MTB

They live in the lung's alveoli, the tiny air sacs where oxygen passes into the bloodstream -- but, as Rothchild has shown in a previous paper, AMs don't mount a robust immune response when they're initially infected by Mtb.

This lack of response seems to be a chink in the body's armor that Mtb exploits to such devastating effect.

"Mtb takes advantage of the immune response," says Rothchild, "and when they infect an AM, they can replicate inside of it for a week or longer. They effectively turn the AM into a Trojan Horse in which the bacteria can hide from the body's defenses."

"What if the AMs responded more effectively to Mtb? How could we change the body's innate immune response? Studies over the last 10 years or so have demonstrated that the innate immune system is capable of undergoing long-term changes, but we are only beginning to understand the underlying mechanisms behind them."

In the second model, the researchers induced a contained Mtb infection, which they previously showed protects against subsequent infections in a form of concomitant immunity.