title: A simple screening assay for receptor switching of avian influenza viruses.
abstract: BACKGROUND
  Adaptation of the receptor-binding preference from alpha2,3- to alpha2,6-linked sialic acid is an essential step for an avian influenza virus to transmit efficiently in human population and become a pandemic virus. The currently available assays for receptor-binding preference are complex and not widely available.
  
  
  OBJECTIVE
  A simple high-throughput screening assay will facilitate early detection of a potential pandemic virus, which is crucial for the prevention and control of the possible pandemic. We wanted to develop a simple assay to differentiate influenza viruses with alpha2,3- or alpha2,6-linked receptor-binding preference.
  
  
  METHODS
  The assay employs a specific sialidase (from Salmonella thyphimurium) that can eliminate alpha2,3-linked sialic acid from red blood cells. A reduction of hemagglutination titer indicates alpha2,3-linked receptor preference in this assay.
  
  
  RESULTS
  Using a panel of H5N1 avian influenza isolates and H1/H3 human influenza isolates, as well as mutated H5 reverse genetics virus, the assay could accurately differentiate the viruses according to their receptor-binding preference. Furthermore, the assay was sufficiently sensitive to detect a minor variant with alpha2,6-linkage-specificity in a background of alpha2,3-linkage-specific virus.
  
  
  CONCLUSIONS
  We have developed a simple screening assay capable of detecting avian influenza viruses that have switched their receptor-binding preference.
authors.affiliation: Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Ornpreya
authors.initials: O
authors.lastname: Suptawiwat
authors.forename: Alita
authors.initials: A
authors.lastname: Kongchanagul
authors.forename: Wisoot
authors.initials: W
authors.lastname: Chan-It
authors.forename: Arunee
authors.initials: A
authors.lastname: Thitithanyanont
authors.forename: Witawat
authors.initials: W
authors.lastname: Wiriyarat
authors.forename: Krisada
authors.initials: K
authors.lastname: Chaichuen
authors.forename: Taweesak
authors.initials: T
authors.lastname: Songserm
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Pilaipan
authors.initials: P
authors.lastname: Puthavathana
authors.forename: Prasert
authors.initials: P
authors.lastname: Auewarakul
mesh_terms: D000818:Animals; D004912:Erythrocytes / Q000737:chemistry / Q000378:metabolism; D005777:Geese; D006386:Hemagglutination Tests / Q000379:methods*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism*; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000378:metabolism*; D009980:Influenza A virus / Q000378:metabolism*; D011991:Receptors, Virus / Q000737:chemistry / Q000378:metabolism*; D012794:Sialic Acids / Q000737:chemistry* / Q000378:metabolism
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D011991:Receptors, Virus; D012794:Sialic Acids