Unexpected RNA modification protects bacteria against viral infection

Adding to the ever-growing list of newly discovered bacterial immune systems, we have characterized the mechanisms of an antiviral system called CmdTAC. CmdTAC blocks virus reproduction by modifying messenger RNA — a molecule needed to create proteins — through a chemical reaction not previously observed on an RNA base. A bacterial enzyme defends against phage infection by adding an ADP-ribose moiety to virus’s messenger RNA.