It’s challenging enough for the bird flu virus to move to humans to make the emergence of new strains of the human influenza relatively rare. However, once the virus has managed to cross the species barrier, it is often able to do significant damage, with many strains causing a high mortality rate. Recently, researchers have zeroed in on what turns out to be a very limited route through which avian influenza is able to cross from birds to man, a discovery that might one day prevent the species-crossing altogether. The research study conducted by scientists at Imperial College London looked into just what changes to the virus mediate their ability to infiltrate mammalian cells, with the aim of pinpointing a new pharmaceutical target that could potentially prevent the influenza infection from replicating in humans. The study involved the insertion of various fragments of chicken DNA into mammalian hamster cells to try and discover exactly where as well as how the infection was able to replicate. By observing in which cells the virus was able to take hold, the team were eventually able to identify the ANP32A protein as a potential candidate. ANP32A is a protein that also exists in a slightly different form in mammals including people. What the researchers discovered was that only when the bird influenza viral ANP32A-binding protein changed its molecular structure to a form that can also bind to mammalian form of ANP32A was the virus able to replicate within mammalian cells. This provides an important new target for the pharmaceutical industry to go after to combat the emergence of new strains of avian influenza and might also one day prevent the spread of the more common human influenzas that infect 800 million humans each year.