Simian immunodeficiency virus

Simian immunodeficiency virus
SIV virion model obtained with cryo-electron microscopy scanning
Virus classification Edit this classification
(unranked): Virus
Realm: Riboviria
Kingdom: Pararnavirae
Phylum: Artverviricota
Class: Revtraviricetes
Order: Ortervirales
Family: Retroviridae
Genus: Lentivirus
Species:
Simian immunodeficiency virus

Simian immunodeficiency virus (SIV) is a species of retrovirus that cause persistent infections in at least 45 species of non-human primates.[1][2] Based on analysis of strains found in four species of monkeys from Bioko Island, which was isolated from the mainland by 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.[3][4]

Virus strains from three of these primate species, SIVsmm in sooty mangabeys, SIVgor in gorillas and SIVcpz in chimpanzees, are believed to have 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.[5][6] 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 modern transportation and 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.[7]

Unlike SIVsmm infection in sooty mangabeys, a recent[when?] study of SIVcpz in wild living chimpanzees suggests that infected chimpanzees experience an AIDS-like illness similar to HIV-1 infected humans. The later stages of SIV infection develop into sAIDS, much like how HIV infection develops into AIDS.

  1. ^ Peeters M, Courgnaud V, Abela B (2001). "Genetic Diversity of Lentiviruses in Non-Human Primates" (PDF). AIDS Reviews. 3: 3–10. Retrieved 2020-07-11.
  2. ^ Peeters M, Courgnaud V (2002). Kuiken C, Foley B, Freed E, Hahn B, Korber B, Marx PA, McCutchan FE, Mellors JW, Wolinsky S (eds.). Overview of Primate Lentiviruses and their Evolution in Non-human Primates in Africa (PDF). HIV sequence compendium. Los Alamos, NM: Theoretical Biology and Biophysics Group, Los Alamos National Laboratory. pp. 2–23. Retrieved 2010-09-19.
  3. ^ McNeil Donald G. Jr (September 16, 2010). "Precursor to H.I.V. Was in Monkeys for Millennia". New York Times. Retrieved 2010-09-17.
  4. ^ Worobey M, Telfer P, Souquière S, Hunter M, Coleman CA, Metzger MJ, et al. (September 2010). "Island biogeography reveals the deep history of SIV". Science. 329 (5998): 1487. Bibcode:2010Sci...329.1487W. doi:10.1126/science.1193550. PMID 20847261. S2CID 37803712..
  5. ^ Sharp PM, Hahn BH (August 2010). "The evolution of HIV-1 and the origin of AIDS". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 365 (1552): 2487–2494. doi:10.1098/rstb.2010.0031. PMC 2935100. PMID 20643738.
  6. ^ Peeters M, D'Arc M, Delaporte E (2014). "Origin and diversity of human retroviruses". AIDS Reviews. 16 (1): 23–34. PMC 4289907. PMID 24584106.
  7. ^ Jasinska AJ, Pandrea I, Apetrei C (2022-01-27). "CCR5 as a Coreceptor for Human Immunodeficiency Virus and Simian Immunodeficiency Viruses: A Prototypic Love-Hate Affair". Frontiers in Immunology. 13: 835994. doi:10.3389/fimmu.2022.835994. ISSN 1664-3224. PMC 8829453. PMID 35154162.