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

• Published in: Antiviral research Vol. 80; no. 3; pp. 316 - 323
• Main Authors: Dang, Lua T., Kondo, Hidehiro, Aoki, Takashi, Hirono, Ikuo
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.12.2008; Elsevier
• Subjects: Animals; Antibiotics. Antiinfectious agents. Antiparasitic agents; Antiviral agents; Antiviral Agents - immunology; Base Sequence; Biological and medical sciences; Cell Line; Fish Diseases - immunology; Fish Diseases - virology; Fish Proteins - genetics; Fish Proteins - immunology; Fishes; Genetic Engineering; Hirame rhabdovirus; HIRRV; IFN; Immunity, Innate; Interferon; Interferons - genetics; Interferons - immunology; Iridovirus; Iridovirus - genetics; Iridovirus - metabolism; MCP; Medical sciences; MicroRNAs - genetics; miRNA; Molecular Sequence Data; Mx protein; Novirhabdovirus - genetics; Novirhabdovirus - metabolism; Pharmacology. Drug treatments; RNA Interference; RNA, Small Interfering - genetics; RNAi; RSIV; Sequence Alignment; siRNA; IFN; RNAi; RSIV; miRNA; Interferon; siRNA; MCP; Mx protein; HIRRV; RNA interference; Cytokine; Micro RNA; Immunity; In vitro; Convergence; Virus; Gene silencing; Cell line; Antiviral
• ISSN: 0166-3542; 1872-9096
• DOI: 10.1016/j.antiviral.2008.07.005

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 β-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.