About This Project

Koala retrovirus (KoRV) causes cancer in koalas with up to 40% of captive animals dying from lymphoma. To make things complicated, many koalas are born with the virus, making it really hard to control control. We plan to set up diagnostic testing for koalas in European zoos, so we can monitor their KoRV status. This will let us predict which koalas might get cancer, and help us improve population health and plan breeding programs."

Ask the Scientists

What is the context of this research?

All koalas in Northern Australia are infected with Koala Retrovirus (KoRV) which has become part of their genome. Retroviruses weaken the immune system, causing hosts to become more susceptible to cancer and chlamydia . Koalas in northern Australia have much higher rates of disease than those in southern Australia, where KoRV is lower. Eliminating and controlling KoRV in captive and wild populations is tricky as we can't just breed KoRV free animals from the south as they also have a number of genetic problems. We know that animals with high viral loads or certain types of virus are more likely to be diseased and we think that a good compromise is to select animals with low KoRV levels for breeding or release.

What is the significance of this project?

It is challenging to do long-term studies of wild populations to understand which animals will progress from merely having KoRV to having more significant disease. Therefore, we plan to monitor captive animals for KoRV viral loads, viral diversity, and disease rates. We suspect that animals with high viral loads to begin with, or those with the "B" variant of the virus, are more likely to go on and develop secondary diseases. This study will demonstrate whether that is true or not. Being able to predict which animals are more likely to get sick will let population managers (both captive and wild) focus resources, like treating sick koalas, on those most likely to stay healthy and contribute to the future population.

What are the goals of the project?

We plan to use qPCR tests to identify which variant of KoRV each koala carries, and link this to their long term health. We are going to design and set up qPCR tests for all the known envelope variants of KoRV (A, B, D and I) to complement the current qPCR test for the polymerase gene which does not tell us which strain they have. We will also set up qPCR tests for a different region of the virus (the LTR region) as we know that some variants of KoRV are missing parts of the other genes of the virus. These tests will then be used for long term studies of animals in European zoos. These animals are very closely monitored and we will have good health records to match with their virus tests to work out whether we can predict which animals go on to get lymphoma.