title: Engineered virus-encoded pre-microRNA (pre-miRNA) induces sequence-specific antiviral response in addition to nonspecific immunity in a fish cell line: convergence of RNAi-related pathways and IFN-related pathways in antiviral response.
abstract: Transfection with synthesized virus-specific small interfering RNAs (siRNAs) efficiently inhibits viral replication in viral-infected fish cell lines, implying the involvement of RNA interference (RNAi)-related pathways in the antiviral response of fish cells. Here, we demonstrate that plasmid expressing virus-encoded pre-microRNAs (pre-miRNAs) can also inhibit viral replication through these pathways. By incorporating sequences encoding miRNAs specific to major capsid protein (MCP) gene of red sea bream iridovirus (RSIV) and a miRNA specific to hirame rhabdovirus (HIRRV) genome into a murine miR-155 pre-miRNA backbone, we were able to intracellularly express viral pre-miRNAs (miR-MCPs and miR-HIRRV) in a fish cell line. The miR-MCPs and miR-HIRRV, delivered as pre-miRNA precursors in transfected cells, inhibited viral replication when these cells were infected with the target virus. Although this may suggest sequence-specific interference, inhibitory effect on viral replication was also observed in cells transfected with a plasmid expressing pre-miRNA targeting beta-galactosidase gene (miR-LacZ) that served as a specificity control. Expression of pre-miRNAs was found to activate interferon (IFN)-related pathways, correlating with upregulation of the antiviral IFN-induced Mx protein. The antiviral effects of viral-miRNAs observed here were partly the result of the antiviral miRNA-related pathways and partly the result of the antiviral IFN-related pathways. We propose that engineered virus-encoded pre-miRNA can engage not only RNAi-related pathways but also IFN-related pathways to induce potent antiviral responses in fish cells.
authors.affiliation: Laboratory of Genome Science, Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan.
authors.forename: Lua T
authors.initials: LT
authors.lastname: Dang
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kondo
authors.forename: Takashi
authors.initials: T
authors.lastname: Aoki
authors.forename: Ikuo
authors.initials: I
authors.lastname: Hirono
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000276:immunology*; D001483:Base Sequence; D002460:Cell Line; D005393:Fish Diseases / Q000276:immunology* / Q000821:virology; D029941:Fish Proteins / Q000235:genetics / Q000276:immunology*; D005399:Fishes; D005818:Genetic Engineering; D007113:Immunity, Innate; D007372:Interferons / Q000235:genetics / Q000276:immunology*; D017994:Iridovirus / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics*; D008969:Molecular Sequence Data; D029141:Novirhabdovirus / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics*; D016415:Sequence Alignment
chemical_list: D000998:Antiviral Agents; D029941:Fish Proteins; D035683:MicroRNAs; D034741:RNA, Small Interfering; D007372:Interferons