While many animals face extinction due to poaching or loss of habitat, Tasmanian devil numbers are sbeing dramatically reduced due to a contagious tumor with a mortality rate of 100 percent. Called Devil Facial Tumor Disease (DFTD), it kills the animal in a matter of months. Now fresh research from the University of Cambridge has delivered new data on the mechanism of the disease which could increase the chances of developing a vaccine.
The iconic Tasmanian devil is only found in the wild in Tasmania, Australia's southern island state. DFTD was first observed in 1996 and as has since devastated the population by an estimated 85 percent and landed the carnivorous marsupial on the Endangered list.
DFTD usually spreads when the animals bite each other during fights over food– something Tasmanian devil's do a lot of. The view so far has been that the tumor cells avoided detection by the animals’ immune system because of the species’ small genetic diversity.
Several approaches to tackling the horrific disease have been tried including isolating healthy populations and studying potential cures such as the natural chemical EBC-46.
The recent Cambridge findings show that the DFTD cancer cells lack major histocompatibility complex (MHC) molecules, which allow the immune system to determine whether a cell presents a threat, and defend the system against it. That’s the bad news. The good news is that the genes that code for these molecules are still intact, with a chance of being reactivated. The scientists have demonstrated that the protein interferon-gamma, which triggers the immune response, could force the DFTD cells to express MHC molecules.
The researchers are cautiously optimistic about the potential of their findings to give the devils a chance of survival. "We still face some hurdles," said Dr Hannah Siddle, lead author of the paper from the University of Cambridge. "The tumor is evolving over time and any vaccine program would have to take this into consideration. Also, because of the difficulties of vaccinating a wild population, it may be more efficient to use a vaccine in the context of returning captive devils to the wild.”
Humans could benefit from the new research as well. Professor Jim Kaufman, from the University of Cambridge’s Department of Pathology, said that the appearance of a contagious form of cancer in humans is a matter of time. “This work gives us insight into how these diseases emerge and evolve,” he said.
Details of the new research, which was carried out in a partnership with the Universities of Tasmania, Sydney and Southern Denmark, appeared in the March 11 edition of the journal PNAS.