Viral fossils are the subject of an emerging field of evolutionary biology dubbed Paleovirology, the study of ancient viruses. Viral fossil or Paleovirus is an informal term for regions of genomes that originate from ancient germline integration of viral genetic material. The scientific term for such regions is endogenous viral element or EVE. EVEs that originate from the integration of retroviruses are known as endogenous retroviruses, or ERVs, and most viral fossils are ERVs. They may be traced to millions of years back, hence the terminology, although strictly speaking, it is impossible to detect an ancient virus in fossils. The most surprising viral fossils originate from non-retroviral DNA and RNA viruses.
Types of Viral fossil
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. Acronyms have been designated to describe different types of viral fossil.
NIRV: Non-retroviral Integrated RNA Virus
Viral fossils originating from non-retroviral RNA viruses have been termed Non-retroviral Integrated RNA Viruses or NIRVs. Unlike other types of viral fossils, NIRV formation requires borrowing the integration machinery that is coded by the host genome or by a co-infecting retrovirus.
Successful attempts to "resurrect" extinct viruses from the DNA fossils have been reported.
- Human Genome Project
- Insertional mutagenesis
- Endogenous retrovirus
- Viral eukaryogenesis
- Ancient DNA
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- "How to Resurrect an Extinct Retrovirus", Scientific American, November 2, 2006