How come we suddenly have this new medication, Tamiflu, for swine flu, so quickly? Where did this come from?
Chris - Well, the answer is weíve actually had Tamiflu, Oseltamivir, and thereís another version of that which works in the same way but is made by a rival company and thatís called Relenza Zanamivir. These agents were quite carefully designed. They were processed on whatís called rational drug design actually. What they do is to target a particle on the surface of a flu virus, which is called the neuraminidase. This is an enzyme that sits down on the surface of the virus. It behaves a bit like a machete and when a virus infects a cell, it tries to bud off or get away from the cell that itís grown in, and in order to do that, it needs to make sure that it doesnít get stuck on to the surface of the cell and also get stuck in any of the mucus, which is on the lining of the airway. And this enzyme cuts the virus adrift and helps it to get free. The way Tamiflu works is by blocking up that enzyme so the virus canít escape from the cell that itís been growing in and this means that it finds it much harder to spread to other cells and this effectively confines the virus to barracks. And so, the infection progresses more slowly, it doesnít infect many other people. It doesnít infect so many other cells in the same person and, therefore, the immune system has a better opportunity to try and curtail the infection a little bit.