Editing Genetic variation (section)

==RNA viruses==

A high mutation rate caused by the lack of a proofreading mechanism appears to be a major source of the genetic variation that contributes to RNA virus evolution.<ref name="Carrasco2017">{{Cite journal |doi=10.1093/ilar/ilx026 |doi-access=free |pmc=7108571 |pmid=28985316|title=Are RNA Viruses Candidate Agents for the Next Global Pandemic? A Review |year=2017 |last1=Carrasco-Hernandez |first1=R. |last2=Jácome |first2=Rodrigo |last3=López Vidal |first3=Yolanda |last4=Ponce De León |first4=Samuel |journal=Ilar Journal |volume=58 |issue=3 |pages=343–358 }}</ref>  Genetic recombination also has been shown to play a key role in generating the genetic variation that underlies RNA virus evolution.<ref name = Carrasco2017/>  Numerous RNA viruses are capable of [[genetic recombination]] when at least two viral [[genome]]s are present in the same host cell.<ref name = Barr2010>{{cite journal | vauthors = Barr JN, Fearns R | title = How RNA viruses maintain their genome integrity | journal = The Journal of General Virology | volume = 91 | issue = Pt 6 | pages = 1373–87 | date = June 2010 | pmid = 20335491 | doi = 10.1099/vir.0.020818-0 | doi-access = free }}</ref>  RNA recombination appears to be a major driving force in determining genome architecture and the course of viral evolution among ''[[Picornavirus|Picornaviridae]]'' ([[positive-sense single-stranded RNA virus|(+)ssRNA]]) (e.g. [[poliovirus]]).<ref name="pmid31540135">{{cite journal | vauthors = Muslin C, Mac Kain A, Bessaud M, Blondel B, Delpeyroux F | title = Recombination in Enteroviruses, a Multi-Step Modular Evolutionary Process | journal = Viruses | volume = 11 | issue = 9 | date = September 2019 | pages = 859 | pmid = 31540135 | pmc = 6784155 | doi = 10.3390/v11090859 | doi-access = free }}</ref> In the ''[[retrovirus|Retroviridae]]'' ((+)ssRNA)(e.g. [[HIV]]), damage in the RNA genome appears to be avoided during [[reverse transcriptase|reverse transcription]] by strand switching, a form of genetic recombination.<ref name="pmid1700865">{{cite journal | vauthors = Hu WS, Temin HM | title = Retroviral recombination and reverse transcription | journal = Science | volume = 250 | issue = 4985 | pages = 1227–33 | date = November 1990 | pmid = 1700865 | doi = 10.1126/science.1700865 | bibcode = 1990Sci...250.1227H }}</ref><ref name="pmid30307534">{{cite journal | vauthors = Rawson JM, Nikolaitchik OA, Keele BF, Pathak VK, Hu WS | title = Recombination is required for efficient HIV-1 replication and the maintenance of viral genome integrity | journal = Nucleic Acids Research | volume = 46 | issue = 20 | pages = 10535–45 | date = November 2018 | pmid = 30307534 | pmc = 6237782 | doi = 10.1093/nar/gky910 |doi-access=free}}</ref><ref name = Bernstein2018>{{cite journal | vauthors = Bernstein H, Bernstein C, Michod RE | title = Sex in microbial pathogens | journal = Infection, Genetics and Evolution | volume = 57 | pages = 8–25 | date = January 2018 | pmid = 29111273 | doi = 10.1016/j.meegid.2017.10.024 | doi-access = free | bibcode = 2018InfGE..57....8B }}</ref>  Recombination also occurs in the ''[[Coronaviridae]]'' ((+)ssRNA) (e.g. [[Severe acute respiratory syndrome|SARS]]).<ref name = Su2016>{{cite journal | vauthors = Su S, Wong G, Shi W, Liu J, Lai AC, Zhou J, Liu W, Bi Y, Gao GF | display-authors = 6 | title = Epidemiology, Genetic Recombination, and Pathogenesis of Coronaviruses | journal = Trends in Microbiology | volume = 24 | issue = 6 | pages = 490–502 | date = June 2016 | pmid = 27012512 | doi = 10.1016/j.tim.2016.03.003 | doi-access = free | pmc = 7125511 }}</ref>  Recombination in RNA viruses appears to be an adaptation for coping with genome damage.<ref name = Barr2010/>  Recombination can occur infrequently between animal viruses of the same species but of divergent lineages. The resulting recombinant viruses may sometimes cause an outbreak of infection in humans.<ref name = Su2016/>