The wave-shaped chart Ratul Chowdhury pulls up on a computer monitor in his office captures the evolutionary cat-and-mouse game his research lab is up against. The undulating curves track variants of the porcine reproductive and respiratory syndrome (PRRS) virus, which causes a swine disease that annually costs the global pork industry more than $1 billion—damage attributable in part to how quickly it adapts to escape from immune defenses.
