A group of researchers at the University of Southampton have been studying the deceptively cute Tasmanian Devil for their unique form of contagious cancer, Devil Facial Tumour Disease (DFTD). The curious case is spread primarily by biting each other’s faces during fighting, and it has reduced the global population of the tassie by more than 60% in the past decade.
Now, a new study has revealed that a new emergent form of cancer, Devil Facial Tumour 2 (DFT2), has the potential to put the population under more threat than ever.
The species is currently endangered on the IUCN Red List, however, DFTD is known to cause close to 100% mortality in infected animals, and with a new threat to these already vulnerable animals, the situation is likely to worsen.
The second contagious cancer DFT2 was first discovered in 2014 and was known to only be prevalent in a small population. Now, however, research published by Dr Hannah Siddle has shown that this disease could be equally as detrimental and has potential to spread rapidly through the already weakened population. The Tasmanian Devil is only found on the island of Tasmania, which adds to their precarious position, as it means that disease easily spreads among these populations with no means of migration or movement, or gene flow between potentially resistant populations.
The reason that these cancers are so difficult to deal with is that all mammal cells have a molecule on their surface called major histocompatibility complex (MHC) which tells the immune system whether the cell is beneficial or one of their own cells, or whether it is an outside cell and could be a threat to the immune system. In the case of DFTD, these MHC complexes are down-regulated, making them invisible and no longer recognisable to the host immune system. However, in the case of DFT2, Siddle’s study has demonstrated that the cells do have MHC molecules, which is promising for the treatment of this new threat.
Although this sounds like a worst-case scenario for the already endangered Tasmanian Devil, the research that Siddle and her fellow researchers have been doing up to this point have put them in good stead for tackling this problem head-on, and for managing other vulnerable island-endemic species.
The paper has been published in eLIFE journal: The newly-arisen Devil facial tumour disease 2 (DFT2) reveals a mechanism for the emergence of a contagious cancer, DOI: 10.7554/eLife.35314