Retrovirus invading koalas

The koala genome is in the middle of an invasion from a retrovirus, presenting a unique opportunity to observe how these viruses incorporate themselves into a wild species, researchers report in this week's Nature.Retroviruses that have integrated themselves into their host genomes, known as endogenous retroviruses, are widespread among mammals. However, all other endogenous retroviruses embedded themselves into genomes thousands -- if not millions -- of years ago, according to coauthor Paul Young at the University of Queensland in Australia. "By studying how koalas deal with this viral invasion, it will give us clues as to how retroviruses first engaged with our ancestors and those of other species," Young told The Scientist.Over time, mutations and deletions often inactivate endogenous retroviruses. Scientists previously identified the koala retrovirus (KoRV) as an endogenous retrovirus because it was present in all koalas tested for it during an earlier experiment. However,...