Evaluation of luciferase and prefusion-stabilized F protein from respiratory syncytial virus mRNA/LNPs in pre-clinical models using jet delivery compared to needle and syringe

•In vivo imaging of luciferase with a luciferase mRNA/LNP using jet or needle/syringe.•Similar In vivo expression of luciferase using jet or needle/syringe.•Similar IgG response to a Prefusion-F RSV mRNA/LNP- jet delivery and needle/syringe.•CMI with a Prefusion-F RSV mRNA/LNP- jet delivery and needle/syringe. Described here is the evaluation of a luciferase (luc) and respiratory syncytial virus (RSV) messenger RNA / lipid nanoparticle (mRNA/LNP) vaccine using a Needle-free Injection System, Tropis®, from PharmaJet® (Golden, Colorado USA). Needle-free jet delivery offers an alternative to needle/syringe. To perform this assessment, compatibility studies with Tropis were first performed with a luc mRNA/LNP and compared to needle/syringe. Although minor changes in particle size and encapsulation efficiency were observed when using Tropis on the benchtop, in vitro luciferase activity remained the same. Next, the luc mRNA/LNP was administered to rats intramuscularly using Tropis or needle/syringe and tracking of the injection and distribution was performed. Lastly, an mRNA encoding a prefusion-stabilized F protein from RSV was delivered intramuscularly using both Tropis and needle/syringe at 1 and 5 mcg mRNA. An equivalent IgG response was observed using both Tropis and needle/syringe. The cell mediated immune (CMI) response was also evaluated, and responses to RSV-F were detected from animals immunized with needle/syringe at all dose levels, and from the animals immunized with Tropis in the 5 and 25 ug groups. These results indicated that delivery of mRNA/LNPs with Tropis is a potential means of administration and an alternative to needle/syringe.