Roles of vaccine perturbations on germinal center dynamics

PROJECT SUMMARY/ABSTRACT Human immunodeficiency virus (HIV) lacks a vaccine despite being a global priority. HIV poses a unique challenge to vaccine design, as many characterized broadly neutralizing antibodies (bnAbs) possess unusually high frequencies of somatic hypermutations. To generate potential bnAbs, B cells must undergo iterative rounds of affinity maturation and selection within germinal centers (GCs). Our lab and collaborators have made significant contributions to the HIV vaccine field. These contributions include sequential immunization strategies to efficiently prime bnAb-precursor B cells to enter GCs and to increase the diversity and length of the GC. Despite our success with these regimens in preclinical models, our understanding of sequential immunization strategies impacts to the GC microenvironment is lacking. We hypothesize that the formulation of an immunization regimen i) can directly influence antibody-secreting and memory B cell differentiation and ii) this is driven by the remodeling of the GC microenvironment. These hypotheses will be tested using different mouse models with sequential immunization strategies designed to track antigen-specific GC B cells and stromal cells. A combination of multiparameter flow cytometry, high resolution microscopy, RNA-sequencing, ELISA, and ELISpot techniques will be used throughout the proposed work. These investigations including the studies of the stromal network underlying the GC microenvironment is a largely underappreciated facet for the generation of adaptive immunity. This work has the potential to reveal novel considerations for the formulation of HIV vaccines with the capacity for long-term retention of B cells within GCs to generate bnAbs.