Overall, 16 of the 302 designs ended up working—that is, the computer-designed phage started to replicate, eventually bursting through the bacteria and killing them. For instance, doctors have sometimes tried “phage therapy” to treat patients with serious bacterial infections. Similar tests are underway to cure cabbage of black rot, also caused by bacteria. He notes that most gene therapy uses viruses to shuttle genes into patients’ bodies, and AI might develop more effective ones. The Stanford researchers say they purposely haven’t taught their AI about viruses that can infect people.