The origin and molecular epidemiology of HIV

Abstract

HIV-1 in humans resulted from at least four cross-species transmissions of simian immunodeficiency viruses (SIVs) from chimpanzees and gorillas in West Central Africa, while HIV-2 viruses resulted from at least eight independent transmissions of SIVs infecting sooty mangabeys in West Africa only, where one of these transmissions (HIV-1 group M) is responsible for the global epidemic. HIV-1 M is subdivided into nine subtypes and a wide diversity of circulating recombinant forms (CRFs) and unique recombinant forms. The heterogenic HIV-1 M subtype/CRF distribution is the result of founder effects. The genetic diversity of HIV-1 continues to increase overtime due to demographic factors such as travel and migration and frequent co/superinfections. In addition, the expanded access to antiretrovirals leads to an increasing number of drug-resistant strains, especially in resource limited countries.

Keywords::

• cross-species transmission
• drug resistance
• evolution
• HIV-1
• HIV-2
• molecular epidemiology
• recombinant
• SIV
• subtype

Financial & competing interest disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was used in the production of this manuscript.

Key issues

• • Simian immunodeficiency virus (SIV) from chimpanzees and gorillas from West Central Africa have crossed the species barrier on at least four occasions leading to HIV-1 in humans and HIV-2 viruses result from at least eight independent transmissions of SIVs infecting sooty mangabeys in West Africa.

• • Only one of these zoonotic transmissions is responsible for the global epidemic which is caused by HIV-1 group M.

• • HIV-1 group M is subdivided into nine subtypes and a wide diversity of circulating recombinant forms (CRFs) and unique recombinant forms (URFs). Today 58 CRFs have been described.

• • The epicenter of the HIV-1 M epidemic is located in the western part of the Democratic Republic of Congo from where the different HIV-1 M variants started to spread across Africa and subsequently to other continents in the world.

• • The heterogenic HIV-1 M subtype/CRF distribution is the result of founder effects related to demographic factors such as travel and migration, and co/superinfections.

• • The genetic diversity of the global HIV-1 M epidemic continues to increase over time. This concerns the intra-subtype diversity and the number of recombinant strains and their complexity.

• • The expanded access to antiretrovirals leads to an increasing number of drug-resistant strains, especially in resource limited countries.

• • Humans are still exposed to a wide diversity of SIVs through hunting and butchering non-human primates for bushmeat and cross-species transmission of other SIVs has to be considered. Due to the long incubation period, human infection with such variants can go unrecognized for several years and lead to another epidemic, especially in areas with poor health systems.

Notes