Study finds mutations needed for bird flu pandemic
WASHINGTON, Mar 16 (Reuters) Scientists said today they had identified some of the mutations the H5N1 avian influenza virus needs to gain a permanent foothold in the human population, causing a greatly feared pandemic.
They said the test they used, called a glycan microarray, might be useful in monitoring the virus in birds and as it infects people, to see if it is mutating into a form that would allow it to pass easily from person to person.
H5N1 has moved steadily across Asia and into Europe since it reappeared in 2003, and has picked up speed in recent weeks.
It has killed just over 100 people but remains mostly a virus of birds.
No one can predict when, or even if, it will evolve into a form that transmits easily from one person to another, but fears are that it will. Scientists have been examining the virus when they can get samples and trying to predict just which changes are needed to make it change from a bird-specific to a human-specific form.
Ian Wilson and a team at The Scripps Research Institute in La Jolla, California looked at a structure on the surface of all influenza viruses called hemagglutinin. It is the ''H'' in H5N1 and there are 16 known types of hemagglutinin.
Only three -- H1, H2 and H3 -- have been known to cause human disease and they caused the last three great influenza pandemics, in 1918, 1957 and 1968.
''When pandemics start, we really don't know, with the first virus that enters the human population, how well it is adapted to humans,'' Wilson said in a telephone interview.
Working with flu experts Terence Tumpey of the Centers for Disease Control and Prevention in Atlanta and Jeffery Taubenberger of the Armed Forces Institute of Pathology in Rockville, Maryland, Wilson's team dissected and imaged a sample of influenza virus that killed a 10-year-old Vietnamese boy in 2004.
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