Viral fossil
Encyclopedia
Viral fossil is an informal term for pieces of genetic code
(DNA
insertions) of a virus
in the genome
of a modern-day host organism. These viruses and their insertions are called fossil viruses or paleoviruses. They may be traced to millions of years back, hence the terminology, although strictly speaking, it is impossible to detect an ancient virus in fossil
s. Viral fossils are among the subject of a recent field dubbed paleovirology.
Most known types of viral fossils originate from retroviruses and are termed endogenous retrovirus
es (ERVs). Other viral fossils originate from DNA viruses such as hepadnaviruses (a group that includes hepatitis B). The most surprising viral fossils originate from non-retroviral RNA viruses. These 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.
Genetic code
The genetic code is the set of rules by which information encoded in genetic material is translated into proteins by living cells....
(DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
insertions) of a virus
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
in the genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
of a modern-day host organism. These viruses and their insertions are called fossil viruses or paleoviruses. They may be traced to millions of years back, hence the terminology, although strictly speaking, it is impossible to detect an ancient virus in fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s. Viral fossils are among the subject of a recent field dubbed paleovirology.
Most known types of viral fossils originate from retroviruses and are termed endogenous retrovirus
Endogenous retrovirus
Endogenous retroviruses are sequences in the genome thought to be derived from ancient viral infections of germ cells in humans, mammals and other vertebrates; as such their proviruses are passed on to the next generation and now remain in the genome....
es (ERVs). Other viral fossils originate from DNA viruses such as hepadnaviruses (a group that includes hepatitis B). The most surprising viral fossils originate from non-retroviral RNA viruses. These 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.