Our immune systems are locked in an arms race with infections and rapidly develop defences against their invaders, research suggests.

Scientists studying genes linked to immunity found that, over many generations, those genes in the front line of defence have to evolve almost ten times faster than normal in order to keep disease at bay.

The study from the University of Edinburgh shows for the first time how fast the immune system has to change to keep up.

Immune systems and infections are locked in an evolutionary arms race – in which each side continually evolves new ways of attack and counter-attack. This study showed that overall, genes linked to immunity develop twice as fast as other genes, with those genes in the front line of defence adapting nearly ten times faster.

The study pinpoints genes that are most affected by this arms race, and will give scientists a greater understanding of how infections and immunity genes develop in tandem.

The research, published in PLoS Genetics, was carried out in collaboration with the Universities of Sheffield and Cambridge and supported by the Wellcome Trust, the Royal Society and the Biotechnology and Biological Sciences Research Council.

We knew that some immunity genes changed faster than others, but this is the first time we've really been able to quantify how much faster.

Dr Darren Obbard

School of Biological Sciences

For more information please contact:

Dr Darren Obbard, School of Biological Sciences, tel 0131 650 5476; email Darren.Obbard@ed.ac.uk

Catriona Kelly, Press and PR Office, tel 0131 651 4401; email Catriona.Kelly@ed.ac.uk

The image, showing immunity pathways, is from the paper: Obbard DJ, Welch JJ, Kim K-W, Jiggins FM (2009) Quantifying Adaptive Evolution in the Drosophila Immune System. PLoS Genet 5(10), e1000698.