All viruses, including relatives of HIV and Ebola, could potentially be 'stowaways' transmitted from generation to generation for millions of years, according to new research.
A team from Oxford University and the Aaron Diamond AIDS Research Center built on the earlier discovery of the 'fossilised remains' of an ancient HIV-like virus in the genomes of animals including sloths, lemurs and rabbits.
They discovered that many more different types of viruses are capable of being transmitted from generation to generation, with 'fossil viruses' turning up in the genomes of creatures as different as mosquitoes, wallabies, and humans.
"Many of these viruses, such as the ancestors of Ebola, are far more ancient and spread across many more animal groups than anyone ever suspected,’ says Dr Aris Katzourakis of Oxford’s Department of Zoology.
"We’ve demonstrated that viruses have been integrating within animal genomes for at least 100 million years. We’ve also shown that, in some cases, viral genes have been domesticated by their hosts, and put to use by the hosts for their own purposes, demonstrating that captured viral sequences may have played a larger than expected role in animal evolution."
The findings could lead to new approaches to combating viruses such as HIV and Ebola. It could also help scientists decide which viruses that cross species are most likely to cause dangerous pandemics in the future.
"We have discovered a large and diverse set of virus sequences preserved in animal genomes, which together include representatives of all known viral groups," says Dr Katzourakis.
"This demonstrates a potential for endogenisation for any virus, and illustrates that viral fossil records may be uncovered for many elusive viral groups."