Plopper: There's a whole set of receptors that are on the surfaces of cells that respond to various types of agents. This is DNA that comes from a bacterium – it's a bacterial type of DNA form and there is one receptor that it responds to specifically. And that generates the type of response that would be to an infection – not an allergic response, but an infectious response.
Narrator: This causes the body to recognize the bacterial DNA as a foreign substance, so the immune system is activated to fight off what appears to be an infection. The vaccine also reversed asthma-induced lung damage. Tests in humans are now being conducted. For Science Today, I'm Larissa Branin.