Senior author Dr. Robert L. Modlin, chief of dermatology at the David Geffen School of Medicine at the University of California, Los Angeles, said these clever bacteria hijack the body's immune response so that they can hide out, unhindered, inside cells.
The findings might also help explain how viral infections like the flu make people more susceptible to subsequent bacterial infections such as pneumonia.
The study is particularly relevant to tuberculosis, which kills 1.4 million people worldwide each year. In the case of the recent Los Angeles outbreak, the findings could provide clues as to how the flu and a lack of vitamin D may have given the tuberculosis bacterium an edge, Modlin said.
"With 8.7 million in the world falling ill with tuberculosis each year, a better understanding of how these bacteria avoid our immune system could lead to new ways to fight them and to better, more targeted treatments," Modlin said in a statement.
The protection of the immune system against bacteria-based diseases and infections depends on the critical response of T cells -- white blood cells that play a central role in fighting infections -- and in particular on the release of a protein called interferon-gamma. Interferon-gamma utilizes the vitamin D hormone to alert and activate cells to destroy invading bacteria, Modlin said.
The findings were published in the journal Science.