Enhancement and diversification of IFN induction by IRF-7-mediated positive feedback

J Interferon Cytokine Res. 2002 Jan;22(1):87-93. doi: 10.1089/107999002753452692.


Interferons (IFN) are potent components of the innate immune response to microbial infection. The genes for type I IFN (IFN-alpha and IFN-beta) are rapidly induced in response to viral infection through a mechanism that involves latent cellular transcription factors that are activated in response to innate recognition of viral components. IFN regulatory factor (IRF) proteins are key to this regulation, and their conversion from latent to active involves virus-induced serine phosphorylation. Differential utilization of distinct IRF proteins by different members of the type I IFN gene family produces a graded induction of gene expression, resulting in tight control of these cytokines through a positive feedback mechanism. Early response to virus causes secretion of a subset of IFN genes through the action of IRF-3 in conjunction with additional transcription factors, such as NF-kappaB and activator protein-1 (AP-1) (c-jun/ATF). This early IFN acts in an autocrine manner to stimulate production of IRF-7, a transcription factor capable of activating the many additional members of the IFN-alpha gene family. The dependence of IRF-7 on virus-induced phosphorylation for its activity insures that IFN production is limited to virus-infected cells. Characterization of the cellular components involved in viral detection and IRF activation will further delineate this vital mechanism of innate immune response.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • DNA-Binding Proteins / physiology*
  • Feedback, Physiological
  • Humans
  • Interferon Regulatory Factor-3
  • Interferon Regulatory Factor-7
  • Interferon Type I / biosynthesis
  • Interferon Type I / genetics*
  • Interferon Type I / physiology
  • Molecular Sequence Data
  • Phosphorylation
  • Promoter Regions, Genetic
  • Protein Structure, Tertiary
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription Factors / physiology*
  • Transcriptional Activation


  • DNA-Binding Proteins
  • IRF3 protein, human
  • IRF7 protein, human
  • Interferon Regulatory Factor-3
  • Interferon Regulatory Factor-7
  • Interferon Type I
  • Transcription Factors