Indian scientists spot harmful TB protein

Indian scientists have identified a protein expressed by the tuberculosis (TB) bacteria (Mycobacterium tuberculosis), which weakens the body's immune response to the deadly disease. They found that the protein, ESAT-6 (early secreted antigenic target protein 6), binds to white blood cells and disrupts their ability to fight off harmful viruses and bacteria. More than a third of the world's population is infected with TB and the infection rate is one new case every second. However, only one in 10 infected persons will develop symptoms of disease and that usually happens when their immune systems are weak. Left untreated, TB kills half its victims. The ESAT-6 protein in TB bacteria binds to certain receptors called TLR2 (Toll-like receptor 2) on the surface of macrophages - a type of white blood cell. When that happens, the macrophages can't function properly and are not able to fight infections by other micro-organisms. Macrophages are important 'sentry cells' in the immune system. They engulf and digest invaders like viruses and bacteria, and stimulate other immune cells to fight the invaders. Indian researchers from the Bose Institute in Calcutta created mice without TLR2 receptors on their macrophages. The scientists then extracted the macrophages and exposed the cells to TB bacteria. The researchers hope to find another cure for treating the disease after knowing what the TB protein can do. The protein could also be harnessed to stop diseases, which are caused by inflammation going out of control, such as hay fever, rheumatoid arthritis and atherosclerosis.