Variant-specific spike conformational dynamics shape memory B cell selection during recall

Broutin, M.; Sokal, A.; Dejoux, A.; Planas, D.; Vanderkerken, M.; Fernandez, I.; Azzaoui, I.; Vandenberghe, A.; Charlet, M.; Arbabian, A.; Megret, J.; Toure, L.; Planchais, C.; Berard, L.; Simon, T.; Weill, J.-C.; Mouquet, H.; Schwartz, O.; Bruhns, P.; Rey, F. A.; Launay, O.; Mahevas, M.; Chappert, P.

doi:10.64898/2026.07.18.739204

Home/Archive/bioRxiv

bioRxiv · 10.64898/2026.07.18.739204

Variant-specific spike conformational dynamics shape memory B cell selection during recall

View original source ↗Export metadata ↓

Abstract

Immune imprinting profoundly shapes antibody responses to breakthrough infections and vaccination against evolving endemic viruses. Current vaccine design primarily focuses on antigen sequence and variant mutations but rarely consider the structural context in which these antigens are being recognized. In this study, we make use of the longitudinal analysis of memory B cell (MBC) responses in boosted individuals enrolled in the COVIBOOST clinical trial to provide a proof of principle that variant-specific conformational dynamics can impact MBC recruitment and protective antibody responses, independently of epitope conservation. Combining functional characterization of MBC-derived monoclonal antibodies, repertoire analysis, epitope mapping and in silico structural modeling of epitope accessibility, we found that the adjuvanted B.1.351 spike vaccine preferentially recalled MBCs targeting exposed receptor-binding domain neutralizing epitopes. This preferential recruitment arises from the more restricted conformational dynamics of the B.1.351 spike compared to the ancestral Hu-1 spike, leading to increased masking of class 4 and 5 cryptic RBD epitopes. These findings demonstrate that antigen conformational dynamics can be leveraged to redirect pre-existing immunity toward neutralizing epitopes upon boost immunization.

Explore related subjects

immunology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Broutin, M., Sokal, A., Dejoux, A., Planas, D., Vanderkerken, M., Fernandez, I., Azzaoui, I., Vandenberghe, A., Charlet, M., Arbabian, A., Megret, J., Toure, L., Planchais, C., Berard, L., Simon, T., Weill, J.-C., Mouquet, H., Schwartz, O., Bruhns, P., Rey, F. A., Launay, O., Mahevas, M., Chappert, P.. 2026-07-20. Variant-specific spike conformational dynamics shape memory B cell selection during recall. https://doi.org/10.64898/2026.07.18.739204

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Melanoma suppresses galectin-9-glycan axis in dendritic cells and galectin-9 restoration limits T regulatory cell expansion

Dendritic cells (DCs) are key orchestrators of anti-tumor adaptive immune responses. Their function is tightly regulated by galectins, a family of carbohydrate-biding proteins that decode extracellular glycans into intracellular signaling. Here, we show that exposure to melanoma-conditioned media (CM) induces loss of galectin-9 (gal-9) at the DC surface. Notably, gal-9 loss, independent of transcriptional regulation, was associated with the acquisition of an immunosuppressive phenotype in CD14cDC2 cells following tumor exposure, with higher-molecular weight fractions of the melanoma secretome as mediators. Notably, gal-9 depletion was mirrored with a reduction in gal-9 ligands on the cell surface, particularly GalNAc-containing glycoepitopes, pointing towards a melanoma-exploited gal-9-glycan axis as a DC-evasive strategy. Interestingly, restoring gal-9 surface levels in CM-exposed CD14cDC2 cells prevented the expansion of regulatory T cells (Tregs), postulating gal-9 as a novel immunomodulatory molecule in DC-mediated Treg induction during melanoma progression. Altogether, our data suggest that melanoma-derived factors remodel the DC glycan-gal-9 axis to enhance T cell differentiation towards regulatory phenotypes and dampen anti-tumor immunity. This identifies the gal-9/glycan axis in CD14cDC2 cells as a vulnerable node in melanoma immune evasion and as a potential therapeutic target.

immunology↗

bioRxiv2026

Repeated shrimp allergen exposure drives 5-lipoxygenase-dependent avoidance and selective gut-brain activation

Peripheral immune processes can shape animal behavior, yet how noninfectious inflammatory reactions affect neural activity and behavioral outputs remains poorly understood. We developed an optimized murine model of shrimp allergy using whole shrimp extract to examine how a complex dietary allergen elicits integrated immune, neural, and behavioral responses. Sensitized mice received repeated oral shrimp challenges and were assessed for allergic pathology, food preference, affective-like behaviors, and neuronal activation in the brain. Repeated exposure increased total IgE and shrimp-specific IgG1, induced mast cell activation, accelerated gastrointestinal transit, caused mild hypothermia consistent with oral anaphylaxis, and increased intestinal length. Shrimp-sensitized mice did not avoid shrimp solution after sensitization alone. Instead, avoidance emerged only after repeated oral challenges and strengthened over time. This delayed aversion occurred without detectable changes in locomotor activity or measures of anxiety-like or depressive-like behavior at the time points tested. Repeated shrimp exposure increased cFOS expression in the area postrema, nucleus of the tractus solitarius, central amygdala, and paraventricular nucleus of the thalamus, implicating brainstem and limbic-thalamic pathways involved in visceral sensing and aversion. Pharmacological inhibition of 5-lipoxygenase partially reversed avoidance and reduced circulating mast cell protease-1 in allergic mice. These findings establish a robust whole-shrimp allergy model and show that a complex food allergen engages gut-brain pathways to promote 5-lipoxygenase-dependent avoidance. The delayed, selective nature of this response supports immune-mediated food aversion as a shared output of food allergy, while suggesting that its kinetics and neural recruitment vary with allergen identity and inflammatory context.

immunology↗

bioRxiv2026

Targeting IL-2 to inflamed tissues via oxidation-specific epitopes enables third-generation bispecific IL-2 therapeutics

Interleukin-2 (IL-2) is essential for the survival and activation of regulatory T cells (Tregs). Low-dose native IL-2 (IL-2LD) therapy restores immune regulation in vivo and has shown reproducible clinical benefit across multiple autoimmune, inflammatory, and neuroimmune diseases. Attempts to improve IL-2 through engineered variants (muteins) have mainly focused on enhancing Treg selectivity by reducing IL-2 receptor {beta}-chain binding, but this strategy profoundly diminishes biological potency, likely contributing to the limited clinical efficacy of IL-2 muteins. Here, we develop a ''third-generation IL-2'' that combines site-specific targeting and bifunctionality. We generated a bivalent fusion protein linking IL-2 to a single-chain antibody recognizing oxidation-specific epitopes (OSEs), which are abundantly expressed at inflamed sites. Targeting OSEs provides not only site-specific localization, but also true bifunctionality as both anti-OSE antibodies and IL-2LD independently show therapeutic benefit in limiting inflammation. We first show that IL-2IT has bifunctional biological activities in vitro. In vivo, IL-2IT had increased specificity for Treg over Teff activation, which we attribute to a conformation-dependent modulation of IL-2 receptor engagement. Importantly, IL-2IT provided precise delivery to inflamed tissues in models of psoriasis and colitis. Altogether, this resulted in superior therapeutic benefit in multiple clinical settings, including in atherosclerosis models. Thus, our strategy illustrates a generalizable approach to cytokine engineering that preserves native signaling while achieving spatial control. Specifically, our findings validate OSE targeting as an efficient strategy to guide therapeutics to sites of inflammation and establish OSE-IL-2 as a promising bispecific Treg engager for treating inflammation.

immunology↗