Discovery of new retroviruses in the genome of koalas

Historical viral infections can be traced in the vertebrate genome. For millions of years, these genomes were repositories of retroviruses that incorporated their code into gametes and were then inherited into what are called endogenous retroviruses, ERV.

Australian koalas carry a well-known retrovirus, KoRV. Researchers at Uppsala University have now examined the koala’s genome and found new endogenous retroviruses in the genome.

Viruses are associated with diseases

The previously known retrovirus is associated with diseases such as cancer in animals and is demonstrated as an endogenous retrovirus in the population. This has contributed to the koala becoming an interesting model for the real-time establishment of retroviruses and their health effects, which are now reinforced by the unexpected distribution pattern of new ERV lines.

One is related to a retrovirus in monkey skull that is commonly found in South and Central America. Several retroviruses of this type have been found in only a few individuals of koalas, indicating that they are relatively new. Researcher Mette Lilly of Uppsala University says this pattern may indicate that establishment is occurring among the population.

More active retroviruses can be found in animal species

Based on the distribution pattern in the population and comparisons of how different ERV lines differ, the researchers concluded that additional active retroviruses could be detected in koalas and other animal species that share the same environment.

The observations are a driving force in the search for potential active retroviruses in Australian animals that have yet to be identified.

Retroviruses left behind after retrovirus infection in the past now make it possible to reveal historical interactions between retroviruses and animal species, such as mapping how the virus is transmitted. Differences in the distribution pattern of the virus within host groups can also become valuable genetic markers, for example, in managing and protecting endangered species, says Patrick Gern of Uppsala University.

Scientific study:

Expansion of the retroviral strain in the koala genomePNAS

Contact:

Mette Lillie, Researcher in the Department of Ecology and Genetics, Zoology, Uppsala University, [email protected]

Patrick Jern, Researcher in the Department of Medical Biochemistry and Microbiology, Uppsala University, [email protected]