“Marked” — The Discovery Files

Many bugs that make us sick–bacteria, viruses, fungi and parasites–hide out in our cells in protective little bubbles called vacuoles. To clear an infection, the immune system must recognize and destroy these vacuoles while leaving the rest of the living cell intact. Now, researchers from Duke University have discovered that our bodies mark pathogen-containing vacuoles for destruction by using a molecule called ubiquitin, commonly known as the “kiss of death.”