A consortium of 54 scientists from around the world came up with the genetic blueprint which sheds light on the fury marsupial's diet as well as the population declines it has suffered as a result of urbanisation and disease.

The researchers say their findings may aid work on a vaccine to protect koalas against one of their biggest killers - chlamydia - as well as aid conservationists in their efforts to protect their dwindling populations.

"In the same the way that the human genome has revolutionised medicine for humans, to the point where you can have your genome sequenced and have your medicine tailor designed, then the idea is that this could be possible for koalas," lead researcher Professor Rebecca Johnson, of the Australian Museum, told AAP.

Using a "supercomputer" at the University of NSW, the scientists sequenced more than 20,000 koala genes and came up with a genome slightly larger than its human counterpart.

Their work revealed information about how the koala survives on a diet of toxic eucalyptus leaves, the impact of chlamydia on their immune system, the protective properties in a mother koala's milk, their population diversity in different parts of Australia and evolution.

Koala numbers have plunged in northern Australia since European settlement but increased in parts of Victoria and South Australia.

Conservationists say the uneven spread is part of the problem in trying to manage the koala population, which is estimated to have fallen to about 329,000.

Another big challenge comes from chlamydia, which can cause infertility in females and blindness, and the widespread retrovirus, an AIDS-like virus about which little is known.

The research found that many different types of the retrovirus have been inserted more than 100 times in the koala genome, and new light was shed on the particular gene categories related to the development of chlamydia.

Prof Johnson said the information could help scientists work out which forms of retrovirus were most dangerous in koalas as well as why some were resistant to chlamydia - information that could aid work on vaccines for both conditions.

"Vaccines for both are in development, which is pretty critical because chlamydia is pretty debilitating in some parts of the koala population," she said.

The study also discovered koalas have high levels of a type of enzyme in their livers that allows them to survive on eucalyptus leaves toxic to most other animals.

Koala populations in NSW and Queensland were also found for the first time to have significant levels of genetic diversity.

"Ensuring this genetic diversity is conserved in concert with other conservation measures to protect habitat, reduce vehicle strikes, dog attacks and disease, are the keys to the long-term survival of the koala," Prof Johnson said.

The findings were published online by the journal Nature Genetics on Tuesday.

Australian Associated Press