For years scientists have sought to unravel the mystery of why about 90% of people infected by Mycobacterium tuberculosis, the bacteria that cause tuberculosis (TB), remain symptom-free for years, while the remaining 10% become sick and may die. A December 15, 2013 study in Nature Medicine by Sarah Fortune, the Melvin J. and Geraldine L. Glimcher associate professor of immunology and infectious diseases at Harvard School of Public Health (HSPH), and University of Pittsburgh researchers revealed new findings about lung lesions in laboratory animals with TB that may help guide scientists seeking to better understand the disease.
The researchers discovered that animals that get sick with tuberculosis and those that remain symptom free for life do not differ as much as previously believed. Indeed, the immune responses in both groups of animals are very effective at killing most of the infecting bacteria. Animals get sick because the immune system loses control of infection at just one or a few sites in the body. These findings provide researchers with a new road map for developing a TB vaccine—where the solution may lie in comparing sites of control with sites of immune failure. “We need to really have a lesional perspective in order to understand what we are going to need to do to build a TB vaccine,” said Fortune in a January 2014 Nature Medicine podcast.