Detection and molecular characterization of foamy viruses in Central African chimpanzees of the Pan troglodytes troglodytes and Pan troglodytes vellerosus subspecies

BACKGROUND: Foamy viruses are exogenous retroviruses that are highly endemic in non-human primates (NHPs). Recent studies, mainly performed in North America, indicated frequent simian foamy virus (SFV) infection in persons occupationally exposed to NHPs. This zoonotic infection was demonstrated mainly after bites by chimpanzees [Pan troglodytes (P. t.)] of the West African P. t. verus subspecies in primatology centers or zoos in the USA. METHODS: We studied 32 chimpanzees from the Central African subspecies P. t. troglodytes and P. t. vellerosus, originating from Cameroon (29 cases) or Gabon (3 cases). We screened first plasma or sera of the animals with a Western blot detecting the SFVs Gag doublet proteins. Then, we performed two nested polymerase chain reactions (PCRs) amplifying a fragment of the integrase and LTR regions and, finally, we made phylogenetical analyses on the sequences obtained from the integrase PCR products. RESULTS: By serological and/or molecular assays, we detected foamy viruses (FVs) infection in 14 chimpanzees. Sequence comparison and phylogenetic analyses of a 425 bp fragment of the integrase gene obtained for 10 of the 14 positive apes, demonstrated a wide diversity of new FVs strains that belong phylogenetically either to the P. t. troglodytes or P. t. vellerosus foamy viral clade. CONCLUSIONS: This study shows that chimpanzees living in these areas of Central Africa are infected by several specific foamy viruses. This raises, in such regions, the potential risk of a human retroviral infection of zoonotic origin linked to chimpanzees contacts, as already exemplified for STLV-1 and SIV infections.     

High Prevalence,Coinfection Rate,and Genetic Diversity of Retroviruses in Wild Red Colobus Monkeys (Piliocolobus badius badius) in Ta? National Park,C?te d'Ivoire

Simian retroviruses are precursors of all human retroviral pathogens. However, little is known about the prevalence and coinfection rates or the genetic diversity of major retroviruses—simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus type 1 (STLV-1), and simian foamy virus (SFV)—in wild populations of nonhuman primates. Such information would contribute to the understanding of the natural history of retroviruses in various host species. Here, we estimate these parameters for wild West African red colobus monkeys (Piliocolobus badius badius) in the Taï National Park, Côte d''Ivoire. We collected samples from a total of 54 red colobus monkeys; samples consisted of blood and/or internal organs from 22 monkeys and additionally muscle and other tissue samples from another 32 monkeys. PCR analyses revealed a high prevalence of SIV, STLV-1, and SFV in this population, with rates of 82%, 50%, and 86%, respectively. Forty-five percent of the monkeys were coinfected with all three viruses while another 32% were coinfected with SIV in combination with either STLV or SFV. As expected, phylogenetic analyses showed a host-specific pattern for SIV and SFV strains. In contrast, STLV-1 strains appeared to be distributed in genetically distinct and distant clades, which are unique to the Taï forest and include strains previously described from wild chimpanzees in the same area. The high prevalence of all three retroviral infections in P. b. badius represents a source of infection to chimpanzees and possibly to humans, who hunt them.Lentiviruses and deltaretroviruses that infect African nonhuman primates have received considerable attention as they are the precursors of all pathogenic human retroviruses: human immunodeficiency virus types 1 and 2 (HIV-1/HIV-2) and human T-cell lymphotropic virus type 1 (HTLV-1). These human infections are the results of past zoonotic transfers of simian immunodeficiency virus (SIV) and simian T-cell lymphotropic viruses type 1 (STLV-1) from wild monkeys and apes into local human populations, presumably through primate hunting and handling of primate bushmeat (13, 19, 43, 46, 55, 58, 59). Via the same route, zoonotic transmission of simian foamy virus (SFV), a spumaretrovirus whose exact pathogenicity in human hosts is still unknown, has also been shown (64). The increasing contact between humans and wild primates implies that further zoonotic transmission of retroviruses is likely to happen (42, 63). Studying the occurrence and circulation of simian retroviruses such as SIV, STLV-1, and SFV in wild primate populations enables us to better understand retrovirus evolution in primates and also provides tools for monitoring possible future retroviral zoonotic events.Systematic studies of SIV, STLV-1, and SFV in wild primates are relatively rare. Many use bushmeat samples, which can vary in their quality and are prone to cross-contamination from butchering and storage with other carcasses. Confiscated primates are also not representative of the situation in the wild since the animals are caught at a young age when the occurrence of different retroviruses may be extremely low (24). The technical possibilities for the detection of various pathogens in noninvasive samples such as urine and feces have greatly improved and are frequently used; however, in general, the sensitivity of detection methods is higher when blood and tissue samples are used (25, 32, 47). Such samples can be collected if fresh carcasses are found, or they can be collected by anesthetizing live primates for sampling purpose, animal translocation, or medical intervention, such as snare removal. The practical and ethical issues of each of the sampling methods have been discussed elsewhere (12, 14).Red colobus monkeys [Procolobus (Piliocolobus)] are interesting subjects for retroviral infection studies for a number of reasons. First, they are widely distributed (yet in a fragmented manner) from East to West Africa, which suggests that red colobus species and subspecies, or more likely ancestor(s) of these, could have been key hosts in transmitting retroviruses across tropical Africa (4, 54). Second, as they are herbivore primates, the hunting of other primates can be excluded as a route of infection. Finally, these monkeys are frequently hunted by humans and chimpanzees and represent a possibly large reservoir for retroviruses and other pathogens that ought to be investigated further (2, 45).Very little information is available about the prevalence and coinfection of SIV, STLV-1, and SFV in wild red colobus monkeys across Africa. In other colobine monkeys only SIV has been documented: in olive colobus (Procolobus verus) in Côte d''Ivoire and in black and white colobus (Colobus guereza) in Cameroon (7, 8). Based on fecal samples from habituated adult individuals, the prevalence of SIV in West African red colobus monkeys (SIVwrc; local subspecies, Piliocolobus badius badius) has been estimated to a minimum of 26% in the Taï National Park, Côte d''Ivoire, but the authors recognized the low sensitivity of viral RNA detection in fecal samples (34). Another study conducted on the same population revealed that 5 out of 10 blood samples were SIV positive (7). These results highlight that the most reliable prevalence data are based on analyses of blood/tissue samples although such sampling is not always feasible for reasons discussed above. Published prevalence information concerning STLV-1 and SFV in wild red colobus monkeys (STLV-1wrc and SFVwrc) in the same area is restricted to results obtained from analyses of a limited number of blood and necropsy samples collected as a part of studies whose focus was on cross-species transmission of these two viruses to chimpanzees (27, 28). However, these samples indicated a high prevalence of STLV-1wrc and SFVwrc in the red colobus monkey population (56% and 90%, respectively). A recent study from Uganda, East Africa, estimated the prevalence of SIV, STLV-1, and SFV in another red colobus species (Piliocolobus rufomitratus tephrosceles) to be 22.6%, 6.4%, and 97%, respectively (15). The study was performed using blood samples collected from anesthetized wild red colobus monkeys living in their natural habitat, which allowed reliable assessment of the prevalence and genetic diversity of these three retroviruses.The preliminary data from the Taï National Park indicate that there might be great variation in the prevalence of retroviruses across the African continent, even in closely related species of wild primates. Here, we aimed at generating reliable prevalence and coinfection data for SIVwrc, STLV-1wrc, and SFVwrc based on the analysis of blood and tissue samples from wild Western red colobus monkeys. We expected that this would allow for proper comparison of retroviral prevalence in the allied species P. b. badius and P. r. tephrosceles.     

Frequent simian foamy virus infection in persons occupationally exposed to nonhuman primates

The recognition that AIDS originated as a zoonosis heightens public health concerns associated with human infection by simian retroviruses endemic in nonhuman primates (NHPs). These retroviruses include simian immunodeficiency virus (SIV), simian T-cell lymphotropic virus (STLV), simian type D retrovirus (SRV), and simian foamy virus (SFV). Although occasional infection with SIV, SRV, or SFV in persons occupationally exposed to NHPs has been reported, the characteristics and significance of these zoonotic infections are not fully defined. Surveillance for simian retroviruses at three research centers and two zoos identified no SIV, SRV, or STLV infection in 187 participants. However, 10 of 187 persons (5.3%) tested positive for SFV antibodies by Western blot (WB) analysis. Eight of the 10 were males, and 3 of the 10 worked at zoos. SFV integrase gene (int) and gag sequences were PCR amplified from the peripheral blood lymphocytes available from 9 of the 10 persons. Phylogenetic analysis showed SFV infection originating from chimpanzees (n = 8) and baboons (n = 1). SFV seropositivity for periods of 8 to 26 years (median, 22 years) was documented for six workers for whom archived serum samples were available, demonstrating long-standing SFV infection. All 10 persons reported general good health, and secondary transmission of SFV was not observed in three wives available for WB and PCR testing. Additional phylogenetic analysis of int and gag sequences provided the first direct evidence identifying the source chimpanzees of the SFV infection in two workers. This study documents more frequent infection with SFV than with other simian retroviruses in persons working with NHPs and provides important information on the natural history and species origin of these infections. Our data highlight the importance of studies to better define the public health implications of zoonotic SFV infections.     

Interspecies transmission of simian foamy virus in a natural predator-prey system

Simian foamy viruses (SFV) are ancient retroviruses of primates and have coevolved with their host species for as many as 30 million years. Although humans are not naturally infected with foamy virus, infection is occasionally acquired through interspecies transmission from nonhuman primates. We show that interspecies transmissions occur in a natural hunter-prey system, i.e., between wild chimpanzees and colobus monkeys, both of which harbor their own species-specific strains of SFV. Chimpanzees infected with chimpanzee SFV strains were shown to be coinfected with SFV from colobus monkeys, indicating that apes are susceptible to SFV superinfection, including highly divergent strains from other primate species.     

Primate and feline lentivirus vector RNA packaging and propagation by heterologous lentivirus virions

Development of safe and effective gene transfer systems is critical to the success of gene therapy protocols for human diseases. Currently, several primate lentivirus-based gene transfer systems, such as those based on human and simian immunodeficiency viruses (HIV/SIV), are being tested; however, their use in humans raises safety concerns, such as the generation of replication-competent viruses through recombination with related endogenous retroviruses or retrovirus-like elements. Due to the greater phylogenetic distance from primate lentiviruses, feline immunodeficiency virus (FIV) is becoming the lentivirus of choice for human gene transfer systems. However, the safety of FIV-based vector systems has not been tested experimentally. Since lentiviruses such as HIV-1 and SIV have been shown to cross-package their RNA genomes, we tested the ability of FIV RNA to get cross-packaged into primate lentivirus particles such as HIV-1 and SIV, as well as a nonlentiviral retrovirus such as Mason-Pfizer monkey virus (MPMV), and vice versa. Our results reveal that FIV RNA can be cross-packaged by primate lentivirus particles such as HIV-1 and SIV and vice versa; however, a nonlentivirus particle such as MPMV is unable to package FIV RNA. Interestingly, FIV particles can package MPMV RNA but cannot propagate the vector RNA further for other steps of the retrovirus life cycle. These findings reveal that diverse retroviruses are functionally more similar than originally thought and suggest that upon coinfection of the same host, cross- or copackaging may allow distinct retroviruses to generate chimeric variants with unknown pathogenic potential.     

The membrane-spanning domain of gp41 plays a critical role in intracellular trafficking of the HIV envelope protein

Background

Each of the pathogenic human retroviruses (HIV-1/2 and HTLV-1) has a nonhuman primate counterpart, and the presence of these retroviruses in humans results from interspecies transmission. The passage of another simian retrovirus, simian foamy virus (SFV), from apes or monkeys to humans has been reported. Mandrillus sphinx, a monkey species living in central Africa, is naturally infected with SFV. We evaluated the natural history of the virus in a free-ranging colony of mandrills and investigated possible transmission of mandrill SFV to humans.

Results

We studied 84 semi-free-ranging captive mandrills at the Primate Centre of the Centre International de Recherches Médicales de Franceville (Gabon) and 15 wild mandrills caught in various areas of the country. The presence of SFV was also evaluated in 20 people who worked closely with mandrills and other nonhuman primates. SFV infection was determined by specific serological (Western blot) and molecular (nested PCR of the integrase region in the polymerase gene) assays. Seropositivity for SFV was found in 70/84 (83%) captive and 9/15 (60%) wild-caught mandrills and in 2/20 (10%) humans. The 425-bp SFV integrase fragment was detected in peripheral blood DNA from 53 captive and 8 wild-caught mandrills and in two personnel. Sequence and phylogenetic studies demonstrated the presence of two distinct strains of mandrill SFV, one clade including SFVs from mandrills living in the northern part of Gabon and the second consisting of SFV from animals living in the south. One man who had been bitten 10 years earlier by a mandrill and another bitten 22 years earlier by a macaque were found to be SFV infected, both at the Primate Centre. The second man had a sequence close to SFVmac sequences. Comparative sequence analysis of the virus from the first man and from the mandrill showed nearly identical sequences, indicating genetic stability of SFV over time.

Conclusion

Our results show a high prevalence of SFV infection in a semi-free-ranging colony of mandrills, with the presence of two different strains. We also showed transmission of SFV from a mandrill and a macaque to humans.     

The value of primate models for studying human immunodeficiency virus pathogenesis

Abstract: Research on human immunodeficiency virus (HIV) infection is compromised by the obvious limitation in having for study only virus-infected individuals or those exposed to the virus. Steps involved in transmission or pathogenesis require planned experimentation. The identification of animal models of acquired immunodeficiency syndrome (AIDS) has therefore been helpful for evaluating phases of HIV pathogenesis. Of the seven subgenera of lentiviruses now recognized, two share the characteristics with HIV of a T cell tropism and the associated loss of CD4+ cells in the host associated with disease: the feline immunodeficiency virus (FIV) and the simian immunodeficiency virus (SIV) (Table 1). The other animal lentiviruses grow best in macrophages and their infection generally reflects clinical sequellae of infection of this cell type. This review addresses those features of SIV, HIV, and SHIV infections of non-human primates that illustrate the importance of the animal models of AIDS.     

Evidence for an increased risk of transmission of simian immunodeficiency virus and malaria in a rhesus macaque coinfection model

In sub-Saharan Africa, HIV-1 infection frequently occurs in the context of other coinfecting pathogens, most importantly, Mycobacterium tuberculosis and malaria parasites. The consequences are often devastating, resulting in enhanced morbidity and mortality. Due to the large number of confounding factors influencing pathogenesis in coinfected people, we sought to develop a nonhuman primate model of simian immunodeficiency virus (SIV)-malaria coinfection. In sub-Saharan Africa, Plasmodium falciparum is the most common malaria parasite and is responsible for most malaria-induced deaths. The simian malaria parasite Plasmodium fragile can induce clinical symptoms, including cerebral malaria in rhesus macaques, that resemble those of P. falciparum infection in humans. Thus, based on the well-characterized rhesus macaque model of SIV infection, this study reports the development of a novel rhesus macaque SIV-P. fragile coinfection model to study human HIV-P. falciparum coinfection. Using this model, we show that coinfection is associated with an increased, although transient, risk of both HIV and malaria transmission. Specifically, SIV-P. fragile coinfected macaques experienced an increase in SIV viremia that was temporarily associated with an increase in potential SIV target cells and systemic immune activation during acute parasitemia. Conversely, primary parasitemia in SIV-P. fragile coinfected animals resulted in higher gametocytemia that subsequently translated into higher oocyst development in mosquitoes. To our knowledge, this is the first animal model able to recapitulate the increased transmission risk of both HIV and malaria in coinfected humans. Therefore, this model could serve as an essential tool to elucidate distinct immunological, virological, and/or parasitological parameters underlying disease exacerbation in HIV-malaria coinfected people.     

Marburg and Ebola virus infections in laboratory non-human primates: a literature review

BACKGROUND AND PURPOSE: Several non-human primate species are used as laboratory animals for various types of studies. Although importation of monkeys may introduce different diseases, special attention has recently been drawn to Marburg and Ebola viruses. This review presented here discusses the potential risk of these viruses for persons working with non-human primates as laboratory animals by focusing on epidemiology, virology, symptoms, pathogenesis, natural reservoir, transmission, quarantine of non-human primates, therapy, and prevention. CONCLUSION: A total of 23 Marburg and Ebola virus outbreaks causing viral hemorrhagic fever has been reported among humans and monkeys since the first outbreak in Marburg, Germany in 1967. Most of the 1,100 human cases, with nearly 800 deaths, developed in Africa due mainly to direct and intimate contact with infected patients. Few human cases have developed after contact with non-human primates used for various scientific purposes. However, adequate quarantine should be applied to prevent human infections not only due to Marburg and Ebola viruses, but also to other infective agents. By following proper guidelines, the filovirus infection risk for people working with non-human primates during quarantine exists, but is minimal. There seems to be little risk for filovirus infections after an adequate quarantine period. Therefore, non-human primates can be used as laboratory animals, with little risk of filovirus infections, provided adequate precautions are taken.     

An endogenous foamy virus in the aye-aye (Daubentonia madagascariensis)

We report the discovery and analysis of an endogenous foamy virus (PSFVaye) within the genome of the aye-aye (Daubentonia madagascariensis), a strepsirrhine primate from Madagascar. Phylogenetic analyses indicate that PSFVaye is divergent from all known simian foamy viruses, suggesting an association between foamy viruses and primates since the haplorrhine-strepsirrhine split. The discovery of PSFVaye indicates that primate foamy virus might be more broadly distributed than previously thought.     

Characterization of a Novel Simian Immunodeficiency Virus (SIV) from L’Hoest Monkeys (Cercopithecus l’hoesti): Implications for the Origins of SIVmnd and Other Primate Lentiviruses

The human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2) appear to have originated by cross-species transmission of simian immunodeficiency virus (SIV) from asymptomatically infected African primates. Few of the SIVs characterized to date efficiently infect human primary lymphocytes. Interesting, two of the three identified to infect such cultures (SIVsm and SIVcpz) have appeared in human populations as genetically related HIVs. In the present study, we characterized a novel SIV isolate from an East African monkey of the Cercopithecus genus, the l’hoest monkey (C. l’hoesti), which we designated SIVlhoest. This SIV isolate efficiently infected both human and macaque lymphocytes and resulted in a persistent infection of macaques, characterized by high primary virus load and a progressive decline in circulating CD4 lymphocytes, consistent with progression to AIDS. Phylogenetic analyses showed that SIVlhoest is genetically distinct from other previously characterized primate lentiviruses but clusters in the same major lineage as SIV from mandrills (SIVmnd), a West African primate species. Given the geographic distance between the ranges of l’hoest monkeys and mandrills, this may indicate that SIVmnd arose through cross-species transmission from close relatives of l’hoest monkeys that are sympatric with mandrills. These observations lend support to the hypothesis that the primate lentiviruses originated and coevolved within monkeys of the Cercopithecus genus. Regarded in this light, lentivirus infections of primates not belonging to the Cercopithecus genus may have resulted from cross-species transmission in the not-too-distant past.     

Evolution and virulence of primate lentiviruses

While the AIDS epidemic caused by human immunodeficiency viruses (HIV) has resulted in the death of over 20 million people worldwide, simian immunodeficiency virus (SIV) infection, found in numerous African primate species, does not induce disease symptoms. The factors accounting for this difference between humans and natural host of SIV remain poorly understood. The entangled nature of the host/virus relationship could be the answer, rather than independent virus or host factors. Such a relationship is as a consequence of host/virus adaptation which has evolved over long periods in naturally infected primate species.     

人工饲养中国猕猴中SRV、STLV和BV的流行病学调查

非人灵长类动物是十分重要的生物医学资源。由于与人类在生理生化、免疫、遗传等方面近似,猕猴是重要的非人灵长类实验动物之一。然而,猕猴作为自然宿主,易感染D型逆转录病毒(simian type D retrovirus,SRV)和T淋巴细胞白血病病毒(simian T lymphotropic virus,STLV)这两种逆转录病毒,并可能会影响AIDS猕猴动物模型等的研究结果。猴B病毒(ceropithecine herpesvirus1,BV)对猕猴及动物从业人员均有危害。云南省拥有较大规模的中国猕猴繁殖种群。基于以上原因,建立SPF级别的中国猕猴种群十分必要。该文应用PCR技术筛查了人工饲养种群中411只中国猕猴的SRV、STLV和BV感染流行情况。结果表明:SRV、STLV和BV的阳性感染率分别为19.71%(81/411)、13.38%(55/411)和23.11%(95/411)。同时比较分析了不同性别及年龄组中国猕猴的病毒感染情况。该研究将有助于建立SPF级别的中国猕猴繁殖种群。     

Antiretroviral activity of ancestral TRIM5alpha

The antiretroviral protein TRIM5α is known to have evolved different restriction capacities against various retroviruses, driven by positive Darwinian selection. However, how these different specificities have evolved in the primate lineages is not fully understood. Here we used ancestral protein resurrection to estimate the evolution of antiviral restriction specificities of TRIM5α on the primate lineage leading to humans. We used TRIM5α coding sequences from 24 primates for the reconstruction of ancestral TRIM5α sequences using maximum-likelihood and Bayesian approaches. Ancestral sequences were transduced into HeLa and CRFK cells. Stable cell lines were generated and used to test restriction of a panel of extant retroviruses (human immunodeficiency virus type 1 [HIV-1] and HIV-2, simian immunodeficiency virus [SIV] variants SIV_mac and SIV_agm, and murine leukemia virus [MLV] variants N-MLV and B-MLV). The resurrected TRIM5α variant from the common ancestor of Old World primates (Old World monkeys and apes, ~25 million years before present) was effective against present day HIV-1. In contrast to the HIV-1 restriction pattern, we show that the restriction efficacy against other retroviruses, such as a murine oncoretrovirus (N-MLV), is higher for more recent resurrected hominoid variants. Ancestral TRIM5α variants have generally limited efficacy against HIV-2, SIV_agm, and SIV_mac. Our study sheds new light on the evolution of the intrinsic antiviral defense machinery and illustrates the utility of functional evolutionary reconstruction for characterizing recently emerged protein differences.     

Serial human passage of simian immunodeficiency virus by unsterile injections and the emergence of epidemic human immunodeficiency virus in Africa

There is compelling evidence that both human immunodeficiency virus (HIV) types emerged from two dissimilar simian immunodeficiency viruses (SIVs) in separate geographical regions of Africa. Each of the two HIVs has its own simian progenitor and specific genetic precursor, and all of the primates that carry these SIVs have been in close contact with humans for thousands of years without the emergence of epidemic HIV. To date no plausible mechanism has been identified to account for the sudden emergence in the mid-20th century of these epidemic HIVs. In this study we examine the conditions needed for SIV to complete the genetic transition from individual human SIV infections to epidemic HIV in humans. The genetic distance from SIV to HIV and the mutational activity needed to achieve this degree of adaptation to human hosts is placed within a mathematical model to estimate the probabilities of SIV completing this transition within a single SIV-infected human host. We found that the emergence of even one epidemic HIV strain, following a single human exposure to SIV, was very unlikely. And the probability of four or more such transitions (i.e. HIV-1 groups M, O and HIV-2 subtypes A and B) occurring in a brief period is vanishingly small. We conclude that SIV cannot become a zoonosis, but requires adaptive mutations to become HIV. Some modern event must have aided in the transition of SIV to HIV. Our research indicates that serial passage of partially adapted SIV between humans could produce the series of cumulative mutations sufficient for the emergence of epidemic HIV strains. We examined the rapid growth of unsterile injections in Africa beginning in the 1950s as a biologically plausible event capable of greatly increasing serial human passage of SIV and generating HIV by a series of multiple genetic transitions. We conclude that increased unsterile injecting in Africa during the period 1950-1970 provided the agent for SIV human infections to emerge as epidemic HIV in the modern era.     

Seroprevalence of specific viral infections in confiscated orangutans (Pongo pygmaeus)

A serological survey of confiscated orangutans was conducted to determine the prevalence of specific viral infections cross reacting with human viruses. Antibodies specific for human hepatitis A (HAV) and B (HBV) viruses, herpes simplex viruses (HSV), and human T-lymphotropic virus (HTLV types I and II), as well as for the simian type D retroviruses (SRV types 1 to 3) and simian immunodeficiency virus (SIV) were tested in samples from 143 orangutans. Results revealed a high prevalence of potential pathogens. The most prevalent viral infection found was HBV (59.4% prevalence) of which 89.4% of infected individuals seroconverted to the non-infectious state and 10.6% remained as chronic carriers. Antibodies to HAV, HSV, HTLV-1, and SRV were also detected but at a lower prevalence. There was no evidence of lentiviral infections in this group of animals. The results confirm the importance of quarantine and the need for diagnostic differentiation of virus infections to determine if they are of human origin or unique orangutan viruses.