Since the 1990’s Australian conservationists have been trying to rescue Tasmanian Devils from the ravages of Devil Facial Tumor Disease (DFTD). The cancer is fatal in more than 80 percent of cases.
The disease is a virus induced cancer exclusive to the species. It has been under extensive study for over 10 years. Early research was handicapped by a lack of knowledge of the disease and a lack of knowledge of the devils. Researchers now have a fuller understanding of the disease and its causes. They also know much more about the devils immune response – and the evasion techniques of the virus. Transmission appears to be through intimate contact. Biting is thought to be a major transmission source.
Recently, there has been more progress. Researchers have located a population showing resistance to the disease. In addition, conservationists have returned devils to the Australian mainland. They have been extinct on the mainland for several thousand years.
The resistance to the disease exhibited by the colony of devils appears to be counterintuitive. Devils have a low diversity of certain genes that that fight off disease. In most cases the more diverse the genes are, the stronger the immune system. It was assumed that the low diversity was the reason the virus could enter the devils.
Research on the immune devils suggests that low diversity might actually be a strength. The virus passes into the devils because the immune system in most devils does not recognize the virus as foreign. But it may be that the devils with the less diverse immune are more likely to recognize the virus and destroy it.
This is because the devils immune system has two genetic sequences. The virus has parts of both. Since most devils have both genetic sequences the virus is not recognized as foreign. The more immune devils have only one or the other sequence. When the virus enters these devils, the immune system recognizes the unknown sequence and destroys the virus.
This may lead to a change in strategy, away from interbreeding to expand diversity and toward isolation, allowing the immune devils to survive and eventually, it is hoped, thrive.
Meanwhile Aussie Ark and other conservationists have released devils into a nature reserve north of Sydney as part of a relocation project that may serve as a reserve against the DFTD. The animals were chosen for breeding suitability and health. Since devils eat both foxes and cats it is hoped that eventually the animals may aid in control of those invasive species.
Tasmanian devils are the largest marsupial carnivore weighing up to 26 pounds. They are mostly nocturnal and are both scavengers and hunters eating prey as small as insects and as large as snakes and reptiles.