TLR5 versus TLR7/8 agonist-dependent modulation of the early gene expression response to inactivated influenza virus vaccine in newborn nonhuman primates

Growing evidence supports Toll-Like Receptor agonists (TLRa) as potent stimulatory molecules to increase vaccine efficacy. We have previously demonstrated that the inclusion of either flagellin (TLR5a) or R848 (TLR7/8a) in an inactivated influenza virus vaccine can improve responses in newborn NHP, with R848 being superior at providing protection upon challenge.

This study sought to identify early immune events induced by inactivated virus alone or adjuvanted with R848 or flagellin through scRNA-seq analysis of draining lymph nodes (dLN) isolated at 24 hours post-vaccination. Our study reveals that globally, R848 enhanced gene expression associated with B cell activation, while flagellin was a stronger modulator of T cells. Analysis of distinct lymph node populations showed that surprisingly, while APCs had a potent transcriptional response to inactivated virus, we observed minimal additional changes in transcriptional activity with addition of a TLRa.