Relationship between HLA and T cell responses to Ebola virus

Ebola virus disease (EVD) is a severe illness caused by infection with Ebola virus (EBOV) which causes sporadic outbreaks in African countries, the last one taking place in West Africa and affecting over 28000 people. Even though several decades have passed since the description of the first EVD cases, there are still many unanswered questions regarding the involvement of the human immune response in the pathophysiology of EVD. Research in this field is challenging because of the requirement of biosafety level 4 containment and the scarcity of human data. During the last EVD outbreak in West Africa, we had the opportunity to establish an immunology lab at Donka hospital in Conakry, Guinea where we collected and analysed leftover blood samples from patients diagnosed by the European Mobile Laboratory. With the use of benchtop multiparametric flow cytometry and subsequent analysis in the biosafety level 4 laboratory in Hamburg, we evaluated the kinetics and phenotype of antigen-presenting cells as well as T cells with the goal to identify immune biomarkers of disease outcome. Our approach was to utilize flow cytometry to characterize cell profiles in blood as well as immunogenetics, in particular analysis of the T-cell receptor clonotypes and HLA polymorphisms. Immune data was then correlated with clinical and epidemiological findings to try to detect potential predictors of outcome and targets for immunotherapy. Our observations highlight the importance of CD16 monocytes in the innate immune response to EBOV infection and in viral clearance. Additionally, we could identify a dysregulation of the adaptive immune response in fatal cases, characterised by the upregulation of the T cell inhibitory markers CTLA-4 and PD-1 and the inability to control viral replication. These results identify CD16 monocytes and the regulatory pathways of T cell responses as potential targets for post-exposure EVD immunotherapy. Moreover, our immunogenetics study evidenced the relevance of the expression of various HLA alleles and the activation of a T cell response through a broad and diverse T cell receptor repertoire in improved disease outcome

Regulation of Ebola virus VP40 matrix protein by SUMO

The matrix protein of Ebola virus (EBOV) VP40 regulates viral budding, nucleocapsid recruitment, virus structure and stability, viral genome replication and transcription, and has an intrinsic ability to form virus-like particles. The elucidation of the regulation of VP40 functions is essential to identify mechanisms to inhibit viral replication and spread. Post-translational modifications of proteins with ubiquitin-like family members are common mechanisms for the regulation of host and virus multifunctional proteins. Thus far, no SUMOylation of VP40 has been described. Here we demonstrate that VP40 is modified by SUMO and that SUMO is included into the viral like particles (VLPs). We demonstrate that lysine residue 326 in VP40 is involved in SUMOylation, and by analyzing a mutant in this residue we show that SUMO conjugation regulates the stability of VP40 and the incorporation of SUMO into the VLPs. Our study indicates for the first time, to the best of our knowledge, that EBOV hijacks the cellular SUMOylation system in order to modify its own proteins. Modulation of the VP40-SUMO interaction may represent a novel target for the therapy of Ebola virus infectionWe thank Sergio Gomez-Medina for excellent technical assistance. Funding at the laboratory of CR is provided by BFU-2014-58530. Work at the laboratory of CSM is supported by BFU2013-41249-P. This work was partially funded by the Lebniz Association (Prämie ERC Starting Grant 2013 to CM-F). The Heinrich-Pette-Institute is financed by the German Federal Ministry of Health and the Freie und Hansestadt Hamburg. AEM is supported by the Spanish Ministry of Economy and Competitiveness (FPI Fellowship). CFC-H is supported by CONACYT. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscriptS

Beziehung zwischen HLA und T-Zell-Reaktionen auf Ebola-Virus

Ebola virus disease (EVD) is a severe illness caused by infection with Ebola virus (EBOV) which causes sporadic outbreaks in African countries, the last one taking place in West Africa and affecting over 28000 people. Even though several decades have passed since the description of the first EVD cases, there are still many unanswered questions regarding the involvement of the human immune response in the pathophysiology of EVD. Research in this field is challenging because of the requirement of biosafety level 4 containment and the scarcity of human data. During the last EVD outbreak in West Africa, we had the opportunity to establish an immunology lab at Donka hospital in Conakry, Guinea where we collected and analysed leftover blood samples from patients diagnosed by the European Mobile Laboratory. With the use of benchtop multiparametric flow cytometry and subsequent analysis in the biosafety level 4 laboratory in Hamburg, we evaluated the kinetics and phenotype of antigen-presenting cells as well as T cells with the goal to identify immune biomarkers of disease outcome. Our approach was to utilize flow cytometry to characterize cell profiles in blood as well as immunogenetics, in particular analysis of the T-cell receptor clonotypes and HLA polymorphisms. Immune data was then correlated with clinical and epidemiological findings to try to detect potential predictors of outcome and targets for immunotherapy. Our observations highlight the importance of CD16 monocytes in the innate immune response to EBOV infection and in viral clearance. Additionally, we could identify a dysregulation of the adaptive immune response in fatal cases, characterised by the upregulation of the T cell inhibitory markers CTLA-4 and PD-1 and the inability to control viral replication. These results identify CD16 monocytes and the regulatory pathways of T cell responses as potential targets for post-exposure EVD immunotherapy. Moreover, our immunogenetics study evidenced the relevance of the expression of various HLA alleles and the activation of a T cell response through a broad and diverse T cell receptor repertoire in improved disease outcome

Monocyte-derived dendritic cells enhance protection against secondary influenza challenge by controlling the switch in CD8+ T-cell immunodominance

Influenza virus infection triggers an increase in the number of monocyte-derived dendritic cells (moDCs) in the respiratory tract, but the role of these cells during antiviral immunity is still unclear. Here we show that during influenza infection, moDCs dominate the late activation of CD8 T cells and trigger the switch in immunodominance of the CD8 T-cell response from acidic polymerase specificity to nucleoprotein specificity. Abrogation of monocyte recruitment or depletion of moDCs strongly compromised host resistance to secondary influenza challenge. These findings underscore a novel function of moDCs in the antiviral response to influenza virus, and have important implications for vaccine design

Discovery of HLA-E-presented epitopes: MHC-E/Peptide binding and t-cell recognition

Understanding the interactions involved during the immunological synapse between peptide, HLA-E molecules, and TCR is crucial to effectively target protective HLA-E-restricted T-cell responses in humans. Here we describe three techniques based on the generation of MHC-E/peptide complexes (MHC-E generically includes HLA-E-like molecules in human and nonhuman species, while HLA-E specifically refers to human molecules), which allow to investigate MHC-E/peptide binding at the molecular level through binding assays and by using peptide loaded HLA-E tetramers, to detect, isolate, and study peptide-specific HLA-E-restricted human T-cells

Ebola Virus Disease Is Characterized by Poor Activation and Reduced Levels of Circulating CD16+ Monocytes.

A number of previous studies have identified antigen-presenting cells (APCs) as key targets of Ebola virus (EBOV), but the role of APCs in human Ebola virus disease (EVD) is not known. We have evaluated the phenotype and kinetics of monocytes, neutrophils, and dendritic cells (DCs) in peripheral blood of patients for whom EVD was diagnosed by the European Mobile Laboratory in Guinea. Acute EVD was characterized by reduced levels of circulating nonclassical CD16(+) monocytes with a poor activation profile. In survivors, CD16(+) monocytes were activated during recovery, coincident with viral clearance, suggesting an important role of this cell subset in EVD pathophysiology

Identification of HLA-E Binding Mycobacterium tuberculosis-Derived Epitopes through Improved Prediction Models

Tuberculosis (TB) remains one of the deadliest infectious diseases worldwide, posing great social and economic burden to affected countries. Novel vaccine approaches are needed to increase protective immunity against the causative agent Mycobacterium tuberculosis (Mtb) and to reduce the development of active TB disease in latently infected individuals. Donor-unrestricted T cell responses represent such novel potential vaccine targets. HLA-E-restricted T cell responses have been shown to play an important role in protection against TB and other infections, and recent studies have demonstrated that these cells can be primed in vitro. However, the identification of novel pathogen-derived HLA-E binding peptides presented by infected target cells has been limited by the lack of accurate prediction algorithms for HLA-E binding. In this study, we developed an improved HLA-E binding peptide prediction algorithm and implemented it to identify (to our knowledge) novel Mtb-derived peptides with capacity to induce CD8+ T cell activation and that were recognized by specific HLA-E-restricted T cells in Mycobacterium-exposed humans. Altogether, we present a novel algorithm for the identification of pathogen- or self-derived HLA-E-presented peptides.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Pattern Recognition and Bioinformatic

Chimeric Mice with Competent Hematopoietic Immunity Reproduce Key Features of Severe Lassa Fever

<div><p>Lassa fever (LASF) is a highly severe viral syndrome endemic to West African countries. Despite the annual high morbidity and mortality caused by LASF, very little is known about the pathophysiology of the disease. Basic research on LASF has been precluded due to the lack of relevant small animal models that reproduce the human disease. Immunocompetent laboratory mice are resistant to infection with Lassa virus (LASV) and, to date, only immunodeficient mice, or mice expressing human HLA, have shown some degree of susceptibility to experimental infection. Here, transplantation of wild-type bone marrow cells into irradiated type I interferon receptor knockout mice (IFNAR^-/-) was used to generate chimeric mice that reproduced important features of severe LASF in humans. This included high lethality, liver damage, vascular leakage and systemic virus dissemination. In addition, this model indicated that T cell-mediated immunopathology was an important component of LASF pathogenesis that was directly correlated with vascular leakage. Our strategy allows easy generation of a suitable small animal model to test new vaccines and antivirals and to dissect the basic components of LASF pathophysiology.</p></div