Tuberculosis lives and thrives in the lungs. When the bacteria that cause the disease are coughed into the air, they are thrust into a comparatively hostile environment, with drastic changes to their surrounding pH and chemistry. How these bacteria survive their airborne journey is key to their persistence, but very little is known about how they protect themselves as they waft from one host to the next.
Now MIT researchers and their collaborators have discovered a family of genes that becomes essential for survival specifically when the pathogen is exposed to the air, likely protecting the bacterium during its flight.
Many of these genes were previously considered to be nonessential, as they didn’t seem to have any effect on the bacteria’s role in causing disease when injected into a host. The new work suggests that these genes are indeed essential, though for transmission rather than proliferation.
“There is a blind spot that we have toward airborne transmission, in terms of how a pathogen can survive these sudden changes as it circulates in the air,” says Lydia Bourouiba, who is the head of the Fluid Dynamics of Disease Transmission Laboratory, an associate professor of civil and environmental engineering and mechanical engineering, and a core faculty member in the Instiute for Medical Engineering and Science at MIT. “Now we have a sense, through these genes, of what tools tuberculosis uses to protect itself.”
The team’s results, appearing this week in the Proceedings of the National Academy of Sciences, could provide new targets for tuberculosis therapies that simultaneously treat infection and prevent transmission.
“If a drug were to target the product of these same genes, it could effectively treat an individual, and even before that person is cured, it could keep the infection from spreading to others,” says Carl Nathan, chair of the Department of Microbiology and Immunology and R.A. Rees Pritchett Professor of Microbiology at Weill Cornell Medicine.
Nathan and Bourouiba are co-senior authors of the study, which includes MIT co-authors and mentees of Bourouiba in the Fluids and Health Network: co-lead author postdoc Xiaoyi Hu, postdoc Eric Shen, and student mentees Robin Jahn and Luc Geurts. The study also includes collaborators from Weill Cornell Medicine, the University of California at San Diego, Rockefeller University, Hackensack Meridian Health, and the University of Washington.