Last of the Tasmanian devils? Infectious cancer to blame

Last of the Tasmanian devils? Infectious cancer to blame


♫MUSIC♫ ANDREW STROFER: Now Tasmanian devils are marsupials, so they’re a type of mammal that has a pouch to hold their young just like kangaroos. And they’re from Australia. They originally were found on the mainland Australia and the island of Tasmania. And a few hundred years ago, they went extinct on the mainland and now are only found in Tasmania, which is a small island south of Melbourne and off of the southern coast of Tasmania. Another interesting fact about Tasmanian devils is that they’re carnivorous marsupials. That is, they’re meat-eaters. Most of these marsupials, like kangaroos, only are vegetarians. That is, they’re herbivores. So Tasmanian devils are now the world’s largest carnivorous marsupial after the Tasmanian tiger went extinct, probably sometime in the 1940’s. We’re not sure exactly how the devils originally got Tasmanian devil facial tumor disease. It started in the northeastern part of Tasmania and was first discovered in 1996. And since then, it’s caused by an infectious cancer. That is, although we’re finding out that a lot of cancer is maybe associated with viral infections, this is actually a tumor and cancer that’s transmissible from one individual to another. And so this cell line has now moved through thousands of devils and about 80% of the way across Tasmania, leaving populations highly decimated as it’s gone through. From the first standpoint, this rare, infectious cancer is a fascinating disease to begin with. How is it that individuals are susceptible to a cancer that’s found in another individual? And this is – there’s only a couple of other instances of infectious cancers that we know about in the animal kingdom, which includes a cancer that is transmitted as a venereal disease between dogs and one that was found in Siberian hamsters in a laboratory setting several years ago. So one of the big questions is – of course, we’re concerned a lot about cancers in humans – is: Why is this particular type of cancer infectious from one individual to another? And why is it so long-lived because we know that cancer cells generally are very unstable. So from a general health stamping, this cancer can be used as a model to maybe increase our understanding of how cancers operate in general. But one of the big questions for Tasmanian devil is: Some of the current models predict that the cancer will actually cause extinction in devils. And so this is an iconic animal from Australia. Of course, in the US we made a cartoon character about it. And so we’re really concerned about this – preserving this animal as part of the natural history of Australia. But another really interesting question is: We want to actually – so the goal of this research is to actually predict disease transmission in populations that are uninfected. We’ll be using genomic analyses of devils that actually have survived the infections in old populations that have been infected for a while to see what parts of their genome give them resistance, seem to be giving them resistance, to the tumor. And then we can look for devils that may have those similar genomic components in new populations that are uninfected. So another conservation goal of this work is to actually take those devils that seem to have the genetic components that make them the most highly resistant and use those to help populate captive breeding programs off the main island of Tasmania, in order to protect devils if they do, unfortunately, go extinct on the mainland of Tasmania.