Bovine tuberculosis bacteria can survive and even grow within small, single-celled organisms that can be found in the soil or in the dung itself according to a new study conducted by researchers at the University of Surrey and the University of Geneva.
These single-celled organisms, known as amoebas, would have always been ideal habitats for this bacterium, so much so that it seems to have wanted to grow under these conditions. Over time the bacterium itself has progressed and evolved to infect large animals, including cattle, and to cause bovine tuberculosis.
The bacterium analyzed by researchers is Mycobacterium bovis, a bacterium that can cause bovine tuberculosis. The discovery was made through laboratory experiments: the researchers injected this bacterium into amoebas called Dictyostelium discoideum. Unlike other bacteria, which were digested and generally used as food sources, with Mycobacterium bovis these amoebas seemed to provide them with a kind of habitat. The bacterium not only remained unharmed but continued to survive for days.
Furthermore, researchers noted that the bacteria, once inside the amoebas, used particular genes that they usually use to avoid being killed by the immune cells of the large animals they infect. They used these genes to avoid being digested by amoebas. Inside amoebas, the bacterium, although slower, continued to grow and could replicate even at temperatures of 25° centigrade, which surprised researchers as it was believed that the bovine tuberculosis bacterium could only reproduce at temperatures of at least 37° centigrade.
These discoveries could perhaps help to combat bovine tuberculosis, a disease that infects cattle and can therefore represent a major problem for the whole livestock sector.