Slumber's end

2019-03-07 07:11:01

By Andy Coghlan PROTEINS that deliver a wake-up call to dormant bacteria could be used to fight tuberculosis, says Michael Young of the University of Wales at Aberystwyth. He and his collaborators are testing the signalling proteins’ potential as vaccines for priming the immune system to attack Mycobac terium tuberculosis. Nearly four years ago, Douglas Kell at Aberystwyth and Arseny Kaprelyants of the Bach Institute of Biochemistry in Moscow discovered that Micrococcus luteus, a harmless relative of M. tuberculosis, secretes a wake-up protein to stir dormant neighbours (New Scientist, 6 January 1996, p 13). They dubbed the protein resuscitation promoting factor (rpf). The researchers wondered whether M. tuberculosis produces its own wake-up protein, and found that it has five genes similar to the one which produces rpf in M. luteus. They inserted copies of all five into Escherichia coli and the bacteria are now producing the proteins that the genes encode. People infected with TB are difficult to treat because the bacteria can lie dormant in the body. In this state they are unaffected by antibiotics and do not spark an immune response. But they can reactivate and cause disease when the body’s immune system is compromised. There are two ways the wake-up proteins might be used therapeutically. One is to trick the bacteria out of dormancy so that they can be zapped with antibiotics. The other is to use the proteins as vaccines. An injection of wake-up proteins might prime the body to notice a subsequent infection earlier than would otherwise be the case and attack the bacteria as they activate. The Moscow team is already testing the original rpf protein as a TB vaccine. Next they plan to test the new M. tuberculosis protein. “We may get a stronger response using proteins derived from M. tuberculosis,