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Breakthrough Could Save The Tassie Devil

Wednesday, October 3, 2007

Diseased Tasmanian Devil

Credit: Sydney University
Sydney University researchers have discovered why the Devil Facial Tumor Disease which has wiped out 90 per cent of some native Tasmanian Devil populations has been so devastating.

The Devil Facial Tumor Disease (DFTD) emerged in the devil population 10 years ago and has steadily spread throughout Eastern Tasmania, decimating devil numbers and threatening the existence of the species in the wild.

Published online in the Proceedings of the National Academy of Sciences, a team of researchers led by Dr Katherine Belov from Sydney University's School of Veterinary Science has confirmed that the tumor is a contagious clonal cell line, essentially a tissue graft that originated from a single source and is now passed between individuals.

"The tumor genotypes are genetically identical (clonal) across the disease range. However, tumor genotypes are different to host genes. We propose that this tumor arose in a single individual and has spread through the population by biting during fights for food and mates," said Dr Belov.

"We found that the Devils do not mount an immune response against the tumor," said Dr Belov. "This was due to a loss of genetic diversity in the most important immune gene region of the genome: the Major Histocompatibility Complex (MHC). Matching of MHC genes is the key to successful tissue or organ transplants. In the case of the devil, genetic diversity at MHC genes is so low, and the MHC type of the tumor and host are so alike, that the host does not see the tumor as "non-self," she said.

"What also worries me is that many other wildlife populations are going through similar bottlenecks - koalas on Kangaroo Island, platypuses on King Island. Loss of genetic diversity in these genes just opens the door for emergence and rapid spread of new and old disease," said Dr Belov.

This information provides a deeper understanding of the nature of the disease and will aid in developing effective disease control strategies. "Essentially, there are no natural barriers to the spread of the disease, so affected individuals must be removed from populations to stop disease transmission," said Dr Belov.

The Sydney University team worked in collaboration with researchers at the University of Tasmania, the Tasmanian Department of Primary Industries and Water and the Australian Museum to understand how a tumor can be contagious.

Source: Sydney University

Time Stamp: 10/3/2007 at 5:06:22 AM CST

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