Characterization of antibody-antigen interactions in human pathogens
We are asking financial support to help continue our program on characterization of antibody-antigen complexes in human pathogens that has yield good publications in recent years. We strive to approach the problem via a truly multidisciplinary approach including structural work, computational simulations, biophysical and functional characterization, cellular assays, confocal microscopy, protein and antibody engineering. We generally rely on collaborations, mostly long-running, for antibody discovery, in vivo experiments and cryo-EM. We are one of the very few groups in the world, and possibly the only one in Switzerland, approaching antibodies by NMR spectroscopy. We recently showed how our NMR guided computational approach can greatly improve the accuracy of relatively low resolution cryo-EM structures (Cell, 2017) and in the past we proved that our NMR guided computational approach is sufficiently accurate to allow rational engineering of antibodies to achieve increased neutralization. The major competitive advantage of NMR, however, is its ability to provide residue-level dynamics information on antigens and antibodies, something largely missing in the scientific literature. During this proposal we aim to investigate how antigen and antibody flexibility affect recognition and selectivity. We will exploit our reagents and expertise in flaviviruses to characterize the impact of dynamics on recognition of flaviviruses. By comparing the binding of antibodies to Zika and Dengue virus surface proteins we aim to determine if increased antibody flexibility correlates with broad selectivity and, conversely, if rigidity affords higher affinity and specificity. We will also investigate if flexibility decreases as affinity and specificity increase during the antibody affinity maturation process. We are not aware of any similar investigation of an antibody-antigen system and believe it will offer valuable insights on general principles of recognition. Chances are that our findings will also provide useful to improve the artificial affinity maturation processes and antibody optimization that are more and more commonly used after antibody humanization or phage display selection.