Possibility of disease resistance in the northwest

The MHC (major histocompatibility complex) of an organism is a group of genes that allows its immune system to differentiate between its own living tissues and any foreign cellular material that finds its way into its own body (e.g. transmitted tumour cells from a member of its own species). In most species there is a tremendous amount of MHC diversity within a given population. Hence, for example, the challenge of matching human donor organs with appropriate recipients.

Tasmanian devils however, are so genetically similar that they can practically be regarded as ‘universal donors’ of organs to one another. This remarkable lack of MHC diversity among Tasmanian devils is regarded as a key factor in the rapid spread of DFTD within the wild population. Therefore, increased MHC variation among devils in the northwest of the state, at the current disease front, may offer real hope for the possibility of a proportion of the devils being resistant to DFTD – if the disease behaves the way it is hoped it will behave. To date, DFTD has not behaved predictably, and any optimism for sustained resistance to the disease by even a small number of devils is tempered by the grim discovery in mid-2008 that the tumour had begun to evolve into a number of identifiable strains, perhaps in response to the varying immune defences of devils encountered during its westward march.

Leading MHC/Tasmanian devil researcher Dr Kathy Belov of Sydney University, has maintained a positive outlook about the possibility of disease resistance among some portion of the devils in the northwest of the state. Dr Belov nevertheless continues to wholeheartedly support the commitment of the STTD Program to encourage and facilitate the establishment of an effective captive population of Tasmanian devils on the Australian mainland, of the widest possible genetic variation. She provides an advisory role in the development of Devil Ark.

As Dr Belov put it recently, even in the eventuation of a ‘best-case’ outcome – where a particular sub-group of devils in the far northwest exhibit sustained resistance to DFTD – the long-term survival of the species will still rely upon the preservation of a far wider range of genetically varied devils from as wide a geographic range as possible. In short, the aims of the Devil Ark program provide an essential element to any successful plan to avert the eventual extinction of the Tasmanian devil. Few, if any, researchers currently believe otherwise.

Sydney University researcher Dr Kathy Belov (left) and her research team acquiring tissue samples from Australian Reptile Park devils.

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