A first report of non-invasive adenovirus detection in wild Assamese macaques in Thailand

Several simian adenoviruses (AdVs) have been detected and isolated in various species of non-human primates with the goals of monitoring the health of wildlife and investigating their potential for zoonotic disease transmission. Here, we provide evidence of AdV infection in wild Assamese macaques (Macaca assamensis assamensis) at Phu Khieo Wildlife Sanctuary, Thailand, based on polymerase chain reaction of non-invasively collected fecal samples. Eight out of 110 fecal samples (7.3%), or five out of 87 monkeys (5.7%), showed evidence of AdV infection. All infected individuals were infants or juveniles. Phylogenetic analysis based on the sequence of hexon and polymerase genes revealed two different AdV genotypes. One genotype clustered in the human AdV-G group, while another showed 100% identity with previously reported AdVs of captive Chinese rhesus macaques (Macaca mulatta), which may be tentatively classified as a new species of AdV in non-human primates while awaiting further supporting evidence.     

Subsets of T cells in healthy rhesus macaques (Macaca mulatta) infected with simian T-lymphotropic virus type 1

Simian T-lymphotropic virus type 1 (STLV-1) is a C-type retrovirus of nonhuman primates that is genetically and antigenically related to human T-lymphotropic virus type 1 (HTLV-1). Infection with STLV-1 has been reported in many species of Old World monkeys and apes, including rhesus macaques (Macaca mulatta). Similar to HTLV infection in humans, STLV infection has been associated with T-cell lymphoproliferative disease or lymphoma in a small proportion of infected animals, predominantly African species. There are conflicting reports of T-cell subset alterations in healthy HTLV-1 carriers. To the authors' knowledge, analysis of T-cell subsets in healthy STLV-1 carrier rhesus macaques has not been reported. Subsets of T cells in peripheral blood from healthy, STLV-1-seropositive rhesus macaques (n = 17) and seronegative controls matched for age and sex (n = 17) were determined by use of fluorescence-activated cell sorter analysis. Parameters measured included CD3, CD4, CD8, CD25, CD28, CD38, and HLA-DR cell sets. Significant differences in T-cell subsets or hematologic parameters were not observed between healthy STLV-seropositive and seronegative groups.     

A natural asymptomatic herpes B virus infection in a colony of laboratory brown capuchin monkeys (Cebus apella)

Herpes B virus (BV) infection of macaques persists in the natural host, but is mainly asymptomatic. However, BV can cause fatal disease in humans and in several non-macaque species such as capuchin monkeys (Cebus apella). The BV infection described here in a colony of capuchin monkeys was persistent but asymptomatic. Initially the infection was detected serologically in five out of seven animals. However, using polymerase chain reaction (PCR) developed specifically for BV, we found the virus in all seven clinically healthy animals. It is probable that the infection was transferred from BV-infected macaques housed in different cages but in the same room for several years. We have no evidence to indicate that similar asymptomatic infections may occur in other New World species but the possibility should not be discounted. We recommend that the housing of capuchin monkeys in close proximity to macaques should be avoided and that greater caution should be used when handling capuchin monkeys and possibly other New World species that have been in contact with macaques. All may act as a source of BV infection in humans, hence routine, repeated testing of all primates is essential.     

Simian T-cell leukemia virus (STLV) infection in wild primate populations in Cameroon: evidence for dual STLV type 1 and type 3 infection in agile mangabeys (Cercocebus agilis)

Three types of human T-cell leukemia virus (HTLV)-simian T-cell leukemia virus (STLV) (collectively called primate T-cell leukemia viruses [PTLVs]) have been characterized, with evidence for zoonotic origin from primates for HTLV type 1 (HTLV-1) and HTLV-2 in Africa. To assess human exposure to STLVs in western Central Africa, we screened for STLV infection in primates hunted in the rain forests of Cameroon. Blood was obtained from 524 animals representing 18 different species. All the animals were wild caught between 1999 and 2002; 328 animals were sampled as bush meat and 196 were pets. Overall, 59 (11.2%) of the primates had antibodies cross-reacting with HTLV-1 and/or HTLV-2 antigens; HTLV-1 infection was confirmed in 37 animals, HTLV-2 infection was confirmed in 9, dual HTLV-1 and HTLV-2 infection was confirmed in 10, and results for 3 animals were indeterminate. Prevalences of infection were significantly lower in pets than in bush meat, 1.5 versus 17.0%, respectively. Discriminatory PCRs identified STLV-1, STLV-3, and STLV-1 and STLV-3 in HTLV-1-, HTLV-2-, and HTLV-1- and HTLV-2-cross-reactive samples, respectively. We identified for the first time STLV-1 sequences in mustached monkeys (Cercopithecus cephus), talapoins (Miopithecus ogouensis), and gorillas (Gorilla gorilla) and confirmed STLV-1 infection in mandrills, African green monkeys, agile mangabeys, and crested mona and greater spot-nosed monkeys. STLV-1 long terminal repeat (LTR) and env sequences revealed that the strains belonged to different PTLV-1 subtypes. A high prevalence of PTLV infection was observed among agile mangabeys (Cercocebus agilis); 89% of bush meat was infected with STLV. Cocirculation of STLV-1 and STLV-3 and STLV-1-STLV-3 coinfections were identified among the agile mangabeys. Phylogenetic analyses of partial LTR sequences indicated that the agile mangabey STLV-3 strains were more related to the STLV-3 CTO604 strain isolated from a red-capped mangabey (Cercocebus torquatus) from Cameroon than to the STLV-3 PH969 strain from an Eritrean baboon or the PPA-F3 strain from a baboon in Senegal. Our study documents for the first time that (i) a substantial proportion of wild-living monkeys in Cameroon is STLV infected, (ii) STLV-1 and STLV-3 cocirculate in the same primate species, (iii) coinfection with STLV-1 and STLV-3 occurs in agile mangabeys, and (iv) humans are exposed to different STLV-1 and STLV-3 subtypes through handling primates as bush meat.     

Occurrence and frequency of transmission of naturally occurring simian retroviral infections (SIV,STLV, and SRV) at the CIRMF Primate Center,Gabon

Abstract: Among the primates held at the CIRMF Primate Center, Gabon, no serological sign of SIV infection could be demonstrated in 68 cynomolgus monkeys, 60 chimpanzees, nine gorillas, and 12 sun-tailed monkeys, while seven of 102 mandrills and six of 24 vervets were infected with SIV. Six mandrills, seven vervets and ten cynomolgus monkeys exhibited a full HTLV type 1 Western blot profile. The sera of two gorillas and one chimpanzee presented with a positive but not typical HTLV Western blot profile. The sera of the gorillas lacked p24 antibodies, and the chimpanzee had a Western blot profile evocative of HTLV-II. All attempts to amplify viruses from these animals by PCR were unsuccessful. Two other chimpanzees and seven gorillas presented with indeterminate HTLV Western blot profiles. In the mandrill colony, only male animals were STLV seropositive and no sexual transmission to females was observed. SIV infection was also more frequent in male than female mandrills and sexual transmission appeared to be a rare event. No SRV infection was observed in macaques.     

Neutralizing antibodies to simian papovavirus SA12 in Old World primates in laboratory colonies: high prevalence in baboons

Sera from 517 laboratory-housed nonhuman primates representing five genera and from 13 laboratory workers were examined for the presence of neutralizing antibodies to SA12 virus. The antibody prevalences were as follows: baboons, 66%; patas and vervet monkeys, 24%; macaques, 8%, and chimpanzees, 2%. The serum of one laboratory worker had antibodies. These results suggest that SA12 virus is a common infection of nonhuman primates in laboratory colonies, especially baboons.     

人工投食行为对非人灵长类社会生态的影响

近年来,国内开展了对几种非人灵长类投食群的研究。借鉴日本猴(Macaca fuscata)、恒河猴(M.mulatta)和黑猩猩(Pan troglodytes)长期积累的研究经验,有利于我们减少人工投食对非人灵长类带来的不利影响,也有利于推动国内非人灵长类社会生态学的深入研究。本文通过比较这三种灵长类野生群和投食群之间的差异,量化地分析了人工投食对灵长类动物社会生态学方面的影响。结果表明在社会行为方面,人工投食会导致灵长类动物的聚集、增加争斗频率、改变个体间等级关系、延缓分群现象、影响活动域和增加新兴行为。在种群数量方面,人工投食会缩短雌性性成熟时间、增加出生率和婴猴存活率、减少成年猴死亡率。而人工投食对雄性性成熟、出生间隔等方面的影响仍需要进一步考证。最后我们讨论了人工投食行为的利弊,并建议应谨慎和妥善地实施人工投食,和对非人灵长类投食群进行合理的监管。     

The chronic course of spontaneous and experimental hepatitis A in rhesus monkeys with viral persistence]

The prolonged (up to 2 years) complex observation of 11 rhesus macaques (Macaca mulatta) with spontaneous hepatitis A and 14 rhesus macaques with experimental hepatitis A developing after their intravenous and/or oral infection with human hepatitis A virus (HAV). Both natural and experimental infection took a chronic course (15-18 months). In 13 monkeys showing morphological changes in the liver during the whole period of the disease elevated enzyme levels in the blood and virus shedding in feces were periodically observed. Only one monkey had acute hepatitis A which lasted 1.5 months. In 11 monkeys the disease took an undulating course with 1-2 relapses when virological, biochemical and morphological signs of the disease could be detected. Seroconversion was observed in all monkeys. Anti-HAV IgM antibodies were retained for not more than 6-7 months and total anti-HAV antibodies, during the whole period of observation. Relapses were found to induce no antibody formation. Evidence on the prolonged (up to 12-16 months) persistence of HAV in primates was obtained for the first time.     

The simian T-lymphotropic/leukemia virus from Pan paniscus belongs to the type 2 family and infects Asian macaques.

The proviral DNA of the simian T-leukemia/lymphotropic virus (STLV) isolate, originally obtained from a captive colony of pygmy chimpanzees (Pan paniscus) (STLV(pan-p)), was cloned from the DNA of the chronically infected human T-cell line L93-79B. The entire proviral DNA sequence was obtained and compared with sequences of the known genotypes of STLV and human T-leukemia/lymphotropic virus types 1 and 2 (HTLV-1 and -2). Phylogenetic analysis indicates that STLV-2(pan-p) is an early divergence within the type 2 lineage and should be referred to as STLV-2(pan-p). Since STLV-2(pan-p) has been found in African nonhuman primates, we investigated its infectiousness and pathogenicity in Asian monkeys. Pigtailed macaques were inoculated with human cells harboring STLV(pan-p), and infection was assessed by virus isolation, PCR analysis of peripheral blood mononuclear cells, and seroconversion against viral antigens in HTLV-1/HTLV-2 and Western blot assay. Pigtailed macaques became persistently infected by STLV-2(pan-p), and the virus could be transferred by blood transfusion from an infected pigtailed macaque to a rhesus macaque. In addition, like HTLV-1 and HTLV-2, STLV-2(pan-p) was infectious in rabbits. In summary, STLV-2(pan-p) is a novel retrovirus distantly related to HTLV-2 and displays a host range similar to that demonstrated for other HTLV and STLV strains.     

Experimental Infection of Macaques with a Wild Water Bird-Derived Highly Pathogenic Avian Influenza Virus (H5N1)

Highly pathogenic avian influenza virus (HPAIV) continues to threaten human health. Non-human primate infection models of human influenza are desired. To establish an animal infection model with more natural transmission and to determine the pathogenicity of HPAIV isolated from a wild water bird in primates, we administered a Japanese isolate of HPAIV (A/whooper swan/Hokkaido/1/2008, H5N1 clade 2.3.2.1) to rhesus and cynomolgus monkeys, in droplet form, via the intratracheal route. Infection of the lower and upper respiratory tracts and viral shedding were observed in both macaques. Inoculation of rhesus monkeys with higher doses of the isolate resulted in stronger clinical symptoms of influenza. Our results demonstrate that HPAIV isolated from a water bird in Japan is pathogenic in monkeys by experimental inoculation, and provide a new method for HPAIV infection of non-human primate hosts, a good animal model for investigation of HPAIV pathogenicity.     

Arenavirus-mediated liver pathology: acute lymphocytic choriomeningitis virus infection of rhesus macaques is characterized by high-level interleukin-6 expression and hepatocyte proliferation

Lymphocytic choriomeningitis virus (LCMV) and Lassa virus can cause hemorrhagic fever and liver disease in primates. The WE strain of LCMV (LCMV-WE) causes a fatal Lassa fever-like disease in rhesus macaques and provides a model for arenavirus pathogenesis in humans. LCMV-WE delivered intravenously or intragastrically to rhesus macaques targets hepatocytes and induces high levels of liver enzymes, interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), and soluble tumor necrosis factor receptors (sTNFRI and -II) in plasma during acute infection. Proinflammatory cytokines TNF-alpha and IL-1beta were not detected in plasma of infected animals, but increased plasma gamma interferon was noted in fatally infected animals. Immunohistochemistry of acute liver biopsies revealed that 25 to 40% of nuclei were positive for proliferation antigen Ki-67. The increases in IL-6, sIL-6R, sTNFR, and proliferation antigen that we observe are similar to the profile of incipient liver regeneration after surgical or toxic injury (N. Fausto, Am. J. Physiol. 277:G917-G921, 1999). Although IL-6 was not directly induced by virus infection in vitro, peripheral blood mononuclear cells from acutely infected monkeys produced higher levels of IL-6 upon lipopolysaccharide stimulation than did healthy controls. Our data confirm that acute infection is associated with weak inflammatory responses in tissues and initiates a program of liver regeneration in primates.     

A field study of infection with human T-cell leukemia virus among African primates

African non-human primates were surveyed seroepidemiologically for natural infection of human T-cell leukemia virus type I (ATLV/HTLV-I) or its closely related virus(es). Materials from three genera (Cercopithecus, Papio, and Theropithecus), four species (grivet monkey, Anubis baboon, Hamadryas baboon, and gelada), totalling 983 animals under natural conditions, were obtained in a field study in Ethiopia. Virus infection was determined by the indirect immunofluorescence test using HTLV-I specific antigens. Animals seropositive for HTLV-I were found among grivet monkeys and Anubis baboons including the hybrid offspring between Anubis and Hamadryas baboons but not pure-Hamadryas baboons and geladas. From these results, the HTLV-I family was proved to be widespread on the African continent and was regarded as a common retrovirus among catarrhines.     

Prevalence of hepatitis B virus infections in nonhuman primates

The aim of this study was to determine the prevalence of hepatitis B virus (HBV) infection in nonhuman primates. Serum samples from Europe, Thailand and Vietnam were analyzed. Sera obtained from 262 apes and 454 monkeys were tested for HBV infection serologically and for HBV DNA using nested PCR (nPCR). A total number of 198 ape sera and all but one (Cercopithecus aethiops) of the 4543 monkey sera had no serological signs of HBV infection. Among the 64 of 262 (24.4%) seropositive ape sera, we found, as in humans, different stages of HBV infection: very early HBV infection, active infection with high level of infectivity, virus carriers with low infectivity, and passed HBV infection. In the cases with passed infection, 47.8% harbored HBV DNA in the presence of protective antibodies to the HBV surface antigen (HBsAb). This indicates HBV persistence in apes despite immune control. In contrast to apes, in monkeys HBV infection is a very rare event.     

H5N1型禽流感病毒感染非人灵长类动物的观察

目的观察H5N1型禽流感病毒对中国非人灵长类动物的易感性并建立动物模型。方法将病毒通过滴鼻接种实验猴,观察感染后动物的临床症状,采血、咽拭子及各器官组织进行血清学、病原学及病理学检查,记录抗体变化、病毒分离情况及病理学改变。结果感染后动物表现轻度食欲下降、一过性体温升高及外周血白细胞减少,肺组织病毒分离及RT-PCR阳性,病理检查感染急性期动物肺组织表现为间质性肺炎,肺泡间隔增宽,充血出血明显,肺泡受压变形,间质及肺泡内有大量炎细胞浸润,符合病毒性肺炎的改变,感染后14 d动物血清IgG抗体水平较感染前升高4倍。结论H5N1病毒可感染非人灵长类动物,可以作为感染模型进行H5N1病毒的发病机制、疫苗评价、药物筛选等研究。     

Prevalence of herpes B virus genome in the trigeminal ganglia of seropositive cynomolgus macaques

Herpes B virus infection is almost asymptomatic in macaques (Macaca spp.), which are the natural hosts of this pathogen, but is the cause of high mortality in humans. Reactivation of the latent virus in the trigeminal ganglia (TG) results in the shedding of infectious particles into the oral mucosal membrane. Saliva contaminated with the reactivated virus from the ganglia of the natural host is considered to be important for viral transmission to humans and other monkeys. In the present study, we investigated the prevalence of the herpes B virus genome in the left and right TG of seropositive asymptomatic cynomolgus macaques. The latent virus genome was detected using a polymerase chain reaction and microplate hybridization assay. We found that the virus DNA was present in one or both TG of 12 of the 30 macaques (40%) tested, with the virus being detected from both TG in five of the 12 macaques and from a single TG in the remaining seven.     

Use of Old World monkeys for acquired immunodeficiency syndrome research

Mangabeys, macaques, and baboons persistently infected with human immunodeficiency virus (HIV)-2 NIH-DZ demonstrated no signs of immunodeficiency disease after 6-11 months following seroconversion. Thus Old World monkeys provide an animal model to investigate the effects of passive immunization (anti-HIV-2 antibodies) on HIV infection in primates.     

Flow cytometric analysis on reactivity of human T lymphocyte-specific and cytokine-receptor-specific antibodies with peripheral blood mononuclear cells of chimpanzee (Pan troglodytes), rhesus macaque (Macaca mulatta), and squirrel monkey (Saimiri sciureus)

Abstract: There are relatively few monoclonal antibodies (mAb) that have been characterized for their applicability in studies on the immune system of various nonhuman primates. In the present study, we identified a large number of mAb that can be used in future immunological studies in three different nonhuman primates, i.e., chimpanzees, rhesus macaques, and squirrel monkeys. The reactivity of 161 anti-human mAb to T-cell antigens and cytokine receptors were tested on peripheral blood mononuclear cells (PBMC) from the three primate species by flow cytometric analysis. A total of 105 (65%), 73 (45%), and 68 (42%) antibodies reacted with PBMC from chimpanzees, rhesus macaques, and squirrel monkeys, respectively. Out of the 161 mAb, 38 reacted with all three species and 112 reacted with one or two of the species. No specific reaction was observed with mAb to receptors to GM-CSF, 4–1BB, FLT3, FLX2, common β-chain, IL-1 (type I receptor), and IL-8.     

Plateau levels of viremia correlate with the degree of CD4+-T-cell loss in simian immunodeficiency virus SIVagm-infected pigtailed macaques: variable pathogenicity of natural SIVagm isolates

Simian immunodeficiency virus from African green monkeys (SIVagm) results in asymptomatic infection in its natural host species. The virus is not inherently apathogenic, since infection of pigtailed (PT) macaques (Macaca nemestrina) with one isolate of SIVagm results in an immunodeficiency syndrome characterized by progressive CD4+-T-cell depletion and opportunistic infections. This virus was passaged once in a PT macaque and, thus, may not be entirely reflective of the virulence of the parental strain. The goal of the present study was to assess the pathogenicity of the PT-passaged isolate (SIVagm9063) and two primary SIVagm isolates in PT macaques, including the parental strain of the PT-passaged variant. Infection of macaques with any of the three isolates resulted in high levels of primary plasma viremia by 1 week after inoculation. Viremia was quickly controlled following infection with SIVagm155; these animals have maintained CD4+-T-cell subsets and remain healthy. The plateau levels among SIVagm90- and SIVagm9063-inoculated macaques varied widely from 100 to 1 million copies/ml of plasma. Three of four animals from each of these groups progressed to AIDS. Setpoint viremia and the degree of CD4+-T-cell loss at 6 months postinfection were not significantly different between macaques inoculated with SIVagm90 and SIVagm9063. However these parameters were significantly different in SIVagm155-inoculated macaques (P values of <0.01). Considering all the macaques, the degree of CD4+-T-cell loss by 6 months postinfection correlated with the plateau levels of viremia. Thus, similar to SIVsm/mac infection of macaques and human AIDS, viral load is an excellent prognostic indicator of disease course. The inherent pathogenicity of natural SIVagm isolates varies, but such natural isolates are capable of inducing AIDS in macaques without prior macaque passage.     

High prevalence of antibodies against hepatitis A virus among captive nonhuman primates

Hepatitis A virus (HAV) can infect not only humans but also several other nonhuman primates. This study has been conducted to evaluate the comprehensive anti-HAV seroprevalence in captive nonhuman primate populations in Thailand. The prevalence of antibodies against HAV in 96 captive nonhuman primates of 11 species was evaluated by competitive enzyme immunoassay (EIA). HAV antibodies were found in 64.7% (11/17) of macaques, 85.7% (6/7) of langurs, 28.4% (10/35) of gibbons, and 94.6% (35/37) of orangutans. However, anti-HAV IgM was not found in any sera. These results indicate that the majority of captive nonhuman primates in Thailand were exposed to HAV. It is possible that some of the animals were infected prior to capture.