Genome mapping of koalas is promising start for understanding how koalas respond to infectious diseases

Apr. 10, 2013 The "holy grail" for understanding how and why koalas respond to infectious diseases has been uncovered in an Australian-led, world-first genome mapping project.

The joint undertaking between QUT and The Australian Museum has unearthed a wealth of data, including the koala interferon gamma (IFN-g) gene -- a chemical messenger that plays a key role in the iconic marsupial's defence against cancer, viruses and intracellular bacteria.

Professor Peter Timms, from QUT's Institue of Health and Biomedical Innovation (IHBI), said the IFN-g gene was the key to finding a cure for diseases such as Chlamydia and Koala Retrovirus (KoRV), currently threatening the vulnerable species.

"We know koalas are infected with various strains of Chlamydia, but we do not know why some animals go on to get severe clinical disease and some do not," Professor Timms said.

"We also know that genes such as IFN-g are very important for controlling chlamydial infections in humans and other animals. Identifying these in the koala will be a major step forward in understanding and controlling diseases in this species. "

The research team -- made up of Professor Timms, Dr Adam Polkinghorne, Dr Ana Pavasovic and Dr Peter Prentis from QUT; The Australian Museum; veterinarians from Australia Zoo and the Port Macquarie Koala Hospital; and bioinformaticians from Ramaciotti Centre and UNSW -- have sequenced the complete transcriptome from several koala tissues.

Dr Polkinghorne from QUT's School of Biomedical Sciences said data sets from immune-related tissues of Birke, a koala who was euthanized following a dog attack, have revealed a wealth of information about the species' immune system including the sequences of at least 390 immune-related genes.

"Virtually nothing is known about the immune system of the koala and the absence of information has been a major hinderance to our efforts to understand how Chlamydia and KoRV infections lead to such debilitating disease in this native species," he said

Since finding the 'holy grail' the QUT team has developed a molecular test to measure IFN-g expression in the blood of healthy and diseased koalas, which has already been applied to a small group of wild koalas taken to the Australia Zoo Wildlife Hospital suffering ocular and reproductive tract disease.

The results will allow researchers to pull apart the complex immune response to better understand how to successfully treat and immunise the vulnerable koala population.

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Genome mapping of koalas is promising start for understanding how koalas respond to infectious diseases