Avian flu: influenza virus receptors in the human airway

Nature. 2006 Mar 23;440(7083):435-6. doi: 10.1038/440435a.


Although more than 100 people have been infected by H5N1 influenza A viruses, human-to-human transmission is rare. What are the molecular barriers limiting human-to-human transmission? Here we demonstrate an anatomical difference in the distribution in the human airway of the different binding molecules preferred by the avian and human influenza viruses. The respective molecules are sialic acid linked to galactose by an alpha-2,3 linkage (SAalpha2,3Gal) and by an alpha-2,6 linkage (SAalpha2,6Gal). Our findings may provide a rational explanation for why H5N1 viruses at present rarely infect and spread between humans although they can replicate efficiently in the lungs.

MeSH terms

  • Animals
  • Birds / virology
  • Bronchi / metabolism
  • Bronchi / virology*
  • Galactose / chemistry
  • Galactose / metabolism
  • Humans
  • Influenza A Virus, H5N1 Subtype / metabolism*
  • Influenza A virus / metabolism
  • N-Acetylneuraminic Acid / chemistry
  • N-Acetylneuraminic Acid / metabolism
  • Pulmonary Alveoli / metabolism
  • Pulmonary Alveoli / virology*
  • Receptors, Virus / chemistry
  • Receptors, Virus / metabolism*
  • Respiratory Mucosa / metabolism
  • Respiratory Mucosa / virology
  • Species Specificity


  • Receptors, Virus
  • N-Acetylneuraminic Acid
  • Galactose