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The number of great apes in Central Africa is dramatically declining and the populations are seriously threatened by diseases, mainly Ebola. However, results of a study show that the role of anthrax in great ape mortality might be underestimated, suggesting that risk identification, assessment, and management for the survival of the last great apes should be performed with an open mind, since various pathogens with distinct characteristics in epidemiology and pathogenicity might impact the populations.

Identifying microbial pathogens with zoonotic potential in wild-living primates can be important to human health, as evidenced by human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2) and Ebola virus. Simian foamy viruses (SFVs) are ancient retroviruses that infect Old and New World monkeys and apes. Although not known to cause disease, these viruses are of public health interest because they have the potential to infect humans and thus provide a more general indication of zoonotic exposure risks. Surprisingly, no information exists concerning the prevalence, geographic distribution, and genetic diversity of SFVs in wild-living monkeys and apes. Here, we report the first comprehensive survey of SFVcpz infection in free-ranging chimpanzees (Pan troglodytes) using newly developed, fecal-based assays. Chimpanzee fecal samples (n = 724) were collected at 25 field sites throughout equatorial Africa and tested for SFVcpzspecific antibodies (n = 706) or viral nucleic acids (n = 392). SFVcpz infection was documented at all field sites, with prevalence rates ranging from 44% to 100%. In two habituated communities, adult chimpanzees had significantly higher SFVcpz infection rates than infants and juveniles, indicating predominantly horizontal rather than vertical transmission routes. Some chimpanzees were co-infected with simian immunodeficiency virus (SIVcpz); however, there was no evidence that SFVcpz and SIVcpz were epidemiologically linked. SFVcpz nucleic acids were recovered from 177 fecal samples, all of which contained SFVcpz RNA and not DNA. Phylogenetic analysis of partial gag (616 bp), pol-RT (717 bp), and pol-IN (425 bp) sequences identified a diverse group of viruses, which could be subdivided into four distinct SFVcpz lineages according to their chimpanzee subspecies of origin. Within these lineages, there was evidence of frequent superinfection and viral recombination. One chimpanzee was infected by a foamy virus from a Cercopithecus monkey species, indicating cross-species transmission of SFVs in the wild. These data indicate that SFVcpz (i) is widely distributed among all chimpanzee subspecies; (ii) is shed in fecal samples as viral RNA; (iii) is transmitted predominantly by horizontal routes; (iv) is prone to superinfection and recombination; (v) has co-evolved with its natural host; and (vi) represents a sensitive marker of population structure that may be useful for chimpanzee taxonomy and conservation strategies. [ABSTRACT FROM AUTHOR]

Western lowland gorillas (Gorilla gorilla gorilla) are infected with a simian immunodeficiency virus (SIVgor) that is closely related to chimpanzee and human immunodeficiency viruses (SIVcpz and HIV-1, respectively) in west central Africa. Although existing data suggest a chimpanzee origin for SIVgor, a paucity of available sequences has precluded definitive conclusions. Here, we report the molecular characterization of one partial (BQ664) and three full-length (CP684, CP2135, and CP2139) SIVgor genomes amplified from fecal RNAs of wild-living gorillas at two field sites in Cameroon. Phylogenetic analyses showed that all SIVgor strains clustered together, forming a monophyletic lineage throughout their genomes. Interestingly, the closest relatives of SIVgor were not SIVcpzPtt strains from west central African chimpanzees (Pan troglodytes troglodytes) but human viruses belonging to HIV-1 group O. In trees derived from most genomic regions, SIVgor and HIV-1 group O formed a sister clade to the SIVcpzPtt lineage. However, in a tree derived from 5' pol sequences (~900 bp), SIVgor and HIV-1 group O fell within the SIVcpzPtt radiation. The latter was due to two SIVcpzPtt strains that contained mosaic pol sequences, pointing to the existence of a divergent SIVcpzPtt lineage that gave rise to SIVgor and HIV-1 group O. Gorillas appear to have acquired this lineage at least 100 to 200 years ago. To examine the biological properties of SIVgor, we synthesized a full-length provirus from fecal consensus sequences. Transfection of the resulting clone (CP2139.287) into 293T cells yielded infectious virus that replicated efficiently in both human and chimpanzee CD4+ T cells and used CCR5 as the coreceptor for viral entry. Together, these results provide strong evidence that P. t. troglodytes apes were the source of SIVgor. These same apes may also have spawned the group O epidemic; however, the possibility that gorillas served as an intermediary host cannot be excluded. [ABSTRACT FROM AUTHOR]

Abstract: It is now well established that the clade of simian immunodeficiency viruses (SIVs) infecting west central African chimpanzees (Pan troglodytes troglodytes) and western gorillas (Gorilla gorilla gorilla) comprises the progenitors of human immunodeficiency virus type 1 (HIV-1). In this study, we have greatly expanded our previous molecular epidemiological survey of SIVcpz in wild chimpanzees in Cameroon. The new results confirm a wide but uneven distribution of SIVcpzPtt in P. t. troglodytes throughout southern Cameroon and indicate the absence of SIVcpz infection in Pan troglodytes vellerosus. Analyzing 725 fecal samples from 15 field sites, we obtained partial nucleotide sequences from 16 new SIVcpzPtt strains and determined full-length sequences for two of these. Phylogenetic analyses of these new viruses confirmed the previously reported phylogeographic clustering of SIVcpzPtt lineages, with viruses related to the ancestors of HIV-1 groups M and N circulating exclusively in southeastern and south central P. t. troglodytes communities, respectively. Importantly, the SIVcpzPtt strains from the southeastern corner of Cameroon represent a relatively isolated clade indicating a defined geographic origin of the chimpanzee precursor of HIV-1 group M. Since contacts between humans and apes continue, the possibility of ongoing transmissions of SIV from chimpanzees (or gorillas) to humans has to be considered. In this context, our finding of distinct SIVcpzPtt envelope V3 sequence clades suggests that these peptides may be useful for the serological differentiation of SIVcpzPtt and HIV-1 infections, and thus the diagnosis of new cross-species transmissions if they occurred. [Copyright &y& Elsevier]

Identifying microbial pathogens with zoonotic potential in wild-living primates can be important to human health, as evidenced by human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2) and Ebola virus. Simian foamy viruses (SFVs) are ancient retroviruses that infect Old and New World monkeys and apes. Although not known to cause disease, these viruses are of public health interest because they have the potential to infect humans and thus provide a more general indication of zoonotic exposure risks. Surprisingly, no information exists concerning the prevalence, geographic distribution, and genetic diversity of SFVs in wild-living monkeys and apes. Here, we report the first comprehensive survey of SFVcpz infection in free-ranging chimpanzees (Pan troglodytes) using newly developed, fecal-based assays. Chimpanzee fecal samples (n = 724) were collected at 25 field sites throughout equatorial Africa and tested for SFVcpz-specific antibodies (n = 706) or viral nucleic acids (n = 392). SFVcpz infection was documented at all field sites, with prevalence rates ranging from 44% to 100%. In two habituated communities, adult chimpanzees had significantly higher SFVcpz infection rates than infants and juveniles, indicating predominantly horizontal rather than vertical transmission routes. Some chimpanzees were co-infected with simian immunodeficiency virus (SIVcpz); however, there was no evidence that SFVcpz and SIVcpz were epidemiologically linked. SFVcpz nucleic acids were recovered from 177 fecal samples, all of which contained SFVcpz RNA and not DNA. Phylogenetic analysis of partial gag (616 bp), pol-RT (717 bp), and pol-IN (425 bp) sequences identified a diverse group of viruses, which could be subdivided into four distinct SFVcpz lineages according to their chimpanzee subspecies of origin. Within these lineages, there was evidence of frequent superinfection and viral recombination. One chimpanzee was infected by a foamy virus from a Cercopithecus monkey species, indicating cross-species transmission of SFVs in the wild. These data indicate that SFVcpz (i) is widely distributed among all chimpanzee subspecies; (ii) is shed in fecal samples as viral RNA; (iii) is transmitted predominantly by horizontal routes; (iv) is prone to superinfection and recombination; (v) has co-evolved with its natural host; and (vi) represents a sensitive marker of population structure that may be useful for chimpanzee taxonomy and conservation strategies.

It is now well established that the clade of simian immunodeficiency viruses (SIVs) infecting west central African chimpanzees (Pan troglodytes troglodytes) and western gorillas (Gorilla gorilla gorilla) comprises the progenitors of human immunodeficiency virus type 1 (HIV-1). In this study, we have greatly expanded our previous molecular epidemiological survey of SIVcpz in wild chimpanzees in Cameroon. The new results confirm a wide but uneven distribution of SIVcpzPtt in P. t. troglodytes throughout southern Cameroon and indicate the absence of SIVcpz infection in Pan troglodytes vellerosus. Analyzing 725 fecal samples from 15 field sites, we obtained partial nucleotide sequences from 16 new SIVcpzPtt strains and determined full-length sequences for two of these. Phylogenetic analyses of these new viruses confirmed the previously reported phylogeographic clustering of SIVcpzPtt lineages, with viruses related to the ancestors of HIV-1 groups M and N circulating exclusively in southeastern and south central P. t. troglodytes communities, respectively. Importantly, the SIVcpzPtt strains from the southeastern corner of Cameroon represent a relatively isolated clade indicating a defined geographic origin of the chimpanzee precursor of HIV-1 group M. Since contacts between humans and apes continue, the possibility of ongoing transmissions of SIV from chimpanzees (or gorillas) to humans has to be considered. In this context, our finding of distinct SIVcpzPtt envelope V3 sequence clades suggests that these peptides may be useful for the serological differentiation of SIVcpzPtt and HIV-1 infections, and thus the diagnosis of new cross-species transmissions if they occurred.