WASHINGTON (dpa-AFX) - Health officials of the U.S. had earlier assured that the probability of human-to-human transmission of bird flu virus, called H5N1, was low. However, a new study found that a single mutation in the virus could make the transmission spread possible.
'In order to get sufficient infection, the virus needs to very efficiently attach to the cells in the airway,' said co-senior study author Jim Paulson, a biochemist at The Scripps Research Institute in La Jolla, California. 'In fact, it's believed that transmission cannot occur until the virus has acquired the human-type receptor specificity.'
So far, the human cases of bird flu in the U.S. have been mild with the patients developing symptoms like redness in eyes or cough. However, a teenage patient in Canada was in critical condition after developing more severe symptoms.
During the study, the scientist analyzed the genetic code of the virus that infected the first person ever known to contract bird flu from a cow. They found that hemagglutinin is the protein needed by the virus to infect cells.
'What we're looking at is a protein that comes from a virus, but it's isolated,' said co-senior author Ian Wilson, a structural biologist at Scripps.
Later, they experimented with isolated hemagglutinin and found that a single mutation called the Gln226Leu substitution could enable the virus to infect humans instead of birds. The preference switch of the virus was 'clear and pronounced' across different tests. However, the mutant virus was not as binding to human cells as to bird cells.
'This is highly concerning,' Aris Katzourakis at the University of Oxford, who was not a part of the study, said to NewScientist. 'Each spillover to a human gives the virus a roll of the dice.'
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