In a long-awaited study that led to triggering a contentious debate over the wisdom of conducting research that had the potential to help as to also harm, scientists reported yesterday that they had engineered a mutant strain of bird flu that could easily pass between ferrets - a laboratory animal that can respond to flu viruses in much the same way as people do.
According to University of Wisconsin virologist Yoshihiro Kawaoka, leader of the study, the development meant that bird flu had "the potential to acquire the ability to transmit in mammals.
He added, only a few mutations were required for the transformation, which suggested that a more contagious strain of bird flu could emerge on its own without scientists' helping the process in any way, in the lab.
Kawaoka's discovery, published online following a month-long delay by the journal Nature, sets back hope that the deadly H5N1 virus was not capable of becoming a highly contagious bug in mammals, including humans.
Kawaoka with his team developed a hybrid bird flu virus that combined an H5 hemagglutinin gene with the help of which viruses bind to host cells, with genes from 2009's pandemic H1N1 flu, also known as swine flu.
They used a kind of selective breeding to favour flu virus strains whose H5 protein could bind with human rather than bird host cells, and were able to develop a version of the virus with four mutations in its H5 that affected ferrets.