DNA Key to Some Bacterial Infections Found

U.S. researchers have discovered a mechanism by which the bacterium Mycobacterium avium compromises the body’s immune system.

Oregon State University scientists said M. avium infects tissue cells — macrophages — resulting in serious lung infections and is prevalent in emphysema and AIDS patients, among other diseases.

The key to the bacterium’s ability to enter environmental amoebas — and ultimately humans — is an island of genetic material acquired through evolution from another bacterium, said to Oregon State University Professor Luiz Bermudez.

Without these acquired genes, the bacterium is very inefficient in infecting environmental amoeba, which is the environmental host, Bermudez said. In fact, its efficiency is close to zero. But with this ‘island’ of acquired genetic material, the bacterium finds a way to get inside the cells and it takes control, not the phagocyte.

Phagocytes are cells that engulf and digest pathogens and cellular debris, and in humans serve as the body’s initial immune response.

The study, conducted in collaboration with University of Nebraska researchers, appears in the online edition of the Proceedings of the National Academy of Sciences.