Vaccination with a Protective Ipa Protein-Containing Nanoemulsion Differentially Alters the Transcriptomic Profiles of Young and Elderly Mice following Shigella Infection

spp. are responsible for bacillary dysentery or shigellosis transmitted via the fecal-oral route, causing significant morbidity and mortality, especially among vulnerable populations. There are currently no licensed vaccines. spp. use a type III secretion system (T3SS) to invade host cells. We have shown that L-DBF, a recombinant fusion of the T3SS needle tip (IpaD) and translocator (IpaB) proteins with the LTA1 subunit of enterotoxigenic labile toxin, is broadly protective against spp. challenge in a mouse lethal pulmonary model. Here, we assessed the effect of LDBF, formulated with a unique TLR4 agonist called BECC470 in an oil-in-water emulsion (ME), on the murine immune response in a high-risk population (young and elderly) in response to challenge. Dual RNA Sequencing captured the transcriptome during infection in vaccinated and unvaccinated mice. Both age groups were protected by the L-DBF formulation, while younger vaccinated mice exhibited more adaptive immune response gene patterns. This preliminary study provides a step toward identifying the gene expression patterns and regulatory pathways responsible for a protective immune response against . Furthermore, this study provides a measure of the challenges that need to be addressed when immunizing an aging population.