Recognition of 5' triphosphate by RIG-I helicase requires short blunt double-stranded RNA as contained in panhandle of negative-strand virus

Immunity. 2009 Jul 17;31(1):25-34. doi: 10.1016/j.immuni.2009.05.008. Epub 2009 Jul 2.


Antiviral immunity is triggered by immunorecognition of viral nucleic acids. The cytosolic helicase RIG-I is a key sensor of viral infections and is activated by RNA containing a triphosphate at the 5' end. The exact structure of RNA activating RIG-I remains controversial. Here, we established a chemical approach for 5' triphosphate oligoribonucleotide synthesis and found that synthetic single-stranded 5' triphosphate oligoribonucleotides were unable to bind and activate RIG-I. Conversely, the addition of the synthetic complementary strand resulted in optimal binding and activation of RIG-I. Short double-strand conformation with base pairing of the nucleoside carrying the 5' triphosphate was required. RIG-I activation was impaired by a 3' overhang at the 5' triphosphate end. These results define the structure of RNA for full RIG-I activation and explain how RIG-I detects negative-strand RNA viruses that lack long double-stranded RNA but do contain blunt short double-stranded 5' triphosphate RNA in the panhandle region of their single-stranded genome.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / genetics
  • DEAD-box RNA Helicases / immunology*
  • Humans
  • Interferon-alpha / biosynthesis
  • Interferon-alpha / immunology
  • Mice
  • Mice, Mutant Strains
  • Monocytes / immunology
  • Monocytes / metabolism
  • Oligoribonucleotides / chemical synthesis
  • Oligoribonucleotides / immunology
  • Polyphosphates / immunology*
  • Polyphosphates / metabolism
  • RNA Viruses / immunology*
  • RNA, Double-Stranded / immunology*
  • RNA, Double-Stranded / metabolism
  • RNA, Viral / immunology*
  • RNA, Viral / metabolism


  • Interferon-alpha
  • Oligoribonucleotides
  • Polyphosphates
  • RNA, Double-Stranded
  • RNA, Viral
  • DDX58 protein, human
  • Ddx58 protein, mouse
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases
  • triphosphoric acid