title: In vivo screening of modified siRNAs for non-specific antiviral effect in a small fish model: number and localization in the strands are important.
abstract: Small interfering RNAs (siRNAs) are promising new active compounds in gene medicine but the induction of non-specific immune responses following their delivery continues to be a serious problem. With the purpose of avoiding such effects chemically modified siRNAs are tested in screening assay but often only examining the expression of specific immunologically relevant genes in selected cell populations typically blood cells from treated animals or humans. Assays using a relevant physiological state in biological models as read-out are not common. Here we use a fish model where the innate antiviral effect of siRNAs is functionally monitored as reduced mortality in challenge studies involving an interferon sensitive virus. Modifications with locked nucleic acid (LNA), altritol nucleic acid (ANA) and hexitol nucleic acid (HNA) reduced the antiviral protection in this model indicative of altered immunogenicity. For LNA modified siRNAs, the number and localization of modifications in the single strands was found to be important and a correlation between antiviral protection and the thermal stability of siRNAs was found. The previously published sisiRNA will in some sequences, but not all, increase the antiviral effect of siRNAs. The applied fish model represents a potent tool for conducting fast but statistically and scientifically relevant evaluations of chemically optimized siRNAs with respect to non-specific antiviral effects in vivo.
authors.affiliation: Department of Poultry, Fish and Fur Animals, National Veterinary Institute, Technical University of Denmark, Hangøvej 2, DK-8200 Aarhus N. bdsc@vet.dtu.dk
authors.forename: Brian Dall
authors.initials: BD
authors.lastname: Schyth
authors.forename: Jesper Bertram
authors.initials: JB
authors.lastname: Bramsen
authors.forename: Malgorzata Maria
authors.initials: MM
authors.lastname: Pakula
authors.forename: Sekar
authors.initials: S
authors.lastname: Larashati
authors.forename: Jørgen
authors.initials: J
authors.lastname: Kjems
authors.forename: Jesper
authors.initials: J
authors.lastname: Wengel
authors.forename: Niels
authors.initials: N
authors.lastname: Lorenzen
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry* / Q000276:immunology / Q000494:pharmacology; D004353:Drug Evaluation, Preclinical; D006801:Humans; D023421:Models, Animal; D059372:Nucleotide Motifs; D009841:Oligonucleotides / Q000737:chemistry; D017686:Oncorhynchus mykiss; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000737:chemistry* / Q000276:immunology / Q000494:pharmacology; D013696:Temperature
chemical_list: D000998:Antiviral Agents; D009841:Oligonucleotides; D034741:RNA, Small Interfering; C477371:locked nucleic acid