Journal: bioRxiv
Article Title: Binding dynamics shape germinal center broadly neutralizing responses to HIV priming
doi: 10.64898/2026.05.12.724749
Figure Lengend Snippet: (A) Schematic of the CH31 precursor transfer and priming strategy. B6.SJL CD45.1 recipients received purified CD45.2⁺ CH31 UCA hom/hom dKI B cells and, after 24h, resulting CH31 UCA hom/hom dKI →WT chimeras (reconstituted at 1:10 5 precursor frequency) were primed for 8 or 16 days with eOD monomers, low-valency tetramers, or high-valency np’s (poly I:C–formulated), or poly I:C alone, prior to GC B cell recovery for flow cytometric phenotyping and 10x paired Ig seq ( n per group indicated). (B) Flow cytometric quantification of donor-derived, on-target GC B cells (live singlet B220⁺CD19⁺CD38⁻GL7⁺CD45.2⁺eODGT bait⁺) shown as the fraction of total GC B cells at day 8 ( top ) or day 16 ( bottom ). Each dot represents one primed CH31 UCA hom/hom dKI chimera. Significance relative to eODGT7 np was determined by Mann–Whitney U tests. *p<0.05; **p<0.01; ***p<0.001; ****p<0.0001. (C–D) Immunofluorescence validation of enhanced CH31 precursor recruitment and GC persistence following eODGT7 np priming. (C) Representative spleen cryosection images from chimeras primed for 16 days with eODGT7 or eODGT8 np’s; boxed regions indicate GC closeups. Note the persistently high fraction of donor CH31 UCA hom/hom dKI (CD45.2⁺) B cells in individual GCs across the spleen (top) of an eODGT7 np–immunized animal at this later time point. (D) Quantification of donor CH31 GC occupancy (CD45.2⁺ area within GL7⁺ GCs) at days 8 and 16, shown as violin plots with medians (blue bars). Each dot represents one GC. Data are pooled from three mice per group. Total GCs analyzed were 698/465 (eODGT7, d8/d16) and 505/325 (eODGT8, d8/d16). Mann–Whitney test; ****p<0.0001. (E-F) SHM magnitude, positional distribution in, and kinetics of, CH31-derived V(D)J rearrangements following eODGT7 np priming, compared with eODGT8 np or eODGT8 tetramer priming. GC B cells were isolated by flow sorting and analyzed by paired 10x Ig-seq. (E) Pie charts show SHM distributions among bona fide on-target CH31 UCA HC/LC pairs, with slices indicating total aa substitutions. ≥1000 unique, non-oligoclonal sequences from ≥5 pooled mice per group were analyzed. Data from eODGT8 np–primed mice are omitted due to insufficient recovered precursors. (F) Frequency of CH31 UCA HC aa mutations by residue position among all on-target pairs. AID hotspots (WRC/GYW and WGCW) are indicated by pink blocks. Previously reported insertion sites from bnAb lineage retracement , or vaccine-induced maturation are marked by arrows. (G) T follicular helper (T fh ) cell responses in chimeras primed for 8 or 16 days with eODGT7 or eODGT8 np’s, or eODGT8 tetramers. Shown is the percentage of live, singlet splenocytes that were T fh (CD4⁺CD44⁺CD62L⁻PD1⁺CXCR5⁺CD25⁻CD127⁺) at peak GC occupancy (d8) or peak SHM (d16). Gating strategy is shown in Fig S16.
Article Snippet: FASTQ files were uploaded from 10x Genomics library sequencing and data was analyzed using the Cell Ranger pipeline ( https://www.10xgenomics.com/support/software/loupe-browser/latest ).
Techniques: Purification, Cell Recovery, Derivative Assay, MANN-WHITNEY, Immunofluorescence, Biomarker Discovery, Isolation, Residue