Systems-level novel understanding of anti-glycan immunity

ended

"Intestinal bacteria have an enormous influence on health, both in the form of major pathogens and as major constituents of the microbiota. We have demonstrated that high-affinity secretory antibodies (sIgA) offer huge potential to protect from infection and to manipulate microbiota composition. However, designing good oral vaccines to induce high-affinity sIgA is a compound problem. Most protective anti-bacterial sIgA targets bacterial glycans, requiring an understanding of inherently difficult glycan biochemistry. We also need to deliver intact antigen via the highly degradative environment of the intestine. Whole-cell inactivated oral vaccines can induce high-affinity sIgA against some glycan structures, but we have an incomplete picture of what determines the success/failure of these vaccines. By combining advanced biophysical methods (e.g. atomic force spectroscopy), fluorescence and electron microscopy, and synthetic biology, we aim to remove this mystery. Our objectives are: 1) Generate a ""toolbox"" for glycan-binding antibody research: Recombinant antibodies, BCR knock-in mice and defined glycan antigens as purified molecules, on whole bacteria or on virus-like particle will be developed for model antigens: Salmonella Typhimurium O-antigen and the E.coli K100 capsule. 2) Determine the quantitative relationship between glycan antigen sampling into gut-associated lymphoid tissues and particle size, glycan flexibility/structure, digestion resistance and natural IgA binding. 3) Determine how biophysical properties of glycan antigens affect B cell antigen uptake, T cell help and antibody affinity maturation. 4) Combine models of antigen sampling efficiency and anti-glycan antibody affinity maturation to generate a systems-level model of mucosal vaccine efficacy. This will uncover the fundamental principles governing the induction of high-affinity anti-glycan sIgA, driving urgently required progress in mucosal vaccine design "