Immunodominance defines the hierarchical immune response to competing antigens in complex immunogens. Little is known regarding B cell and antibody immunodominance despite its importance to immunity to viruses and other pathogens. We show that B cells and serum antibodies from inbred mice demonstrate a reproducible immunodominance hierarchy to the five major antigenic sites in the influenza A virus hemagglutinin globular domain. The hierarchy changes as the immune response progresses and depending on antigen formulation and delivery. Passive antibody transfer and sequential infection experiments demonstrate “original antigenic suppression”, where antibodies suppress memory responses to the priming antigenic site. Our study provides a template for attaining deeper understanding of antibody immunodominance to viruses and other immunogens.

Broadly neutralizing antibodies (bnAbs) can protect against HIV infection but have not been induced by human vaccination. A key barrier to bnAb induction is vaccine priming of rare bnAb-precursor B cells. In a randomized, double-blind, placebo-controlled phase 1 clinical trial, the HIV vaccine–priming candidate eOD-GT8 60mer adjuvanted with AS01 B had a favorable safety profile and induced VRC01-class bnAb precursors in 97% of vaccine recipients with median frequencies reaching 0.1% among immunoglobulin G B cells in blood. bnAb precursors shared properties with bnAbs and gained somatic hypermutation and affinity with the boost. The results establish clinical proof of concept for germline-targeting vaccine priming, support development of boosting regimens to induce bnAbs, and encourage application of the germline-targeting strategy to other targets in HIV and other pathogens.

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