It starts very simply. A virus, just one, latches on to one of your cells and fools that cell into making lots more. Lots, lots more, like a million new viruses. This animation shows you how viruses trick healthy cells to join the dark side.  David Bolinsky and his team at XVIVO designed this animation for a research company called Zirus (and we thank Zirus for letting us play with their pictures). Bolinsky says what you see in the video actually happens much, much faster in real life — in a fraction of a fraction of a second. So this is a very slow motion version of cellular activity. And for those of you who were wondering, yes, the designers did add color. Proteins, DNA, organelles, and the teeny things inside a human cell are so small, and the insides of cells are so dark, that for all practical purposes, they are colorless. So the copying molecule isn’t really pink. But once you decide to colorize, pink is just as accurate as maroon or yellow. One Last Thing In our video we ask, if a flu virus inside your body can multiply by the millions within seconds, why don’t we topple over and die quickly? Here’s a better, longer answer than the one in the video. First, some new viruses get caught in mucus and other fluids inside your body and are destroyed. Other viruses get expelled in coughs and sneezes. Second, lots of those new viruses are lemons. They don’t work that well. Some don’t have the right “keys” to invade healthy cells so they can’t spread the infection. And third, as the animation shows, your immune system is busy attacking the viruses whenever and wherever possible. That is why most of the time, after a struggle (when you get a fever and need to lie down), your immune system rebounds, and, in time, so do you.