New inherited retroviruses identified in the koala genome
Historical virus infections can be traced in the genome of vertebrates. For millions of years, these genomes have been repositories for retroviruses that incorporated their code into germline cells and were inherited as endogenous retroviruses (ERVs). Researchers from Uppsala University are now delivering new findings on retroviral settlement in the koala genome. The findings are published in the journal PNAS†
The researchers examined the koala genome and found new ERV lines, in addition to the previously known koala retrovirus (KoRV). KoRV has been linked to disease in koalas, such as cancer, and is in the process of establishing itself in the population as ERVs. This has contributed to the koala being seen as a potential model for the real-time settlement of retroviruses and their health effects, a potential now enhanced by the unexpected distribution pattern of new ERV lines.
“By screening available koala genomes, we identified new ERV lines. One is related to the squirrel monkey retrovirus, which is normally found in South/Central America. Many ERVs of this type are only found in a few koala individuals, which indicates that they are relatively new. It may even indicate an ongoing settlement in the population,” said Mette Lillie, lead author of the study.
Large-scale sequencing of whole genomes of species populations allows researchers to draw parallels between the new ERVs and retroviruses that are currently establishing themselves, such as KoRV. Based on the distribution pattern of ERVs in the population and comparisons of how ERV lines differ, the researchers conclude that additional active retroviruses may be discovered in koalas and other animal species that share the same environment. The observations are a driving force in the search for potentially active retroviruses in the Australian fauna, which have not yet been identified.
“The ERVs left behind after retrovirus infections in the past now make it possible to uncover historical interactions between retroviruses and animal species, such as mapping how virus transmission has occurred. Variations in ERV distribution patterns within host populations may also be valuable as genomic markers , for example in the management and protection of endangered species,” said Patric Jern, who led the study.
Retroviruses rewrite the koala genome and cause cancer
Extension of a retrovirus lineage in the koala genome, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2201844119†
Quote: New inherited retroviruses identified in the koala genome (2022, June 13) retrieved June 14, 2022 from https://phys.org/news/2022-06-inherited-retroviruses-koala-genome.html
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