Paleovirology

Paleovirology

Paleovirology

The study of ancient viruses


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


References

  1. Laidler, J.R.; Stedman, K.M. (2010). "Virus Silicification under Simulated Hot Spring Conditions". Astrobiology. 10 (6): 569–576. Bibcode:2010AsBio..10..569L. doi:10.1089/ast.2010.0463. PMID 20735248. S2CID 7274625.
  2. Katzourakis, Aris; Gifford, Robert J. (18 November 2010). "Endogenous Viral Elements in Animal Genomes". PLOS Genetics. 6 (11): e1001191. doi:10.1371/journal.pgen.1001191. PMC 2987831. PMID 21124940.
  3. Pakorn Aiewsakun, Aris Katzourakis (2015). "Endogenous viruses: Connecting recent and ancient viral evolution". J. Virol. 479–480: 26–37. doi:10.1016/j.virol.2015.02.011. PMID 25771486.
  4. Aris Katzourakis, Robert J. Gifford (2010). "Endogenous Viral Elements in Animal Genomes". PLOS Genet. 6 (11): e1001191. doi:10.1371/journal.pgen.1001191. PMC 2987831. PMID 21124940.
  5. Yong, Ed (3 March 2014). "Giant virus resurrected from 69,000-year-old ice". Nature. doi:10.1038/nature.2014.14801. S2CID 87146458.

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