Conserv online dating
At select field sites, mitochondrial and microsatellite analyses of host DNA were also used to confirm sample integrity and to determine the number of tested individuals. In contrast, other SIVs, such as those of sooty mangabeys and African green monkeys, are much more widely and evenly distributed and infect their hosts at generally higher prevalence rates (Phillips-Conroy et al. Sites where SIV infections were detected are highlighted in yellow. Importantly, all of more than 30 sequenced SIVcpz strains show an identical mosaic genome structure.Figure 3A summarizes current molecular epidemiological data derived from the analysis of over 7,000 chimpanzee fecal samples collected at nearly 90 field sites (Santiago et al. The upper panel depicts the ranges of the four subspecies of the common chimpanzee (, brown) gorillas (map courtesy of Lilian Pintea, The Jane Goodall Institute). Moreover, there is no evidence that chimpanzees harbor any other SIV, although they, as well as bonobos, are routinely exposed to SIVs through their hunting behavior (Mitani and Watts 1999; Surbeck and Hohmann 2008; Leendertz et al. Initially, SIVcpz was thought to be harmless for its natural host.Here, we describe the origins and evolution of these viruses, and the circumstances that led to the AIDS pandemic.Both HIVs are the result of multiple cross-species transmissions of simian immunodeficiency viruses (SIVs) naturally infecting African primates.We discuss how host restriction factors have shaped the emergence of new SIV zoonoses by imposing adaptive hurdles to cross-species transmission and/or secondary spread.We also show that AIDS has likely afflicted chimpanzees long before the emergence of HIV.Most of these transfers resulted in viruses that spread in humans to only a limited extent.However, one transmission event, involving SIVcpz from chimpanzees in southeastern Cameroon, gave rise to HIV-1 group M—the principal cause of the AIDS pandemic.
That is, viral sequences from members of the same species form a monophyletic clade in evolutionary trees.
The prevalence of naturally occurring SIV infections varies widely, ranging from 1% in some species to over 50% in others (Aghokeng et al.
2010), and it is tempting to speculate that less ubiquitous SIVs were acquired more recently and/or may be more pathogenic.
Four subspecies were defined on the basis of mitochondrial DNA sequences (Gagneux et al. To determine the distribution of SIVcpz among these populations, fecal (and in some cases urine) samples were collected at different field sites and tested for the presence of virus specific antibodies. SIVcpz was detected at multiple sites throughout the ranges of both central and eastern chimpanzees in an area ranging from Cameroon to Tanzania, but there was no evidence of infection in western and Nigeria-Cameroonian chimpanzees, nor in bonobos, despite testing of multiple communities. Indeed, phylogenetic analyses of full-length proviral sequences revealed that SIVcpz represents a complex mosaic, generated by recombination of two lineages of SIVs that infect monkeys (Bailes et al. In the 5′ half of the genome, as well as the ) monkeys (Bailes et al. Chimpanzees are known to hunt and kill other mammals, including monkeys (Goodall 1986), suggesting that they acquired SIV in the context of predation.
Antibody positive fecal specimens were then subjected to RNA extraction and reverse transcriptase polymerase chain reaction (RT-PCR) amplification to molecularly characterize the infecting virus strain. In addition, SIVcpz prevalence rates among central and eastern chimpanzees varied widely, ranging from 30% to 50% in some communities to rare or absent infection in others. Nonetheless, the puzzle of why SIVcpz was so scarce among captive chimpanzees was finally resolved: As it turned out, most of these apes were imported from West Africa and thus were members of the ) gorillas have been sampled are shown (each site is identified by a two-letter code; because of space limitations, only a subset is depicted). The current range of the central chimpanzee overlaps those of red-capped mangabeys and the various species, and so it is likely that the cross-species transmission events that led to the emergence of SIVcpz occurred in that area, and that SIVcpz later spread to eastern chimpanzees, although it is unclear whether this occurred during or subsequent to their divergence from the central subspecies.