Stephanie DeWitte-Orr, Wilfrid Laurier University

Richardson SA1, DeWitte-Orr SJ1,2 1Department of Biology, Wilfrid Laurier University, Waterloo, ON, Canada 2Department of Health Sciences, Wilfrid Laurier University, Waterloo, ON, Canada

Fighting & Responding

Long double-stranded RNA (LdsRNA), produced during viral replication, is a central trigger of innate antiviral immunity. While exogenous LdsRNA has long been used to stimulate type I interferon (IFN) responses, its instability, rapid degradation, and dose-dependent toxicity limit its broader application and use in mechanistic studies. Improving delivery while preserving immune potency remains a key challenge. We have developed a phytoglycogen (PhG)-based nanoparticle platform to enhance LdsRNA stability and modulate its immunostimulatory activity. Quaternary aminated PhG, which carries a net positive charge, readily complexes negatively charged LdsRNA to form nanoscale complexes. These complexes induce robust type I IFN responses at substantially lower doses than LdsRNA alone. We are now investigating how nanoparticle chemistry and complexation parameters influence antiviral signalling. Quaternary and primary aminated PhG variants are being compared for their ability to stably complex LdsRNA across varied storage conditions while maintaining immune activity. We are assessing how net particle charge affects IFN induction and complex stability. Interestingly, both anionic and cationic LdsRNA–PhG complexes induce strong IFN responses, although cationic complexes show reduced stability over time. Comparative studies in human and rainbow trout reporter cell lines highlight the conserved nature of LdsRNA sensing and enable cross-species analysis of nanoparticle-enhanced antiviral responses. Together, this work advances a tunable LdsRNA delivery system as a tool to interrogate and amplify innate antiviral immunity.