Breakthrough in Australian hunt for devil vaccine

Australian scientists on Tuesday hailed a breakthrough discovery in the hunt for a vaccine against a savage facial tumour disease threatening the endangered Tasmanian devil with extinction. A research team headed by University of Tasmania immunologist Greg Woods has established how the disfiguring cancer, spread from devil to devil by biting during fights, manages to take hold and grow so rapidly. Devil facial tumour disease (DFTD), first recorded in the wild in 1996, typically causes death within three to six months and has seen numbers plunge 91 percent in the wild to near-critical levels. Scientists have long believed that successive generations of in-breeding that has seen the species' genetic diversity dwindle, weakening their immune systems, was the main factor in the cancer's devastating impact. But Woods said his team found a key immune-triggering marker usually seen on the surface of mammalian cells, called the major histocompatibility complex molecule (MHC), was not found in DTFD cells. Without MHC markers the tumour's cells were not seen as foreign by the devils' immune systems and allowed to proliferate. Importantly, Woods said the genetic code for MHC molecules remained intact in DFTD cells, meaning they could potentially be switched back on. "This work highlights the potential for the development of a vaccine," Woods said. "By introducing signalling molecules such as interferon-gamma, a protein which triggers the immune response, the DFTD cells can be forced to express MHC molecules." The team's next step would be to study cells from devils who had relapsed after initial success in fighting off the tumour in the wild "to understand the potential for the evolution of tolerance to the disease". The study, published in the latest edition of the Proceedings of the National Academy of Sciences, was a collaboration between the University of Tasmania and Cambridge, Sydney and South Denmark universities. Research on the DFTD is a small field and many of its top experts were involved in this study. DFTD has seen the rat-like, carnivorous nocturnal marsupial plunge from a pest species to endangered in a very short period, with their numbers -- once in excess of 250,000 -- now estimated in the low tens of thousands. They once roamed Australia but the devil is thought to have died out on the mainland several hundred years ago and are now isolated to Tasmania, an island state in the southern Tasman sea.