Profile of the B cell receptor repertoire and antibody responses upon 17DD-YF vaccine boosting

Abstract

Although the 17DD-YF vaccine is highly effective in conferring long-term immunity, recent studies suggest that booster doses may be necessary in endemic areas. In this study, we characterized the dynamics of the B cell repertoire following 17DD-YF booster vaccination and examined its impact on antibody kinetics. Using a combined approach of serological analysis and B cell receptor (BCR) sequencing, we investigated molecular features of the antibody response in four vaccinated individuals from a YFV-endemic region. Our results indicate that the booster induces a transient antibody response, with limited effect on the neutralization capacity against DENV1-4 and ZIKV. Notably, we observed a rapid clonal expansion of B cells within 14 days post-vaccination, predominantly involving IgA and IgG isotypes. However, this expansion was short-lived, with reduced magnitude and persistence of these lineages by day 28. Interestingly, some of the expanded lineages shared sequence similarity with previously characterized anti-DENV and anti-ZIKV antibodies, although further validation is required to assess their functional relevance and presence in circulating serum. Together, these findings highlight the transient nature and isotype composition of the antibody response following YFV revaccination and provide insights into the complex interplay between pre-existing immunity and recall responses in individuals living in endemic regions.

Keywords: Antibody Response; B Cell Receptor; Flavivirus Immunity; Immunoglobulin Repertoire.

Figure 1:. Longitudinal flavivirus antibody responses.

A Schematic representation of YFV vaccination and longitudinal blood sampling. 17DD-YF vaccine was used to immunize four healthy donors against yellow fever virus. Blood draws were performed before (T0), 7, 14, 28 and 180 days following vaccination to obtain both plasma and PBMCs from each donor at each time point. B-D IgG responses against YFV (B), DENV (C) and ZIKV (D). Binding levels were measured using indirect ELISA and the data was expressed as mean IU/ml for YFV, Panbio Units for DENV and AU for ZIKV. Dot lines represent the cut-off for positivity. E Neutralizing antibody titers against YFV, DENV1–4, and ZIKV presented by each donor at distinct time points. Results were obtained by performing soroneutralization assay and cut-off criterion for positive mFRNT results were: ≥ 1:100 (YFV), ≥ 1:30 (DENV1–4), and PRNT results ≥1:140 (ZIKV).

Figure 2:. Dynamics of repertoire diversity and expansion following 17DD-YF vaccine boost.

A Average of IgG, IgA and IgM lineages across donors that are and are not shared between the indicated time points 0, 7 and 14 days after vaccination. B Diversity of IgG (B), IgA (C) and IgM (D) repertoires was assessed by Shannon diversity index at 0, 7 and 14 days following vaccination. C Proportion of expanded and non expanded IgG, IgA and IgM lineages in each vaccinee repertoire at 0, 7 and 14 days after 17DD-YF booster dose. Lineages were classified into non expanded (< 0.1%) and expanded (≥ 0.1%) according to their frequencies in the repertoire. *p < 0.01 and ** p ≤ 0.005.

Figure 3:. Overview of the repertoire expansion state over the two weeks after 17DD-YF boosting.

Diagram representing the top 200 most frequent B cell lineages from each IgG, IgA and IgM repertoire. Each circle represents a B cell lineage with size proportional to its frequency in the repertoires at 0, 7 and 14 days after revaccination. Expansion levels were defined as non expanded for lineages presenting frequency below to 0.1%, medium expanded for lineages with frequency between 0.1% and 1% and hyperexpanded for lineages presenting frequencies greater than 1%.

Figure 4:. Analysis of persisting-expanded and new lineages.

A Proportion of persisting-expanded and new expanded lineages found in the repertoires on day 7 and 14. B-C Proportion of persisting-expanded and new expanded lineages according to the isotype. D SHM average loads presented by IgG, IgA and IgM clonal lineages found in expanded repertoire on day 0 and on T14 by persisting-expanded and new expanded lineages. E CDRH3 average length of clonal lineages. *p < 0.05, ***p ≤ 0.001, ****p ≤ 0.0001.

Figure 5:. Representative histogram of the top 50 most expanded clonal lineages (IgG, IgA and IgM) that comprise the YFV vaccinees’ repertoire at 14 days after vaccination.

Bars indicate the relative frequency of each lineage in the repertoire and * shows the persistent lineages.

Figure 6:. Analysis of putative anti-flaviviruses antibodies present in the analyzed repertoires.

A Number of discovered hits that display specificity to YFV and cross-reactivity to ZIKV, DENV or ZIKV and DENV. B Fraction of cross-reactive lineages that are either persisting-expanded or new expanded lineages. The number in the center of the pie chart shows the total number of lineages belonging to the isotype. C SHM rates of IgG, IgA and IgM lineages that may display cross-reactivity. D VH germline gene usage of cross-reactivity lineages. E CDRH3 length distribution of lineages that may present cross-reactivity to DENV and/or ZIKV. F Physicochemical properties and amino acid usage of the cross-reactive lineages CDRH3.

Figure 7:. Antigenic sites and functional properties of the lineages elicited by 17DD-YF vaccine booster.

A Antigenic sites targeted by cross-reactive lineages. Crystal structure of YFV E dimer (Protein Data Bank ID code 6IW2) represented as space filling model. Domains I, II and III are highlighted in red, yellow and blue respectively, in each monomer. FL is colored in green. Labels show the proportion of the mAbs targeting epitopes within each structural region. B Prediction of neutralization potential of each mAb according to data in published literature.