Researchers Uncover a Secret of the Black Death

Yersinia pestis, the bacteria that causes plague, is a sneaky little intruder with a remarkable ability to evade the body’s immune system. Upon entering an organism, Y. pestis employs a variety of strategies to slip below the radar of the innate immune response—the body’s front line of defense against invading pathogens—and in many cases kills the host before its more specific antibacterial response can develop.