Berard, L. | Search bioRxiv

bioRxiv2026

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

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.

immunology↗

bioRxiv2025

Phenological turnover matters when making trait-based predictions of plant-pollinator interactions

1. Understanding the processes determining species interactions is key to predicting and safeguarding ecological networks under rapid environmental change. One approach to estimating interactions is to use morphologies of taxa interacting across trophic levels to reveal suites of traits they are more likely to interact with (i.e. a trait niche). 2. Previous work studying these morphological trait niches has typically used interactions between species that are pooled in space and time. However, species assemblages, and the traits of individuals within species, can change across even small landscapes over a season, leading to morphological trait space being dynamically reshaped. Therefore, it is unclear how morphological trait turnover affects our inferences of trait niches, and our ability to answer this is in part limited by a lack of individual-level trait data. 3. Here, we directly address this by studying a montane Arctic plant-pollinator community over five growing seasons (>1,300 hours of fieldwork). Specifically, we linked every recorded plant-bumblebee interaction with the traits of the bee individual involved (n = 1,150), to investigate 1) whether plant taxa (n = 10) exhibited bee trait niches by interacting with specific regions of multidimensional trait space of visiting bumblebees, and 2) how our inference of these trait niches was affected by considering bumblebee trait turnover and plant taxon turnover. 4. When not considering turnover (interactions in space and time are pooled), plant taxa demonstrated bee trait niches. However, next we considered how bee trait space is reshaped over the elevational and seasonal gradient (especially with the emergence of different castes), and how this reshaping co-occurs with different spatiotemporal ranges of the plant taxa. From this we found the degree to which plant taxa exhibited trait niches declined significantly, and that seasonal reshaping of bee trait space was the primary driver of this trend. 5. Overall, in highly dynamic systems, like the Arctic, overlooking community turnover could mask and even overestimate the ability of morphology to explain interactions. Hence, determining how morphological traits of individual interaction partners are in phenological synchrony at localised scales will be fundamental to understanding the role morphology plays in underpinning plant-pollinator interactions.

ecology↗