Structural and functional diversity of viral IRESes

Biochim Biophys Acta. 2009 Sep-Oct;1789(9-10):542-57. doi: 10.1016/j.bbagrm.2009.07.005. Epub 2009 Jul 24.


Some 20 years ago, the study of picornaviral RNA translation led to the characterization of an alternative mechanism of initiation by direct ribosome binding to the 5' UTR. By using a bicistronic vector, it was shown that the 5' UTR of the poliovirus (PV) or the Encephalomyelitis virus (EMCV) had the ability to bind the 43S preinitiation complex in a 5' and cap-independent manner. This is rendered possible by an RNA domain called IRES for Internal Ribosome Entry Site which enables efficient translation of an mRNA lacking a 5' cap structure. IRES elements have now been found in many different viral families where they often confer a selective advantage to allow ribosome recruitment under conditions where cap-dependent protein synthesis is severely repressed. In this review, we compare and contrast the structure and function of IRESes that are found within 4 distinct family of RNA positive stranded viruses which are the (i) Picornaviruses; (ii) Flaviviruses; (iii) Dicistroviruses; and (iv) Lentiviruses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • 5' Untranslated Regions*
  • Codon
  • Encephalomyelitis / virology
  • Genes
  • HIV-2 / genetics
  • Humans
  • Models, Genetic
  • Nucleic Acid Conformation
  • Open Reading Frames
  • Picornaviridae / genetics*
  • Poliovirus / genetics
  • Poly A
  • Protein Biosynthesis
  • RNA, Messenger / metabolism
  • RNA, Viral
  • Ribosomes / metabolism
  • Transcriptional Activation
  • Virus Replication


  • 5' Untranslated Regions
  • Codon
  • RNA, Messenger
  • RNA, Viral
  • Poly A