Comparative Analysis of B-Cell Receptor Repertoires Induced by Live Yellow Fever Vaccine in Young and Middle-Age Donors

Abstract

Age-related changes can significantly alter the state of adaptive immune system and often lead to attenuated response to novel pathogens and vaccination. In present study we employed 5'RACE UMI-based full length and nearly error-free immunoglobulin profiling to compare plasma cell antibody repertoires in young (19-26 years) and middle-age (45-58 years) individuals vaccinated with a live yellow fever vaccine, modeling a newly encountered pathogen. Our analysis has revealed age-related differences in the responding antibody repertoire ranging from distinct IGH CDR3 repertoire properties to differences in somatic hypermutation intensity and efficiency and antibody lineage tree structure. Overall, our findings suggest that younger individuals respond with a more diverse antibody repertoire and employ a more efficient somatic hypermutation process than elder individuals in response to a newly encountered pathogen.

Keywords: age; immunoglobulin repertoire; plasma cell; vaccination; yellow fever.

Figure 1

CDR3 characteristics. (A) CDR3 length, aa. (B) Number of non-template added N nucleotides within V-D-J junction. (C) Physicochemical properties for the 5 amino acids residues in the middle of CDR3: Kidera factor 4 (hydrophobicity, lower values refer to more hydrophobic amino acids), potential “energy” of interaction (49) (lower values refer to stronger interaction), “strength” and “volume.” All characteristics were calculated “weighted”—i.e., accounting for IGH clonotype size. ANOVA p-values for age and for isotype adjusted using Benjamini & Hochberg correction are shown on top of each plot.

Figure 2

Isotype and IGHV segments usage for YF-vaccinated subjects from the two age groups. (A) Isotype usage. (B) IGHV usage.

Figure 3

Antibody lineage analysis. (A) Diversity of antibody lineages: Gini inequality coefficient for the number of nodes (clonotypes) in a tree (clone), and number of “trees” that include only one node. Both parameters are significantly different (p < 0.05) between young and middle-age donors. Two-tailed T-test, p-values adjusted using Benjamini & Hochberg method. (B,C) Top IGH trees by size containing equal number of 270 nodes for united data of all young (B) and middle-age (C) individuals are shown.

Figure 4

Bulk analysis of somatic hypermutations. (A) Somatic hypermutations per clonotype, without using trees information (NS, ANOVA). (B) Somatic hypermutations within roots of the trees with >2 nodes (NS, ANOVA). (C) Selection strength estimated using BASELINe framework. Adjusted p = 0.011 for CDR, 0.011 for FWR.

Figure 5

Patterns of newly acquired somatic hypermutations in young and middle-age donors vaccinated with YF. (A) Summary profile of somatic hypermutations observed in the study. IGH regions are marked with color. The distribution of silent (S) and replacement (R) hypermutations are shown with dashed and solid lines, respectively. For CDR3 region, mutation analysis was done using the root as reference. Data were pooled for all young and all middle-age individuals. (B) Frequency of newly acquired somatic hypermutations (SHMs) in young (red) and middle-age (blue) donors. ANOVA p = 0.0005 for age, 0.14 for isotype. (C,D) Mean replacement:silent ratio (R:S ratio) for newly acquired somatic hypermutations (SHMs) in young and middle-age donors, for isotypes (C, ANOVA p = 0.058 for age, 0.69 for isotype) and regions (D, ANOVA p = 0.0013 for age, 0.00014 for regions).