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

Antiviral Res. 2008 Dec;80(3):316-23. doi: 10.1016/j.antiviral.2008.07.005. Epub 2008 Aug 5.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antiviral Agents / immunology*
  • Base Sequence
  • Cell Line
  • Fish Diseases / immunology*
  • Fish Diseases / virology
  • Fish Proteins / genetics
  • Fish Proteins / immunology*
  • Fishes
  • Genetic Engineering
  • Immunity, Innate*
  • Interferons / genetics
  • Interferons / immunology*
  • Iridovirus / genetics
  • Iridovirus / metabolism
  • MicroRNAs / genetics*
  • Molecular Sequence Data
  • Novirhabdovirus / genetics
  • Novirhabdovirus / metabolism
  • RNA Interference
  • RNA, Small Interfering / genetics*
  • Sequence Alignment


  • Antiviral Agents
  • Fish Proteins
  • MicroRNAs
  • RNA, Small Interfering
  • Interferons