HIV: If Only Chimps Were Strict Vegetarians!
Abstract & Commentary
Synopsis: The chimpanzee simian immunodeficiency virus, the virus from which HIV-1 originated, arose as the result of recombination between retroviruses of 2 smaller primates that may serve as a food source for the chimp.
Source: Bailes E, et al. Hybrid origin of SIV in chimpanzees. Science. 2003;300:1713.
Bailes and colleagues examined the protein sequences of the Gag, Pol (PR-RT), Pol (IN), and Env domains of representatives of 8 clades of simian immunodeficiency virus (SIV) strains. They are the chimpanzee retrovirus, SICcpz, as well as those of the red-capped mangabey (SICrcm) and the greater spot-nosed monkey (SIVgsn). Phylogenetic analysis found that SICcpz appeared to be a recombinant, clustering closely with SIVrcm in Pol and with SIVgsn in Env. This result was interpreted as consistent with SIVcpz having arisen as the result of recombination between ancestors of SIVrcm and SIVgsn.
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Table |
| SIV: simian immunodeficiency virus |
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SIVcpz: SIV of chimpanzee origin |
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SIVrcm: SIV of red-capped mangabey |
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SIVgsn: SIV of greater spot-nosed monkey |
Comment by Stan Deresinski, MD, FACP
The ranges of the red-capped mangabey and the greater spot-nosed monkey overlap with that of Pan troglodytes troglodytes, the chimpanzee species that, along with P. t. schweinfurthii, has been implicated as the source of HIV-1. Since chimpanzees hunt and eat monkeys, it can be conjectured that a host chimp became infected with both SIVrcm and SIVgsn and that these 2 viruses recombined to create SIVcpz, which became the ancestor of HIV-1, which was introduced into the human population approximately 70 years ago.
Beatrice Hahn’s group reported in 1999 that HIV-1 originated in P. t. troglodytes, the common central (actually, central West Africa) chimpanzee.1 This large primate is found in both rain forests and open woodland forests in Cameroon, the Central African Republic, Congo, Gabon, Nigeria, and the Democratic Republic of Congo. While chimpanzees primarily eat fruits, seeds, leaves, bark, insects, and honey, they are omnivorous. Red-capped mangabeys and greater spot-nosed monkeys are both vegetarian. When the opportunity and desire arises, chimps will occasionally hunt and kill monkeys and other small mammals for food. The killing and butchering of the prey is, by necessity, a bloody process, which could allow the transmission of blood-borne pathogens from the prey to predator.
This study provides convincing evidence of the origin of SIVcpz, which, in turn, was the progenitor of HIV-1. HIV-2 originated in an SIV of the sootey mangabey. A recent survey of 788 monkeys that are hunted in the rain forests of Cameroon for bush meat or kept as pets discovered 5 new phylogenetic SIV lineages.2 At the same time, the slaughter of animals by humans for bush meat is increasing. One wonders what the future holds.
Dr. Derenski is Clinical Professor of Medicine, Stanford; Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center.
References
1. Gao F, et al. Origin of HIV-1 in the chimpanzee Pan troglodytes troglodytes. Nature. 1999;397:436-441.
2. Peeters M, et al. Risk to human health from a plethora of simian immunodeficiency viruses in primate bushmeat. Emerg Infect Dis. 2002;8:451-457.
The chimpanzee simian immunodeficiency virus, the virus from which HIV-1 originated, arose as the result of recombination between retroviruses of 2 smaller primates that may serve as a food source for the chimp.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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