Antibodies are destined to neutralize pathogens and can prevent and fight infectious diseases. Over the last years, advances in single B cell cloning resulted in the isolation of highly potent and broad HIV-1 neutralizing antibodies (bNAbs) that have been shown to prevent SHIV infection in non-human primates (NHPs). Recently, we have demonstrated that a combination of bNAbs can suppress HIV-1 replication in humanized mice, reducing viremia to undetectable levels. Moreover, bNAb therapy of SHIV-infected NHPs induced a rapid decline in viremia, followed by a prolonged control due to the long half-life of the antibodies. While these results strongly encourage the clinical evaluation of bNAbs in HIV-1 therapy, it is of critical importance to understand how the therapeutic potential of antibodies can be harnessed in the most effective way. Therefore, we aim to: I.) Identify exceptionally potent HIV-1 neutralizing antibodies that will be a crucial component of immunotherapy. By establishing novel methods for single-cell sorting and high-throughput sequencing we want to identify bNAbs targeting novel epitopes. II.) Prevent HIV-1 escape applying rationally designed treatment strategies targeting conserved functional sites for HIV-1 entry. III.) Evaluate immune markers and function in relation to bNAb administration in humans. Being at the forefront of one of the first clinical trials studying an HIV-1-directed bNAb, we will have the unique opportunity to investigate the interplay of antibody therapy and the host immune system. This proposal aims to strongly advance the field of HIV-1 antibody therapy and therefore enable the introduction of a new therapeutic modality for HIV-1, and will gain insights for antibody-mediated therapy in other infectious diseases.

A fundamental question in neuroscience is to reveal the energy constrains governing the plasticity of brain circuits. Mitochondrial energy metabolism is increasingly recognized for regulating the activity and integrity of existing synaptic terminals, however it is unclear how changes in mitochondrial function are coupled with the generation of new neurons and the ensuing circuit remodelling, e.g. in response to experience or disease. We have recently shown that a regionalized restructuring of the mitochondrial network in astrocytes upon cortical injury underlies their ability to enter a state of reactivity and sustain cellular energy metabolism, suggesting that local changes in mitochondrial network architecture govern cellular adaptations in register with local metabolic demand. Here, I focus on the adult hippocampal circuitry and its almost unique structural plasticity to broaden this fundamental concept and evaluate whether local mitochondrial remodelling orchestrates the metabolic changes underlying the directed genesis of new neurons and their evolving connectivity in face of experience. First, we will utilize state-of-the-art imaging and genetic techniques to investigate the precise role of mitochondria in regulating adult neural stem cells (NSCs) quiescence, mode of division and neurogenic potential in response to experience. This will set the stage for examining whether state-specific energy metabolism programs regulate the fate plasticity of adult NSCs, as following their directed differentiation towards distinct lineages in vivo (Aim I). We will then elucidate whether mitochondria contribute to mechanisms of metabolic and synaptic competition in new neurons, in particular to their critical period of heightened structural and functional synaptic plasticity (Aim II). Lastly, we will use novel tracing techniques to dissect the local energy needs for activity- and experience-dependent remodelling of new neuron functional connectivity (Aim III).

Mitochondria are found within every human cell and are responsible for the majority of energy production in the cell. When the mitochondria do not function properly, they cause devastating diseases affecting many and often multiple organs with the highest energy needs, such as skeletal muscle, brain, heart and liver. Over the years we have steadily increased our understanding of the genetic and molecular mechanisms leading to mitochondrial disease, developed different models and biomarkers. Unfortunately, development of effective therapeutic approaches able to improve the outcome of the diseases or at least to ameliorate or postpone the symptoms was much less effective. Today, therapeutic options for mitochondrial diseases still remain focused on supportive dietary interventions aimed at relieving complications. Therefore, it would be ideal if a single approach could be developed that would be equally effective with various mitochondrial diseases most often characterized by complex I deficiency. Our preliminary data show that by removing the major mitochondrial matrix protease CLPXP, and therefore stabilizing CI, we could ameliorate the symptoms of respiratory deficiency in different cellular models of mitochondrial dysfunction. The loss of CLPP in these models resulted not only in increased stability of CI, but also normalized NAD+/ NADH that collectively resulted in improved proliferation and survival rates. Remarkably, even partial loss of ClpXP activity in respiratory deficient cells led to mild increase in the CI levels, opening an exciting prospect for therapeutic interventions. Therefore, the overall goal of this project is to explore the possibility of targeting CLPP activity to ameliorate symptoms of mitochondrial diseases in in vivo models through genetic interventions and search for specific protease inhibitors.