to autologous neutralization. Complementary studies with HCV derived from cell culture (HCVcc) are in progress We hope that the results of this study may be helpful to better understand early steps of HCV infection, which is of great interest for the development of immunoprophylaxis and vaccine strategies
Welman, Mélanie. "Étude du rôle des domaines structuraux et du motif de ciblage YXXO dans le transport intracellulaire et de l'activité fusogénique de la gp41 du VIH-1." Thèse, 2006. http://hdl.handle.net/1866/15818.
Full textEl, Kasmi Imane. "L’étude de la glycoprotéine gM du virus Herpès simplex de type 1 (HSV-l) : identification de ses partenaires viraux et cellulaires et leur rôle dans la régulation de l’infection virale." Thèse, 2017. http://hdl.handle.net/1866/20239.
Full textVeillette, Maxime. "Rôle de la conformation des glycoprotéines de l’enveloppe du VIH-1 dans la réponse cytotoxique cellulaire dépendante des anticorps et impact des protéines virales Nef et Vpu." Thèse, 2016. http://hdl.handle.net/1866/15993.
Full textWhile huge efforts are put forth to develop therapeutic strategies against HIV-1 infection, it is necessary to better understand the viral determinants that will help the effectiveness of these approaches. Moreover, a voluminous scientific literature suggests that antibodies against HIV-1 that have the ability to induce an Fc-mediated effector response can play an important role in the prevention and control of the disease. However, little information is available regarding the determinants recognized by these antibodies and how the virus protects itself from this response. The aim of the work presented in this thesis is therefore to better elucidate the viral mechanisms controlling recognition of infected cells by antibodies capable of inducing effector responses. In regards to the correlates of protection identified in the RV144 vaccine trial, the work presented here focuses on antibody-dependant cellular cytotoxicity (ADCC), since this effector response was suggested to have played a role in the protection observed in the RV144 trial. In addition, many antibodies that induce this response against HIV are known to recognize the virus surface glycoprotein (Env) in an open conformation, that is to say, the conformation adopted by the binding of Env with the CD4 receptor (CD4i epitopes). We have developed two in vitro techniques to study these conformational changes and their impact on ADCC responses. The techniques developed, a cell-based ELISA to measure Env conformational changes and the measure of ADCC responses by flow cytometry, allowed us to demonstrate how the virus prevents exposure of Env CD4i epitopes. The simultaneous activity of viral accessory proteins Vpu and Nef on the removal of CD4 from the surface of infected cells and the Vpu-mediated inhibition of the restriction factor Tetherin / BST-2 control both Env and CD4 levels at the cell surface, thus modulating Env-CD4 interaction. This ultimately results in a decrease in the susceptibility of infected cells to ADCC responses against CD4i epitopes recognized by antibodies that are highly prevalent during HIV infection. Also, we demonstrate how using small compounds mimicking the CD4 binding of Env forces the exposure of CD4i epitopes, even in the presence of Nef and Vpu proteins, and therefore increases the susceptibility to ADCC responses against infected cells. Another discovery is presented here that demonstrates how the soluble portion of Env produced by infected cells can interact with the CD4 receptor on the bystanders non-infected cells and induce their recognition and elimination by ADCC responses against Env. Overall, the modulation of ADCC responses by Env-CD4 interaction is an important pillar of HIV-1 host – pathogen interaction from the perspective of Fc effector functions. The work presented in this thesis has the potential to be used in the development of new antiviral strategies while expanding the fundamental understanding of HIV-1 host - pathogen interactions.