An article entitled, “The Potential for Respiratory Droplet Transmissible A/H5N1 Influenza Virus to Evolve in a Mammalian Host”, was published in June 22, 2012, issue of Science 336:1541–1547. The lead author Colin A. Russell with eighteen other associates from twelve research groups demonstrated the possibility of transmission of avian H5N1 influenza viruses between mammals hitherto considered to be transmitted only from birds to mammals. Their results revealed that potentially as few as five mutations (amino acid substitutions), or four mutations followed by their re-assortment may generate avian H5N1 flu which can become airborne causing transmission between mammals, including humans. However, until now, it was not known whether these mutations evolved in nature. They first analyzed all their surveillance data available on avian H5N1 influenza viruses from the last 15 years, focusing on birds and humans. It was discovered that two of the five mutations seen in the experimental viruses had occurred in numerous existing avian flu strains. In addition, a number of the viruses were characterized with both the mutations. The results suggest that the remaining three mutations could evolve in a single human host, making the virus evolving in nature posing potentially a serious threat. [Summarized by a graduate student, Samsad Razzaque.] Read more..