Elicitation of pan-influenza A antibodies via simple B cell development pathways

About This Grant

Project Summary / Abstract This is a R01 application from Dr. Daniel Lingwood (PI) an Associate Professor of Medicine at the Ragon Institute of MGH, MIT and Harvard and Dr. Batista (co-PI), a Professor of Medicine at the same institution. These investigators define immunological decision making by B cells to inform vaccine design and have built humanized mouse systems that recapitulate human antibody responses. Dr. Andrew Ward (co-I) is Professor in the Department of Structural and Computational Biology at Scripps and specializes in high resolution cryoEM of antibody:antigen complexes. The application goal is universal influenza vaccine development, centered on their discovery of a human broadly neutralizing antibody (bnAb) pathway that the investigators can vaccine-elicit to protect against all influenza A viruses (IAV), the major source influenza disease and all pandemic events. Differences in N-glycosylation generally prevents antibodies from engaging the otherwise conserved hemagglutinin (HA) stem of group 1 versus group 2 IAV. To solve this issue, the investigators engineered nanoparticle immunogens that elicit cross-group IAV immunity by selectively triggering and maturing germline B cell receptors (BCRs) encoding VH1-18 QxxV class bnAbs, a rare but genetically reproducible or ‘public’ category of human pan-IAV bnAbs that accommodates N-glycan diversity on the HA stem. The investigators successfully elicit this cross-group bnAb response using a single shot within a humanized vaccine model containing the VH1-18 QxxV bnAb precursors at physiologically relevant human frequency within the naïve B cell pool. The immunogens select for key affinity enhancing mutations, including N55T in the CDRH2, a hallmark of VH1-18 QxxV bnAbs. The investigators show that N55T alone provides cross-group IAV protection by a novel antibody tilting mechanism that accommodates N-glycan diversity on the HA stem. The investigators will now test the central hypothesis that this ‘molecular switch’ endows humans with an exceptionally simple vaccine- expandable pathway for eliciting broad spectrum IAV immunity. In Aim 1, the investigators will apply their modular human vaccine model to define the number of naive VH1-18 QxxV B cells needed for pan-IAV vaccine protection; if these bnAb precursors are absent, the germline stimulating nanoparticles no longer elicit pan-IAV bnAbs, revealing a human B cell repertoire effect encoding for unprecedently broad IAV immunity. In Aim 2, the investigators will define whether their nanoparticle immunogens can co-expand multiple classes of cross-group IAV bnAbs within their human vaccine model. Critically, their engineered nanoparticle immunogens also bear germline stimulating affinity for the naïve BCRs encoding the other known classes of genetically reproducible pan-IAV bnAbs produced by humans, potentiating multiclass bnAb elicitation via pan-germline stimulation. In the Aim 3, the investigators will define how prior exposure to IAV modulates (and enhances) germline stimulation and vaccine elicitation of pan-IAV bnAbs via imprinting effects. Collectively, this proposal will exploit novel genetically hardcoded templates for eliciting cross-group IAV immunity in humans.