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Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. [1] [2] Viruses have short generation times, and many—in particular RNA viruses—have relatively high mutation rates (on the order of one point mutation or more per genome per round of replication).
New groups of viruses might have repeatedly emerged at all stages of the evolution of life. [16] There are three major theories about the origins of viruses: [16] [17] Regressive theory Viruses may have once been small cells that parasitised larger cells. Eventually, the genes they no longer needed for a parasitic way of life were lost.
Further, the viral origins of the modern eukaryotic nucleus may have relied on multiple infections of archaeal cells carrying bacterial mitochondrial precursors with lysogenic viruses. [4] The viral eukaryogenesis hypothesis depicts a model of eukaryotic evolution in which a virus, similar to a modern pox virus, evolved into a nucleus via gene ...
The rapid rate of evolution in viruses allows molecular clock models to be estimated from genetic sequences, thus providing a per-year rate of evolution of the virus. With the rate of evolution measured in real units of time, it is possible to infer the date of the most recent common ancestor (MRCA) for a set of viral sequences. The age of the ...
Furthermore, extensive virus evolution seems to have preceded the LUCA, since the jelly-roll structure of capsid proteins is shared by RNA and DNA viruses across all three domains of life. [75] [76] LUCA's viruses were probably mainly dsDNA viruses in the groups called Duplodnaviria and Varidnaviria.
New viruses and strains of viruses were discovered in every decade of the second half of the 20th century. These discoveries have continued in the 21st century as new viral diseases such as SARS [72] and nipah virus [73] have emerged. Despite scientists' achievements over the past one hundred years, viruses continue to pose new threats and ...
Gamma phage, an example of virus particles (visualised by electron microscopy) Virology is the scientific study of biological viruses.It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host cells for reproduction, their interaction with host organism physiology and immunity, the diseases they ...
While short-term (for example, intra-host) evolution is observable and measurable, viruses may appear to be relatively static in the long term for decades (as seen with antigenic variants of FMDV [102]) or longer. Intra-host evolution is generally more rapid than inter-host evolution, as documented with viruses [10] and other biological systems ...