Scientists found that phages, viruses that infect bacteria, trigger widespread protein modifications inside host cells that help them evade bacterial immune defenses.

When a phage infects a bacterium, it must overcome the cell’s defenses before those defenses can destroy the invading virus. Researchers have now uncovered an unusual strategy used by T7 phage: a single enzyme triggers a massive wave of protein modifications inside the infected bacterium, helping disable its immune systems.

Phages, viruses that infect bacteria, are locked in a constant molecular arms race with their hosts. Bacteria evolve defenses against infection, while phages develop ways to evade or suppress those defenses. The new work shows for the first time how one phage protein can initiate a cascade of molecular changes capable of disarming multiple bacterial defense mechanisms.