How lethal bird flu viruses evolved
Deadly H7N9 avian flu viruses infected people for the first time earlier this year in China, but little is known about how they evolved to become harmful to humans. In a study published by Cell Press on September 19 in Cell Host & Microbe, an in-depth evolutionary analysis of whole-genome sequences of different types of avian flu viruses has revealed that new H7N9 viruses emerged from distinct H9N2 viruses in a two-step process, first occurring in wild birds and then continuing in domestic birds.
"A deep understanding of how the novel H7N9 viruses were generated is of ...