'DNA sensor' sounds the alarm when viruses invade

Researchers at Imperial College London have identified a molecule that sounds the alarm when viruses invade our cells.

Our immune system has evolved to recognise distinctive features of infectious agents like bacteria, fungi and viruses in order to fight infections, but some viruses are hard to detect. Now scientists have discovered a molecule that reacts to DNA from viruses and sets off danger signals.

The discovery may help to improve the body's response to viruses such as HIV and vaccines, and to develop treatments for diseases where the immune system is working abnormally.

The study was carried out by Dr Nicholas Peters with Dr Brian Ferguson as part of Professor Geoffrey Smith's group in the Department of Medicine. It is published today in the new open-access journal eLife.

Viruses reproduce by invading host cells and hijacking their internal machinery. All viruses have a genetic code, like us. In some, though not all, it is encoded in DNA molecules. These viruses are particularly hard to catch because it is almost impossible to tell their DNA apart from ours.

However, our DNA is always inside a cell's nucleus, a secure central compartment. Viruses have to bring their DNA into the body of the cell as the first step in invasion. By catching it there, DNA sensors discover infection early.