593 results on '"Meyerhans, Andreas"'
Search Results
252. Nonlocal Reaction–Diffusion Model of Viral Evolution: Emergence of Virus Strains.
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Bessonov, Nikolai, Bocharov, Gennady, Meyerhans, Andreas, Popov, Vladimir, and Volpert, Vitaly
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REACTION-diffusion equations , *HOST-virus relationships , *VIRUSES , *VIRUS inactivation , *BIOLOGICAL evolution , *VIRUS diseases , *IMMUNE response - Abstract
This work is devoted to the investigation of virus quasi-species evolution and diversification due to mutations, competition for host cells, and cross-reactive immune responses. The model consists of a nonlocal reaction–diffusion equation for the virus density depending on the genotype considered to be a continuous variable and on time. This equation contains two integral terms corresponding to the nonlocal effects of virus interaction with host cells and with immune cells. In the model, a virus strain is represented by a localized solution concentrated around some given genotype. Emergence of new strains corresponds to a periodic wave propagating in the space of genotypes. The conditions of appearance of such waves and their dynamics are described. [ABSTRACT FROM AUTHOR]
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- 2020
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253. Labyrinthopeptins Exert Broad-Spectrum Antiviral Activity through Lipid-Binding-Mediated Virolysis.
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Prochnow, Hans, Rox, Katharina, Birudukota, N. V. Suryanarayana, Weichert, Loreen, Hotop, Sven-Kevin, Klahn, Philipp, Mohr, Kathrin, Franz, Sergej, Banda, Dominic H., Blockus, Sebastian, Schreiber, Janine, Haid, Sibylle, Oeyen, Merel, Martinez, Javier P., Süssmuth, Roderich D., Wink, Joachim, Meyerhans, Andreas, Goffinet, Christine, Messerle, Martin, and Schulz, Thomas F.
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KAPOSI'S sarcoma-associated herpesvirus , *WEST Nile virus , *MEMBRANE lipids , *DENGUE viruses , *HERPES simplex virus , *HERPESVIRUSES , *HEPATITIS C virus - Abstract
To counteract the serious health threat posed by known and novel viral pathogens, drugs that target a variety of viruses through a common mechanism have attracted recent attention due to their potential in treating (re)emerging infections, for which direct-acting antivirals are not available. We found that labyrinthopeptins A1 and A2, the prototype congeners of carbacyclic lanthipeptides, inhibit the proliferation of diverse enveloped viruses, including dengue virus, Zika virus, West Nile virus, hepatitis C virus, chikungunya virus, Kaposi's sarcoma-associated herpesvirus, cytomegalovirus, and herpes simplex virus, in the low micromolar to nanomolar range. Mechanistic studies on viral particles revealed that labyrinthopeptins induce a virolytic effect through binding to the viral membrane lipid phosphatidylethanolamine (PE). These effects are enhanced by a combined equimolar application of both labyrinthopeptins, and a clear synergism was observed across a concentration range corresponding to 10% to 90% inhibitory concentrations of the compounds. Time-resolved experiments with large unilamellar vesicles (LUVs) reveal that membrane lipid raft compositions (phosphatidylcholine [PC]/PE/cholesterol/sphingomyelin at 17:10:33:40) are particularly sensitive to labyrinthopeptins in comparison to PC/PE (90:10) LUVs, even though the overall PE amount remains constant. Labyrinthopeptins exhibited low cytotoxicity and had favorable pharmacokinetic properties in mice (half-life [t1/2] = 10.0 h), which designates them promising antiviral compounds acting by an unusual viral lipid targeting mechanism. [ABSTRACT FROM AUTHOR]
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- 2020
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254. Prediction of PD-L1 inhibition effects for HIV-infected individuals.
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Zheltkova, Valerya, Argilaguet, Jordi, Peligero, Cristina, Bocharov, Gennady, and Meyerhans, Andreas
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CYTOTOXIC T cells , *IMMUNOGLOBULIN producing cells , *PROGRAMMED cell death 1 receptors , *T cells , *CD4 lymphocyte count , *CELL physiology , *HIV infections - Abstract
The novel therapies with immune checkpoint inhibitors hold great promises for patients with chronic virus infections and cancers. This is based mainly on the partial reversal of the exhausted phenotype of antigen-specific cytotoxic CD8 T cells (CTL). Recently, we have shown that the restoration of HIV-specific T cell function depends on the HIV infection stage of an infected individual. Here we aimed to answer two fundamental questions: (i) Can one estimate growth parameters for the HIV-specific proliferative responsiveness upon PD-L1 blockade ex vivo? (ii) Can one use these parameter estimates to predict clinical benefit for HIV-infected individuals displaying diverse infection phenotypes? To answer these questions, we first analyzed HIV-1 Gag-specific CD8 T cell proliferation by time-resolved CFSE assays and estimated the effect of PD-L1 blockade on division and death rates, and specific precursor frequencies. These values were then incorporated into a model for CTL-mediated HIV control and the effects on CTL frequencies, viral loads and CD4 T cell counts were predicted for different infection phenotypes. The biggest absolute increase in CD4 T cell counts was in the group of slow progressors while the strongest reduction in virus loads was observed in progressor patients. These results suggest a significant clinical benefit only for a subgroup of HIV-infected individuals. However, as PD1 is a marker of lymphocyte activation and expressed on several lymphocyte subsets including also CD4 T cells and B cells, we subsequently examined the multiple effects of anti-PD-L1 blockade beyond those on CD8 T cells. This extended model then predicts that the net effect on HIV load and CD4 T cell number depends on the interplay between positive and negative effects of lymphocyte subset activation. For a physiologically relevant range of affected model parameters, PD-L1 blockade is likely to be overall beneficial for HIV-infected individuals. Author summary: Immune checkpoint inhibitors can revitalize exhausted virus-specific CD8 T cells (CTL) and thus hold great promises for patients with chronic virus infections. Based on the hypothesis that gain in the proliferation of CTL by such interventions may positively influence HIV-1 disease progression, we developed a general framework of how to quantify the proliferative CTL responsiveness after PD-L1 blockade, and translate it to patient outcome predictions. However, PD-L1 blockade also activates (i) exhausted CD4 T cells generating additional HIV target cells for virus expansion as well as (ii) exhausted B cells producing increasing antibody levels that potentially inhibit HIV spread. To assess these virus-specific effects of a PD-L1 blockade, we then extended our basic model and incorporated experimentally determined CD4 T cell proliferation gains and estimates on HIV-specific antibody increases. Altogether, the blockade effect is predicted to be infection phenotype-dependent and in most cases beneficial. Our general approach can be expanded to other immunotherapies and is an important step forward towards personalized treatment strategies in infectious diseases and cancers. [ABSTRACT FROM AUTHOR]
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- 2019
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255. Lymphocyte Activation Dynamics Is Shaped by Hereditary Components at Chromosome Region 17q12-q21.
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Carreras-Sureda, Amado, Rubio-Moscardo, Fanny, Olvera, Alex, Argilaguet, Jordi, Kiefer, Kerstin, Mothe, Beatriz, Meyerhans, Andreas, Brander, Christian, and Vicente, Rubén
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LYMPHOCYTE transformation , *CHROMOSOMES , *SINGLE nucleotide polymorphisms , *ASTHMA risk factors , *HAPLOTYPES , *GENE expression - Abstract
Single nucleotide polymorphisms (SNPs) located in the chromosome region 17q12-q21 are risk factors for asthma. Particularly, there are cis-regulatory haplotypes within this region that regulate differentially the expression levels of ORMDL3, GSDMB and ZPBP2 genes. Remarkably, ORMDL3 has been shown to modulate lymphocyte activation parameters in a heterologous expression system. In this context, it has been shown that Th2 and Th17 cytokine production is affected by SNPs in this region. Therefore, we aim to assess the impact of hereditary components within region 17q12-q21 on the activation profile of human T lymphocytes, focusing on the haplotype formed by allelic variants of SNPs rs7216389 and rs12936231. We measured calcium influx and activation markers, as well as the proliferation rate upon T cell activation. Haplotype-dependent differences in mRNA expression levels of IL-2 and INF-γ were observed at early times after activation. In addition, the allelic variants of these SNPs impacted on the extent of calcium influx in resting lymphocytes and altered proliferation rates in a dose dependent manner. As a result, the asthma risk haplotype carriers showed a lower threshold of saturation during activation. Finally, we confirmed differences in activation marker expression by flow cytometry using phytohemagglutinin, a strong polyclonal stimulus. Altogether, our data suggest that the genetic component of pro-inflammatory pathologies present in this chromosome region could be explained by different T lymphocyte activation dynamics depending on individual allelic heredity. [ABSTRACT FROM AUTHOR]
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- 2016
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256. Immunotherapy of chronic virus infections : Exhausted CD8+ T cell subsets are differentially regulated by XCR1 + DC
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Domenjó Vila, Eva, 1993, Meyerhans, Andreas, Argilaguet Marqués, Jordi, 1977, and Universitat Pompeu Fabra. Departament de Ciències Experimentals i de la Salut.
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T cell exhaustion ,Therapeutic vaccination ,Vacunes terapèutiques ,Cèl.lules dentrítiques cospresentadores d'antígens ,Anti-PD-L1 immunotherapy ,Cèl.lules T citotòxiques ,Cross-presenting XCR1+DC ,LCMV chronic infection ,Immunoteràpia anti-PD-L1 ,Infecció crònica per LCMV - Abstract
The contribution of cross-presenting XCR1+ dendritic cells (DC) in maintaining T cell function during exhaustion and immuno-therapeutic interventions of chronic infections remains poorly characterized. Using the mouse model of chronic LCMV infection, we found that XCR1+ DC were more resistant to infection and highly activated compared to SIRPɑ+ DC. Exploiting XCR1+ DC via Flt3L-mediated expansion or XCR1-targeted vaccination notably reinvigorated CD8+ T cells and improved virus control. Upon PD-L1 blockade, XCR1+ DC were not required for the proliferative burst of progenitor exhausted CD8+ T (TPEX) cells, but proved indispensable to sustain the functionality of exhausted CD8+ T (TEX) cells. Combining anti-PD-L1 therapy with increased frequency of XCR1+ DC improved functionality of TPEX and TEX subsets, while increase of SIRPɑ+ DC dampened their proliferation. Together, this demonstrates that XCR1+ DC are crucial for the success of checkpoint inhibitor-based therapies through differential activation of exhausted CD8+ T cell subsets. La participació de les cèl·lules dendrítiques (DC) cros-presentadores d’antígens, XCR1+ DC, en mantenir la funció de cèl·lules T CD8+ durant infeccions cròniques, i en la reactivació promoguda per immunoteràpies no està totalment caracteritzada. Emprant el model d’infecció crònica amb LCMV, hem determinat que XCR1+ DC són més resistents a infecció que SIRPɑ+ DC i mantenen alts nivells d’activació. Augmentar el número de XCR1+ DC via injecció de Flt3L o utilitzar vacunes dirigides al receptor XCR1 són estratègies capaces de reactivar cèl·lules T CD8+, millorant el control del virus. Durant el tractament d’immunoteràpia anti-PD-L1, XCR1+ DC no són necessàries per l’increment en proliferació de les cèl·lules T CD8+ progenitores (TPEX) però, són indispensables per sostenir la funcionalitat de la progènie (TEX). La combinació d’anti-PD-L1 i l’augment del número de XCR1+ DC incrementa la funció en TPEX i en TEX, mentre que augmentar el número de SIRPɑ+ DC en dificulta la proliferació. En conjunt, aquest estudi evidencia el paper crucial de XCR1+ DC en intervencions d’immunoteràpia mitjançant l’activació diferencial dels subconjunts de cèl·lules T CD8+ esgotades.
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- 2022
257. Human DDX3 protein is a valuable target to develop broad spectrum antiviral agents.
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Brai, Annalaura, Fazi, Roberta, Tintori, Cristina, Zamperini, Claudio, Bugli, Francesca, Sanguinetti, Maurizio, Stigliano, Egidio, Esté, José, Badia, Roger, Franco, Sandra, Martinez, Miguel A., Martinez, Javier P., Meyerhans, Andreas, Saladini, Francesco, Zazzi, Maurizio, Garbelli, Anna, Maga, Giovanni, and Botta, Maurizio
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POLYPEPTIDES , *ANTIVIRAL agents , *VIRAL replication , *VIRAL disease treatment , *ANTI-infective agents - Abstract
Targeting a host factor essential for the replication of different viruses but not for the cells offers a higher genetic barrier to the development of resistance, may simplify therapy regimens for coinfections, and facilitates management of emerging viral diseases. DEAD-box polypeptide 3 (DDX3) is a human host factor required for the replication of several DNA and RNA viruses, including some of the most challenging human pathogens currently circulating, such as HIV-1, Hepatitis C virus, Dengue virus, and West Nile virus. Herein, we showed for the first time, to our knowledge, that the inhibition of DDX3 by a small molecule could be successfully exploited for the development of a broad spectrum antiviral agent. In addition to the multiple antiviral activities, hit compound 16d retained full activity against drug-resistant HIV-1 strains in the absence of cellular toxicity. Pharmacokinetics and toxicity studies in rats confirmed a good safety profile and bioavailability of 16d. Thus, DDX3 is here validated as a valuable therapeutic target. [ABSTRACT FROM AUTHOR]
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- 2016
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258. Calcineurin and mTOR inhibitors have opposing effects on regulatory T cells while reducing regulatory B cell populations in kidney transplant recipients.
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Latorre, Irene, Esteve-Sole, Ana, Redondo, Dolores, Giest, Sandra, Argilaguet, Jordi, Alvarez, Sara, Peligero, Cristina, Forstmann, Isabelle, Crespo, Marta, Pascual, Julio, and Meyerhans, Andreas
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CALCINEURIN , *B cells , *T cells , *KIDNEY transplantation , *IMMUNOSUPPRESSIVE agents - Abstract
Background Regulatory B (Breg) and T (Treg) cells represent a biomarker for tolerance in transplant patients. Despite the importance of Treg and Breg in transplantation and the suggested crosstalk between both suppressive cell populations, little is known on how they are influenced by long-term immunosuppressive treatment. The aim of the present study was to investigate the effect of different immunosuppressive drugs used in routine clinical practice on Treg and Breg cell numbers. Methods Thirty-six kidney transplant recipients with stable graft function were recruited and classified according to their concomitant therapy: 22 patients received calcineurin inhibitors (CNI) and 14 patients received mammalian target of rapamycin (mTOR) inhibitors. A group of 8 healthy untreated subjects was included as control. Absolute numbers of peripheral blood-derived IL10-producing B cells (CD19 + IL10 + ), CD19 + CD24 hi CD38 hi transitional B cells and Treg cells (CD4 + CD25 + FOXP3 + ) were quantified in all KT patients and controls by flow cytometry. Results CD19 + CD24 hi CD38 hi transitional B cells increased over time and seem to be related with long-term therapeutic graft survival irrespective of the treatment regimen. CNI and mTOR inhibitors significantly reduced numbers of Breg cells when compared with healthy individuals, whereas mTOR inhibitors expanded Treg cells in comparison with CNI drugs. Conclusions Bridging the drug-mediated reduction of Breg cell numbers in vivo with the requirements of Breg cells for long-term transplant success remains an as yet unresolved task for therapeutic intervention. Further larger cohort studies that evaluate the effect of different treatment regimen on defined lymphocyte subpopulations are warranted. [ABSTRACT FROM AUTHOR]
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- 2016
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259. PD-L1 Blockade Differentially Impacts Regulatory T Cells from HIV-Infected Individuals Depending on Plasma Viremia.
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Peligero, Cristina, Argilaguet, Jordi, Güerri-Fernandez, Roberto, Torres, Berta, Ligero, Carmen, Colomer, Pilar, Plana, Montserrat, Knobel, Hernando, García, Felipe, and Meyerhans, Andreas
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T cells , *LYMPHOCYTES , *CELL-mediated lympholysis , *VIREMIA , *BLOODBORNE infections - Abstract
Blocking the PD-1/PD-L1 pathway has emerged as a potential therapy to restore impaired immune responses in human immunodeficiency virus (HIV)-infected individuals. Most reports have studied the impact of the PD-L1 blockade on effector cells and neglected possible effects on regulatory T cells (Treg cells), which play an essential role in balancing immunopathology and antiviral effector responses. The aim of this study was to define the consequences of ex vivo PD-L1 blockade on Treg cells from HIV-infected individuals. We observed that HIV infection led to an increase in PD-1+ and PD-L1+ Treg cells. This upregulation correlated with disease progression and decreased under antiretroviral treatment. Treg cells from viremic individuals had a particularly high PD-1 expression and impaired proliferative capacity in comparison with Treg cells from individuals under antiretroviral treatment. PD-L1 blockade restored the proliferative capacity of Treg cells from viremic individuals but had no effect on its suppressive capacity. Moreover, it increased the viral production in cell cultures from viremic individuals. This increase in viral production correlated with an increase in Treg cell percentage and a reduction in the CD4/Treg and CD8/Treg cell ratios. In contrast to the effect of the PD-L1 blockade on Treg cells from viremic individuals, we did not observe a significant effect on the proliferative capacity of Treg cells from individuals in whom viremia was controlled (either spontaneously or by antiretroviral treatment). However, PD-L1 blockade resulted in an increased proliferative capacity of HIV-specific-CD8 T cells in all subjects. Taken together, our findings suggest that manipulating PD-L1 in vivo can be expected to influence the net gain of effector function depending on the subject’s plasma viremia. [ABSTRACT FROM AUTHOR]
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- 2015
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260. Soraphen A: A broad-spectrum antiviral natural product with potent anti-hepatitis C virus activity.
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Koutsoudakis, George, Romero-Brey, Inés, Berger, Carola, Pérez-Vilaró, Gemma, Monteiro Perin, Paula, Vondran, Florian Wolfgang Rudolf, Kalesse, Markus, Harmrolfs, Kirsten, Müller, Rolf, Martinez, Javier P., Pietschmann, Thomas, Bartenschlager, Ralf, Brönstrup, Mark, Meyerhans, Andreas, and Díez, Juana
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ANTIVIRAL agents , *HEPATITIS C virus , *NATURAL products , *BACTERIAL metabolites , *ACETYL-CoA carboxylase , *LIPID synthesis - Abstract
Background & Aims Soraphen A (SorA) is a myxobacterial metabolite that inhibits the acetyl-CoA carboxylase, a key enzyme in lipid biosynthesis. We have previously identified SorA to efficiently inhibit the human immunodeficiency virus (HIV). The aim of the present study was to evaluate the capacity of SorA and analogues to inhibit hepatitis C virus (HCV) infection. Methods SorA inhibition capacity was evaluated in vitro using cell culture derived HCV, HCV pseudoparticles and subgenomic replicons. Infection studies were performed in the hepatoma cell line HuH7/Scr and in primary human hepatocytes. The effects of SorA on membranous web formation were analysed by electron microscopy. Results SorA potently inhibits HCV infection at nanomolar concentrations. Obtained EC 50 values were 0.70 nM with a HCV reporter genome, 2.30 nM with wild-type HCV and 2.52 nM with subgenomic HCV replicons. SorA neither inhibited HCV RNA translation nor HCV entry, as demonstrated with subgenomic HCV replicons and HCV pseudoparticles, suggesting an effect on HCV replication. Consistent with this, evidence was obtained that SorA interferes with formation of the membranous web, the site of HCV replication. Finally, a series of natural and synthetic SorA analogues helped to establish a first structure–activity relationship. Conclusions SorA has a very potent anti-HCV activity. Since it also interferes with the membranous web formation, SorA is an excellent tool to unravel the mechanism of HCV replication. [ABSTRACT FROM AUTHOR]
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- 2015
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261. Mathematical modelling of the within-host HIV quasispecies dynamics in response to antiviral treatment.
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Bocharov, Gennady A., Telatnikov, Ilya S., Chereshnev, Valery A., Martinez, Javier, and Meyerhans, Andreas
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MATHEMATICAL models , *HIV infections , *ANTIVIRAL agents , *COMPARATIVE studies , *GENETIC algorithms , *AZIDOTHYMIDINE - Abstract
The aim of this work is the construction, calibration, and comparative analysis of mathematical models of the evolution of the human immunodeficiency virus (HIV) in the course of infection when the models are based on deterministic principles of the quasispecies theory (Eigen-Schuster) and on stochastic approaches of genetic algorithms (Holland). The models take into account the replication of viral genomes and selection of descendants according to their fitness, point mutations, multi-infection of target cells and recombination of genomes at the stage of formation of proviral DNA. The processes of diversification of the virus population under the action of the antiviral drug azidothymidine (AZT) that blocks reverse transcription of the virus are simulated. A four-letter alphabet is used in the stochasticmodel for description of nucleotide sequences. The parameters of the model are estimated using original data on the degree of adaptation of the HIV mutants that are partly or completely resistant to this drug. The influence of parameters of infection on the characteristics of viral mutants population diversity is studied [ABSTRACT FROM AUTHOR]
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- 2015
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262. Immune Screening Identifies Novel T Cell Targets Encoded by Antisense Reading Frames of HIV-1.
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Berger, Christoph T., Llano, Anuska, Carlson, Jonathan M., Brumme, Zabrina L., Brockman, Mark A., Cedeño, Samandhy, Harrigan, P. Richard, Kaufmann, Daniel E., Heckerman, David, Meyerhans, Andreas, and Brander, Christian
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T cells , *LYMPHOCYTES , *ANTISENSE DNA , *PROTEIN genetics , *IMMUNITY - Abstract
Cytotoxic-T lymphocyte (CTL) responses to epitopes in alternative HIV reading frames have been reported. However, the extent of CTL responses to putative proteins encoded in antisense reading frames is unknown. Using sequence alignments and computational approaches, we here predict five potential antisense HIV proteins and characterize common CTL responses against them. Results suggest that antisense-derived sequences are commonly transcribed and translated and could encode functional proteins that contain important targets of anti-HIV cellular immunity. [ABSTRACT FROM AUTHOR]
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- 2015
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263. Spatiotemporal differences of early type I interferon response in acute and chronic viral infections
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Casella, Valentina, 1991, Meyerhans, Andreas, Argilaguet Marqués, Jordi, 1977, and Universitat Pompeu Fabra. Departament de Ciències Experimentals i de la Salut
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Infection fate decision ,Macrófagos CD169+ ,CD169+ macrophages ,Fibrosis de tejido linfático ,Regulación del desarrollo de infección ,Interferón de tipo I ,Interacciones virus-huésped ,Type I interferon ,Virus-host interactions ,Lymphoid tissue fibrosis - Abstract
The main aim of this project was to uncover the spatiotemporal events influencing type I interferon (IFN-I) dynamics during the early phase of acute and chronic viral infections. Time-resolved spleen-transcriptome analysis of LCMV-infected mice revealed two waves of IFN-I expression in acute infection, while in chronically infected mice a single wave of IFN-I genes was induced. We identified CD169+ macrophages as the source of the second wave of IFN-I only during acute infection, and characterized its polyfunctional role involving (i) the induction of pro-inflammatory macrophages, and (ii) the expansion of virus-specific CD8 T cells. Importantly, the IFN-I-mediated antiviral CD8 T cell response resulted in the development of fibrosis in lymphatic tissue. In contrast, during chronic infection the early CD8 T cell-mediated depletion of CD169+ macrophages resulted in a lack of IFN-I production and the subsequent IFN-I-mediated-pro-inflammatory response. Overall, we demonstrated that the spatiotemporal regulation of IFN-I production in the early stages of infection is crucial for the induction of sequential immune events that lead to viral infection resolution. El objetivo principal de este proyecto fué analizar los eventos espacio-temporales que determinan la dinámica de la respuesta de interferón de tipo I (IFN-I) durante la fase inicial de las infecciones virales agudas o crónicas. El análisis de los transcriptomas de bazos de ratones infectados por LCMV reveló dos olas de expresión de IFN-I durante la infección aguda, en contraste con un único pico de expresión durante una infección crónica. Estudios posteriores permitierón demostrar que la segunda ola de producción de IFN-I durante una infección aguda está mediada por macrófagos CD169+, y que entre sus funciones se encuentran la inducción de (i) macrófagos proinflamatorios, y (ii) células T CD8 antivirales, las cuales son finalmente responsables de la aparición de fibrosis en tejido linfático. Por otro lado, durante una infección crónica los macrófagos CD169+ son eliminados por acción de las células CD8+, impidiendo así la producción de IFN-I y de la consiguiente respuesta proinflamatoria. En resumen, en este trabajo demostramos que la regulación espacio-temporal de la producción de IFN-I en las primeras etapas de una infección viral es determinante para la inducción de eventos inmunológicos secuenciales, que finalmente afectan el desarrollo de la misma.
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- 2021
264. Human yeast-specific CD8 T lymphocytes show a nonclassical effector molecule profile.
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Breinig, Tanja, Scheller, Nicoletta, Glombitza, Birgit, Breinig, Frank, and Meyerhans, Andreas
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MEDICAL microbiology , *YEAST , *CANDIDA , *PERFORINS , *GRANULYSIN , *GRANZYMES , *LYMPHOCYTES - Abstract
Pathogenic yeast and fungi represent a major group of human pathogens. The consequences of infections are diverse and range from local, clinically uncomplicated mycosis of the skin to systemic, life-threatening sepsis. Despite extensive MHC class I-restricted frequencies of yeast-specific CD8 T lymphocytes in healthy individuals and the essential role of the cell-mediated immunity in controlling infections, the characteristics and defense mechanisms of antifungal effector cells are still unclear. Here, we describe the direct analysis of yeast-specific CD8 T lymphocytes in whole blood from healthy individuals. They show a unique, nonclassical phenotype expressing granulysin and granzyme K in lytic granules instead of the major effector molecules perforin and granzyme B. After stimulation in whole blood, yeast-specific CD8 T cells degranulated and, upon cultivation in the presence of IL-2, their granula were refilled with granulysin rather than with perforin and granzyme B. Moreover, yeast-specific stimulation through dendritic cells but not by yeast cells alone led to degranulation of the effector cells. As granulysin is the only effector molecule in lytic granules known to have antifungal properties, our data suggest yeast-specific CD8 T cells to be a nonclassical effector population whose antimicrobial effector machinery seems to be tailor-made for the efficient elimination of fungi as pathogens. [ABSTRACT FROM AUTHOR]
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- 2012
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265. Estimation of Cell Proliferation Dynamics Using CFSE Data.
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Banks, H., Sutton, Karyn, Clayton Thompson, W., Bocharov, Gennady, Roose, Dirk, Schenkel, Tim, and Meyerhans, Andreas
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CELL proliferation , *ESTERS , *PARTIAL differential equations , *INVERSE problems , *FLUORESCENCE , *FLOW cytometry , *CELL populations - Abstract
dvances in fluorescent labeling of cells as measured by flow cytometry have allowed for quantitative studies of proliferating populations of cells. The investigations (Luzyanina et al. in J. Math. Biol. 54:57-89, ; J. Math. Biol., ; Theor. Biol. Med. Model. 4:1-26, ) contain a mathematical model with fluorescence intensity as a structure variable to describe the evolution in time of proliferating cells labeled by carboxyfluorescein succinimidyl ester (CFSE). Here, this model and several extensions/modifications are discussed. Suggestions for improvements are presented and analyzed with respect to statistical significance for better agreement between model solutions and experimental data. These investigations suggest that the new decay/label loss and time dependent effective proliferation and death rates do indeed provide improved fits of the model to data. Statistical models for the observed variability/noise in the data are discussed with implications for uncertainty quantification. The resulting new cell dynamics model should prove useful in proliferation assay tracking and modeling, with numerous applications in the biomedical sciences. [ABSTRACT FROM AUTHOR]
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- 2011
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266. Low Seroprevalence of West Nile Virus in Blood Donors from Catalonia, Spain.
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Piron, Maria, Plasencia, Antoni, Fleta-Soriano, Eric, Martinez, Ana, Martinez, Javier P., Torner, Nuria, Sauleda, Silvia, Meyerhans, Andreas, Escalé, Josefina, Trilla, Antoni, Pumarola, Tomás, and Martinez, Miguel Julian
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WEST Nile virus , *SEROPREVALENCE , *BLOOD donors , *ARBOVIRUSES , *ENZYME-linked immunosorbent assay , *NEUTRALIZATION (Chemistry) - Abstract
West Nile virus (WNV) is an emerging arbovirus first recognized in Europe in the 1950s. Since then, outbreaks have been reported in several European countries. In 2010, the first WNV outbreak was recorded in Spain, affecting the southern part of the country. We conducted a seroprevalence study in the Catalonia region (northeastern Spain), an area considered at high risk of arbovirus transmission. A total of 800 serum samples from blood donors were collected and screened for antibodies against WNV by enzyme-linked immunosorbent assay (ELISA) and confirmed by a microneutralization assay. More than 50 samples tested positive by ELISA, but only one sample contained neutralizing antibodies against WNV and was obtained from a donor native of Pakistan. The low seroprevalence detected may serve as reference baseline data for monitoring WNV activity in our region in future years. [ABSTRACT FROM AUTHOR]
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- 2015
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267. Early Depletion of Mycobacterium tuberculosis-Specific T Helper 1 Cell Responses after HIV-1 Infection.
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Geldmacher, Christof, Schuetz, Alexandra, Ngwenyama, Njabulo, Casazza, Joseph P., Sanga, Erica, Saathoff, Elmar, Boehme, Catharina, Geis, Steffen, Maboko, Leonard, Singh, Mahavir, Minja, Fred, Meyerhans, Andreas, Koup, Richard A., and Hoelscher, Michael
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MYCOBACTERIUM tuberculosis , *CELLS , *HIV infections , *IMMUNOLOGICAL deficiency syndromes , *PROTEINS , *CYTOKINES , *TUBERCULIN , *CELL populations , *TUBERCULOSIS , *INFECTION - Abstract
Background. The acid-fast bacillus Mycobacterium tuberculosis is often the first manifestation of acquired immunodeficiency syndrome in patients infected with human immunodeficiency virus (HIV). This study was conducted to better understand the mechanism underlying M. tuberculosis-specific pathogenicity early after onset of HIV infection. Methods. M. tuberculosis-specific T helper 1 (Th1) cells were studied in HIV negative (n = 114) and chronically HIV infected (n = 68) Tanzanian subjects by using early secreted antigenic target 6 (ESAT6) protein or tuberculin (purified protein derivative) with interferon-γ ELISPOT and intracellular cytokine staining. In a longitudinal study, the effect of acute HIV infection on M. tuberculosis-specific Th1 cells was determined by polychromatic flow cytometric analysis in 5 subjects with latent M. tuberculosis infection who became infected with HIV. Results. In tuberculosis (TB)-asymptomatic subjects (i.e., subjects with unknown TB status who did not show clinical signs suggestive of TB), chronic HIV infection was associated with a decreased percentage of subjects with detectable M. tuberculosis-specific Th1 cells (P = .001), a decrease which was not observed among subjects with active TB. Acute HIV infection induced a rapid depletion of M. tuberculosis-specific Th1 cells in 4 subjects remained TB asymptomatic, whereas the population of these cells remained stable in subjects who remained HIV negative (P = .01). Conclusions. Taken together, these data suggest a mechanism of rapid M. tuberculosis-specific Th1 cell depletion that may contribute to the early onset of TB in individuals with latent M. tuberculosis infection who become HIV infected. [ABSTRACT FROM AUTHOR]
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- 2008
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268. T cell activation on a single-cell level in dielectrophoresis-based microfluidic devices
- Author
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Kirschbaum, Michael, Jaeger, Magnus Sebastian, Schenkel, Tim, Breinig, Tanja, Meyerhans, Andreas, and Duschl, Claus
- Subjects
- *
T cells , *LYMPHOCYTES , *TH1 cells , *TH2 cells - Abstract
Abstract: The gentle and careful in vitro processing of live cells is essential in order to make them available to future therapeutic applications. We present a protocol for the activation of single-T cells based on the contact formation with individual anti-CD3/anti-CD28 presenting microbeads in a lab-on-chip environment. The chips consist of microfluidic channels and microelectrodes for performing dielectrophoretic manipulation employing a.c. electric fields. The dielectrophoretic guiding elements allow the assembly of cell–bead pairs while avoiding ill-defined physical contacts with their environment. After overnight cultivation of the manipulated cells, 77% of the bead-associated T cells expressed the activation marker molecule CD69. Physiological stress on the cells was shown to be mainly due to the single-cell cultivation and not to the manipulation in the chips. The same approach could be useful for the in vitro regulation of stem cell differentiation. [Copyright &y& Elsevier]
- Published
- 2008
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- View/download PDF
269. The Autographa californica nuclear polyhedrosis virus AcNPV induces functional maturation of human monocyte-derived dendritic cells
- Author
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Schütz, Alexandra, Scheller, Nicoletta, Breinig, Tanja, and Meyerhans, Andreas
- Subjects
- *
DENDRITIC cells , *LYMPHOID tissue , *IMMUNIZATION , *CYTOKINES - Abstract
Abstract: The initiation of an adaptive immune response is critically dependent on the activation of dendritic cells (DCs). Therefore, vaccination strategies targeting DCs have to ensure a proper presentation of the immunogen as well as an activation of DCs to accomplish their full maturation. Viral vectors can achieve gene delivery and a subsequent presentation of the expressed immunogen, however, the immunization efficiency may be hampered by an inhibition of DC activation. Here we report that the insect born Autographa californica nuclear polyhedrosis virus (AcNPV), which is already used for genetic immunization, is able to activate human monocyte-derived DCs. This activation induces the production of tumor necrosis factor alpha (TNF-α), an up-regulation of the surface molecules CD83, CD80, CD86, HLA-DR and HLA-I and increases the T cell stimulatory capacity of DCs. Thus, AcNPV represents a promising vector for vaccine trials. [Copyright &y& Elsevier]
- Published
- 2006
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270. Cross-presentation of HLA class I epitopes from influenza matrix protein produced in Saccharomyces cerevisiae
- Author
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Wadle, Andreas, Held, Gerhard, Neumann, Frank, Kleber, Sascha, Wuellner, Beate, Asemissen, Anne Marie, Kubuschok, Boris, Scheibenbogen, Carmen, Breinig, Tanja, Meyerhans, Andreas, and Renner, Christoph
- Subjects
- *
LEAVENING agents , *VIRUS diseases , *EXTRACELLULAR matrix proteins , *SACCHAROMYCES cerevisiae - Abstract
Abstract: Here we report that genetically engineered yeast of the strain Saccharomyces cerevisiae expressing full-length influenza matrix protein (IMP) attached to the yeast cell wall are a very versatile host for antigen delivery. Feeding of dendritic cells with either intact yeast expressing IMP protein or soluble IMP protein cleaved off the cell wall resulted in protein uptake, processing and cross-presentation of IMP-derived peptides. This process was analysed using previously established T-cell lines recognizing the immuno-dominant 58–66 peptide when presented by HLA-A2*0201 complexes. In addition, IMP58–66/HLA-A2*0201-specific antibodies were selected from a naive phage library which confirmed that peptide presentation was an active process of endocellular uptake and not just a result of external peptide loading. Moreover, MHC peptide antibodies could block the recognition of peptide-presenting dendritic cells by IMP58–66-specific T-cells in a dose dependent manner. There was no difference in T-cell recognition when either intact yeast or yeast cell extracts were used for DC feeding. Together, these data demonstrate that yeast derived proteins either in their soluble form or as part of a whole yeast vaccine are taken up, processed and presented by dendritic cells in HLA class I context. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
271. Schlafen 12, a novel HIV restriction factor involved in latency
- Author
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Smutná, Katarína, 1991, Meyerhans, Andreas, Díez Antón, Juana, 1962, and Universitat Pompeu Fabra. Departament de Ciències Experimentals i de la Salut
- Subjects
Proliferación homeostática ,Latency ,Latencia ,HIV ,Post transcriptional block ,Schlafen12 ,Inhibición post-transcripcional ,Homeostatic proliferation - Abstract
The process of HIV latency establishment and maintenance is not clearly understood. Homeostatic proliferation (HSP) is a major mechanism by which long-lived naive and memory CD4 T cells are maintained in vivo. HSP also contributes to the persistence of HIV latent reservoir. Furthermore, HIV-infected naive CD4 T cells cultured under HSP condition are refractory to reactivation, in contrast to TCR-activated memory CD4 T cells. This might be due to the suggested post-transcriptional block in naive HSP-cultured cells. Here we compared a transcriptomic signature of naive and memory CD4 T cells. Among differentially expressed genes that may influence HIV latency, we identified Schlafen 12 (SLFN12) as an interesting candidate for a potential HIV restriction factor. Our results showed that SLFN12 establishes post-transcriptional block in HIV infected cells and thus inhibits both, HIV production as well as its reactivation from latently infected cells. These findings may help to better understand the mechanisms underlying HIV latency and its reversal in HSP-maintained naive CD4 T cells. All together it might contribute to the design of novel HIV eradication strategies. El proceso por el cual el virus de la Inmunodeficiencia Humana (VIH) establece y mantiene un estado de latencia no se conoce en su totalidad. La proliferación homeostática (HSP, de sus siglas en ingés “Homeostatic proliferation”) es uno de los mecanismos por el cual las células T CD4 “naive” y de memoria se mantienen in vivo. Además, HSP también contribuye al mantenimiento del reservorio de virus en forma latente. Además, las células T CD4 “naive” infectadas y cultivadas en condiciones de HSP no son capaces de reactivarse a diferencia de las células T CD4 de memoria activadas vía TCR. Estudios previos sugieren que esta observación se debe a un bloqueo post-transcripcional en células T “naive” cultivadas en condiciones de HSP. En esta tesis comparamos la perfil del transcriptoma de células T CD4 “naive” y de memoria. Entre los genes diferencialmente expresados que podrían participar en el proceso de latencia del VIH, identificamos Schlafen 12 (SLFN12) como un candidato interesante que podría ser un factor de restricción del virus. Los resultados de este trabajo muestran que SLFN12 establece un bloqueo post-transcripcional en células infectadas por VIH, y de esta forma inhibe tanto la producción del virus como su reactivación en células infectadas de forma latente. Estas observaciones pueden ser de gran ayuda para entender mejor los mecanismos subyacentes a la latencia del VIH así como su reactivación en células CD4 T “naive” mantenidas bajo condiciones de HSP. En su conjunto, estos resultados podrían contribuir al diseño de nuevas estrategias para erradicar el VIH.
- Published
- 2019
272. Intracellular Life Cycle Kinetics of SARS-CoV-2 Predicted Using Mathematical Modelling.
- Author
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Grebennikov, Dmitry, Kholodareva, Ekaterina, Sazonov, Igor, Karsonova, Antonina, Meyerhans, Andreas, and Bocharov, Gennady
- Subjects
- *
SARS-CoV-2 , *DRUG target , *MATHEMATICAL models , *COVID-19 , *PARAMETER identification - Abstract
SARS-CoV-2 infection represents a global threat to human health. Various approaches were employed to reveal the pathogenetic mechanisms of COVID-19. Mathematical and computational modelling is a powerful tool to describe and analyze the infection dynamics in relation to a plethora of processes contributing to the observed disease phenotypes. In our study here, we formulate and calibrate a deterministic model of the SARS-CoV-2 life cycle. It provides a kinetic description of the major replication stages of SARS-CoV-2. Sensitivity analysis of the net viral progeny with respect to model parameters enables the identification of the life cycle stages that have the strongest impact on viral replication. These three most influential parameters are (i) degradation rate of positive sense vRNAs in cytoplasm (negative effect), (ii) threshold number of non-structural proteins enhancing vRNA transcription (negative effect), and (iii) translation rate of non-structural proteins (positive effect). The results of our analysis could be used for guiding the search for antiviral drug targets to combat SARS-CoV-2 infection. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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273. Retrovirus variation: a finger on the pulse
- Author
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Meyerhans, Andreas
- Published
- 1996
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274. Time-resolved systems analysis of virus infection fate regulation
- Author
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Pedragosa Marín, Mireia, Meyerhans, Andreas, Argilaguet Marqués, Jordi, and Universitat Pompeu Fabra. Departament de Ciències Experimentals i de la Salut
- Subjects
Cèl.lules dendrítiques XCR1 ,Choriomeningitis virus ,Biologia de sistemes ,Virus infection fate ,Time-resolved transcriptome ,Transcriptoma resolt en el temps ,Systems biology ,Lymphocytic ,Destí de la infecció vírica ,Virus de la coriomeningitis limfocítica - Abstract
The processes and mechanisms of virus infection fate decisions that are the result of a dynamic virus - immune system interaction with either an efficient effector response and virus elimination or an alleviated immune response and chronic infection are poorly understood. Here, we characterized the host response to acute and chronic lymphocytic choriomeningitis virus (LCMV) infections by gene coexpression network analysis of time-resolved splenic transcriptomes. We found first, an early attenuation of inflammatory monocyte/macrophage prior to the onset of T cell exhaustion and second, a critical role of the XCL1-XCR1 communication axis during the functional adaptation of the T cell response to the chronic infection state. These findings not only reveal an important feedback mechanism that couples T cell exhaustion with the maintenance of a lower level of effector T cell response but also suggest therapy options to better control virus levels during the chronic infection phase. Encara són poc coneguts els processos i mecanismes resultants de la interacció dinàmica entre el virus i l’hoste que determinen que una infecció es resolgui favorablement gràcies a una resposta efectora eficient o que esdevingui crònica degut a l’atenuació de la resposta immunitària. En aquesta tesi, hem caracteritzat la resposta de l’hoste en front a una infecció aguda o crònica amb el virus de la coriomeningitis limfocítica (LCMV) mitjançant l’anàlisi de xarxes de coexpressió de gens derivades de transcriptomes de melsa. Els resultats obtinguts mostren, primer, una atenuació de monòcits/macròfags inflamatoris durant els primers dies després de la infecció i abans de que hi hagi esgotament de les cèl·lules T i, segon, un rol important de l’eix XCL1-XCR1 durant l’adaptació funcional de la resposta de cèl·lules T a la fase crònica de la infecció. Aquests descobriments, no només posen al descobert un mecanisme important de retroalimentació que uneix les cèl·lules T esgotades amb el manteniment d’un cert nivell de resposta efectora, sinó que també suggererixen noves opcions terapèutiques per intentar controlar la expansió del virus durant la fase crònica de la infecció.
- Published
- 2018
275. Myxobacteria: natural pharmaceutical factories.
- Author
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Diez, Juana, Martinez, Javier P., Mestres, Jordi, Sasse, Florenz, Frank, Ronald, and Meyerhans, Andreas
- Subjects
- *
MYXOBACTERALES , *BACTERIA , *GLIDING bacteria , *PHARMACEUTICAL industry , *DRUG development - Abstract
Myxobacteria are amongst the top producers of natural products. The diversity and unique structural properties of their secondary metabolites is what make these social microbes highly attractive for drug discovery. Screening of products derived from these bacteria has revealed a puzzling amount of hits against infectious and non-infectious human diseases. Preying mainly on other bacteria and fungi, why would these ancient hunters manufacture compounds beneficial for us? The answer may be the targeting of shared processes and structural features conserved throughout evolution. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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- View/download PDF
276. Importance of structure-based studies for the design of a novel HIV-1 inhibitor peptide.
- Author
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Gomara, María J., Perez, Yolanda, Gomez-Gutierrez, Patricia, Herrera, Carolina, Ziprin, Paul, Martinez, Javier P., Meyerhans, Andreas, Perez, Juan J., and Haro, Isabel
- Subjects
- *
PEPTIDOMIMETICS , *PEPTIDES , *HIV infection transmission , *MUCOUS membranes , *MOLECULAR dynamics - Abstract
Based on the structure of an HIV-1 entry inhibitor peptide two stapled- and a retro-enantio peptides have been designed to provide novel prevention interventions against HIV transmission. The three peptides show greater inhibitory potencies in cellular and mucosal tissue pre-clinical models than the parent sequence and the retro-enantio shows a strengthened proteolytic stability. Since HIV-1 fusion inhibitor peptides need to be embedded in the membrane to properly interact with their viral target, the structural features were determined by NMR spectroscopy in micelles and solved by using restrained molecular dynamics calculations. Both parent and retro-enantio peptides demonstrate a topology compatible with a shared helix–turn–helix conformation and assemble similarly in the membrane maintaining the active conformation needed for its interaction with the viral target site. This study represents a straightforward approach to design new targeted peptides as HIV-1 fusion inhibitors and lead us to define a retro-enantio peptide as a good candidate for pre-exposure prophylaxis against HIV-1. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
277. Viral Infection Dynamics Model Based on a Markov Process with Time Delay between Cell Infection and Progeny Production.
- Author
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Sazonov, Igor, Grebennikov, Dmitry, Kelbert, Mark, Meyerhans, Andreas, and Bocharov, Gennady
- Subjects
- *
VIRUS diseases , *MARKOV processes , *ALGORITHMS , *HIV - Abstract
Many human virus infections including those with the human immunodeficiency virus type 1 (HIV) are initiated by low numbers of founder viruses. Therefore, random effects have a strong influence on the initial infection dynamics, e.g., extinction versus spread. In this study, we considered the simplest (so-called, 'consensus') virus dynamics model and incorporated a delay between infection of a cell and virus progeny release from the infected cell. We then developed an equivalent stochastic virus dynamics model that accounts for this delay in the description of the random interactions between the model components. The new model is used to study the statistical characteristics of virus and target cell populations. It predicts the probability of infection spread as a function of the number of transmitted viruses. A hybrid algorithm is suggested to compute efficiently the system dynamics in state space domain characterized by the mix of small and large species densities. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
278. Broad-spectrum host-acting antivirals: identification and characterization of anti-HIV drugs
- Author
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Fleta Soriano, Eric, 1983, Meyerhans, Andreas, and Universitat Pompeu Fabra. Departament de Ciències Experimentals i de la Salut
- Subjects
Host-actings antivirals ,Antiviral contra hospedador ,Soraphen A ,HIV ,VIH ,Antiiviral amplio aspectro ,Ratjadone A ,Broad-spectrum antivirals - Abstract
Hundreds of host factors related to viral infections like HIV, hepatitis C virus, dengue virus or West Nile virus have been identified. As many of these host factors are shared by different viruses, chemical blockade of key virus-associated cellular components may effectively act as broad-spectrum antiviral treatment. Broad-spectrum host-acting antivirals (HAAs) may reduce treatment complexity and costs, increase adherence to the therapy and may pose a higher barrier to develop resistance. In this thesis a high-throughput anti-HIV assay was used to screen for virus inhibitory effects of a library of secondary metabolites derived from myxobacteria. Compounds with high anti-HIV activity and low toxicity were classified as hits and two of them (ratjadone A and soraphen A) were selected for further analysis. The mechanism of HIV inhibition of both compounds is described here. The results presented in this thesis show that broad-spectrum HAAs are a feasible option for antiviral treatment and that the compounds identified can be further studied for hit-to-lead compound development., Cientos de factores del huésped relacionados con infecciones virales por VIH, hepatitis C, dengue o virus del Nilo occidental han sido identificados. Como muchos de esos factores del huésped son compartidos por diferentes virus, el bloqueo químico de un componente celular clave asociado al virus podría actuar de forma efectiva como un tratamiento antiviral de amplio espectro. Antivirales de amplio espectro contra factores del huésped podrían reducir la complejidad y el coste del tratamiento, incrementar el cumplimiento de la terapia y pueden suponer una barrera mayor al desarrollo de resistencia. En esta tesis un cribado de alta capacidad anti-VIH fue aplicado a una librería de metabolitos secundarios de myxobacteria. Compuestos con alta actividad anti-VIH y baja toxicidad fueron clasificados como hits y dos de ellos (ratjadone A y soraphen A) fueron seleccionados para posteriores estudios. El mecanismo de inhibition de VIH de ambos compuestos es descrito aquí. Los resultados presentados en esta tesis muestran que usar antivirales de amplio espectro contra factores del huésped es un opción viable para tratamientos antivirales y que los compuestos identificados pueden ser estudiados para el desarrollo de fármacos.
- Published
- 2015
279. Peptide Assembly on the Membrane Determines the HIV-1 Inhibitory Activity of Dual-Targeting Fusion Inhibitor Peptides.
- Author
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Gomara, Maria J., Perez, Yolanda, Martinez, Javier P., Barnadas-Rodriguez, Ramon, Schultz, Anke, von Briesen, Hagen, Peralvarez-Marin, Alex, Meyerhans, Andreas, and Haro, Isabel
- Abstract
Novel strategies in the design of HIV-1 fusion/entry inhibitors are based on the construction of dual-targeting fusion proteins and peptides with synergistic antiviral effects. In this work we describe the design of dual-targeting peptides composed of peptide domains of E2 and E1 envelope proteins from Human Pegivirus with the aim of targeting both the loop region and the fusion peptide domains of HIV-1 gp41. In a previous work, we described the inhibitory role of a highly conserved fragment of the E1 protein (domain 139-156) which interacts with the HIV-1 fusion peptide at the membrane level. Here, two different dual-targeting peptides, where this E1 peptide is located on the N- or the C-terminus respectively, have been chemically synthesized and their antiviral activities have been evaluated with HIV pseudotyped viruses from different clades. The study of the functional behaviour of peptides in a membranous environment attending to the peptide recognition of the target sites on gp41, the peptide conformation as well as the peptide affinity to the membrane, demonstrate that antiviral activity of the dual-targeting peptides is directly related to the peptide affinity and its subsequent assembly into the model membrane. The overall results point out to the necessity that fusion inhibitor peptides that specifically interfere with the N-terminal region of gp41 are embedded within the membrane in order to properly interact with their viral target. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
280. PD-L1 blockade : impact on regulatory T cells from HIV-infected individuals
- Author
-
Peligero Cruz, Cristina, 1986, Meyerhans, Andreas, and Universitat Pompeu Fabra. Departament de Ciències Experimentals i de la Salut
- Subjects
Cèl·lules T reguladores ,Human immunodeficiency virus ,Immunoteràpia ,Bloquejar PD-L1 ,Regulatory T cells ,Immunotherapy ,Virus de la immunodeficiència humana ,PD-L1 blockade - Abstract
Bloquejar la via PD-1/PD-L1 ha sorgit com una estratègia prometedora per a restaurar la resposta immune efectora en individus infectats amb el virus de la immunodeficiència humana (VIH). Malgrat l’extensa recerca duta a terme en aquest camp, es desconeixen els efectes que aquesta immunoteràpia pot tenir en les cèl•lules T reguladores (Treg). En la present tesi he investigat l’expressió de PD-1/PD-L1 i l'impacte de bloquejar PD-L1 en les Treg de pacients infectats amb el VIH. Hem observat que la infecció pel VIH indueix l’augment del percentatge de Treg PD-1+ i PD-L1+, i que aquest augment correlaciona amb la progressió de la malaltia. Bloquejar PD-L1 augmenta la capacitat de proliferar de les Treg d’individus virèmics i a més causa un increment en la reactivació de virus. Al contrari, bloquejar PD-L1 no augmenta significativament la proliferació de les Treg d’individus que controlen la virèmia, però augmenta la capacitat de proliferar de les cèl•lules T-CD8 en tots els grups de pacients estudiats. En conjunt, aquests resultats indiquen que la virèmia de l’individu pot influir en el guany net de la funció efectora després de bloquejar PD-L1., Blocking the PD-1/PD-L1 pathway has emerged as a potential therapy to restore impaired immune responses in human immunodeficiency virus (HIV)-infected individuals. Most reports have studied the impact of the PD-L1 blockade on effector cells and neglected possible effects on regulatory T cells (Treg). In this thesis I investigated PD-1 and PD-L1 expression on Treg and the impact of ex vivo PD-L1 blockade on Treg from HIV-infected individuals. We observed that HIV infection led to an increase in PD-1+ and PD-L1+ Treg, which correlated with disease progression. Ex vivo PD-L1 blockade increased the proliferative capacity of Treg from viremic individuals and increased viral reactivation. In contrast, PD-L1 blockade had no significant effect on the proliferative capacity of Treg from individuals that control viremia, but increased CD8 T cell proliferation in all HIV-study groups. Taken together, this suggests that the net gain of T cell effector function after PD-L1 blockade may critically depend on the plasma viremia of the host.
- Published
- 2015
281. Hepatitis C Virus-Infektionsstudien an primären Zellen monozytärer Herkunft
- Author
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Ehrhardt, Michael and Meyerhans, Andreas
- Subjects
Dendritische Zelle ,neohepatocyte ,ddc:570 ,Makrophage ,monocyte ,Monozyt ,denditric cell ,Hepatitis-C-Virus ,macrophage ,ddc:620 ,Neohepatozyt - Abstract
Basierend auf der Notwendigkeit eines patientenspezifischen Systems für HCV-Infektionsstudien wurden Neohepatozyten im Rahmen der vorliegenden Arbeit als alternatives Zellsystem zu hepatischen Zelllinien charakterisiert. Infektionsexperimente mit HIV-HCVpp zeigten, dass humanes Serum, unabhängig vom Vorhandenssein HCV-neutraliserender Antikörper, donorabhängig steigernde oder inhibierende Einflüsse auf die Infektion von Neohepatozyten haben konnte. Die gleichen Seren wirkten stets inhibierend auf die Infektion von Huh7-Zellen. Dies korrelierte mit der Expression von Fcγ-Rezeptoren, die nur auf Zellen monozytärer Herkunft nachgewiesen werden konnten. Interessanterweise sind aber Neohepatozyten, unabhängig von der breiten Expression von Fcγ-Rezeptoren, die einzigen Zellen monozytärer Herkunft, die effizient infiziert werden konnten. Dies konnte zum Teil auf die differenzielle Expression des HCV-Eintrittsfaktors Occludin zurückgeführt werden. Durch mehrfache, zeitlich versetzte Präparationen von Neohepatozyten aus Monozyten konnten wir deutliche donorspezifische Unterschiede in den Infektionsfrequenzen beobachten. Des Weiteren wurden in dieser Arbeit Neohepatozyten anhand ihres miRNA-Profils zweifelsfrei als eine Makrophagen-Subpopulation klassifiziert. Insgesamt betrachtet sind Neohepatozyten ein effizientes System zur Untersuchung des HCV-Zelleintritts unter Beibehaltung donorspezifischer Eigenschaften. Based on the necessity of a more physiological and patient-specific system for HCV infection studies, neohepatocytes were characterized as an alternative cell system to hepatic cell lines. Infection experiments with HIV-HCVpp showed a donor-dependend influence of human serum on the infection of neohepatocytes independend of the existence of neutralizing antibodies. The same sera had a inhibiting influence on Huh7 infection. This correlated with the expression of Fcγ-receptors, that could only be observed on cells of monocytic origin. Interestingly neohepatocytes are the only cells of monocytic origin that could be infected efficiently independend of the broad expression of Fcγ-receptors. This could partly be due to the differential expression of the HCV entry factor Occludin. We could observe distinct differences in infection frequency at neohepatocytes prepared at different time points out of monocytes from two representative donors. Furthermore we were able to identify neohepatocytes as a macrophage subpopulation with their miRNA-profiles. Altogether neohepatocytes are an efficient system for analysing the HCV entry into target cells with donor-specific characteristics.
- Published
- 2012
- Full Text
- View/download PDF
282. Streit um den Zehnten in Männedorf
- Author
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Bersorger, Walter, University of Zurich, Kränzle, Andreas, Meyerhans, Andreas, Mosca-Rau, Bettina, and Bersorger, Walter
- Subjects
10109 Institute of History ,900 History - Published
- 2012
283. Der gemeine Hofrodel als mobiles Wissen
- Author
-
Halter-Pernet, Colette, University of Zurich, Kränzle, Andreas, Meyerhans, Andreas, Mosca-Rau, Bettina, and Halter-Pernet, Colette
- Subjects
10109 Institute of History ,900 History - Published
- 2012
284. Technik im Detail: Die Sägemühle an der Alp
- Author
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Bersorger, Walter, University of Zurich, Kränzle, Andreas, Meyerhans, Andreas, Mosca-Rau, Bettina, and Bersorger, Walter
- Subjects
10109 Institute of History ,900 History - Published
- 2012
285. Das Buch der Stifter und Guttäter – ein frühneuzeitliches Sponsorenbuch
- Author
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Bersorger, Walter, University of Zurich, Kränzle, Andreas, Meyerhans, Andreas, Mosca-Rau, Bettina, and Bersorger, Walter
- Subjects
10109 Institute of History ,900 History - Published
- 2012
286. Von schwarzen Schimmeln, Tintenfrass und Mäusebiss – Bestandserhaltung im Kloster
- Author
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Bersorger, Walter, University of Zurich, Kränzle, Andreas, Meyerhans, Andreas, Mosca-Rau, Bettina, and Bersorger, Walter
- Subjects
10109 Institute of History ,900 History - Published
- 2012
287. Die Qual der Wahl des Marmors
- Author
-
Bersorger, Walter, University of Zurich, Kränzle, Andreas, Meyerhans, Andreas, Mosca-Rau, Bettina, and Bersorger, Walter
- Subjects
10109 Institute of History ,900 History - Published
- 2012
288. Namen, Zinsen und Betten - Urbare des 14. Jahrhunderts
- Author
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Halter-Pernet, Colette, University of Zurich, Kränzle, Andreas, Meyerhans, Andreas, Mosca-Rau, Bettina, and Halter-Pernet, Colette
- Subjects
10109 Institute of History ,900 History - Published
- 2012
289. Consequences of HIV-1 multinfection of single cells
- Author
-
Martinez, Javier Pablo and Meyerhans, Andreas
- Subjects
ddc:610 ,ddc:620 - Published
- 2011
- Full Text
- View/download PDF
290. Entwicklung eines Personen-spezifischen Zellkultursystems zur Untersuchung von Hepatitis C Virus Infektionen
- Author
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Hohn, Christina R. and Meyerhans, Andreas
- Subjects
cell culture ,Zellkultur ,stem cells ,ddc:570 ,Virusinfektion ,Leberepithelzelle ,liver cells ,Hepatitis-C-Virus ,viral infection ,ddc:620 ,hepatitis C ,digestive system diseases ,Stammzelle - Abstract
Etwa 200 Millionen HCV-Infektionen weltweit machen Hepatitis C zu einem globalen Gesundheitsproblem (WHO, 2008). In vivo sind Hepatozyten die primären Zielzellen der HCV-Infektion, doch ihre Verwendbarkeit für in vitro Studien ist stark limitiert. Humane Leberkarzinom-Zelllinien wie Huh7 bieten daher bislang die einzige Möglichkeit den HCV-Lebenszyklus zu untersuchen. Aufgrund ihres degenerierten Genoms sowie ihres abweichenden Stoffwechsels spiegeln Huh7-Zellen aber keineswegs die in vivo Situation einer Leberzelle wider. Basierend auf der Notwendigkeit eines alternativen hepatischen Zellsystems wurde im Rahmen dieser Arbeit untersucht, ob Monozyten-basierte Neohepatozyten als alternatives Zellsystem für HCV-Studien eingesetzt werden können. Im Rahmen dieser Arbeit konnte gezeigt werden, dass die Expressionsprofile von Neohepatozyten und Huh7-Zellen große Ähnlichkeiten im Hinblick auf Hepatozyten-spezifische Faktoren aufweisen. Neben Albumin und den bis dato bekannten HCV-Rezeptoren konnte zudem die Leberzell-spezifische miRNA122 nachgewiesen werden. Die Generation der Neohepatozyten gelang dabei sowohl aus PBMC gesunder Spender, als auch aus den Blutzellen von HCV-Patienten. Infektionsexperimente mit hepatotrophen HCVpp konnten belegen, dass der Großteil der Neohepatozyten für die virale Infektion zugänglich ist. Humanes AB-Serum war dabei ebenso wie das Polysaccharid DEAE-Dextran in der Lage, die HCVpp-Infektionsfrequenz positiv zu beeinflussen. Die Neutralisation der HCVpp-Infektion durch antiCD81-, antiSR-BI- und antiCLDN1-Antikörper zeigte zudem, dass die HCVpp-Infektion in Neohepatozyten über die gleichen Rezeptoren vermittelt wird wie in Hepatozyten. Neutralisierende antiE1E2-Antikörper aus HCV-Patienten hatten dagegen in Neohepatozyten und Huh7-Zellen gegensätzliche Effekte. Während die Infektions-Frequenz in Huh7-Zellen in Anwesenheit der Antikörper gesenkt wurde, hatten die Patienten-Antikörper in Neohepatozyten einen infektionssteigernden Effekt. Dies könnte auf unterschiedliche Wechselwirkungen der Virus-Antikörper-Komplexe mit zellulären Fc-Rezeptoren oder andere Personen-spezifische Faktoren hindeuten. Aufgrund ihrer Eigenschaften als primäre Zellen kam dieser Effekt in Neohepatozyten wahrscheinlich deutlich stärker zum Tragen als in Huh7-Zellen. Der Unterschied zwischen Neohepatozyten und Huh7-Zellen wurde auch im Kontext der HCVcc-Infektion deutlich. Während die getesteten Huh7.5-Zellen aufgrund ihrer Mutation im RIG-Gen den HCVcc-Eintritt sowie die Replikation der viralen Partikel erlaubten, konnte in den Neohepatozyten keine effektive HCVcc-Infektion detektiert werden. Da primäre humane Hepatozyten vergleichbare Ergebnisse zeigten, scheinen Neohepatozyten den in vivo Zustand einer Leberzelle wohl besser zu reflektieren als Huh7-Zellen. Zusammenfassend kann gesagt werden, dass Neohepatozyten ein effizientes System darstellen, um den HCV-Zelleintritt Patienten-spezifisch zu untersuchen. Replikations-Studien sind ersten Erkenntnissen zufolge nicht möglich. Die Weiterentwicklung dieses Systems, z.B. im Kleintiermodell könnte allerdings dazu beitragen, Wirts-Faktoren zu identifizieren, die einen Einfluss auf die HCV-Persistenz und -Pathogenese haben. Bezogen auf eine therapeutische Anwendbarkeit könnte die fehlende Replikationseffizienz zudem Vorteile haben: Leberzell-Transplantate wären aus autologen Körperzellen generierbar und eine erneute HCV-Infektion könnte ausgeschlossen werden. Inwieweit diese Ansätze allerdings praktisch umsetzbar sind, müssen künftige Experimente zeigen. HCV is a major cause of chronic liver disease. There is a growing interest in ex vivo generated hepatocytes for several therapeutic issues as well as for infection analysis under relevant ex vivo conditions. Primary human hepatocytes (PHH) represent the primary target cells of HCV, supporting viral replication in vivo, but their availability is limited and establishing and maintaining cultures of PHH has proven difficult. So by now, HCV studies are limited to human hepatoma cell lines like Huh7 that lack a substantial set of liver-specific functions and exhibit a degenerated karyotype with numerous abnormalities. A full understanding of the pathogenesis of HCV requires a tissue culture model that allows studies in a physiological context. According to previous studies we generated a hepatocyte-like cell system (termed Neohepatocytes) from peripheral blood monocytes by culture conditions that promote hepatocyte differentiation (Ruhnke et al., 2005). Based on this system it was investigated, whether Neohepatocytes can be used as a person-specific cell system for HCV infection studies. A first line of investigation showed that Neohepatocytes express hepatocyte-specific markers like albumin as well as the essential HCV receptors CD81, SR-BI and CLDN-1 in comparable levels to Huh7 cells. Additionally the liver-specific miRNA122 is detectable within these cells, although in lower concentrations than within Huh7 cells. Furthermore, the majority of Neohepatocytes is infectable with hepatotrophic HCV pseudotypes and antibodies against the known HCV host cell entry factors CD81, SR-BI and CLDN-1 are able to neutralize HCVpp infection. The frequency of HCVpp infection could be enhanced by human sera and DEAE-Dextran. Interestingly, neutralizing antibodies derived from chronically infected HCV patients appeared to show a different pattern of neutralization in Neohepatocytes compared to Huh7 cells. While anti-HCV antibodies neutralized HCVpp infection in the Huh7 cell system, nearly all patient-derived IgGs increased the infection rate of HCVpp in Neohepatocytes. These observations could be related to specific interactions of virus-antibody complexes with cellular Fc receptors or with other person-specific surface factors lost in Huh7 cells. HCVcc infection experiments unraveled additional differences between Neohepatocytes and Huh7 cells. While HCVcc infection and viral replication took place in the RIG-deficient Huh7.5 cells, no effective HCVcc infection could be detected in Neohepatocytes. PHH also fail to allow an efficient HCVcc infection, indicating a higher similarity to Neohepatocytes than to Huh7 cells. Taken together, the here established infection system may represent a valuable cell system to analyze patient-specific virus-host interactions during HCV infection. So far replication studies have been found impossible. But further development of the neohepatic cell system e.g. in a small animal model could help to identify host genetic markers that modify HCV persistence and pathogenesis. For clinical application the missing replication capacity could be even advantageous: transplantation of autologous cells would prevent negative immune responses and reinfection by HCV could be circumvented. However, the practicability of this theory remains to be determined by future investigations.
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- 2009
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291. Die Methode der Fluoreszenz-In-Situ-Hybridisierung zur Analyse von HIV- und SIV-Genomen auf Einzelzellebene
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Schultz, Anke and Meyerhans, Andreas
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Einzelzellanalyse ,Evolution ,ddc:570 ,virus diseases ,HIV ,Rekombination ,ddc:620 ,Fluoreszenz-in-situ-Hybridisierung ,single-cell-analysis ,fluorescence in situ hybridization ,recombination - Abstract
HIV zeichnet sich durch eine hohe genetische Variabilität aus. Die fehlerbehaftete Replikation stellt ein wesentliches Charakteristikum und die Grundlage für die Pathogenität dar. Um Einblicke in grundlegende Veränderungsmechanismen von HIV zu gewinnen, ist eine Analyse auf Ebene einzelner infizierter Zellen von Patienten notwendig. Die HIV-spezifische FISH spielt bei den Untersuchungen auf Einzelzellebene eine entscheidende Rolle. In dieser Arbeit konnte sowohl die RNA-FISH als auch die DNA-FISH erfolgreich etabliert und optimiert werden. Mit Hilfe beider Methoden gelang es, Patientenmaterial bezüglich der Zahl produktiv-infizierter Zellen und der Provirus-Kopienzahl zu analysieren. In einzelnen Zellen aus lymphatischen Geweben von SIV-infizierten Rhesus Makaken wurden von der Primärvirämie bis zum späten Stadium der Infektion zwei bis drei provirale SIV-Sequenzen spezifisch detektiert. Der Nachweis der Mehrfachinfektion in einzelnen MNC aus der Milz eines Rhesusaffens zwei Wochen nach Beginn der Infektion zeigte, dass der Grundstein zur Steigerung der Variantenvielfalt über Rekombinationsereignisse in der frühen Phase der Infektion gelegt wird. Die Bestimmung multipler Proviren während des gesamten Infektionsverlaufs demonstriert, dass dieser Prozess als ein kontinuierlich stattfindendes Ereignis während des Infektionsgeschehens anzusehen ist. Diese Daten dienen nun als Basis mathematischer Modellrechnungen zur HIV-Evolution. The pathogenic retrovirus HIV is characterized by a high genetic diversity, which is induced by different error processes. To get detailed insights into mechanisms that contribute to the genetic variants, the analysis of single infected cells of HIV-positive patients is essential. The HIV-specific FISH is of great importance for analysing HIV-infection on the single cell level. In the present work, the technical improvement of both, the HIV-specific RNA-FISH and the HIV-specific DNA-FISH, was successful. Using both techniques, productively infected cells and the provirus copy number in patient material could be determined. With the help of the SIV-specific DNA-FISH, two or three integrated proviral SIV-sequences were detected in single splenocytes of SIV-infected rhesus macaques from the primary viremia to the late stage of infection. The detection of multiple proviruses within single cells two weeks post infection shows that the increase of genetic diversity via recombination begins in the primary stage of infection. Furthermore, the detection of multiinfection in single cells during the complete course of infection demonstrates that recombination is a dominant continuous mechanism for generating new virus variants. These results will be incorporated as fundamental parameters in a mathematical model for simulating HIV-evolution.
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- 2009
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292. Das Cytomegalovirus Tegumentprotein pp65 ist ein potentielles Trägerproetin für Antigene
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Furtwängler, Conrad Julian Rhoikos and Meyerhans, Andreas
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ddc:610 ,ddc:620 - Published
- 2007
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293. Detaillierte Analyse der HIV-spezifischen CD8-T-Zell-Antwort in HIV-Infizierten
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Geldmacher, Christof and Meyerhans, Andreas
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Zelluläre Immunität ,gag ,HIV Subtypen ,HIV ,HLA class I ,HIV-Infektion ,CD8 Tcell crossrecognition ,Antigen CD8 ,ddc:570 ,Multiple Infektion ,dual infection ,ddc:620 - Abstract
The importance of HLA class I restricted CD8 T cell response in the control of HIV infection is generally accepted, yet few studies have shown a correlation of the CD8 T cell response with markers of HIV disease progression. Disease progression is dependent on several factors such as the virus load at set-point, rarely occurring mutations in the HIV co-receptor genes or the HLA class I alleles expressed by an HIV infected individual. It has been shown previously that particular HLA class I alleles are associated with a low plasma viral load. However, a relationship between these "protective'; HLA class I alleles and an efficient HIV-specific CD8 T cell response has not yet been demonstrated. In order to study the mechanism underlying the beneficial effect of "protective'; HLA class I alleles, 53 HIV-1 seropositive individuals from a high-risk cohort in southwest Tanzania were HLA-typed and the plasma viral load and CD4 counts were determined. The recognition of CD8 T cell epitopes within Gag, Nef and Env was analysed using a gamma interferon ELISPOT assay and freshly isolated peripheral blood mononuclear cells (PBMC). Gag and Nef were frequent targets of the HIV-specific CD8 T cell response with a median recognition of 3 Gag, 2 Nef and 1 Env epitopes per individual. The HLA class I alleles B5801, B8101 and B0702 were associated with a low median plasma viral load. At the same time expression of these correlated with a broader recognition of Gag epitopes (P = 0.0035), if compared with all other common HLA class I alleles. Further analysis of the Gag-specific T cell response revealed an inverse linear relationship between the number of Gag epitopes recognized and the plasma viral load (R = -0.36, P = 0.0016). Particularly, recognition of multiple epitopes within two regions of Gag (aa001-aa075 and aa248-aa500) was strongly associated with the maintenance of a low viral load, indicating that this pattern of HIV-specific CD8 T cell recognition is important for the control of viral replication during the chronic phase of HIV infection. In the second part of the present work, recognition of Gag and Nef variant epitopes was analysed using HIV-1 subtype A, C and D derived peptides. 83% of the Gag-specific responses were detected with subtype C derived peptides, whereas only 51% and 57% of responses were detected with subtype A or D peptides, respectively. The superiority of the subtype C Gag peptides for detecting CD8 T cell responses may in part reflect the predominance of subtype C and C-containing recombinant HIV-1 strains within the studied cohort. Nonetheless, screening for CD8 T cell responses with any one subtype-specific peptide set detected fewer responses and underestimated the breadth and the magnitude of responses within individuals, compared to the combined peptide sets from the three subtypes. Cross-subtype recognition for the 16 most frequently recognized peptides was identical only when the peptide sequences were invariant; in 9 of these 16 peptides, diminished recognition was the result of subtype-related sequence variation, and a frame-of-epitope effect diminished or abrogated recognition in 4 peptides. A minimal set of 15 frequently recognized Gag and Nef peptides was then designed and tested with cells from 50 HIV seropositive individuals and elicited responses in 47 of them, at a mean frequency of 715 SFC/106 peripheral blood mononuclear cells. Therefore incomplete cross-recognition between subtypes A, C, and D can be partially overcome using a defined peptide set representing frequently recognized epitopes, and potentially, by adjusting epitope frame within peptides. These strategies can help to define optimal vaccine epitopes. In the third part of the present work, the Gag-specific CD8 T cell response of individuals infected with a single HIV strain was compared with the response observed in individuals infected with multiple HIV-1 strains. Breadth of Gag epitope recognition and cross-recognition of subtype-specific peptide pools was enhanced in multiply infected study subjects, whereas CD8 T cell recognition of Nef or Env appeared to be unaffected. Therefore the increased viral diversity in individuals infected with multiple HIV-1 strains affects the Gag-specific T cell response. As a consequence inclusion of multiple Gag variants in a HIV vaccine is likely to enhance vaccine-induced CD8 T cell responses and cross-recognition of HIV epitopes. Es ist allgemein akzeptiert, daß die HLA Klasse I restringierte CD8 T Zellantwort bei der Kontrolle der Virusreplikation während einer HIV Infektion eine entscheidene Rolle spielt. Allerdings konnten nur wenige Studien eine Korrelation zwischen der HIV-spezifischen CD8 T Zellantwort und dem Krankheitsverlauf nachweisen. Der Krankheitsverlauf hängt von verschiedenen Faktoren ab, darunter die Viruslast nach der Primaervirämie, selten vorkommenden Mutationen in den HIV Korezeptorgenen, oder den HLA Klasse I Allelen. So geht beispielsweise die Expression bestimmter HLA Klasse I Allele mit einer niedrigen Plasma Viruslast einher. Eine Verbindung zwischen solchen "protektiven'; HLA Klasse I Allelen und einer effizienten HIV-spezifischen CD8 T Zellantwort konnte jedoch bisher noch nicht nachgewiesen werden. Zur Beantwortung des zugrundeliegenden Mechanismus, der mit "protektiven" HLA Allelen verbunden ist, wurden 53 HIV infizierte Frauen einer Hochrisikokohorte im Südwesten Tansanias bezüglich des HLA Typs, der Viruslast im Plasma und der CD4 T Zellzahl charakterisiert. Gleichzeitig wurde die Gag-, Nef- und Env-spezifische CD8 T Zell Antwort unter Verwendung eines Interferon gamma ELISPOT Assays bestimmt. Am häufigsten fanden sich in den Studienteilnehmerinnen CD8 T Zellantworten gegen Epitope in Gag und Nef, weniger häufig gegen Epitope in Env (Median: 3 Gag, 2 Nef und 1 Env erkannte Epitope/Individuum). Die HLA Klasse I Allele B5801, B8101 und B0702 waren mit einer niedrigen Viruslast assoziiert. Gleichzeitig korrelierte die Expression von einem oder zwei dieser Allele mit einer breiteren Erkennung von Gag Epitopen (P =0,0035, Median:4 erkannte Epitope/Individuum) verglichen mit anderen HLA Klasse I Allelen (Median: 2 erkannte Epitopen/Individuum). Die weitere Analyse der Gag-spezifischen CD8 T Zell Antwort offenbarte ein inverses lineares Verhätnis zwischen der Anzahl der erkannten Gag Epitope und der Viruslast im Plasma (R =-0,36 ; P = 0,0016). Des weiteren war die Erkennung von multiplen Epitopen in 2 Regionen des Gag Proteins (as001-as075 und as 248-500, GagR1R3) stark mit einer dauerhaften Kontrolle der Virusreplikation nach Serokonversion assoziiert. Zusammenfassend lassen diese Ergebnisse darauf schließen, daß die Erkennung multipler Epitope im Gag Protein, ganz besonders in GagR1R3, wichtig für die Kontrolle der Virusreplikation während der chronischen Phase der HIV Infektion ist. Im zweiten Teil der vorliegenden Arbeit wurde die Erkennung von HIV-1 Subtyp A-, C- und D-spezifischen Gag und Nef Epitopvarianten durch CD8 T Zellen untersucht. 83% der Gag-spezifischen Epitopantworten wurden mit den Subtyp C Peptiden detektiert, während lediglich 51% und 57% der Gag-spezifischen Epitopantworten mit den Subtyp A beziehungsweise Subtyp D Peptiden detektiert wurden. Die erhöhte Frequenz Subtyp C-spezifischer Antworten könnte zum Teil mit dem vorherrschenden Vorkommen Subtyp C und Subtyp C-beinhaltenender rekombinanter HIV-I Stämme in Südwest Tanzania zusammenhängen. Dennoch würde die Anzahl der Gag-spezifischen Epitopantworten durch die ausschließliche Verwendung von Subtyp C-spezifischen Peptiden unterschätzt. Die Erkennung von Subtyp-spezifischen Peptidevarianten durch CD8 T Zellen war lediglich für Peptide gleicher Aminosäuresequenz identisch. Für 9 der 16 am häufigsten erkannten Peptide konnte eine abgeschwächte Erkennung von Varianten des selben Peptids mit Aminosäuresequenzunterschieden erklärt werden. Für 4 Peptide konnte eine abgeschwächte Erkennung von Peptidvarianten mit einer unterschiedlichen Positionierung des Epitops innerhalb der Peptidvarianten erklärt werden. Aufgrund dieser Ergebnisse wurde ein minimales Set aus 15 der am häufigsten erkannten Peptiden zusammengestellt Dieses bestand vor allem aus Subtyp C-spezifischen, aber auch aus Subtyp A- und D-spezifischen Peptiden und wurde anschließend mit peripheren mononuklären Blutzellen ("peripheral blood mononuclear cells", PMBC) von 50 HIV infizierten Personen auf Erkennung getestet. Dieser Peptidpool wurde mit einer durchschnittlichen Frequenz von 715 SFC/106 PBMC von 47 dieser Personen erkannt. Zusammenfassend könnte diese Strategie dazu beitragen, optimale CD8 T Zell Epitopevarianten zu identifizieren, die in HIV Impfungen beinhaltet sein sollten. Im dritten Teil der vorliegenden Arbeit wurde die Gag-spezifische CD8 T Zell Antwort von Studienteilnehmerinnen verglichen, die mit einem oder mehreren verschiedenen HIV-1 Stämmen infiziert waren. Eine Mehrfachinfektion führt dazu, daß mehr Gagepitope erkannten werden. Darüber hinaus war auch die gleichzeitige Erkennung von subtypspezifischen Peptiden in diesen Studienteilnehmerinnen besser ausgeprägt. ... Für einen potentiellen HIV Impfstoff lässt sich aus der vorliegenden Arbeit schließen, daß es entscheidend sein kann, eine effiziente CD8 T Zellantwort zu induzieren. Vor allem sollten hierbei Gag-spezifische Epitopevarianten verschiedener Subtypen berücksichtigt werden.
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- 2006
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294. Untersuchungen zur Effizienz von DNA-und Protein-Trägersystemen zur Induktion von zellulären Immunantworten durch Dendritische Zellen
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Scheller, Nicoletta and Meyerhans, Andreas
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Dendritische Zelle ,Zelluläre Immunität ,carrier ,DNS ,viruses ,ddc:570 ,dendritic cells ,DNA ,cellular immunity ,ddc:620 - Abstract
In der vorliegenden Arbeit wurden unterschiedliche Verfahren zur Induktion von zellulären Immunantworten untersucht, die vor allem einen Schutz gegen intrazelluläre Erreger, wie virale Infektionen bieten sollen. In vivo sind hauptsächlich DCs in der Lage, effizient naive T-Zellen zu stimulieren und so primäre Immunantworten zu induzieren. Außerdem sind DCs die einzigen Zellen, die Protein-Antigene in vivo im MHC-I-Präsentationsweg prozessieren und so ein Cross-Priming von T Zellen induzieren können. Strategien, die die Expression oder die Präsentation eines Antigens in DCs in vivo und in vitro ermöglichen, würden demnach eine erfolgsversprechende Immunisierungs-Strategie darstellen. Darauf basierend wurde im Rahmen dieser Arbeit untersucht: (1) ob und in welchen Rahmen DCs bei Immunisierungs-Strategien mit "Autographa californica multiple nuclear polyhedrosis virus" (AcMNPV) transfiziert werden und (2) ob das HCMV-Tegumentprotein pp65 Eigenschaften aufweist, die es als potentielles Trägersystem für Proteinantigene in den Cross-Präsentationsweg von iDCs geeignet macht. (1) Es konnte in Rahmen dieser Arbeit gezeigt werden, dass humane iDCs in geringem Umfang gp64-abhängig durch rAcMNPV infiziert werden. Dies erlaubt eine transiente Expression von Reportergenen in den iDCs. Allerdings sinkt die Expression schnell ab, so dass zu dem Zeitpunkt optimaler Aktivierung der DCs durch AcMNPV die Expressionsstärke gering ist. Im Gegensatz zu iDCs können hingegen optimal aktivierte mDCs nicht von rAcMNPV infiziert werden. Da AcMNPV im hohen Grade in der Lage ist, DCs zu aktivieren, aber nur mit geringer Effizienz die iDCs infiziert, ist die Immunisierung mit rAcMNPV in vivo demnach wahrscheinlich von der Cross-Präsentation von Antigenen aus infizierten Körperzellen abhängig. (2) Das HCMV-Tegumentprotein pp65 vermittelt eine effizientere Bindung gekoppelter Proteine an iDCs, als die beschriebenen Protein-Transduktionsdomänen TatPTD und Penetratin. Außerdem vermittelt pp65 die Aufnahme fusionierter Proteine in iDCs. Darüber hinaus wird pp65 in iDCs effizient in den Cross-Präsentationsweg geschleust und induziert bei geringer Stoffmengenkonzentration CD4+ und CD8+ Gedächtnis- T Zell-Antworten. Obwohl pp65 keinen Einfluß auf die Aktivierung von DCs hat, stellt es ein vielversprechendes System dar, um fusionierte Proteine in den Cross-Präsentationsweg von DCs zu schleusen. In Kombination mit einem Adjuvans könnten so effektive zelluläre Immunantworten induziert werden. Die getesteten Systeme zur DNA- als auch Protein-Immunisierung sind beide Kandidaten zur Induktion von zellulären Immunantworten. Sie besitzen spezifische Eigenschaften, beispielsweise führt AcMNPV zu einer sehr effizienten Aktivierung von DCs, pp65 dagegen nicht. Andererseits ist die Effizienz der Infektion von iDCs durch AcMNPV gering, während pp65 sehr effizient von iDCs cross-präsentiert wird. Die vorliegenden Untersuchungen bieten in ihrer Gesamtheit einen Ansatzpunkt, um die Systeme für eine spezifische Anwendung in vivo zu optimieren. Intracellular pathogens, like viruses, are eliminated by cellular immune responses. During this work I investigated several systems to induce these immune responses. In vivo, primary T cell are mainly induced by dendritic cells (DCs). These are also the only cells to cross-present and finally cross-prime naive T cells with protein antigens in vivo. Immunization-strategies address therefore the expression and the presentation of antigens in DCs. Based on these findings, it was investigated: (1) whether and how efficient "Autographa californica multiple nuclear polyhedrosis virus" (AcMNPV) is able to infect DCs and (2) whether the HCMV-tegument-protein pp65 shows properties of an efficient carrier system for antigens into DCs. (1) Human iDCs got infected by rAcMNPV with low efficiency. This infection was dependent on gp64. The infection of iDCs resulted in a transient expression of the reporter genes encoded by rAcMNPV. The levels of expression were decreasing rapidly. This results in low expression levels at the timepoint of optimal AcMNPV-mediated activation of DCs. In contrast activated mDCs were not infectable by rAcMNPV. Taken together, AcMNPV strongly activates DCs, but does infect DCs only with low efficiency. Therefore it is likely, that In-Vivo-immunization with rAcMNPV leads mainly to the infection of body cells other than DCs. The antigen from these cells might then be cross-presented by rAcMNPV-activated DCs. (2) Proteins, fused to HCMV-tegument-protein pp65 were bound with higher efficiency to DCs than those fused to the described protein-transduction-domains (PTD) TatPTD and Penetratin. Furthermore, the fusion of pp65 to proteins also led to an enhanced uptake by iDCs. Pp65 alone is inducing strong CD4+ und CD8+ memory-T cell-responses when taken up by DCs. Therefore it is also efficiently cross-presented by these cells. Taken together, pp65 is a promising candidate to direct fused antigens into the cross-presentation pathway of DCs. The pp65 does not activate DCs, but could be used to induce effective T cell responses in combination with adjuvants. The tested systems both contribute to the induction of cellular immunity. They both harbour specific advantages and disadvantages. Whereas AcMNPV leads to a very efficient activation of DCs, pp65 is not able to activate these cells. On the other hand, rAcMNPV does infect iDCs with low frequency. In contrast to this, pp65 is taken up and cross-presented very efficiently. These findings allow further optimization of the systems for specific In-Vivo-application.
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- 2006
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295. Siedlungs- und Bevölkerungsgeschichte (des Kantons Schwyz) seit dem 18. Jahrhundert
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Schuler, Martin and Meyerhans, Andreas
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Développement régional ,Démographie ,Histoire de l'habitat ,Schwytz - Abstract
Siedlungs- und Bevölkerungsgeschichte (des Kantons Schwyz) seit dem 18. Jahrhundert. La "Geschichte des Kantons Schwyz“ a été éditée en sept volumes sous la direction de la Société historique du Canton de Schwytz. Parmi la cinquantaine de contributions de ce très bel ouvrage, richement illustré, se trouve une contribution du Professeur Martin Schuler portant sur l’évolution démographique de l’habitat du 18e siècle à nos jours. L’article met l’accent sur la comparaison de périodes démographiques très différentes, allant de l’expansion de l’habitat vers les hautes altitudes durant les 18e et 19e siècles, et ce, en lien avec l’intensification de la production fromagère, puis de l’industrialisation à domicile, vers une longue période d’émigration et d’exode rural jusqu’en 1950, suivi par l’intégration du canton dans l’agglomération zurichoise, puis – très récemment – la création de pôles métropolitains au bord du Lac de Zurich. L’article, appuyé par une cartographie abondante, se base sur une saisie historique de l’habitat dispersé sur trois périodes (1910, 1960, 2000). L’évolution de l’habitat de Schwytz est marqué par des interventions parmi les plus massives connues en Suisse : la destruction de Goldau par l’éboulement du Rossberg en 1806, la création de grands barrages avec relocalisation de nombreuses habitants (Wägital 1922, Sihlsee, 1937), mais aussi la création de nouveaux villages, au 19e siècle, liés à l’industrialisation (Siebnen), au tourisme (Brunnen), au chemin de fer (Goldau, Pfäffikon) ou encore aux institutions ecclésiastiques (Ingenbohl, Immensee et bien sûr le vieux site d’Einsiedeln). Le canton de Schwyz a donc vécu sa modernisation en marge des structures communales traditionnelles et sans les traits classiques de l’urbanisation. Et, plus récemment, le canton marque un revirement tardif et fondamental, se hissant à la tête des cantons suisse quant à sa croissance démographique.
296. Heterologous mRNA/MVA delivering trimeric-RBD as effective vaccination regimen against SARS-CoV-2: COVARNA Consortium.
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Marcos-Villar L, Perdiguero B, López-Bravo M, Zamora C, Sin L, Álvarez E, Sorzano CÓS, Sánchez-Cordón PJ, Casasnovas JM, Astorgano D, García-Arriaza J, Anthiya S, Borrajo ML, Lou G, Cuesta B, Franceschini L, Gelpí JL, Thielemans K, Sisteré-Oró M, Meyerhans A, García F, Esteban I, López-Bigas N, Plana M, Alonso MJ, Esteban M, and Gómez CE
- Subjects
- Animals, Mice, Humans, Female, Nanoparticles administration & dosage, Vaccination, mRNA Vaccines administration & dosage, Mice, Transgenic, Vaccines, Synthetic immunology, Vaccines, Synthetic administration & dosage, Vaccines, Synthetic genetics, CD8-Positive T-Lymphocytes immunology, Angiotensin-Converting Enzyme 2 immunology, Angiotensin-Converting Enzyme 2 genetics, Liposomes, COVID-19 Vaccines immunology, COVID-19 Vaccines administration & dosage, SARS-CoV-2 immunology, SARS-CoV-2 genetics, Spike Glycoprotein, Coronavirus immunology, Spike Glycoprotein, Coronavirus genetics, COVID-19 prevention & control, COVID-19 immunology, Antibodies, Viral immunology, Antibodies, Viral blood, Antibodies, Neutralizing immunology, Mice, Inbred C57BL, Vaccinia virus genetics, Vaccinia virus immunology
- Abstract
Despite the high efficiency of current SARS-CoV-2 mRNA vaccines in reducing COVID-19 morbidity and mortality, waning immunity and the emergence of resistant variants underscore the need for novel vaccination strategies. This study explores a heterologous mRNA/Modified Vaccinia virus Ankara (MVA) prime/boost regimen employing a trimeric form of the receptor binding domain (RBD) of the SARS-CoV-2 spike (S) protein compared to a homologous MVA/MVA regimen. In C57BL/6 mice, the RBD was delivered during priming via an mRNA vector encapsulated in nanoemulsions (NE) or lipid nanoparticles (LNP), followed by a booster with a replication-deficient MVA-based recombinant virus (MVA-RBD). This heterologous mRNA/MVA regimen elicited strong anti-RBD binding and neutralizing antibodies (BAbs and NAbs) against both the ancestral SARS-CoV-2 strain and different variants of concern (VoCs). Additionally, this protocol induced robust and polyfunctional RBD-specific CD4 and CD8 T cell responses, particularly in animals primed with mLNP-RBD. In K18-hACE2 transgenic mice, the LNP-RBD/MVA combination provided complete protection from morbidity and mortality following a live SARS-CoV-2 challenge compared with the partial protection observed with mNE-RBD/MVA or MVA/MVA regimens. Although the mNE-RBD/MVA regimen only protects half of the animals, it was able to induce antibodies with Fc-mediated effector functions besides NAbs. Moreover, viral replication and viral load in the respiratory tract were markedly reduced and decreased pro-inflammatory cytokine levels were observed. These results support the efficacy of heterologous mRNA/MVA vaccine combinations over homologous MVA/MVA regimen, using alternative nanocarriers that circumvent intellectual property restrictions of current mRNA vaccine formulations.
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- 2024
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- View/download PDF
297. Author Correction: Modulating the immune response to SARS-CoV-2 by different nanocarriers delivering an mRNA expressing trimeric RBD of the spike protein: COVARNA Consortium.
- Author
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Marcos-Villar L, Perdiguero B, Anthiya S, Borrajo ML, Lou G, Franceschini L, Esteban I, Sánchez-Cordón PJ, Zamora C, Sorzano CÓS, Jordá L, Codó L, Gelpí JL, Sisteré-Oró M, Meyerhans A, Thielemans K, Martínez-Jiménez F, López-Bigas N, García F, Alonso MJ, Plana M, Esteban M, and Gómez CE
- Published
- 2024
- Full Text
- View/download PDF
298. Anti-PD-L1 Immunotherapy of Chronic Virus Infection Improves Virus Control without Augmenting Tissue Damage by Fibrosis.
- Author
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Casella V, Cebollada Rica P, Argilaguet J, Vidal E, González-Cao M, Güerri-Fernandez R, Bocharov G, and Meyerhans A
- Subjects
- Animals, Female, Mice, Chronic Disease, Disease Models, Animal, Mice, Inbred C57BL, Spleen immunology, Spleen virology, Viral Load, B7-H1 Antigen antagonists & inhibitors, B7-H1 Antigen immunology, CD8-Positive T-Lymphocytes immunology, Fibrosis, Immune Checkpoint Inhibitors therapeutic use, Immune Checkpoint Inhibitors pharmacology, Immunotherapy, Lymphocytic Choriomeningitis complications, Lymphocytic Choriomeningitis immunology, Lymphocytic Choriomeningitis therapy, Lymphocytic choriomeningitis virus immunology
- Abstract
Immunotherapy with checkpoint inhibitors, albeit commonly used against tumors, is still at its infancy against chronic virus infections. It relies on the reinvigoration of exhausted T lymphocytes to eliminate virus-infected cells. Since T cell exhaustion is a physiological process to reduce immunopathology, the reinvigoration of these cells might be associated with an augmentation of pathological changes. To test this possibility, we here analyzed in the model system of chronic lymphocytic choriomeningitis virus (LCMV)-infected mice whether treatment with the checkpoint inhibitor anti-PD-L1 antibody would increase CD8 T cell-dependent fibrosis. We show that pre-existing spleen fibrosis did not worsen under conditions that increase CD8 T cell functionality and reduce virus loads suggesting that the CD8 T cell functionality increase remained below its pathogenicity threshold. These promising findings should further encourage immunotherapeutic trials against chronic virus infections.
- Published
- 2024
- Full Text
- View/download PDF
299. Modulating the immune response to SARS-CoV-2 by different nanocarriers delivering an mRNA expressing trimeric RBD of the spike protein: COVARNA Consortium.
- Author
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Marcos-Villar L, Perdiguero B, Anthiya S, Borrajo ML, Lou G, Franceschini L, Esteban I, Sánchez-Cordón PJ, Zamora C, Sorzano CÓS, Jordá L, Codó L, Gelpí JL, Sisteré-Oró M, Meyerhans A, Thielemans K, Martínez-Jiménez F, López-Bigas N, García F, Alonso MJ, Plana M, Esteban M, and Gómez CE
- Abstract
Vaccines based on mRNA technology have revolutionized the field. In fact, lipid nanoparticles (LNP) formulated with mRNA are the preferential vaccine platform used in the fight against SARS-CoV-2 infection, with wider application against other diseases. The high demand and property right protection of the most potent cationic/ionizable lipids used for LNP formulation of COVID-19 mRNA vaccines have promoted the design of alternative nanocarriers for nucleic acid delivery. In this study we have evaluated the immunogenicity and efficacy of different rationally designed lipid and polymeric-based nanoparticle prototypes against SARS-CoV-2 infection. An mRNA coding for a trimeric soluble form of the receptor binding domain (RBD) of the spike (S) protein from SARS-CoV-2 was encapsulated using different components to form nanoemulsions (NE), nanocapsules (NC) and lipid nanoparticles (LNP). The toxicity and biological activity of these prototypes were evaluated in cultured cells after transfection and in mice following homologous prime/boost immunization. Our findings reveal good levels of RBD protein expression with most of the formulations. In C57BL/6 mice immunized intramuscularly with two doses of formulated RBD-mRNA, the modified lipid nanoparticle (mLNP) and the classical lipid nanoparticle (LNP-1) were the most effective delivery nanocarriers at inducing binding and neutralizing antibodies against SARS-CoV-2. Both prototypes fully protected susceptible K18-hACE2 transgenic mice from morbidity and mortality following a SARS-CoV-2 challenge. These results highlight that modulation of mRNAs immunogenicity can be achieved by using alternative nanocarriers and support further assessment of mLNP and LNP-1 prototypes as delivery vehicles for mRNA vaccines., (© 2024. The Author(s).)
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- 2024
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300. Pan-pox-specific T-cell responses in HIV-1-infected individuals after JYNNEOS vaccination.
- Author
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Sisteré-Oró M, Du J, Wortmann DDJ, Filippi MD, Cañas-Ruano E, Arrieta-Aldea I, Marcos-Blanco A, Castells X, Grau S, García-Giralt N, Perez-Zsolt D, Boreika R, Izquierdo-Useros N, Güerri-Fernandez R, and Meyerhans A
- Subjects
- Humans, CD4-Positive T-Lymphocytes, Vaccination, HIV-1, HIV Infections
- Abstract
People living with human immunodeficiency virus (HIV) are the individuals most affected by the current Monkeypox virus outbreak that was first announced in May 2022. Here we report Pan-pox-specific T-cell responses in a cohort of HIV-1-infected individuals after receiving the nonreplicative, attenuated smallpox vaccine JYNNEOS from Bavarian Nordic. Intradermal (i.d.) and subcutaneous (s.c.) vaccination was safe without major side effects. Dose-sparing i.d. vaccination was superior to s.c. vaccination and promoted T-cell polyfunctionality, and the expression of the gut-homing marker α4β7 integrin on lymphocytes. HIV-1-infected individuals with CD4 T-cell counts ≤500/mm
3 blood required at least a booster vaccination to exhibit efficient virus-specific T-cell responses. The magnitude of the Th1 response after this booster directly correlated with the CD4 T-cell count of the vaccinees. Further studies with a larger number of participants are warranted to confirm and expand our observations., (© 2023 The Authors. Journal of Medical Virology published by Wiley Periodicals LLC.)- Published
- 2024
- Full Text
- View/download PDF
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