Background: The identification of new biomarkers is essential to making it possible to predict the degree of protection following vaccination. Very few human studies have focused on baseline characteristics including microbiota and gene expression to underlie vaccine immune responsiveness. We investigated the host whole-blood transcriptome and microbiome before vaccination, to assess the likelihood of their involvement in an effective MVA-neutralizing antibody response (MVA-Nab) two months later.
Results: We based our analyses on data obtained from a randomized clinical study in which participants (n=10) were vaccinated with the MVA-HIV clade B vaccine (MVA-B). Samples were collected at 2-time points prior vaccination (week-2, w0) to study blood transcriptome. Skin wrap (site of vaccination) and stool microbiota were analysed for diversity and abundance (16S rRNAseq). MVA-neutralizing antibody responses were measured at week 8. The levels of MVA-Nab responses were positively correlated with an abundance of Eubacterium in stool and Prevotella in skin. The simultaneous investigation of blood transcriptome and host microbiota before vaccination showed that genus diversity and bacterial abundance at that time correlated significantly with the expression of genes involved in B cell development stages. The combination of gene expression and microbiota makes it possible to forecast strong responders to MVA-B vaccination.
Conclusion: To our knowledge, this is the first study integrating host blood gene expression and microbiota before vaccination to predict the intensity of humoral response months later. The genes identified are involved in B cell differentiation might open an avenue of research in this field to optimize vaccination strategies.