A toxic gas present in air pollution and tobacco smoke plays a significant role in masking tuberculosis infection and so contributes to its spread, according to UAB research published online in The Journal of Biological Chemistry.

Carbon monoxide (CO), a colorless, odorless gas present in tobacco smoke and emissions and produced naturally in brushfires and volcanic gas, causes the bacteria that produces tuberculosis to become dormant and escape detection.

The researchers discovered that Mycobacterium tuberculosis (Mtb) proteins sense CO at the molecular level and the interaction spurs a series of biological steps that sends Mtb into latency. "This is the first description of a role for CO in mycobacterial pathogenesis," said Adrie Steyn, Ph.D., assistant professor of microbiology and lead author.

These findings may help speed up clean-air measures to improve public health and may lead to the discovery of new ways to fight extreme drug-resistant tuberculosis, or XDR TB, the researchers said.

Undetectable forms of tuberculosis hinder screening and eradication efforts, and tuberculosis is the leading cause of death in the world from a single bacterial infection, killing 1.5 million people per year.

"We're talking about huge socio-economic and public health implications," said Steyn.

Environmental exposure to CO is not the only cause of this latency. The study also showed that low levels of CO in the body caused by inflammation, infection and oxidative stress are capable of triggering tuberculosis latency, Steyn said.

Research published by Steyn in 2007 showed that combined production of CO, oxygen and nitric oxide should be used in future models of Mtb persistence.