Avian Flu Scan for Aug 05, 2014

H5N1 mutations in Canada case
Korean H5N8 origins

Letter raises possibility of human-adapted H5N1 in Canada case

An H5N1 avian flu virus that killed a Canadian woman in January had two uncommon mutations that may have helped increase its ability to bind to human cells, researchers from Singapore and Canada reported yesterday in a letter in Emerging Infectious Diseases.

The woman, who had visited China before her illness in December, had neurologic symptoms and no known contact with poultry. She remains Canada's only H5N1 patient.

The investigators note two previously reported mutations, R189K and G221R, in the hemagglutinin protein in the virus isolated from the patient. They write that both mutations are found in the immediate receptor-binding pocket, and G225R has been known to change specificity of an H3N2 virus toward human erythrocytes. The authors note that the two receptor-binding pocket mutations were not seen in the most closely related Asian H5N1 sequences.

They write, "Our results suggest that G225R could incur a relative predicted increase in binding to the human-like receptors. . . . The role of R193K is less clear with a slight predicted tendency of favoring avian-like receptors.
Aug 4 Emerg Infect Dis letter


Study: Korean H5N8 outbreak strain likely involved farm reassortment

Recent H5N8 avian flu outbreaks in South Korea were likely the result of introduction of the virus from wild birds to farm poultry, according to a separate letter yesterday in Emerging Infectious Diseases.

South Korean researchers conducted a BLAST (Basic Local Alignment Search Tool) search to identify the closest gene sequences of H5N8 isolates collected from waterfowl droppings in the area where the outbreak began in January and has since led to the culling of more than 12 million Korean poultry. They compared viruses from wild birds with those from affected poultry.

The scientists surmise that, because all eight genes of the waterfowl are closely related to an isolate from a duck farm, it is likely the outbreak strain originated from infected waterfowl that had visited poultry on an outbreak farm. They also determined that the H5N8 outbreak strain likely is a reassortment of segments from H5N1-like, H4N2-like, and H5N8-like strains.

The authors conclude, "Taken together, our data suggest that A/waterfowl/Korea/S005/2014 (H5N8) may have been reassorted in a duck farm in South Korea."
Aug 4 Emerg Infect Dis letter

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