Reading the viral signature by Toll-like receptors and other pattern recognition receptors

J Mol Med (Berl). 2005 Mar;83(3):180-92. doi: 10.1007/s00109-004-0620-6. Epub 2005 Jan 6.


Successful host defense against viral infections relies on early production of type I interferon (IFN) and subsequent activation of a cellular cytotoxic response. The acute IFN and inflammatory response against virus infections is mediated by cellular pattern-recognition receptors (PRRs) that recognize specific molecular structures on viral particles or products of viral replication. Toll-like receptors (TLRs) constitute a class of membrane-bound PRRs capable of detecting microbial infections. While TLR2 and TLR4, which were first identified to recognize Gram-positive and Gram-negative bacteria, respectively, sense specific viral proteins on the cell surface, TLRs 3, 7, 8, and 9 serve as receptors for viral nucleic acids in endosomic compartments. In addition to TLRs, cells express cytoplasmic PRRs such as the RNA helicase retinoic acid inducible gene I and the kinase double-stranded RNA-activated protein kinase R, both of which sense dsRNA, a characteristic signature of viral replication, and initiate a protective cellular response. Here we review the recent progress in our understanding of PRRs and viral infections and discuss the molecular and cellular responses evoked by virus-activated PRRs. Finally, we look into what is currently known about the role of PRRs in viral infections in vivo.

Publication types

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

MeSH terms

  • Animals
  • Gene Expression Regulation / genetics
  • Humans
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Signal Transduction
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptors
  • Virus Diseases / genetics
  • Virus Diseases / metabolism*
  • Virus Diseases / virology*


  • Membrane Glycoproteins
  • Receptors, Cell Surface
  • TLR2 protein, human
  • TLR4 protein, human
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Toll-Like Receptors