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Analysis of hemagglutinin-mediated entry tropism of H5N1 avian influenza

  • Authors: Guo Y, Rumschlag-Booms E, Wang J, Xiao H, Yu J, Wang J, Guo L, Gao GF, Cao Y, Caffrey M, Rong L

  • Journal: Virol J. 2009 Apr 2;6:39

  • Type: Article

  • Directorate: Christophe Mérieux Laboratory and GABRIEL

  • Published: 2009


Background: Avian influenza virus H5N1 is a major concern as a potential global pandemic. It is thought that multiple key events must take place before efficient human-to-human transmission of the virus occurs. The first step in overcoming host restriction is viral entry which is mediated by HA, responsible for both viral attachment and viral/host membrane fusion. HA binds to glycans-containing receptors with terminal sialic acid (SA). It has been shown that avian influenza viruses preferentially bind to alpha2,3-linked SAs, while human influenza A viruses exhibit a preference for alpha2,6-linked SAs. Thus it is believed the precise linkage of SAs on the target cells dictate host tropism of the viruses.

Results: We demonstrate that H5N1 HA/HIV pseudovirus can efficiently transduce several human cell lines including human lung cells. Interestingly, using a lectin binding assay we show that the presence of both alpha2,6-linked and alpha2,3-linked SAs on the target cells does not always correlate with efficient transduction. Further, HA substitutions of the residues implicated in switching SA-binding between avian and human species did not drastically affect HA-mediated transduction of the target cells or target cell binding.

Conclusion: Our results suggest that a host factor(s), which is yet to be identified, is required for H5N1 entry in the host cells.

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