title: MS2 viruslike particles: a robust, semisynthetic targeted drug delivery platform.
abstract: We show that viruslike particles (VLPs) reassembled in vitro with the RNA bacteriophage MS2 coat protein and an RNA conjugate encompassing a siRNA and a known capsid assembly signal can be targeted to HeLa cells by covalent attachment of human transferrin. The siRNA VLPs protect their cargoes from nuclease, have a double-stranded conformation in the capsid and carry multiple drug and targeting ligands. The relative efficiency of VLP reassembly has been assessed, and conditions have been determined for larger scale production. Targeted VLPs have been purified away from unmodified VLPs for the first time allowing improved analysis of the effects of this synthetic virion system. The particles enter cells via receptor-mediated endocytosis and produce siRNA effects at low nanomolar concentrations. Although less effective than a commercial cationic lipid vector at siRNA delivery, the smaller amounts of internalized RNA with VLP delivery had an effect as good as if not better than the lipid transfection route. This implies that the siRNAs delivered by this route are more accessible to the siRNA pathway than identical RNAs delivered in complex lipid aggregates. The data suggest that the MS2 system continues to show many of the features that will be required to create an effective targeted drug delivery system. The fluorescence assays of siRNA effects described here will facilitate the combinatorial analysis of both future formulations and dosing regimes.
authors.affiliation: Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Francis A
authors.initials: FA
authors.lastname: Galaway
authors.forename: Peter G
authors.initials: PG
authors.lastname: Stockley
mesh_terms: D002213:Capsid / Q000378:metabolism; D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D004337:Drug Carriers / Q000378:metabolism; D016503:Drug Delivery Systems / Q000379:methods*; D004705:Endocytosis / Q000235:genetics / Q000502:physiology; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D017909:Levivirus / Q000235:genetics* / Q000378:metabolism*; D012317:RNA Phages / Q000235:genetics* / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection / Q000379:methods; D014168:Transferrin / Q000235:genetics / Q000378:metabolism; D014771:Virion / Q000235:genetics* / Q000378:metabolism*
chemical_list: D036022:Capsid Proteins; D004337:Drug Carriers; D034741:RNA, Small Interfering; D014168:Transferrin