Christina Stallings, PhD

How Protein Helps TB Bacteria Stand Up to Immune System’s Assaults

Mycobacterium tuberculosis (Mtb), which infects one-third of the world’s population, caused an estimated 1.4 million TB-related deaths in 2010. This health crisis is worsened by the alarming emergence of drug-resistant strains.

“We will apply for funding for a larger National Institutes of Health grant based on everything we’ve done so far, which we hope will lead to new drug targets for TB.”
During infection, mycobacteria must withstand an arsenal of assaults by the body’s immune system. “Mtb is a pretty amazing pathogen,” says Christina Stallings, PhD. “It can infect people for their entire lives, even if they have a robust immune system that fights it.” That is because Mtb has its own defenses that fight the immune system, she explains.

Using an American Lung Association Biomedical Research Grant, Dr. Stallings is studying how Mtb defends itself. She is focusing on a protein called mycobacterial CarD, which regulates the response of Mtb to assaults by the immune system, and is essential for acute and persistent infection.

Dr. Stallings has found that when a mutant form of Mtb that has less CarD is exposed to immune system assaults, the bacteria is much more sensitive and dies much faster. “That showed us that Mtb absolutely needs CarD to combat these stresses imposed by the immune system,” she says. She then used this strain of Mtb and infected mice with it. She found that the mouse immune system was able to kill the bacteria.

In the second year of her grant, Dr. Stallings is studying the mechanism by which CarD helps Mtb fight the immune system. “If we can figure out how it works, we could target it with new antibiotics and chemicals to compromise its activity,” she says.

The American Lung Association grant has been instrumental in her research, she says. “The grant has allowed us to characterize the protein, produce a mutant version of Mtb and bring it to a mouse model. We will apply for funding for a larger National Institutes of Health grant based on everything we’ve done so far, which we hope will lead to new drug targets for TB.”