ERC FUNDED PROJECTS

The overall goal of this project is to understand the molecular mechanisms that lead to the generation of potent and broadly neutralizing antibodies against medically relevant pathogens, and to identify the factors that limit their production in response to infection or vaccination with current vaccines. We will use high-throughput cellular screens to isolate from immune donors clonally related antibodies to different sites of influenza hemagglutinin, which will be fully characterized and sequenced in order to reconstruct their developmental pathways. Using this approach, we will ask fundamental questions with regards to the role of somatic mutations in affinity maturation and intraclonal diversification, which in some cases may lead to the generation of autoantibodies. We will combine crystallography and long time-scale molecular dynamics simulation to understand how mutations can increase affinity and broaden antibody specificity. By mapping the B and T cell response to all sites and conformations of influenza hemagglutinin, we will uncover the factors, such as insufficient T cell help or the instability of the pre-fusion hemagglutinin, that may limit the generation of broadly neutralizing antibodies. We will also perform a broad analysis of the antibody response to erythrocytes infected by P. falciparum to identify conserved epitopes on the parasite and to unravel the role of an enigmatic V gene that appears to be involved in response to blood-stage parasites. The hypotheses tested are strongly supported by preliminary observations from our own laboratory. While these studies will contribute to our understanding of B cell biology, the results obtained will also have translational implications for the development of potent and broad-spectrum antibodies, for the definition of correlates of protection, and for improving vaccine design.

1 867 500 €

Start date: 2015-10-01, End date: 2020-09-30

Cholera is one of the oldest infectious diseases known and remains a major burden in many developing countries. The World Health Organization estimates that up to 4 million cases of cholera occur annually. The transmission of cholera by contaminated water, particularly under epidemic conditions, was first reported in the 19th century. However, early volunteer studies suggested that an incredibly high infectious dose (ID) is required to produce disease symptoms, in contrast to most other intestinal pathogens. Therefore, the mechanism of infection of index cases at the onset of an outbreak is unclear. This proposal aims to fill this knowledge gap by studying how the environmental lifestyle of the causative agent of the disease, the bacterium Vibrio cholerae, may prime the pathogen for intestinal colonization. We hypothesize that one of the natural niches of the bacterium (chitinous surfaces) fosters biofilm formation and provides a competitive advantage over co-colonizing bacteria. As an adaptive trait, passage of chitin-attached sessile V. cholerae through the acidic environment of the human stomach might be vastly facilitated compared to planktonic bacteria. Moreover, interbacterial warfare exerted by V. cholerae on these biotic surfaces may help the pathogen overcome the colonization barrier imposed by the human microbiota upon ingestion. The mechanism by which V. cholerae leaves the sessile lifestyle and the regulatory circuits involved in this process will also be investigated in this project. In summary, our goal is to elucidate the environmental community structures of V. cholerae that may enhance transmissibility from the ecosystem to humans in endemic areas resulting in the infection of index cases.

1 999 988 €

Start date: 2018-02-01, End date: 2023-01-31

Cytotoxic T lymphocytes (CTL) and natural killer (NK) cells release granzyme and perforin from cytotoxic granules into the immune synapse to induce apoptosis of target cells that are either virus-infected or cancerous. Granzyme A activates a caspase-independent apoptotic pathway and induces mitochondrial damage characterized by superoxide anion production and loss of the mitochondrial transmembrane potential, without disrupting the integrity of the mitochondrial outer membrane; while causing single-stranded DNA damage. GzmB induces both caspase-dependent and caspase-independent cell death. In the caspase-dependent pathway, mitochondrial functions are altered as evidenced by the loss of mitochondrial transmembrane potential and the generation of reactive oxygen species (ROS). The mitochondrial outer membrane (MOM) is disrupted, resulting in the release of apoptogenic factors. To date, research on mitochondrial-dependent apoptosis has focused on mitochondrial outer membrane permeabilization (MOMP) however whether the generation of ROS is incidental or essential to the execution of apoptosis remains unclear. Like human GzmA, human GzmB promotes cell death in a ROS-dependent manner. Preliminary data suggest that human GzmB can induce ROS in a MOMP-independent manner as Bax and Bak double knockout MEF cells treated with human GzmB and perforin still display a robust ROS production and dye in an ROS-dependent manner. Since GzmA and GzmB induce cell death in a ROS-dependent manner, we hypothesize that oxygen free radicals are central to the execution of programmed cell death induced by the cytotoxic granules. Therefore, the goal of this proposal is to dissect the key molecular events triggered by ROS that lead to Citotoxic Tcell-induced target cell death. A combination of biochemical, genetic and proteomic approaches in association with Electron Spin Resonance (ESR) spectroscopy methodology will be used to unravel the essential role ROS play in CTL-mediated killing.

1 500 000 €

Start date: 2011-05-01, End date: 2016-04-30

New biomedical technologies and public health strategies are being tested world-wide with the goal of eradicating the HIV epidemic. Achieving a world without AIDS has become the flagship of the vast global health apparatus, rallying governments, international organisations, philanthropic and pharmaceutical capital, research networks and activists. Mass screening and treatment, preventive drugs and gels, and molecular maps of sexual networks have shifted the biomedical paradigm from one of control to one of eradication. The biopolitical armamentarium of the push to eradicate may inadvertently enable unexpected biological, cultural, social and political transformations. Mass treatment and preventive drugs require very high levels of compliance to achieve the desired public health effects, foreshadowing the coercive potential of eradication efforts. Intensified mapping of “most at-risk populations” marks a shift from the existing emphasis on rights and empowerment to one of surveillance and discipline. As these approaches remain unproven, eradication constitutes a global public health experiment of unprecedented proportions, whose outcomes will shape global health efforts for decades to come. Eradication efforts to rid the world of HIV are attempts to order nature as revealed through a global epidemic, putting them squarely at the centre of anthropological concern. The two overarching questions are: what will HIV eradication efforts achieve? What are the reasons for the outcome, be it partial success or partial failure? To answer these questions, a multi-sited ethnography will be conducted in Africa, Europe and North America of the science and politics of HIV eradication. It will focus on the testing, preparation, and implementation of the three key technologies of HIV eradication: universal testing and mass treatment, molecular mapping of sexual and social networks.

1 999 980 €

Start date: 2014-11-01, End date: 2019-10-31

The ubiquitous FIC domain catalyzes post-translational modifications (PTMs) of target proteins; i.e. adenylylation (=AMPylation) and, more rarely, uridylylation and phosphocholination. Fic proteins are thought to play critical roles in intrinsic signaling processes of prokaryotes and eukaryotes; however, a subset encoded by bacterial pathogens is translocated via dedicated secretion systems into the cytoplasm of mammalian host cells. Some of these host-targeted Fic proteins modify small GTPases leading to collapse of the actin cytoskeleton and other drastic cellular changes. Recently, we described a large set of functionally diverse homologues in pathogens of the genus Bartonella that are required for their “stealth attack” strategy and persistent course of infection [1, 2]. Our preliminary functional analysis of some of these host-targeted Fic proteins of Bartonella demonstrated adenylylation activity towards novel host targets (e.g. tubulin and vimentin). Moreover, in addition to the canonical adenylylation activity they may also display a competing kinase activity resulting from altered ATP binding to the FIC active site. Finally, we described a conserved mechanism of FIC active site auto- inhibition that is relieved by a single amino acid exchange [1], thus facilitating functional analysis of any Fic protein of interest. Despite this recent progress only a few Fic proteins have been functionally characterized to date; our understanding of the functional plasticity of the FIC domain in mediating diverse target PTMs and their specific roles in infection thus remains limited. In this project, we aim to study the vast repertoire of host-targeted Fic proteins of Bartonella to: 1) identify novel target proteins and types of PTMs; 2) study their physiological consequences and molecular mechanisms of action; and 3) analyze structure-function relationships critical for FIC-mediated PTMs and infer from these data determinants of target specificity, type of PTM and mode of regulation. At the forefront of infection biology research, this project is ground-breaking as (i) we will identify a plethora of novel host target PTMs that are critical for a “stealth attack” infection strategy and thus will open new avenues for investigating fundamental mechanisms of persistent infection; and (ii), we will unveil the molecular basis of the remarkable functional versatility of the structurally conserved FIC domain.

1 699 858 €

Start date: 2014-02-01, End date: 2019-01-31

Unprecedented urbanization is threatening landscape diversity, bringing along new social and environmental problems. Standardized business centers, single family residential areas and shopping malls displace highly productive agricultural land, while the culture and lifestyles of local communities become absorbed into the sphere of globalization. This dramatic uniformisation is nurtured by the ever increasing global human migration. People are losing their sense of place and their motivation to initiate change. Uniformed international landscapes start dominating peri-urban areas. The result is a tremendous increase in fragility of these new landscapes of the twenty-first century, calling for an active and creative landscape shaping process to secure the long-term provision of critical ecosystem services. Up until now, however, models and tools developed in land system science have not caught up with the needs to understand and ultimately foster humans’ capacities to shape their landscapes. This project will contribute to a next generation of tools and methods to foster the development of resilient landscapes. I suggest linking design and probabilistic modeling in a collaborative landscape development tool to enable the transformation of spaces into places. This unconventional approach is necessary to deal with the probabilistic nature of landscapes. Landscapes can only be defined by including the observer – a concept severally neglected in today’s research efforts. Anchored in four peri-urban case studies, the interdisciplinary experimental and modeling work will have impact far beyond predicting transformation pathways of peri-urban landscapes under increased globalization. The resulting methods and tool will redefine the status quo of current geodesign tools, promote novel ways of deliberative decision-making and governance, and ultimately support humans to intentionally transform peri-urban landscapes.

1 498 106 €

Start date: 2018-06-01, End date: 2023-05-31

The gut is the major interface between microbes and their animal hosts and constitutes the main entry route for pathogens. As a consequence gut cells must be armed with efficient immune defenses to combat invasion and colonisation by pathogens. However, the gut also harbors a flora of commensal bacteria, with potentially beneficial effects for the host, which must be tolerated without a chronic, and harmful, immune response. In recent years Drosophila has emerged as a powerful model to dissect host-pathogen interactions, leading to the paradigm of antimicrobial peptide regulation by the Toll and Imd signaling pathways. The strength of this model derives from the availability of powerful and cost effective genetic and genomic tools as well as the high degree of similarities to vertebrate innate immunity. However, in spite of growing interest in gut mucosal immunity generally, very little is known about the immune response of the Drosophila gut. Using powerful new tools and those developed in the study of the systemic response, we propose to raise our understanding of Drosophila gut immunity to the same level as that of systemic immunity within the next five years. This project will involve integrated approaches to dissect not only the gut immune response but also gut homeostasis in the presence of commensal microbiota, as well as strategies used by entomopathogens to circumvent these defenses. We believe that the fundamental knowledge generated on Drosophila gut immunity will serve as a paradigm of epithelial immune reactivity and have a wider impact on our comprehension of animal defense mechanisms.

1 485 627 €

Start date: 2009-04-01, End date: 2014-03-31

Multiple sclerosis (MS) is a prototypic CD4+ T cell-mediated autoimmune disease that damages the central nervous system. MS affects young adults and women twice as often as men. Neurological deficits cause substantial disability at an early age with high socioeconomic impact. Both a complex genetic trait and environmental factors are involved in MS etiology. Similar to other autoimmune diseases it has been known for almost 40 years that certain HLA-class II genes, in MS the two DR15 alleles DRB1*15:01 and DRB5*01:01, confer by far most of the genetic risk. Despite this clear role remarkably little is known about the functional contribution of these genes to MS pathogenesis, and this holds also true for all other T cell-mediated autoimmune diseases. It is assumed that the DR15 alleles present peptides from organ-specific self-proteins to T cells and select an autoreactive CD4+ T cell repertoire that can be activated by certain environmental triggers. Interestingly, the effects of the three known environmental risk factors in MS, Epstein Barr virus (EBV), low vitamin D3 and smoking, are all amplified by DR15. This core issue of research on autoimmune diseases and also MS, how disease-associated HLA-class II molecules contribute to disease development at the functional level, will be studied with state-of-the-art methodologies and a series of novel approaches. These will include in silico modeling approaches, studies of self-peptides, T cell receptor (TCR) repertoire and HLA-DR/peptide complexes, clonally expanded T cells from MS brain tissue and hypothesis-open methods such as combinatorial chemistry and tissue-derived cDNA libraries to identify target antigens. Finally, translational studies will investigate the relationship between the above aspects and MS disease heterogeneity and explore antigen-specific tolerization in proof-of concept clinical trials in MS.

2 368 068 €

Start date: 2015-01-01, End date: 2019-12-31

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