Innate immune responses to influenza A H5N1: friend or foe?

Trends Immunol. 2009 Dec;30(12):574-84. doi: 10.1016/ Epub 2009 Oct 26.


Avian influenza A H5N1 remains unusual in its virulence for humans. Although infection of humans remains inefficient, many of those with H5N1 disease have a rapidly progressing viral pneumonia that leads to acute respiratory distress syndrome and death, but its pathogenesis remains an enigma. Comparison of the virology and pathogenesis of human seasonal influenza viruses (H3N2 and H1N1) and H5N1 in patients, animal models and relevant primary human cell cultures is instructive. Although the direct effects of viral replication and differences in the tropism of the virus for cells in the lower respiratory tract clearly contribute to pathogenesis, we focus here on the possible contribution of the host innate immune response in the pathogenesis of this disease.

Publication types

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

MeSH terms

  • Animals
  • Humans
  • Immunity, Innate*
  • Influenza A Virus, H1N1 Subtype / immunology
  • Influenza A Virus, H1N1 Subtype / pathogenicity
  • Influenza A Virus, H3N2 Subtype / immunology
  • Influenza A Virus, H3N2 Subtype / pathogenicity
  • Influenza A Virus, H5N1 Subtype / immunology*
  • Influenza A Virus, H5N1 Subtype / pathogenicity
  • Influenza, Human / epidemiology
  • Influenza, Human / immunology*
  • Influenza, Human / pathology
  • Influenza, Human / physiopathology
  • Interferons / metabolism
  • Mice
  • Orthomyxoviridae Infections / immunology
  • Orthomyxoviridae Infections / physiopathology
  • Respiratory Distress Syndrome, Adult / immunology
  • Tumor Necrosis Factor-alpha / metabolism


  • Tumor Necrosis Factor-alpha
  • Interferons