Avian Influenza Virus Genome Contains Mutations Favorable for Growth in Humans

Several characteristic amino acid changes in HA and the PB2 RNA polymerase subunit probably facilitated binding to human-type receptors and efficient replication in mammals, respectively, highlighting the pandemic potential of the novel A(H7N9) viruses.

"The human isolates, but not the avian and environmental ones, have a protein mutation that allows for efficient growth in human cells and that also allows them to grow at a temperature that corresponds to the upper respiratory tract of humans, which is lower than you find in birds," said contributing author Dr. Yoshihiro Kawaoka, professor of virology at the University of Wisconsin. "These viruses possess several characteristic features of mammalian influenza viruses, which likely contribute to their ability to infect humans and raise concerns regarding their pandemic potential. Although it is too early to predict its potential to cause a pandemic, signs that the virus is adapting to mammalian and, in particular, human hosts are unmistakable."

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