The World's Flu Hunters Race to Prevent Pandemic

On April 25, Rod Daniels, the Deputy Director of the World Influenza Center in London, was at a meeting in Germany when he received a call from a co-worker: an influenza outbreak had been reported in Mexico and the first samples of the virus were on their way to London for examination. A virologist who has studied flu for over 30 years, Daniels knew exactly what he was looking for. Influenza A viruses — the type that can cause pandemics — use a protein called hemagglutinin to bind to the cells of their animal hosts. When a virus jumps from animals to humans, its contagiousness is largely determined by what is called the "binding specificity" of this protein. An Alpha-2,3 binding specificity means the virus is well suited to the cells in an animal respiratory tract, but probably not human cells. An Alpha-2,6 binding specificity, on the other hand, means the virus can easily bind to human cells.