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H7N9 likely evolved from four origins
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The novel avian influenza A(H7N9) virus in China may have evolved from four origins and has evolved into at least two different lineages, researchers from Institute of Microbiology, Chinese Academy of Sciences in Beijing reported in The Lancet.
So far, there have been 131 laboratory-confirmed cases of H7N9 and 36 deaths, according to WHO. There has been no evidence of human-to-human transmission, but close contacts of the cases are being closely monitored.
The researchers found that there were multiple reassortment events that led to the origination of H7N9. The HA gene may be of duck origin and the NA gene may have been transferred from wild birds. Six internal genes were likely originated from two different H9N2 viruses isolated from chickens. Reassortment of the genes from these four sources likely led to the H7N9 virus currently affecting humans.
“We believe that the estimated times to most recent common ancestor for the eight genomic fragments and the frequent poultry transportation in China account for the increased number of confirmed sporadic cases of human infection,” the researchers wrote. “In particular, this novel H7N9 virus has diversified into different lineages since its emergence several months ago.”
Disclosure: The researchers report no relevant financial disclosures.
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