Hepatitis A and B: serologic survey of human and nonhuman primate sera

Sera of humans and seven species of nonhuman primates were tested by radioimmunoassay and enzyme immunoassay for the presence of hepatitis A antibody, hepatitis B surface antigen and antibody to hepatitis B surface antigen. The outcome of testing a total of 276 serum or plasma specimens was as follows: with the exception of squirrel monkeys (0%) and cotton-top marmosets (0%), a considerable percentage of all other species tested had detectable antibodies to hepatitis A virus: humans 45.9%, chimpanzees 36.6%, baboons 38.2%, vervets 57.9%, cebus monkeys 40.0% and common marmosets 50.0%. Only one human and two chimpanzees were carriers of hepatitis B surface antigen. Antibodies to hepatitis B surface antigen were detected in human (11.3%), chimpanzees (29.9%), baboons (36.2%) and squirrel monkeys (5%). Chimpanzees showed an increasing prevalence of antibodies to hepatitis A virus and hepatitis B surface antigen with age.     

Serological evidence of alpha herpesvirus infection in sooty mangabeys

Contact between sooty mangabeys (SMs) and a pigtailed macaque prompted the serological screening of SMs for evidence of infection with B virus. Serological tests detected SM antibodies that reacted with B virus polypeptides. Additional testing was performed with sera from SMs with no previous contact with macaques. Results from these tests indicated that 56% (33/59) of the SMs had antibodies that reacted with B virus and SA8. SM antibodies also reacted with herpesvirus papio 2 and to a lesser extent with human alpha herpesviruses (HSV-1 and HSV-2). There was an age-related increase in the presence of these antibodies in SMs that was consistent with the serological pattern of reactivity observed in other nonhuman primate species infected with alpha herpesviruses. These data suggest that SMs may be a host for a herpesvirus that is antigenically similar to those viruses present in other Old World nonhuman primates.     

Optimization of a Novel Non-invasive Oral Sampling Technique for Zoonotic Pathogen Surveillance in Nonhuman Primates

Free-ranging nonhuman primates are frequent sources of zoonotic pathogens due to their physiologic similarity and in many tropical regions, close contact with humans. Many high-risk disease transmission interfaces have not been monitored for zoonotic pathogens due to difficulties inherent to invasive sampling of free-ranging wildlife. Non-invasive surveillance of nonhuman primates for pathogens with high potential for spillover into humans is therefore critical for understanding disease ecology of existing zoonotic pathogen burdens and identifying communities where zoonotic diseases are likely to emerge in the future. We developed a non-invasive oral sampling technique using ropes distributed to nonhuman primates to target viruses shed in the oral cavity, which through bite wounds and discarded food, could be transmitted to people. Optimization was performed by testing paired rope and oral swabs from laboratory colony rhesus macaques for rhesus cytomegalovirus (RhCMV) and simian foamy virus (SFV) and implementing the technique with free-ranging terrestrial and arboreal nonhuman primate species in Uganda and Nepal. Both ubiquitous DNA and RNA viruses, RhCMV and SFV, were detected in oral samples collected from ropes distributed to laboratory colony macaques and SFV was detected in free-ranging macaques and olive baboons. Our study describes a technique that can be used for disease surveillance in free-ranging nonhuman primates and, potentially, other wildlife species when invasive sampling techniques may not be feasible.     

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.     

A naturally occurring epizootic of simian agent 8 in the baboon

An epizootic of genital lesions was observed on baboons (four Papio sub-species) housed in two different outdoor breeding corrals. Serological analysis revealed strong prevalence of antibodies to Simian Agent 8 (SA8). This herpesvirus was subsequently recovered from skin lesions and identified by restriction endonuclease digestion of infected cell DNA. Observations of lesion type, frequency and location were suggestive of venereal transmission. The remarkable similarity between infection resulting from SA8 in baboons and herpes simplex virus in man suggests that the baboon is an excellent model in which to study genital herpes virus transmission and infection.     

Genetic research with nonhuman primates: serving the needs of mankind Symposium summary and future prospects

The wide array of papers delivered at this symposium, ranging from population genetics to molecular genetics, is convincing evidence that genetic research with nonhuman primates is in full bloom. In fact, progress has been quite remarkable considering that a significant number of pedigreed colonies of nonhuman primates have been available for less than 25 years, which is hardly enough time to raise 3 generations of chimpanzees, 5 generations of baboons or 6 generations of rhesus monkeys. Were it not for these pedigreed colonies, we would not have been privileged to have this assemblage of papers on behavior, social structure, predisposition to disease and management of breeding colonies. It is indeed exciting that preliminary evidence has been obtained for major genes that play a role in susceptibility to dyslipoproteinemias in baboons, and that monoclonal antibodies and DNA markers are helping us to understand cholesterol metabolism. And thanks to computers, we can now rank animals in a colony in terms of their useful genotypes as well as their productivity. One can not help but be impressed with the commonality of humans and nonhuman primates at the structural and functional levels. For example, the major histocompatibility systems and the maternal-fetal relationships are very similar. We heard that this similarity is even more striking at the chromosomal, biochemical and DNA levels. A provocative question yet to be answered is, “what accounts for the obvious differences between humans and nonhuman primates in view of these incredible similarities?” In light of these advances, this symposium was at the cutting edge of primate genetics and the papers published in this issue of Genetica are certain to be hallmarks in the literature.     

Serum leptin in nonpregnant and pregnant women and in old and new world nonhuman primates

Leptin is a hormone that is produced during mammalian pregnancy in the placental trophoblast and other tissues, including! fetal and maternal adipocytes. Synthesis of the polypeptide and the presence of its specific receptors throughout the human maternal fetoplacental unit suggest direct effects on conceptus growth and development. However, both the physiologic roles of leptin and the mechanisms regulating leptin synthesis in human pregnancy differ from those in laboratory and domestic species, necessitating the development of non-human primate research models. Therefore, we compared serum leptin concentrations in nonpregnant and pregnant women with those in both old world nonhuman primates (i.e., baboon, rhesus monkey, cynomolgus monkey) and new world nonhuman primates (i.e., squirrel monkey, titi monkey). As expected, maternal leptin levels were elevated in human and baboon pregnancies (P < 0.05 and P < 0.001, respectively). Levels in both species of old world monkeys were also greatly enhanced (P < 0.001). Although maternal serum concentrations were slightly elevated compared to nonpregnant levels in both species of new world monkeys, overall concentrations were dramatically lower than for either old world primates or humans. Results provide comparisons of serum leptin concentrations in pregnant and nonpregnant humans and baboons with those in both old and new world monkeys and further characterize these nonhuman primates as models for the investigation of leptin dynamics in pregnancy.     

Seroprevalence of West Nile virus in nonhuman primates as related to mosquito abundance at two national primate research centers

West Nile virus (WNV) surfaced as an emerging infectious disease in the northeastern United States in 1999, gradually spread across the continent, and is now endemic throughout North America. Outdoor-housed nonhuman primates at the Tulane National Primate Research Center (TNPRC) in Louisiana were documented with a relatively high prevalence (36%) of antibodies to West Nile virus. We examined the prevalence of antibodies to WNV in a nonhuman primate population housed in outdoor colonies at the Yerkes National Primate Research Center Field Station located near Atlanta, Georgia. We screened rhesus macaques (Macaca mulatta) and sooty mangabeys (Cercocebus atys) that were at least 3 y old by serum neutralization for antibodies to WNV and confirmed these results by hemagglutination-inhibition assay. None of the 45 rhesus monkeys had antibodies to WNV, but 3 of the 45 mangabeys (6.6%) were positive by both serum neutralization and hemagglutination-inhibition tests. The ratio of seroprevalences in the TNPRC and Yerkes primate populations was similar to the ratio of WNV incidences in people in Louisiana and Georgia from 2002 to 2004. The difference in the exposure of nonhuman primates (and possibly humans) to WNV between these 2 regions is consistent with the difference in the abundance of mammal-biting WNV-infectious mosquitoes, which was 23 times lower near Yerkes than around TNPRC in 2003 and 33 times lower in 2004.     

Serological evidence of Ebola virus infection in Indonesian orangutans

Ebola virus (EBOV) and Marburg virus (MARV) belong to the family Filoviridae and cause severe hemorrhagic fever in humans and nonhuman primates. Despite the discovery of EBOV (Reston virus) in nonhuman primates and domestic pigs in the Philippines and the serological evidence for its infection of humans and fruit bats, information on the reservoirs and potential amplifying hosts for filoviruses in Asia is lacking. In this study, serum samples collected from 353 healthy Bornean orangutans (Pongo pygmaeus) in Kalimantan Island, Indonesia, during the period from December 2005 to December 2006 were screened for filovirus-specific IgG antibodies using a highly sensitive enzyme-linked immunosorbent assay (ELISA) with recombinant viral surface glycoprotein (GP) antigens derived from multiple species of filoviruses (5 EBOV and 1 MARV species). Here we show that 18.4% (65/353) and 1.7% (6/353) of the samples were seropositive for EBOV and MARV, respectively, with little cross-reactivity among EBOV and MARV antigens. In these positive samples, IgG antibodies to viral internal proteins were also detected by immunoblotting. Interestingly, while the specificity for Reston virus, which has been recognized as an Asian filovirus, was the highest in only 1.4% (5/353) of the serum samples, the majority of EBOV-positive sera showed specificity to Zaire, Sudan, Cote d'Ivoire, or Bundibugyo viruses, all of which have been found so far only in Africa. These results suggest the existence of multiple species of filoviruses or unknown filovirus-related viruses in Indonesia, some of which are serologically similar to African EBOVs, and transmission of the viruses from yet unidentified reservoir hosts into the orangutan populations. Our findings point to the need for risk assessment and continued surveillance of filovirus infection of human and nonhuman primates, as well as wild and domestic animals, in Asia.     

Primate viral diseases in perspective

The recent occurrence of fatal Herpesvirus simiae (B virus) infection in human subjects has again focused the attention of primatologists on this virus. B virus, however, is only one of a number of viral diseases that plays a role in primate colony management. This report is to emphasize to the primatologist a number of viruses other than H. simiae, with high morbidity and mortality rates, of importance for health management of nonhuman primate animal colonies. This concept is supported by the recent occurrence in colonies of nonhuman primates of simian hemorrhagic fever virus, SA8, herpesvirus, respiratory syncytial virus, encephalomyocarditis virus, Ebola virus, and simian immunodeficiency viruses.     

Iliac biopsy for histomorphometric analysis of trabecular bone in cynomolgus monkeys and baboons

A humane, repeatable surgical technique was developed to harvest trabecular bone for histomorphometry from nonhuman primates. Using a direct surgical approach to the iliac crest, bone specimens with a mean cross sectional area of trabecular bone plus marrow (AT) of 12.02 and 18.07 mm2 were harvested from cynomolgus monkeys (Macaca fascicularis) and baboons (Papio anubis) respectively. The method provides bone samples with little artifact or bone dust contamination, and easy orientation and reproducibility of the plane of section. None of the cynomolgus monkeys were affected adversely by the surgery, but the baboons were quieter than normal for 12-24 hours afterward. The technique offers excellent biopsy specimens, repeatability and a minimum of stress to the subjects.     

Nonhuman primate infections after organ transplantation

Nonhuman primates, primarily rhesus macaques (Macaca mulatta), cynomolgus macaques (Macaca fascicularis), and baboons (Papio spp.), have been used extensively in research models of solid organ transplantation, mainly because the nonhuman primate (NHP) immune system closely resembles that of the human. Nonhuman primates are also frequently the model of choice for preclinical testing of new immunosuppressive strategies. But the management of post-transplant nonhuman primates is complex, because it often involves multiple immunosuppressive agents, many of which are new and have unknown effects. Additionally, the resulting immunosuppression carries a risk of infectious complications, which are challenging to diagnose. Last, because of the natural tendency of animals to hide signs of weakness, infectious complications may not be obvious until the animal becomes severely ill. For these reasons the diagnosis of infectious complications is difficult among post-transplant NHPs. Because most nonhuman primate studies in organ transplantation are quite small, there are only a few published reports concerning infections after transplantation in nonhuman primates. Based on our survey of these reports, the incidence of infection in NHP transplant models is 14%. The majority of reports suggest that many of these infections are due to reactivation of viruses endemic to the primate species, such as cytomegalovirus (CMV), polyomavirus, and Epstein-Barr virus (EBV)-related infections. In this review, we address the epidemiology, pathogenesis, role of prophylaxis, clinical presentation, and treatment of infectious complications after solid organ transplantation in nonhuman primates.     

Anti-idiotypic antibody response to monoclonal anti-CD4 preparations in nonhuman primate species.

A series of mouse monoclonal anti-CD4 preparations was characterized for the ability to recognize overlapping epitopes on CD4 and to inhibit HIV/simian immunodeficiency virus (SIV) syncytium formation. Based on this characterization, mAb able to recognize CD4 epitopes overlapping the HIV binding site were selected and used to immunize nonhuman primates to elicit the production of specific anti-Id antibodies. Five baboons and five rhesus monkeys were immunized with either individual or a cocktail consisting of several monoclonal anti-CD4 preparations. All the nonhuman primates produced specific anti-Id that recognized either private or cross-reactive Id depending on the monoclonal anti-CD4 used to generate the anti-Id response. Inhibition assays were performed to ascertain the ability of: 1) soluble CD4 to inhibit the Id-anti-Id reaction and 2) the various anti-Id to inhibit the CD4-monoclonal anti-CD4 reaction. These studies demonstrated that some of the anti-Id recognized a cross-reactive Id that was associated with the Ag-combining site. In addition, some of the anti-Id weakly recognized SIV gp120 by Western blot analysis. These studies may be useful in designing experiments that may lead to a better understanding of the CD4-HIV gp120 interaction and to the production of Id and/or anti-Id reagents that might be used to manipulate this virus-receptor interaction.     

Advantages and limitations of nonhuman primates as animal models in genetic research on complex diseases

Abstract: The genetic similarity between humans and nonhuman primates makes nonhuman primates uniquely suited as models for genetic research on complex physiological and behavioral phenotypes. By comparison with human subjects, nonhuman primates, like other animal models, have several advantages for these types of studies: 1) constant environmental conditions can be maintained over long periods of time, greatly increasing the power to detect genetic effects; 2) different environmental conditions can be imposed sequentially on individuals to characterize genotype-environment interactions; 3) complex pedigrees that are much more powerful for genetic analysis than typically available human pedigrees can be generated; 4) genetic hypotheses can be tested prospectively by selective matings; and 5) essential invasive and terminal experiments can be conducted. Limitations of genetic research with nonhuman primates include cost and availability. However, the ability to manipulate both genetic and environmental factors in captive primate populations indicates the promise of genetic research with these important animal models for illuminating complex disease processes. The utility of nonhuman primates for biomedical research on human health problems is illustrated by examples concerning the use of baboons in studies of osteoporosis, alcohol metabolism, and lipoproteins.     

Leishmania major: the suitability of East African nonhuman primates as animal models for cutaneous leishmaniasis

The susceptibility of four species of East African nonhuman primates to experimental infection with Leishmania major was investigated. Four Syke's monkeys (Cercopithecus mitis), two vervet monkeys (Cercopithecus aethiops), two baboons (Papio cynocephalus), and two brown bushbabies (Galago garnettii) were each inoculated intradermally on the left eyelid, left ear, and nose with 0.1 ml of medium containing 1 x 10(7) promastigotes of a characterized L. major strain. All the nonhuman primates except the bushbabies developed erythema and conspicuous nodules on the eyelids and ears by 3 weeks PI. The nodules increased rapidly in size and ulceration was evident on the eyelids and ears by 49 days PI in the vervets, Syke's, and baboons. The aspirates were positive in culture or smears at 35, 49, 63, and 77 days PI. No parasites were observed in cultures or smears at 92, 105, 128, 147, and 161 days PI. The lesions in these animals began resolving by 84 days PI and were completely healed by 112 days PI. The exception was one baboon in which lesion healing did not start until around 147 days and was completely healed by 182 days PI. Cultures from the liver failed to demonstrate visceralization of the parasite in any of the animals throughout the 68 weeks of the experiment. Challenge with the same strain of L. major 6 months PI, corresponding to about 3 months after self cure, failed to produce infection in any of these experimental hosts. All the nonhuman primates except the bushbaby when challenged with the same strain of L. major at 12 months PI developed lesions and were positive for parasites at 14 and 28 days PI. Positive cultures were obtained from the eyelid and ear of one vervet up to 42 days PI. However, the lesion sizes in all these animals were smaller than in the initial infection and did not ulcerate. The nodules disappeared within 6 to 8 weeks as compared to 16 weeks in the initial infection. The histopathological appearance of the lesions varied from diffuse infiltration of plasma cells and lymphocytes which increased progressively to granulomata with epitheloid cells. This study shows that the vervets, Syke's, and the baboons are equally susceptible to L. major infection, while bushbabies are refractory. The vervets, Syke's, and baboons demonstrate a self-healing phenomenon within about 3 months which is comparable to that observed in humans infected with L. major. These three species of nonhuman primates are therefore considered as suitable models for drug or vaccine trials against human zoonotic cutaneous leishmaniasis.     

Biosafety in acquired immunodeficiency syndrome (AIDS) studies using nonhuman primates

The safety recommendations for studies on acquired immunodeficiency syndrome (AIDS) using nonhuman primates are based on knowledge about the epidemiology of the disease in humans, characteristics of the virus, and standard methods for handling nonhuman primates in the laboratory. Appropriate procedures avoid exposure to potentially infectious materials by skin puncture or to mucous membranes by using appropriate disinfecting agents, physical containment, protective clothing, and animal handling techniques.     

High Prevalence of Simian T-Lymphotropic Virus Type L in Wild Ethiopian Baboons

Simian T-cell leukemia viruses (STLVs) are the simian counterparts of human T-cell leukemia viruses (HTLVs). A novel, divergent type of STLV (STLV-L) from captive baboons was reported in 1994, but its natural prevalence remained unclear. We investigated the prevalence of STLV-L in 519 blood samples from wild-living nonhuman primates in Ethiopia. Seropositive monkeys having cross-reactive antibodies against HTLV were found among 22 out of 40 hamadryas baboons, 8 of 96 anubis baboons, 24 of 50 baboons that are hybrids between hamadryas and anubis baboons, and 41 of 177 grivet monkeys, but not in 156 gelada baboons. A Western blotting assay showed that sera obtained from seropositive hamadryas and hybrid baboons exhibited STLV-L-like reactivity. A PCR assay successfully amplified STLV sequences, which were subsequently sequenced and confirmed as being closely related to STLV-L. Surprisingly, further PCR showed that nearly half of the hamadryas (20 out of 40) and hybrid (19 out of 50) baboons had STLV-L DNA sequences. In contrast, most of the seropositive anubis baboons and grivet monkeys carried typical STLV-1 but not STLV-L. These observations demonstrate that STLV-L naturally prevails among hamadryas and hybrid baboons at significantly high rates. STLV-1 and -2, the close relative of STLV-L, are believed to have jumped across simian-human barriers, which resulted in widespread infection of HTLV-1 and -2. Further studies are required to know if STLV-L is spreading into human populations.     

Rearing of conventional and gnotobiotic nonhuman primates (Pan troglodytes, Papio cynocephalus, Saguinus nigricollis).

Rearing techniques for conventional and gnotobiotic nonhuman primates are described. Up to four months of age there was no significant difference in weight gain between conventionally and gnotobiotically reared chimpanzees or baboons. After four months, gnotobiotic chimpanzees exceeded their conventional counterparts in weight gain, whereas conventional baboons showed higher weight gain than gnotobiotic baboons. Gnotobiotic chimpanzees and baboons had significantly lower absolute numbers of neutrophils than their conventional counterparts, but the absolute numbers of lymphocytes were not different. The gnotobiotic rearing of marmosets is also reported.     

Uptake Hydrogenase Activity Determined by Plasmid pRL6JI in Rhizobium leguminosarum Does Not Increase Symbiotic Nitrogen Fixation

We examined three groups of wild baboons (Papio cynocephalus) in Amboseli National Park, Kenya, to determine the prevalence of aerobic antibiotic-resistant fecal bacteria in nonhuman primates with and without contact with human refuse. Using standard isolation and replica plating techniques, we found only low numbers of antibiotic-resistant gram-negative enteric bacteria in two groups of baboons leading an undisturbed existence in their natural habitat and having limited or no contact with humans. However, resistance was significantly higher among enteric bacteria from the third group of baboons living in close proximity to a tourist lodge and having daily contact with unprocessed human refuse. Conjugation studies and analysis of the cell DNA by gel electrophoresis showed that in many cases resistance was plasmid-borne and transferable. These data suggest that wild nonhuman primates in frequent contact with human debris have a higher proportion of antibiotic-resistant enteric bacteria than do conspecifics without this contact. The findings further suggest that such groups of wild animals may constitute a heretofore overlooked source of antibiotic resistance in the natural environment.