A simple screening assay for receptor switching of avian influenza viruses.
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.
Suptawiwat
Ornpreya
O
Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Kongchanagul
Alita
A
Chan-It
Wisoot
W
Thitithanyanont
Arunee
A
Wiriyarat
Witawat
W
Chaichuen
Krisada
K
Songserm
Taweesak
T
Suzuki
Yasuo
Y
Puthavathana
Pilaipan
P
Auewarakul
Prasert
P
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
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D011991:Receptors, Virus; D012794:Sialic Acids