COLUMBUS, Ohio Common strains of tuberculosis-causing bacteria have hijacked the human body's immune response to play tricks on cells in the lungs, scientists say.
The results of this takeover are mixed. The cells essentially welcome the bacteria into the lungs and invite them to stay a while, meaning the human host becomes infected with the TB bacterium. But in about 90 percent of these cases, the infection remains latent and the infected person never has any symptoms of illness.
The secret weapon in this stealth attack is sugar.
Ohio State University researchers have determined that Mycobacterium tuberculosis has learned through evolution to coat itself with a sugar called mannose, which makes the bacterium attractive to cells in the lungs that are looking to clean up and discard unwanted sugar in the body. Those lung cells absorb the TB bacteria, giving the infecting bacteria a place to live for the long term.
"The bug sugarcoats itself and creates this magical interaction that allows it to slip by the immune system. We think that this is a beautiful example of the concept of host adaptation," said Larry Schlesinger, professor of internal medicine and director of the division of infectious diseases at Ohio State. "TB has evolved in humans. We're the reservoir. It has had centuries to develop a sophisticated way to deal with its encounter with the human, and the lung is the special portal of entry."
Schlesinger, also director of Ohio State's Center for Microbial Interface Biology, reported on TB's adaptation to the human respiratory system Friday (9/26) at the First International Congress "Mycobacteria: A Challenge for the 21st Century" in Bogot, Colombia.
Part of his presentation in Colombia touched on the most recent discovery in his lab two strains of TB bacteria that do not show these signs of adaptation. The existence of these other strains suggests that some strains of TB bacteria can be t
|Contact: Larry Schlesinger|
Ohio State University