A baseline transcriptional signature associates with clinical malaria risk in RTS,S/AS01-vaccinated African children

In a phase 3 trial in African infants/children, the RTS,S/AS01 (GSK) vaccine showed moderate efficacy against clinical malaria. We aimed to identify RTS,S/AS01-induced signatures associated with clinical malaria by analyzing antigen-stimulated peripheral blood mononuclear cells sampled from a subset of trial participants at baseline and month 3 (one month post-final dose). RTS,S/AS01 vaccination was associated with downregulation of B-cell and monocyte-related blood transcriptional modules (BTMs) and upregulation of T-cell related BTMs, as well as higher month 3 (vs baseline) (CSP)-specific CD4+ T-cell responses. For some RTS,S/AS01-associated BTMs, month 3 levels correlated with anti-circumsporozoite protein (CSP) IgM and inversely with anti-CSP IgG responses. There were few RTS,S/AS01-associated BTMs whose month 3 levels correlated with malaria risk. In contrast, baseline levels of dendritic cell and monocyte RTS,S/AS01-associated BTMs correlated with malaria risk. A cross-study analysis supported generalizability of these correlations to healthy, malaria-naïve adults, suggesting inflammatory monocytes may inhibit protective RTS,S/AS01-induced responses. Overall design: 1,900 samples were sequenced in 5 batches of 384-well plates. Two positive (human universal reference) and two negative (water) controls were included in each plate. No replicates of samples were performed.