Conventional and Unconventional Mechanisms for Capping Viral mRNA

Nat Rev Microbiol. 2011 Dec 5;10(1):51-65. doi: 10.1038/nrmicro2675.


In the eukaryotic cell, capping of mRNA 5' ends is an essential structural modification that allows efficient mRNA translation, directs pre-mRNA splicing and mRNA export from the nucleus, limits mRNA degradation by cellular 5'-3' exonucleases and allows recognition of foreign RNAs (including viral transcripts) as 'non-self'. However, viruses have evolved mechanisms to protect their RNA 5' ends with either a covalently attached peptide or a cap moiety (7-methyl-Gppp, in which p is a phosphate group) that is indistinguishable from cellular mRNA cap structures. Viral RNA caps can be stolen from cellular mRNAs or synthesized using either a host- or virus-encoded capping apparatus, and these capping assemblies exhibit a wide diversity in organization, structure and mechanism. Here, we review the strategies used by viruses of eukaryotic cells to produce functional mRNA 5'-caps and escape innate immunity.

Publication types

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

MeSH terms

  • Guanine / analogs & derivatives
  • Guanine / metabolism
  • Metabolic Networks and Pathways
  • Models, Biological
  • Models, Molecular
  • RNA Caps / metabolism*
  • RNA, Viral / metabolism*
  • Viral Proteins / metabolism


  • RNA Caps
  • RNA, Viral
  • Viral Proteins
  • Guanine
  • 7-methylguanine