Tripping the Innate Immune Response

Join Our Community of Science Lovers!

On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.

When a bacterium enters the body, the first line of defense it encounters is the innate immune system. This rapid-response system recognizes common bacterial components such as lipoproteins, lipocarbohydrates or bacterial DNA, and sets off a chain of reactions to kill the invader and alert the adaptive immune system, which can offer a more targeted attack, if needed. Now researchers from Japan and Germany have found a specific receptor protein, called Toll-like receptor 9, that the innate immune system requires for the recognition of bacterial DNA. They report their findings in today's Nature.

Unlike the DNA of body cells, DNA from bacteria frequently contains a motif of two particular bases, C and G in its unmethylated form. The scientists bred mice that lack Toll-like receptor 9 and found that these animals, unlike their wildtype cousins, no longer showed any innate immune response to CG-containing DNA. Furthermore, these mice did not die from the shock that CG-containing DNA can induce in normal mice. Understanding the exact mechanism of how bacterial DNA stimulates the innate immune system can possibly help scientists improve the effects of DNA vaccines, which work by getting the immune system's attention.

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American