Two of the four lineages of HIV-1 viruses have originated in western lowland gorillas, a new study reported in the Proceedings of the National Academy of Sciences has found.
Colorized scanning electron micrograph of HIV-1, grown in cultured lymphocytes; virions are seen as small spheres on the surface of the cells. Image credit: C. Goldsmith.
HIV-1, the virus that causes AIDS, has jumped species to infect humans on at least four separate occasions, generating four HIV-1 lineages – groups M, N, O, and P.
Group M gave rise to the AIDS pandemic, infecting more than 40 million people worldwide by spreading across Africa and throughout the rest of the world.
Groups N and P, at the other extreme, have only been found in a few individuals from Cameroon.
However, group O, although not as widespread and prevalent as group M, has nonetheless infected about 100,000 people in west central Africa.
According to previous studies, groups M and N originated in geographically distinct chimpanzee communities in southern Cameroon.
But the origins of groups O and P remained uncertain, until now.
In a new study of simian immunodeficiency virus (SIV) infection in African gorillas, a multinational group of scientists co-led by Prof Beatrice Hahn of the University of Pennsylvania and Dr Martine Peeters of the University of Montpellier screened fecal samples from western lowland gorillas, eastern lowland gorillas, and mountain gorillas in Cameroon, Gabon, the Democratic Republic of Congo, and Uganda.
They identified four field sites in southern Cameroon where western lowland gorillas harbor SIV.
“Viral sequencing revealed a high degree of genetic diversity among the different gorilla samples,” Prof Hahn said.
“Two of the gorilla virus lineages were particularly closely related to HIV-1 groups O and P.”
“This told us that these two groups originated in western lowland gorillas (one of two subspecies of the western gorilla)”
Dr Peeters added: “understanding emerging disease origins is critical to gauge future human infection risks.”
From this study it has become clear that both chimpanzees and gorillas harbor viruses that are capable of crossing the species barrier to humans and have the potential to cause major disease outbreaks.
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Mirela D’arc et al. Origin of the HIV-1 group O epidemic in western lowland gorillas. PNAS, published online March 2, 2015; doi: 10.1073/pnas.1502022112
