Tuberculosis infection process pinpointed

BMJ 1997; 315 doi: (Published 30 August 1997) Cite this as: BMJ 1997;315:501
  1. Jacqui Wise
  1. BMJ

    Mycobacterium tuberculosis, the bacterium that causes tuberculosis, uses an underhand trick to invade cells, researchers announced last week.

    The body's immune system normally tags any invading bacteria with proteins that alert macrophages to consume it. One of these proteins, C2a, then floats in the blood with no known function.

    The researchers from Washington University School of Medicine in St Louis showed that M tuberculosis manages to associate with this discarded C2a protein and use it to create a new label that helps the bacteria adhere to the macrophage and enter it. Once inside the macrophage, the mycobacteria multiply until the cell ruptures and the bacteria are then released to repeat the process (Science 1997;277:1091-3).

    Previous studies have described other invasion techniques used by mycobacteria, but this strategy stands out because it is used only by the types of mycobacteria that cause disease. Jeffrey Schorey, one of the lead authors, said: “Understanding how the bacterium invades cells may be an important first step towards developing a vaccine to prevent tuberculosis.”

    Tuberculosis is a growing problem, with eight million new cases of pulmonary tuberculosis a year and three million deaths. As many as one third of the world's population is infected with M tuberculosis.


    Tuberculosis kills three million people a year


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