(Phys.org)—A team of researchers affiliated with several institutions in Hong Kong and mainland China has isolated a change in a single nucleotide that is responsible for allowing the H7N9 flu virus to replicate in both birds and humans. In their paper published in the journal Nature Communications, the team describes their efforts in searching for the factors involved when avian flu jumps to humans and what their findings could mean for reducing the spread of future flu epidemics.