Viral fossils buried in DNA may protect against future virus infections, a new marsupial study suggests.

Researchers at UNSW Sydney, who examined the DNA and RNA of 13 Australian marsupial species, believe that viral fossils may be helping protect animals from infection.

«These viral fragments have been retained for a reason. Over millions of years of evolution, we would expect all DNA to change, however these fossils are preserved and kept intact,» says doctoral student and lead researcher Emma Harding, from UNSW’s School of Biotechnology and Biomolecular Sciences.

«Our study shows how the viruses buried in the animals’ DNA are used to make what we call non-coding RNAs, which carry out tasks inside the animal cells such as protecting against outside infection.

«The animal DNA has basically grabbed a viral sequence — which used to harm it — and ends up using it for its own benefit.»

If Ms Harding is right, her theory may have important implications for our understanding of the role of viral fossils in our own DNA and the animal kingdom in general. For example, viral fossils can be turned into RNA that binds specifically to the virus — and destroys it — if it tries to infect the cell again.

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Materials provided by University of New South Wales. Original written by Lachlan Gilbert. Note: Content may be edited for style and length.