Distinct baseline immune characteristics associated with responses to conjugated and unconjugated pneumococcal polysaccharide vaccines in older adults [bulk RNA-seq]

Pneumococcal infections cause serious illness and death among older adults. A capsular polysaccharide vaccine PPSV23 (Pneumovax®) and a conjugated polysaccharide vaccine PCV13 (Prevnar®) are used to prevent these infections, yet underlying immunological responses, and baseline predictors remain unknown. We recruited and vaccinated 39 older adults (>60 years) with PPSV23 or PCV13. Both vaccines induced strong antibody responses at day 28 and similar plasmablast transcriptional signatures at day 10, however, their baseline predictors were distinct. Analyses of baseline flow cytometry and RNA-seq data (bulk and single cell) revealed a novel baseline phenotype that is specifically associated with weaker PCV13 responses, characterized by i) increased expression of cytotoxicity-associated genes and increased CD16+ NK frequency; ii) increased Th17 and decreased Th1 cell frequency. Men were more likely to display this cytotoxic phenotype and mounted weaker responses to PCV13 than women. Baseline expression levels of a distinct gene set was predictive of PPSV23 responses. This first precision vaccinology study for pneumococcal vaccine responses of older adults uncovered novel and distinct baseline predictors that might transform vaccination strategies and initiate novel interventions. In this study, we performed bulk RNA-sequencing of peripheral blood mononuclear cells (PBMCs) obtained from 30 healthy adults aged 60 years and older at four distinct time points. Out of the 30 participants, 14 individuals received the Prevnar 13 vaccine (Pfizer), a conjugated 13-valent vaccine, while the remaining 16 participants received the Pneumovax 23 vaccine (Merck), a non-conjugated 23-valent vaccine. The four time points considered in this study included: Day -7 (baseline), Day 1, Day 10, and Day 60 (± 5 days) post-vaccination. ***Submitter declares that the raw data will be available through dbGAP (phs002361) due to patient privacy concerns ***