125 research outputs found
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Selective expansion of myeloid and NK cells in humanized mice yields human-like vaccine responses
Mice engrafted with components of a human immune system have become widely-used models for studying aspects of human immunity and disease. However, a defined methodology to objectively measure and compare the quality of the human immune response in different models is lacking. Here, by taking advantage of the highly immunogenic live-attenuated yellow fever virus vaccine YFV-17D, we provide an in-depth comparison of immune responses in human vaccinees, conventional humanized mice, and second generation humanized mice. We demonstrate that selective expansion of human myeloid and natural killer cells promotes transcriptomic responses akin to those of human vaccinees. These enhanced transcriptomic profiles correlate with the development of an antigen-specific cellular and humoral response to YFV-17D. Altogether, our approach provides a robust scoring of the quality of the human immune response in humanized mice and highlights a rational path towards developing better pre-clinical models for studying the human immune response and disease.National Institute of General Medical Sciences (U.S.) (Award T32GM007753)Searle Scholars ProgramArnold and Mabel Beckman Foundation (Young Investigator Program)National Institutes of Health (U.S.) (1DP2OD020839)National Institutes of Health (U.S.) (5U24AI118672)National Institutes of Health (U.S.) (1U54CA217377)National Institutes of Health (U.S.) (1R33CA202820)National Institutes of Health (U.S.) (2U19AI089992)National Institutes of Health (U.S.) (21R01HL134539)National Institutes of Health (U.S.) (2RM1HG006193)National Institutes of Health (U.S.) (2R01HL095791)National Institutes of Health (U.S.) (P01AI039671)Bill & Melinda Gates Foundation (OPP1139972
Up-regulation of the ATP-binding cassette transporter A1 inhibits hepatitis C virus infection.
International audienceHepatitis C virus (HCV) establishes infection using host lipid metabolism pathways that are thus considered potential targets for indirect anti-HCV strategies. HCV enters the cell via clathrin-dependent endocytosis, interacting with several receptors, and virus-cell fusion, which depends on acidic pH and the integrity of cholesterol-rich domains of the hepatocyte membrane. The ATP-binding Cassette Transporter A1 (ABCA1) mediates cholesterol efflux from hepatocytes to extracellular Apolipoprotein A1 and moves cholesterol within cell membranes. Furthermore, it generates high-density lipoprotein (HDL) particles. HDL protects against arteriosclerosis and cardiovascular disease. We show that the up-regulation of ABCA1 gene expression and its cholesterol efflux function in Huh7.5 hepatoma cells, using the liver X receptor (LXR) agonist GW3965, impairs HCV infection and decreases levels of virus produced. ABCA1-stimulation inhibited HCV cell entry, acting on virus-host cell fusion, but had no impact on virus attachment, replication, or assembly/secretion. It did not affect infectivity or properties of virus particles produced. Silencing of the ABCA1 gene and reduction of the specific cholesterol efflux function counteracted the inhibitory effect of the GW3965 on HCV infection, providing evidence for a key role of ABCA1 in this process. Impaired virus-cell entry correlated with the reorganisation of cholesterol-rich membrane microdomains (lipid rafts). The inhibitory effect could be reversed by an exogenous cholesterol supply, indicating that restriction of HCV infection was induced by changes of cholesterol content/distribution in membrane regions essential for virus-cell fusion. Stimulation of ABCA1 expression by GW3965 inhibited HCV infection of both human primary hepatocytes and isolated human liver slices. This study reveals that pharmacological stimulation of the ABCA1-dependent cholesterol efflux pathway disrupts membrane cholesterol homeostasis, leading to the inhibition of virus-cell fusion and thus HCV cell entry. Therefore besides other beneficial roles, ABCA1 might represent a potential target for HCV therapy
Hepatitis C virus quasispecies and pseudotype analysis from acute infection to chronicity in HIV-1 co-infected individuals
HIV-1 infected patients who acquire HCV infection have higher rates of chronicity and liver disease progression than patients with HCV mono-infection. Understanding early events in this pathogenic process is important. We applied single genome sequencing of the E1 to NS3 regions and viral pseudotype neutralization assays to explore the consequences of viral quasispecies evolution from pre-seroconversion to chronicity in four co-infected individuals (mean follow up 566 days). We observed that one to three founder viruses were transmitted. Relatively low viral sequence diversity, possibly related to an impaired immune response, due to HIV infection was observed in three patients. However, the fourth patient, after an early purifying selection displayed increasing E2 sequence evolution, possibly related to being on suppressive antiretroviral therapy. Viral pseudotypes generated from HCV variants showed relative resistance to neutralization by autologous plasma but not to plasma collected from later time points, confirming ongoing virus escape from antibody neutralization
Translational rodent models for research on parasitic protozoa â a review of confounders and possibilities
Rodents, in particular Mus musculus, have a long and invaluable history as models for human diseases in biomedical research, although their translational value has been challenged in a number of cases. We provide some examples in which rodents have been suboptimal as models for human biology and discuss confounders which influence experiments and may explain some of the misleading results. Infections of rodents with protozoan parasites are no exception in requiring close consideration upon model choice. We focus on the significant differences between inbred, outbred and wild animals, and the importance of factors such as microbiota, which are gaining attention as crucial variables in infection experiments. Frequently, mouse or rat models are chosen for convenience, e.g., availability in the institution rather than on an unbiased evaluation of whether they provide the answer to a given question. Apart from a general discussion on translational success or failure, we provide examples where infections with single-celled parasites in a chosen lab rodent gave contradictory or misleading results, and when possible discuss the reason for this. We present emerging alternatives to traditional rodent models, such as humanized mice and organoid primary cell cultures. So-called recombinant inbred strains such as the Collaborative Cross collection are also a potential solution for certain challenges. In addition, we emphasize the advantages of using wild rodents for certain immunological, ecological, and/or behavioral questions. The experimental challenges (e.g., availability of species-specific reagents) that come with the use of such non-model systems are also discussed. Our intention is to foster critical judgment of both traditional and newly available translational rodent models for research on parasitic protozoa that can complement the existing mouse and rat models
Formation option "Conférence" !
Florian Douam, doctorant Ă lâENS de Lyon et prĂ©sident du bureau exĂ©cutif de lâassociation ConfĂ©rENS, revient sur lâhistoire de cette association Ă©tudiante qui met en place chaque annĂ©e une dizaine de confĂ©rences sur des sujets scientifiques, sociĂ©taux ou littĂ©raires. Il dĂ©voile les coulisses de cette belle organisation, revient sur les motivations des participants et prĂ©cise lâintĂ©rĂȘt de la dĂ©marche. Une initiative Ă forte valeur ajoutĂ©e pour les Ă©tudiants !  Un manque Ă combler⊠Encore en M..
Pourquoi la science a plus que jamais besoin du web - Par Florian Douam, doctorant en biologie
Florian Douam propose un retour d'expĂ©rience, suite Ă la soirĂ©e âMĂ©diation culturelle des sciences sur le webâ, organisĂ©e par le service Science & SociĂ©tĂ© de lâUniversitĂ© de Lyon Ă lâAtelier des MĂ©dias, dans le cadre des off du www2012, en partenariat avec le collectif Le Grand Mix, et faisant suite Ă la journĂ©e de rencontre et de rĂ©flexion organisĂ©e en mars 2011 (vidĂ©os en ligne). Vous pouvez retrouver en ligne un compte-rendu multimĂ©dia (Storify) de cette soirĂ©e, effectuĂ© par lâĂ©quipe de Kn..
Les réseaux de co-évolution au sein des protéines E1 et E2 du Virus de l'Hépatite C révÚlent leurs dialogues fonctionnels et proposent de nouvelles stratégies thérapeutiques
Hepatitis C Virus (HCV) infects more than 170 million people worldwide but no vaccine is available yet. HCV entry may represent a promising target for therapies and is mediated by two envelope glycoproteins, E1 and E2, assembled as heterodimer onto the virus surface. However, how E1 and E2 dialog, structurally rearrange and act together during these steps remain poorly defined. In this work, we aimed to clarify the interrelation of E1E2 during virus entry, thus opening ways to potential new therapeutic strategies. We first investigated whether a strong genetic divergence between E1E2 heterodimers may highlight distinct functions. We observed that B-cell derived E1E2 were specialized for B-cell infection, suggesting that new functions can emerge from the E1E2 conformational plasticity. In a second approach, we identified a conserved dialog between E1 and the domain III of E2 that was critical for virus binding and fusion. Moreover, a computational model predicted a strong co-evolution between E1 and E2 as well as potential structural rearrangements, suggesting that HCV E2 is likely a fusion protein able to fold over via its domain III through the mediation of E1. Altogether, these different works highlight that E1 and E2 are involved in complex dialogs that regulate the heterodimer folding and functions, suggesting that E1E2 heterodimer is more likely a single functional protein entity than an association of two proteins with specific functions.Le Virus de lâHĂ©patite C (VHC) infecte 170 millions de personnes dans le monde mais aucun vaccin nâest encore disponible. Le processus dâentrĂ©e du VHC dans les hĂ©patocytes reprĂ©sente une cible prometteuse pour le dĂ©veloppement de stratĂ©gie thĂ©rapeutique et est finement rĂ©gulĂ© par un nombre par les deux glycoprotĂ©ines dâenvelope du VHC, E1 et E2, assemblĂ© sous la forme dâun hĂ©tĂ©rodimĂšre incorporĂ© Ă la surface des particules virales. Cependant, comment E1 et E2 dialoguent, modifient leurs conformations et se coordonnent mutuellement au cours de lâentrĂ©e reste encore Ă ĂȘtre dĂ©finit. Dans ce travail, nous avons souhaitĂ© clarifier lâinterrelation entre E1 and E2 au cours de lâentrĂ©e afin dâouvrir la voie Ă de potentiels stratĂ©gies thĂ©rapeutiques. Nous avons tout dâabord examinĂ© si une importante divergence gĂ©nĂ©tique entre des hĂ©tĂ©rodimĂšres E1E2 pouvait ĂȘtre liĂ©e Ă lâexistence de fonctions particuliĂšres. Nous avons observĂ© une spĂ©cialisation des E1E2 isolĂ© des Lymphocytes B pour lâinfection de ces mĂȘmes cellules mais pas des hĂ©patocytes, suggĂ©rant que de nouvelles fonctions peuvent Ă©merger de la plasticitĂ© conformationel de E1E2. Dans un second temps, nous sommes parvenus Ă identifier un dialogue conservĂ© entre E1 et le domaine III de E2 (E2 DIII), critique pour les processus dâattachement et de fusion du VHC. Nous avons aussi montrĂ© grĂące Ă une approche bio-informatique lâexistence dâune co-Ă©volution trĂšs importante entre E1 et E2. Cette approche a Ă©galement prĂ©dit de potentiel changement de conformations au sein de lâhĂ©tĂ©rodimĂšre, suggĂ©rant que E2 est sans doute une protĂ©ine de fusion capable de se replier sur elle-mĂȘme via le repliement de son domaine III et lâaide de E1. Ainsi, ces diffĂ©rents travaux soulignent lâimplication de E1 et E2 au sein de dialogues fins et complexes, qui rĂ©gulent Ă la fois les conformations et les fonctions de lâhĂ©tĂ©rodimĂšre. Ainsi, cela suggĂšre que lâhĂ©tĂ©rodimĂšre E1E2 reprĂ©sente plutĂŽt une unitĂ© fonctionnelle et structurale unique, plutĂŽt que lâassociation de deux protĂ©ines aux fonctions distinctes
Pourquoi la science a plus que jamais besoin du web - Par Florian Douam, doctorant en biologie
Florian Douam propose un retour d'expĂ©rience, suite Ă la soirĂ©e âMĂ©diation culturelle des sciences sur le webâ, organisĂ©e par le service Science & SociĂ©tĂ© de lâUniversitĂ© de Lyon Ă lâAtelier des MĂ©dias, dans le cadre des off du www2012, en partenariat avec le collectif Le Grand Mix, et faisant suite Ă la journĂ©e de rencontre et de rĂ©flexion organisĂ©e en mars 2011 (vidĂ©os en ligne). Vous pouvez retrouver en ligne un compte-rendu multimĂ©dia (Storify) de cette soirĂ©e, effectuĂ© par lâĂ©quipe de Kn..
Recommended from our members
The use of humanized mice for studies of viral pathogenesis and immunity.
Humanized mice, i.e. animals engrafted with human tissues and/or expressing human genes, have
been instrumental in improving our understanding of the pathogenesis and immunological
processes that define some of the most challenging human-tropic viruses. In particular, mice
engrafted with components of a human immune system (HIS) offer unprecedented opportunities
for mechanistic studies of human immune responses to infection. Here, we provide a brief
overview of the current panel of HIS mouse models available and cite recent examples of how
such humanized animals have been used to study immune responses and pathogenesis elicited by
human-tropic viruses. Finally, we will outline some of the challenges that lay ahead and strategies
to improve and refine humanized mice with the goal of more accurately recapitulating human
immune responses to viral infection
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