Conformation of Single Condensed RNA Molecules in Polyethylenimine Solutions Used for Vaccination

Messenger RNA (mRNA) constitutes a novel option for therapeutic intervention as, after application to a patient, virtually any therapeutic protein can be expressed. Currently, several RNA based products for vaccination against Covid-19 are in clinical development. For application to patients, delivery vehicles, usually consisting of cationic lipids or polymers, are required. Among the polymers, polyethylenimine (PEI), is an established system for RNA delivery. We have identified a novel form of RNA polyplex formulations based on PEI, which has demonstrated to be suitable for vaccination in combination with self-amplifying RNA (saRNA), that results in superior activity in. Here we want to further investigate the structure and molecular organization of these RNA complexes by SANS using D2O/H2O contrast variation, that can lead to further improvements in such PEI-saRNA formulations.