Phages Caught Sleeping

Bacteria use hibernating viruses to immunize themselves

- Humberto Basilio

THE IDEA THAT A SINGLE-CELLED bacterium can defend itself against viruses in a similar way as the 1.8-trillion-cell human immune system is still “mind-blowing” for molecular biologist Joshua W. Modell of Johns Hopkins University.

Scientists discovered about 20 years ago that bacteria employ an adaptive defense system called CRISPR, which lets microbes recognize and destroy viral invaders on repeat encounters. In a recent study published in Cell Host & Microbe, Modell and his team deepened scientists’ understanding of how bacteria use this system to “vaccinate” themselves against phages, the viruses that try to kill them. The findings could help develop treatments to fight antimicrobial resistance, which contributes to millions of deaths annually.