Anewly discovered “anti-CRISPR” system in viruses could help us control CRISPR gene-editing technologies and lead to better weapons against antibiotic-resistant superbugs. The background: Your immune system has ways to remember viruses you’ve encountered before and help defend you if they appear again — and, amazingly, some single-celled bacteria do, too. These microbes evolved the CRISPR system to protect themselves from the viruses that infect bacteria, called phages. The bacteria will take a little bit of a virus’ DNA sequence and add it to their own genome, like a memory of past infections. They then create CRISPR-associated (Cas) proteins containing copies...