Paleovirology Explained

Paleovirology is the study of viruses that existed in the past but are now extinct. In general, viruses cannot leave behind physical fossils,[1] therefore indirect evidence is used to reconstruct the past. For example, viruses can cause evolution of their hosts, and the signatures of that evolution can be found and interpreted in the present day.[2] Also, some viral genetic fragments which were integrated into germline cells of an ancient organism have been passed down to our time as viral fossils,[2] or endogenous viral elements (EVEs).[3] EVEs that originate from the integration of retroviruses are known as endogenous retroviruses, or ERVs,[4] and most viral fossils are ERVs. They may preserve genetic code from millions of years ago, hence the "fossil" terminology, although no one has detected a virus in mineral fossils.[2] The most surprising viral fossils originate from non-retroviral DNA and RNA viruses.

Terminology

Although there is no formal classification system for EVEs, they are categorised according to the taxonomy of their viral origin. Indeed, all known viral genome types and replication strategies, as defined by the Baltimore classification, have been found in the genomic fossil record.[5] [6] Acronyms have been designated to describe different types of viral fossil.

Other viral fossils originate from DNA viruses such as hepadnaviruses (a group that includes hepatitis B).[10]

Resurrection

Successful attempts to "resurrect" extinct viruses from the DNA fossils have been reported.[11] In addition, Pithovirus sibericum was revived from a 30,000-year-old ice core harvested from permafrost in Siberia, Russia.[12] [13]

See also

Notes and References

  1. Laidler . J.R. . Stedman . K.M. . 2010 . Virus Silicification under Simulated Hot Spring Conditions . Astrobiology . 10 . 6. 569–576 . 10.1089/ast.2010.0463 . 20735248 . 2010AsBio..10..569L . 7274625 .
  2. Emerman . M. . Malik . H.S. . 2010. Paleovirology – Modern Consequences of Ancient Viruses . . 8 . 2. e1000301. 10.1371/journal.pbio.1000301 . 20161719 . 2817711 . free .
  3. Katzourakis. Aris. Gifford, Robert J.. Endogenous Viral Elements in Animal Genomes. PLOS Genetics. 18 November 2010. 6. 11. e1001191. 10.1371/journal.pgen.1001191. 21124940. 2987831 . free .
  4. Weiss. RA. The discovery of endogenous retroviruses.. Retrovirology. Oct 3, 2006. 3. 67. 17018135. 10.1186/1742-4690-3-67. 1617120 . free .
  5. Endogenous viruses: Connecting recent and ancient viral evolution . Pakorn Aiewsakun, Aris Katzourakis . J. Virol. . 2015 . 10.1016/j.virol.2015.02.011 . 25771486 . 479–480 . 26–37. free .
  6. Endogenous Viral Elements in Animal Genomes . Aris Katzourakis, Robert J. Gifford . PLOS Genet . 2010 . 10.1371/journal.pgen.1001191 . 21124940 . 2987831 . 6 . 11. e1001191 . free .
  7. Taylor. D. J.. J. Bruenn. The evolution of novel fungal genes from non-retroviral RNA viruses. BMC Biology. 2009. 7. 10.1186/1741-7007-7-88. 20021636. 88. 2805616 . free .
  8. Koonin. E.. Taming of the shrewd: novel eukaryotic genes from RNA viruses. BMC Biology. 2010. 8. 10.1186/1741-7007-8-2. 2. 2823675. 20067611 . free .
  9. Lida . Atsuo . Heritable endogenization of an RNA virus in a mammalian species . bioRxiv . 2020 . 10.1101/2020.01.19.911933. free .
  10. http://www.scientificamerican.com/article.cfm?id=fossil-virus-bird-genome "Ancient "Fossil" Virus Shows Infection to Be Millions of Years Old"
  11. http://www.scientificamerican.com/article.cfm?id=how-to-resurrect-an-extin "How to Resurrect an Extinct Retrovirus"
  12. Yong . Ed . 10.1038/nature.2014.14801 . Giant virus resurrected from 69,000-year-old ice . Nature . 3 March 2014. 87146458 .
  13. News: Rebecca . Morelle . Rebecca Morelle . 30,000-year-old giant virus 'comes back to life' . 3 March 2014 . BBC News.

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