ERC FUNDED PROJECTS

RNA interference (RNAi) is a conserved sequence-specific, gene-silencing mechanism that is induced by double-stranded RNA (dsRNA). One of the functions of this pathway is the defense against parasitic nucleic acids: transposons and viruses. Previous results demonstrated that viral infections in Drosophila melanogaster are fought by an antiviral RNAi response and that components of the endocytic pathway are required for dsRNA entry to initiate the RNAi response. Recently we have shown that infected insect cells spread a systemic silencing signal that elicits a protective RNAi-dependent immunity throughout the organism. This suggests that the cell-autonomous RNAi response is insufficient to control a viral infection and that flies also rely on systemic immune response to fight against such infections. As a junior group leader, I will study the mechanisms that mediate the RNAi-based antiviral response in insects. By combining biochemical, cellular, molecular and genomic approaches, both in vivo and in cell culture, I will analyze the mechanisms underlying viral tropism, systemic propagation of the antiviral signal and the basis of the persistence of the antiviral state. Furthermore, I will examine whether the dsRNA-uptake pathway is conserved in mosquitoes and its relationship with viral immunity in that host. This comprehensive approach will tackle how this nucleic acid-based immunity works in insects to generate an anti-viral stage. A better understanding of the role of RNA silencing in insects during virus infection will allow the exploitation of this pathway for improvement of public health related problems such as arbovirus infection and disease.

1 900 000 €

Start date: 2009-10-01, End date: 2014-12-31

Immunological memory confers long term protection against pathogens and is the basis of successful vaccination. Following antigenic stimulation long lived plasma cells and memory B cells are maintained for a lifetime, conferring immediate protection and enhanced responsiveness to the eliciting antigen. However, in the case of variable pathogens such as influenza virus, B cell memory is only partially effective, depending on the extent of similarity between the preceding and the new viruses. The B cell response is dominated by serotype-specific antibodies and heterosubtypic antibodies capable of neutralizing several serotypes appear to be extremely rare. Understanding the basis of broadly neutralizing antibody responses is a critical aspect for the development of more effective vaccines. In this project we will explore the specificity and dynamics of human antibody responses to influenza virus by using newly developed technological platforms to culture human B cells and plasma cells and to analyze the repertoire of human naïve and memory T cells. High throughput functional screenings, structural analysis and testing in animal models will provide a thorough characterization of the human immune response. The B cell and T cell analysis aims at understanding fundamental aspects of the immune response such as: the selection and diversification of memory B cells; the individual variability of the antibody response, the mechanisms of T-B cooperation and the consequences of the original antigenic sin and of aging on the immune response. This analysis will be complemented by a translational approach whereby broadly neutralizing human monoclonal antibodies will be developed and used: i) for passive vaccination against highly variable viruses; ii) for vaccine design through the identification and production of recombinant antigens to be used as effective vaccines; and iii) for active vaccination in order to facilitate T cell priming and jump start the immune responses.

1 979 200 €

Start date: 2010-09-01, End date: 2015-08-31

Overall objective and Specific Aims. The overall objective of this proposal is to elucidate the pathogenesis of HBV infection with the ultimate hope that this knowledge will lead to the development of new therapeutic strategies to terminate persistent infection and its attendant costs and complications. Our approach is to dissect poorly understood cellular and molecular pathways responsible for both liver disease and viral clearance taking advantage of technological advances in the field of live imaging and unique mouse models of HBV infection. Three specific aims will be pursued: 1. Visualize and characterize where and how naïve and effector CTL of different specificities adhere to vessels and recognize/kill HBV-expressing hepatocytes within the “normal”, fibrotic/cirrhotic or cancerous liver. 2. Characterize the role of platelets in HBV pathogenesis. 3. Characterize the role of Kupffer cells in HBV pathogenesis.

2 046 200 €

Start date: 2010-09-01, End date: 2016-03-31

MHC class II molecules are crucial for specific immune responses. In a complicated series of cell biological events, they catch a peptide in the endosomal route for presentation at the plasma membrane to the immune system. At present some 20 factors have been identified as involved in the process of MHC class II antigen presentation that are potential targets for manipulating these responses as MHC class II molecules are involved in most auto-immune diseases. Defining further targets for manipulating MHC class II responses would have implications for various disease states when these can be inhibited by chemical compounds or biologicals. We have performed a genome-wide FACS-based siRNA screen for molecules affecting MHC class II expression and peptide loading. After 100.000 individual 2-color FACS analyses, we identified 276 proteins that can be functionally sub-clustered for expression and for cell biological effects. We now propose to study the cell biology of these 276 hits to elucidate the molecular and cell biological mechanisms of MHC class II antigen presentation (the MHC class II-ome). As a first step, the 276 hits are sub-clustered for effects on MHC class II transcription or cell biology. These sub-clusters may correspond to networks. We propose to validate and extend these networks by experiments by a team of scientists concentrating on the various aspects of the cell biology of MHC class II antigen presentation. A parallel chemical compound screen will be performed to identify compounds affecting MHC class II antigen presentation. By cross-correlating the biological phenotypes of compounds with those of siRNA silencing, novel target-lead combinations will be defined by reciprocal chemical genetics. Our experiments should result in a global understanding of MHC class II antigen presentation. In addition, it should reveal target-lead combinations for manipulation of MHC class II antigen presentation in infection, auto-immune disease and transplantation.

2 112 300 €

Start date: 2010-09-01, End date: 2015-08-31