Cellular and Molecular Life Sciences CMLS

, Volume 57, Issue 12, pp 1770–1784

Avian influenza viruses infecting humans

  • K. Subbarao*
  • J. Katz

DOI: 10.1007/PL00000657

Cite this article as:
Subbarao*, K. & Katz, J. CMLS, Cell. Mol. Life Sci. (2000) 57: 1770. doi:10.1007/PL00000657


Avian species, particularly waterfowl, are the natural hosts of influenza A viruses. Influenza viruses bearing each of the 15 hemagglutinin and nine neuraminidase subtypes infect birds and serve as a reservoir from which influenza viruses or genes are introduced into the human population. Viruses with novel hemagglutinin genes derived from avian influenza viruses, with or without other accompanying avian influenza virus genes, have the potential for pandemic spread when the human population lacks protective immunity against the new hemagglutinin. Avian influenza viruses were thought to be limited in their ability to directly infect humans until 1997, when 18 human infections with avian influenza H5N1 viruses occurred in Hong Kong. In 1999, two human infections with avian influenza H9N2 viruses were also identified in Hong Kong. These events established that avian viruses could infect humans without acquiring human influenza genes by reassortment in an intermediate host and highlighted challenges associated with the detection of human immune responses to avian influenza viruses and the development of appropriate vaccines.

Key words. Influenza; avian influenza; pandemic; H5N1; genetic features; pathogenesis. 

Copyright information

© Birkhäuser Verlag Basel, 2000

Authors and Affiliations

  • K. Subbarao*
    • 1
  • J. Katz
    • 1
  1. 1.Influenza Branch, Centers for Disease Control, 1600 Clifton Road, Atlanta (Georgia 30333, USA), Fax +1 404 639 2334, e-mail: ksubbarao@cdc.govUS

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