
==== Front
bioRxiv
BIORXIV
bioRxiv
2692-8205
Cold Spring Harbor Laboratory

10.1101/2024.08.19.608655
preprint
1
Article
Vaccines combining slow delivery and follicle targeting of antigens increase germinal center B cell clonal diversity and clonal expansion
Rodrigues Kristen A. http://orcid.org/0000-0002-0680-9834

Zhang Yiming J. http://orcid.org/0000-0002-8102-3815

Aung Aereas
Morgan Duncan M.
Maiorino Laura
Yousefpour Parisa
Gibson Grace
Ozorowski Gabriel
Gregory Justin R.
Amlashi Parastoo
Buckley Maureen
Ward Andrew B.
Schief William R.
Love J. Christopher
Irvine Darrell J. http://orcid.org/0000-0002-8637-1405

19 8 2024
2024.08.19.608655https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which allows reusers to copy and distribute the material in any medium or format in unadapted form only, for noncommercial purposes only, and only so long as attribution is given to the creator.
http://biorxiv.org/lookup/doi/10.1101/2024.08.19.608655
nihpp-2024.08.19.608655.pdf
Abstract

Vaccines incorporating slow delivery, multivalent antigen display, or immunomodulation through adjuvants have an important role to play in shaping the humoral immune response. Here we analyzed mechanisms of action of a clinically relevant combination adjuvant strategy, where phosphoserine (pSer)-tagged immunogens bound to aluminum hydroxide (alum) adjuvant (promoting prolonged antigen delivery to draining lymph nodes) are combined with a potent saponin nanoparticle adjuvant termed SMNP (which alters lymph flow and antigen entry into lymph nodes). When employed with a stabilized HIV Env trimer antigen in mice, this combined adjuvant approach promoted substantial enhancements in germinal center (GC) and antibody responses relative to either adjuvant alone. Using scRNA-seq and scBCR-seq, we found that the alum-pSer/SMNP combination both increased the diversity of GC B cell clones and increased GC B cell clonal expansion, coincident with increases in the expression of Myc and the proportion of S-phase GC B cells. To gain insight into the source of these changes in the GC response, we analyzed antigen biodistribution and structural integrity in draining lymph nodes and found that the combination adjuvant approach, but not alum-pSer delivery or SMNP alone, promoted accumulation of highly intact antigen on follicular dendritic cells, reflecting an integration of the slow antigen delivery and altered lymph node uptake effects of these two adjuvants. These results demonstrate how adjuvants with complementary mechanisms of action impacting vaccine biodistribution and kinetics can synergize to enhance humoral immunity.
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