Editing Simian immunodeficiency virus (section)

{{Short description|Species of retrovirus}}
{{Virusbox
| name = Simian immunodeficiency virus
| image = SIV virion in 3D.jpg
| image_caption = SIV virion model obtained with cryo-electron microscopy scanning
| parent = Lentivirus
| species = Lentivirus simimdef
}}

'''Simian immunodeficiency virus''' ('''SIV''') is a species of [[retrovirus]] that cause persistent infections in at least 45 species of non-human [[primate]]s.<ref name="Peeters_2001">{{Cite journal | vauthors = Peeters M, Courgnaud V, Abela B | title=Genetic Diversity of Lentiviruses in Non-Human Primates| journal =AIDS Reviews| volume =3| pages =3–10| year =2001| url =https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers19-09/010055042.pdf| access-date =2020-07-11}}</ref><ref name = "Peeters">{{Cite book | vauthors = Peeters M, Courgnaud V | veditors = Kuiken C, Foley B, Freed E, Hahn B, Korber B, Marx PA, McCutchan FE, Mellors JW, Wolinsky S | title = Overview of Primate Lentiviruses and their Evolution in Non-human Primates in Africa | url = http://hcv.lanl.gov/content/sequence/HIV/COMPENDIUM/2002/partI/Peeters.pdf | series = HIV sequence compendium | year = 2002 | pages = 2–23 | place = Los Alamos, NM | publisher = Theoretical Biology and Biophysics Group, Los Alamos National Laboratory | access-date = 2010-09-19 }}</ref> Based on analysis of strains found in four species of [[Old World monkey|monkeys]] from [[Bioko|Bioko Island]], which was isolated from the mainland by [[Sea level#Change|rising sea levels]] about 11,000 years ago, it has been concluded that SIV has been present in monkeys and apes for at least 32,000 years, and probably much longer.<ref name=millennia>{{Cite news |author=McNeil Donald G. Jr |title=Precursor to H.I.V. Was in Monkeys for Millennia |url=https://www.nytimes.com/2010/09/17/health/17aids.html?_r=1&src=me&ref=general |work=[[New York Times]] |date=September 16, 2010 |access-date=2010-09-17 }}</ref><ref>{{cite journal | vauthors = Worobey M, Telfer P, Souquière S, Hunter M, Coleman CA, Metzger MJ, Reed P, Makuwa M, Hearn G, Honarvar S, Roques P, Apetrei C, Kazanji M, Marx PA | display-authors = 6 | title = Island biogeography reveals the deep history of SIV | journal = Science | volume = 329 | issue = 5998 | pages = 1487 | date = September 2010 | pmid = 20847261 | doi = 10.1126/science.1193550 | s2cid = 37803712 | bibcode = 2010Sci...329.1487W }}.</ref>

Virus [[Strain (biology)|strain]]s from three of these primate species, SIVsmm in [[sooty mangabey]]s, SIVgor in [[gorilla]]s and SIVcpz in [[Common chimpanzee|chimpanzees]], are believed to have [[zoonosis|crossed the species barrier]] into humans, resulting in [[HIV-2]] and [[HIV-1]] respectively, the two [[HIV]] viruses. The most likely route of transmission of HIV-1 to humans involves contact with the blood of chimps and gorillas that are often hunted for [[bushmeat]] in Africa. Four subtypes of HIV-1 (M, N, O, and P) likely arose through four separate transmissions of SIV to humans, and the resulting HIV-1 group M strain most commonly infects people worldwide.<ref>{{cite journal | vauthors = Sharp PM, Hahn BH | title = The evolution of HIV-1 and the origin of AIDS | journal = Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences | volume = 365 | issue = 1552 | pages = 2487–2494 | date = August 2010 | pmid = 20643738 | pmc = 2935100 | doi = 10.1098/rstb.2010.0031 }}</ref><ref>{{cite journal | vauthors = Peeters M, D'Arc M, Delaporte E | title = Origin and diversity of human retroviruses | journal = AIDS Reviews | volume = 16 | issue = 1 | pages = 23–34 | date = 2014 | pmid = 24584106 | pmc = 4289907 }}</ref> Therefore, it is theorized that SIV may have previously crossed the species barrier into human hosts multiple times throughout history, but it was not until recently, after the advent of [[History of transport|modern transportation]] and [[commuter|global commuterism]], that it finally took hold, spreading beyond localized decimations of a few individuals or single small tribal populations.

Unlike HIV-1 and HIV-2 infections in humans, SIV infections in their natural simian non-human hosts appear in many cases to be non-pathogenic due to evolutionary adaptation of the hosts to the virus. Extensive studies in sooty mangabeys have established that SIVsmm infection does not cause any disease in these primates, despite high levels of circulating virus. Regulation of the activity of the [[CCR5]] coreceptor is one of the natural strategies to avoid disease in some natural host species of SIV.<ref>{{Cite journal |vauthors = Jasinska AJ, Pandrea I, Apetrei C |date=2022-01-27 |title=CCR5 as a Coreceptor for Human Immunodeficiency Virus and Simian Immunodeficiency Viruses: A Prototypic Love-Hate Affair |journal=Frontiers in Immunology |volume=13 |pages=835994 |doi=10.3389/fimmu.2022.835994 |pmid=35154162 |issn=1664-3224 |pmc= 8829453 |doi-access=free}}</ref>

Research on SIVcpz in chimpanzees suggests that infected chimpanzees experience an AIDS-like illness similar to HIV-1 infected humans. The later stages of SIVcpz infection in chimpanzees develop into an illness with characteristics that strongly resemble end-stage AIDS in humans.<ref>{{cite journal|vauthors=Peeters M, Delaporte E|date=June 2012|title=Simian retroviruses in African apes|journal=Clin Microbiol Infect|volume=18|issue=6|pages=514–520|doi= 10.1111/j.1469-0691.2012.03843.x|pmc=|pmid=22515409|url=https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(14)64143-4/fulltext}}</ref>