ABSTRACT A principal goal of the Program Project is to chart the changes in influenza antibody repertoire following vaccination or infection and to build on those results to direct immunogen design efforts. Core C, the Ig-Seq and NGS Core, will serve the overall goals of the Program Project by providing high-throughput antibody repertoire profiling services. Specifically, it will provide in-depth NextGen Sequencing (NGS) of antibody transcripts from B cells (BCR-Seq) and quantitative high-resolution proteomic analysis of serum antibody molecules (Ig-Seq). From these sequence analyses, the Core will generate full-length antibody sequences for recombinant expression and characterizations as monoclonal antibodies.The Core will also serve all Projects and Cores of the Program Project by providing a centralized data repository, management of all antibody sequence data, robust and consistent data analysis. The specific aims of Core C are: (1) provide the NGS service to define the B cell repertoire; (2) provide the proteomic-based antibody analysis service to define serum antibody repertoire; (3) provide a centralized data repository and analysis for antibody sequences generated by all the Projects and Cores; and (4) expand and optimize the provided services. The Ig-Seq and NGS Core is critical for the success of the Program Project, offering high-throughput tools for deep and comprehensive monitoring of changes in three distinct components of antibody repertoires: serum antibody molecules, memory B cells, and plasmablasts.