Cytomegalovirus produces an RNA that takes over the cell's power plant, keeping the cell alive and producing energy during the course of infection.

When a human cell is infected by a virus, one of the first lines of defence is suicide - if the cell dies, the virus is destroyed with it. A cell that detects a viral infection can therefore undergo a controlled self-destruction that involves its energy-producing organelles, the mitochondria. Viruses have evolved many proteins to block this process, but research on cytomegalovirus has revealed a completely new twist: an RNA that migrates into the cell's mitochondria and keeps the cell alive.

Cytomegalovirus is a member of the herpes family; it typically causes mild symptoms, although in rare cases it can have long-lasting complications. It produces many RNAs that encode proteins, but one of its RNAs is unable to be made into a protein.

The new research reveals that this RNA physically interacts with mitochondrial proteins, where it helps to prevent premature cell death. In addition, the RNA ensures that the cell's mitochondria continue to produce energy long after the infection would otherwise have caused them to stop.

Although the details of how an RNA can reprogram the mitochondria remain unclear, these results do make it clear that nucleic acids can control some sophisticated behaviour without being made into a protein.

Image: Cytomagalovirus

External links

• Reeves MB et al. Complex I binding by a virally encoded RNA regulates mitochondria-induced cell death. Science 2007;316(5829):1345-8.