Subtypes of HIV

Human immunodeficiency viruses
	Phylogenetic tree of the SIV and HIVs
Scientific classification
(unranked):	Virus
Realm:	Riboviria
Kingdom:	Pararnavirae
Phylum:	Artverviricota
Class:	Revtraviricetes
Order:	Ortervirales
Family:	Retroviridae
Subfamily:	Orthoretrovirinae
Genus:	Lentivirus
Groups included
	Human immunodeficiency virus 1; Human immunodeficiency virus 2;
Cladistically included but traditionally excluded taxa
	Simian immunodeficiency virus (subgroups i, ii);

The subtypes of HIV include two main subtypes, known as HIV type 1 (HIV-1) and HIV type 2 (HIV-2). These subtypes have distinct genetic differences and are associated with different epidemiological patterns and clinical characteristics.

HIV-1 exhibits a genetic relation to viruses indigenous to chimpanzees and gorillas that inhabit West Africa, while HIV-2 viruses are affiliated with viruses present in the sooty mangabey, a vulnerable West African primate.^[2]

HIV-1 viruses can be further stratified into groups M, N, O, and P. Among these, HIV-1 group M viruses are the most prevalent, infecting nearly 90% of people living with HIV and are responsible for the global AIDS pandemic. Group M can be further subdivided into subtypes based on genetic sequence data. Certain subtypes are known for their increased virulence or drug resistance to different medications used to treat HIV.

HIV-2 viruses are generally considered to be less virulent and less transmissible than HIV-1 M group viruses, although HIV-2 is also known to still cause AIDS.

One of the prevailing challenges in the pursuit of effective management of HIV is the virus's pronounced genetic variability and rapid viral evolution.^[3]

^ Although ICTV lists HIV-1 and HIV-2 as distinct species from SIV, they do cladistically fall into the group of SIV.
^ Sharp PM, Hahn BH (September 2011). "Origins of HIV and the AIDS pandemic". Cold Spring Harbor Perspectives in Medicine. 1 (1): a006841. doi:10.1101/cshperspect.a006841. PMC 3234451. PMID 22229120.
^ Robertson DL, Hahn BH, Sharp PM (March 1995). "Recombination in AIDS viruses". Journal of Molecular Evolution. 40 (3): 249–259. Bibcode:1995JMolE..40..249R. doi:10.1007/BF00163230. PMID 7723052. S2CID 19728830.

[1] Although ICTV lists HIV-1 and HIV-2 as distinct species from SIV, they do cladistically fall into the group of SIV.

[doi10.1101/cshperspect.a006841-2] Sharp PM, Hahn BH (September 2011). "Origins of HIV and the AIDS pandemic". Cold Spring Harbor Perspectives in Medicine. 1 (1): a006841. doi:10.1101/cshperspect.a006841. PMC 3234451. PMID 22229120.

[pmid7723052-3] Robertson DL, Hahn BH, Sharp PM (March 1995). "Recombination in AIDS viruses". Journal of Molecular Evolution. 40 (3): 249–259. Bibcode:1995JMolE..40..249R. doi:10.1007/BF00163230. PMID 7723052. S2CID 19728830.

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