Epizootic of Tularemia in an Outdoor Housed Group of Cynomolgus Monkeys (Macaca fascicularis)

Tularemia is a highly contagious infectious zoonosis, transmissible by inoculation, ingestion, or inhalation of the infectious agent Francisella tularensis. The disease is perpetuated by infected rodents, blood-sucking arthropods, and by contaminated water. Therefore, nonhuman primates housed outdoors may be at risk for exposure. An epizootic of F. tularensis occurred in an indoor/outdoor-housed group of cynomolgus monkeys ( Macaca fascicularis) at the German Primate Center. Tularemia was diagnosed in 18 out of 35 animals within a period of 2 years. Six animals died with unspecific clinical symptoms; 12 animals developed seroconversion and were still alive. Pathologic findings were similar in all monkeys that died and resembled the clinical picture of the human disease, including an ulceroglandular syndrome with local lymphadenopathy, gingivostomatitis, and systemic spread, with manifestations such as subacute necrotizing hepatitis, granulomatous splenitis, and pneumonia. Tularemia was diagnosed by culture, real-time polymerase chain reaction, and ELISA techniques. This is the largest outbreak in nonhuman primates and the first report of tularemia in cynomolgus monkeys. An overview of the recent literature about tularemia in nonhuman primates is given.

Ischiopagus tripus conjoined twins in a western lowland gorilla (Gorilla gorilla)

Conjoined twinning is rare in man and non-human primates. The current report describes a case of ischiopagus tripus conjoined Western Lowland gorilla (Gorilla gorilla) twins. The female twins were joined at the umbilical and pelvic region, involving the liver, xiphoid, umbilicus, body wall and skin. Computed tomography revealed two complete spines. The combined pelvic space was formed by two sacra, each connected with two iliac bones. The twins were only conjoined by a common pubis. Cause of death was attributed to cardiac and circulatory collapse resulting from a large patent foramen ovale (8 mm in diameter) of one twin and neonatal asphyxia.

Oncocytic adrenocortical carcinoma in a putty-nosed monkey (Cercopithecus nictitans) with hyperadrenocorticism

Oncocytic adrenocortical tumours are rare in man and have never been described in non-human primates. An oncocytic adrenocortical carcinoma was identified in an 18-year-old female putty-nosed monkey (Cercopithecus nictitans) with hyperadrenocorticism and invasive aspergillosis. Microscopically, the tumour consisted of large cells with abundant eosinophilic, granular cytoplasm containing numerous mitochondria as identified by electron microscopy. Tumour cells had large nuclei with occasional intranuclear cytoplasmic pseudoinclusions. Immunohistochemically, tumour cells expressed vimentin, synaptophysin and neuron-specific enolase, while they were negative for cytokeratin, chromogranin-A, melan-A and S100.

Prion infected rhesus monkeys to study differential transcription of Alu DNA elements and editing of Alu transcripts in neuronal cells and blood cells

BACKGROUND

Rhesus monkeys were used as a non-human primate model to study small non-coding RNA after infection with human sporadic and variant Creutzfeldt-Jakob prions.

METHODS

Tissue-specific Alu DNA element transcription and editing of transcripts were assessed in neuronal - and blood cells (Buffy Coat).

RESULTS

Tissue/cell-specific transcription and editing patterns were obtained. Active Alu DNA elements belonged to several Alu DNA families, they could be located on several chromosomes, and their genomic sites were identified. Deamination by adenosine deaminase acting on RNA and apolipoprotein B editing complex was found.

CONCLUSIONS

Different Alu transcription and editing programmes exist and may depend on the infection status.

Mucocutaneous candidiasis in a mandrill (Mandrillus sphinx)

An adult male mandrill (Mandrillus sphinx) suffered from chronic ulceration of the facial and gluteal skin and the oral and nasal mucosa. The ulcers were resistant to therapy and led to deterioration in the general condition of the animal. Microscopical examination revealed a severe, chronic, multifocal, granulomatous and eosinophilic dermatitis and panniculitis. There was also stomatitis and rhinitis with numerous intralesional fungal elements. These organisms were identified by immunohistochemistry, transmission electron microscopy, polymerase chain reaction and fungal culture as Candida albicans. Species identification was confirmed by MALDI-TOF mass spectrometry. A specific predisposing immunosuppressive factor for the deep chronic mucocutaneous candidiasis was not identified; however, social stress and/or a primary defect in cell-mediated immunity could not be excluded as possible causes for a predisposing immunodeficiency in the animal.

The pathology of experimental poxvirus infection in common marmosets (Callithrix jacchus): further characterization of a new primate model for orthopoxvirus infections

Zoonotic orthopoxvirus (OPV) can induce severe disease in man and the virus has potential for use in bioterrorism. New vaccines and therapeutics against OPV infections must be tested in animal models. The aim of this study was to characterize the clinical course and pathology of a new OPV isolate, calpox virus, which is infectious in marmosets. Infection experiments were performed with 28 common marmosets (Callithrix jacchus) exposed to different challenge doses of calpox virus by the intravenous, oropharyngeal and intranasal (IN) routes. The median marmoset IN infectious dose corresponded to 8.3 × 10(2)plaque forming units of calpox virus. Infected animals developed reproducible clinical signs and died within 4-15 days post infection. Characteristic pox-like lesions developed in affected organs, particularly in the skin, mucous membranes, lymph nodes, liver and spleen. Calpox virus disease progression and pathological findings in the common marmoset appear to be consistent with lethal OPV infections in man and in other non-human primate (NHP) models. IN inoculation with low virus doses mimics the natural route of the human variola virus infection. Thus, the marmoset model of calpox virus infection can be considered to be relevant to investigation of the mechanisms of OPV pathogenesis and pathology and for the evaluation of new vaccines and antiviral therapies.

Bronchoconstriction in nonhuman primates: a species comparison

Bronchoconstriction is a characteristic symptom of various chronic obstructive respiratory diseases such as chronic obstructive pulmonary disease and asthma. Precision-cut lung slices (PCLS) are a suitable ex vivo model to study physiological mechanisms of bronchoconstriction in different species. In the present study, we established an ex vivo model of bronchoconstriction in nonhuman primates (NHPs). PCLS prepared from common marmosets, cynomolgus macaques, rhesus macaques, and anubis baboons were stimulated with increasing concentrations of representative bronchoconstrictors: methacholine, histamine, serotonin, leukotriene D₄ (LTD₄), U46619, and endothelin-1. Alterations in the airway caliber were measured and compared with previously published data from rodents, guinea pigs, and humans. Methacholine induced maximal airway constriction, varying between 74 and 88% in all NHP species, whereas serotonin was ineffective. Histamine induced maximal bronchoconstriction of 77 to 90% in rhesus macaques, cynomolgus macaques, and baboons and a lesser constriction of 53% in marmosets. LTD₄ was ineffective in marmosets and rhesus macaques but induced a maximum constriction of 44 to 49% in cynomolgus macaques and baboons. U46619 and endothelin-1 caused airway constriction in all NHP species, with maximum constrictions of 65 to 91% and 70 to 81%, respectively. In conclusion, PCLS from NHPs represent a valuable ex vivo model for studying bronchoconstriction. All NHPs respond to mediators relevant to human airway disorders such as methacholine, histamine, U46619, and endothelin-1 and are insensitive to the rodent mast cell product serotonin. Only PCLS from cynomolgus macaques and baboons, however, responded also to leukotrienes, suggesting that among all compared species, these two NHPs resemble the human airway mechanisms best.

Treponema infection associated with genital ulceration in wild baboons

The authors describe genital alterations and detailed histologic findings in baboons naturally infected with Treponema pallidum. The disease causes moderate to severe genital ulcerations in a population of olive baboons (Papio hamadryas anubis) at Lake Manyara National Park in Tanzania. In a field survey in 2007, 63 individuals of all age classes, both sexes, and different grades of infection were chemically immobilized and sampled. Histology and molecular biological tests were used to detect and identify the organism responsible: a strain similar to T pallidum ssp pertenue, the cause of yaws in humans. Although treponemal infections are not a new phenomenon in nonhuman primates, the infection described here appears to be strictly associated with the anogenital region and results in tissue alterations matching those found in human syphilis infections (caused by T pallidum ssp pallidum), despite the causative pathogen's greater genetic similarity to human yaws-causing strains.

Outbreak of Streptococcus equi subsp. zooepidemicus infection in a group of rhesus monkeys (Macaca mulatta)

Background  A severe upper respiratory tract infection occurred in a breeding group of rhesus monkeys housed together in one of six indoor/outdoor corals of the German Primate Center. The clinical signs of the disease included severe purulent conjunctivitis, rhinitis, pharyngitis, respiratory distress and lethargy. Six of 45 animals died within a few days after developing signs of infection.

Methods and results  Histopathologic and microbiologic examinations of the dead animals were consistent with a severe fibrinopurulent bronchopneumonia. Microbiology revealed a Lancefield group C streptococcus identified as Streptococcus equi subsp. zooepidemicus as the causative agent of infection.

Conclusions  The infection was passed on from animal to animal but did not spread to the other five breeding groups nearby. Extensive diagnostic testing failed to reveal the consisting presence of copathogens in individual cases. A visitor with upper respiratory disease was suspected as source of infection.

Leucoencephalopathy with cerebral calcinosis in a young chimpanzee (Pan troglodytes) - a case report

CASE HISTORY

A 4-year-old chimpanzee (Pan troglodytes) had a clinical history of a 2-year progressive central nervous dysfunction including convulsions and severe paralysis.

RESULTS

Gross pathology revealed cerebral atrophy, ventricular enlargement and a severe encephalomalacia with extensive calcifications. Histologically, the white matter showed diffuse demyelination as well as vascular and perivascular calcifications which also involved the basal ganglia. Blood vessels with less distinctive calcium deposits exhibited periodic acid Schiff positive hyalinosis. Large areas of necrosis, hemorrhage and intense gliosis were also present. Activation of astrocytes and macrophages was confirmed by immunohistochemical methods.

CONCLUSIONS

The etiology of the leucoencepalopathy could not be ascertained by macroscopic, histological and immunohistochemical examinations. Potential differential diagnoses include the rarely occurring Fahr's disease in humans, arteriosclerosis, storage disease and the Aicardi-Goutières syndrome. Based on the results of the postmortal examinations Fahr's disease is regarded as the most likely diagnosis in the present case of the chimpanzee.

Alopecia areata in a rhesus monkey (Macaca mulatta)

BACKGROUND

A 14-year-old female rhesus monkey (Macaca mulatta) of Chinese origin has been suffering from alopecia universalis since childhood.

METHODS

Recently, the health status of the animal was recorded comprehensively by detailed clinical examination including hematology and serology supplemented by histological and immunohistochemical investigations of skin biopsies and molecular biological techniques to clarify the causes of the persistent hair loss.

RESULTS AND CONCLUSIONS

The hairless gene (hr) nonsense mutation was ruled out by polymerase chain reaction and by sequencing of the corresponding gene. Histological examinations revealed a prominent chronic lymphocytic perifolliculitis and folliculitis affecting anagen stage hair follicles as well as miniaturized hair follicles. Immunohistochemistry using the antibodies CD3, CD20 and CD4 confirmed the diagnosis of a T-cell-mediated autoimmune disease resembling alopecia areata universalis in humans.

[The need for experiments using primates from a scientific point of view]

Concerning the public discussion on animal experiments using primates, various research fields are demonstrated where non-human primates are necessary for certain scientific reasons at this time. Non-human Primates are used in Germany mainly in regulatory toxicology and pharmaceutical safety studies.A small amount is disposed in different fields of biological or biomedical basic research. This includes in particular neurosciences and infection research. 2006 New and Old World monkeys were needed in Germany in 2005. No chimpanzees are used anymore as laboratory animals in Germany since many years. Several examples are presented to demonstrate that certain research fields need non-human primates as laboratory animals in the foreseeable future.

Fatal poxvirus outbreak in a colony of New World monkeys

An epizootic infection was observed in a colony of 80 New World monkeys consisting of various species including a group of marmosets and Saguinus species. During the summer and autumn of 2002, 30 animals died of unknown diseases. Six animals were sent to the German Primate Center for investigation of the cause of death. A complete pathologic and histologic investigation was carried out. The animals exhibited erosive-ulcerative lesions of the oral mucous membranes. Advanced stages of the disease were characterised by hemorrhagic lesions on the skin distributed randomly over the body, but principally on the face, scrotal region, soles, and palms. Electron microscopy revealed virus particles with orthopox-like morphology within intracytoplasmic inclusions in epithelial cells. The DNA samples from various tissues were analyzed by use of a set of orthopox virus-specific, real-time polymerase chain reaction assays. Amplification products were sequenced to define the virus more precisely. Sequencing confirmed the presence of an orthopox virus. Sequence data indicated that all six animals were infected with the same virus. Propagation of the virus on Vero cells resulted in a rapidly progressive cytopathogenic effect. Preliminary phylogenetic analyses of two genes revealed closest homology to cowpox viruses. The origin of this poxvirus outbreak remains unexplained, and the strain and genus of the virus need to be determined in detail.

Tubuloreticular structures in rectal biopsies of SIV-infected rhesus monkeys (Macaca mulatta)

Tubuloreticular structures (TRS) are considered to be a specific ultrastructural marker for AIDS in various organs. Experimental SIV infection in rhesus macaques is the most appropriate animal model of HIV infection. In 8 rhesus monkeys, experimentally infected with SIVmac251/MPBC, rectum biopsies were taken prior to and post infection (day 3; 1, 2, 4, 12 weeks p.i.) and were investigated by transmissionelectron microscopy to determine incidence and extent of tubuloreticular structures as well as affected cells. From the first week p.i. on TRS were found in all experimental animals as tubuli with a diameter of 20-30 nm. The tubuli were arranged in regular paracristalline formations and formed intracytoplasmatic heterogenous, polymorph accumulations, which were localized close to the endoplasmatic reticulum. In the rectal lamina propria macrophages, endothelial cells, plasma cells, lymphocytes, fibroblasts, and neutrophilic granulocytes were the affected cell types. In 5 control biopsies TRS were detected, too, but, in contrast to SIV-infected animals, they appeared only singular and very small. The results indicate that TRS are a characteristic morphologic criteria of intestinal SIV infection. They appear in very early stages of the infection. In the rectum, they can be detected as bigger, conspicuous, and abundant formations in several cells and have a restricted diagnostic and prognostic validity.

[Species-specific primate husbandry]

With about 300 species primates represent one of the largest animal groups within mammals. They are kept in zoological gardens, as laboratory animals or in private ownership. Against this background it is difficult to define all species-specific aspects of a primate husbandry. The paper describes the basic requirements for primates like nutrition, possibilities for social interactions and species specific behaviour, stimuli for activities, health care and environmental conditions. Although no definitive regulations exist by law, the Appendix A (Species-specific Provisions for Non-human Primates) of the European Convention for the Protection of Vertebrate Animals used for Experimental and other Scientific Purposes (ETS 123) will be of great importance in the future.

Intraperitoneal foreign body disease in a baboon (Papio hamadryas)

In a baboon group housed at the German Primate Center one animal became conspicuous with signs of massive abdominal pain in the upper gastric region. After clinical investigation an acute bloat-syndrome was suspected as cause of the animals' sickness. Symptomatic therapy was started but the animal died within a few hours. At necropsy a large piece of wood was found within the right kidney and liver. Prior to this, the foreign body passed the gastrointestinal tract and perforated the proximal colon. A clinico-pathologic description of this uncommon spontaneous foreign body disease is given. The significance of injuries related to environmental enrichment is discussed.

[Comments on present-day spread and epidemiology of BSE and prion diseases]

Prion diseases of animals and man are neurological diseases with amyloidal deposition of the respective proteins. As to prion disease, the cellular prion protein is in its abnormal isoform(s) an essential component of prion protein aggregates found in affected tissue. In contrast to all neurodegenerative diseases like Morbus Alzheimer or Huntington's disease, prion diseases are transmissible. Therefore, prion diseases were designated Transmissible Spongiform Encephalopathies (TSE). The diseases have been well known for decades. Scrapie was first described around 1750, a BSE case was reported in the 1850-ties most likely a misdiagnosis, and in 1920/1930 the human Creutzfeldt-Jakob disease (CJD) had been described. Transmission of CJD i. e. Kuru had been suspected in the early 1950 s and was erroneously classified as slow virus disease. The CJD transmission posed a problem to humans when transplants from CJD cases were used for treatment. Fortunately, these iatrogenic transmissions remained limited. But with the advent of BSE and appearance of variant CJD cases in the UK and some places in Europe scientists suspected that transmission from cattle to man could have happened. From animal models we know of successful transmission via several routes. Species barriers do not completely prevent transmission. Rather, transmission barriers might exist controlling individual susceptibility against prions. Modes of transmission, susceptibility to transmission, identification of receptor molecules as well as molecular mechanisms of the transmission process are being investigated with great intensity. Current knowledge leads us to assume that inapparent stages of prion infection wrongly suggest a (non-existent) species barrier. This inapparent infection precedes overt disease, and, hence, most research focuses on the development of highly sensitive assay systems for detection of minute amounts of pathological prion protein in suspected cases. Inapparence also should warn us to underestimate BSE or human vCJD cases; at present, approx. 145 cases occurred in Europe and one probable case in Hong Kong (June 2003). Whether BSE had spread to other parts of the world by animal nutrition components or meat can neither be excluded nor confirmed at this time. New data on transmission and consequences of BSE for the human population are summarised in this review.

Mhc class II DRB sequences of lion-tailed macaques (Macaca silenus)

The lion-tailed macaque (Macaca silenus) is an endangered species. Research into the genetics of this species is important as a basis for coordinated breeding programs of captive populations. Therefore, we sought to analyze the Mhc class II DRB genes of this species because of it is highly polymorphic in genetically heterogeneous populations of most species. Ten individuals from seven families were evaluated. Nine DRB second exon sequences belonging to eight allelic lineages were identified. These lineages are also present in the best-studied macaque species: the rhesus (Macaca mulatta). Although only these relatively few alleles could be isolated, they display variation on the lineage level. This may be a mechanism for increasing their functional diversity.

Fatal Herpes simplex infection in a group of common marmosets (Callithrix jacchus)

An outbreak of classical herpetic infection causing vesicoulcerative stomatitis in a family group (eight animals) of Callithrix jacchus is described. In all eight infected animals, human herpesvirus 1 (HHV-1) was identified as the causative agent. This was confirmed by histologic, immunohistologic, and molecular biologic investigations, as well as by virus isolation. The clinical picture, the macroscopic appearance, and the histologic results indicated a herpes infection as the cause of mortality. Alterations of the oral mucous membranes were erosive to ulcerative with typical intranuclear inclusions. Immunohistologic and molecular biologic techniques clearly identified the HHV-1 virus and excluded other possible primate herpesviruses such as B-virus, SA8, HVP-2, and Herpes tamarinus. The significance of this herpesvirus infection for colony management is discussed.

[Electron microscopic investigation of CD4+ lymphocyte cell line C8166 after infection with simian immunodeficiency virus (SIV)]

The SIV infection of rhesus macaques (Macaca mulatta) is the most appropriate animal model in HIV research. The permanent human T-cell line C8166 is used for in vitro SIV propagation. This paper describes ultrastructural features of the cells after infection with SIVmac. The C8166 cells are ultrastructurally characterized by a heterogenous morphology which is independent of the infection. SIV induced cell syncytia are observed 18 hours after infection. Viral particles and budding occur 48 hours p.i with a peak at the day 8. Viral particles present the typical lentiviral morphology. Using the monoclonal antibody anti SIVp28 and ultra small (0.8 nm) immunogold-silver enhancement technique, we are able to demonstrate SIV antigen immunoelectron microscopically. Therefore, this ultrastructural method is suitable to detect SIV antigen in in vivo experiments with C8166 cells from day 8 p.i. serving as positive control.

Reactivation of a Trypanosoma cruzi infection in a rhesus monkey (Macaca mulatta) experimentally infected with SIV

Trypanosoma cruzi-like flagellates were incidentally noted in blood smears of a routinely monitored rhesus monkey experimentally infected with the simian immunodeficiency virus (SIV). Immunodeficiency in the course of the SIV infection reactivated a chronic infection of Chagas' disease that had been unnoticed when the macaque was imported to Europe. The animal developed no specific clinical symptoms of American trypanosomiasis, but histologically a chagasic myocarditis was detected. Analysis of the small subunit rRNA gene of the trypanosome identified the protozoan as T. cruzi.

[Basic research on BSE transmission to people]

Prion diseases of animal and man belong to neurological diseases with amyloidal deposition of the respective proteins. As to prion disease, the cellular prionprotein is in its abnormal isoform(s) an essential component of prionprotein aggregates found in affected tissue. In contrast to all neurodegenerative diseases like Morbus Alzheimer or Huntington's disease, prion diseases are transmissible. Therefore, prion diseases were designated Transmissible Spongiform Encephalopathies (TSE). The diseases are well known since decades. Scrapie was first described around 1750, a BSE case was reported in the 1850, most likely a misdiagnosis, and in 1920/1930 the human Creutzfeldt-Jakob disease (CJD) had been described. Transmission of CJD i.e. Kuru had been suspected in the early 1950s and erronously classified as slow virus disease. The CJD transmission posed a problem to humans when transplants from CJD cases were used for treatment. Fortunately, these iatrogenic transmissions remained limited. But with the advent of BSE and appearance of variant CJD cases in the UK and some places in Europe scientists suspected that transmission from cattle to man could have happened. From animal models we know of successful transmission via several routes. Species barriers do not completely prevent transmission. Rather transmission barriers might exist controlling individual susceptibility against prions. Modes of transmission, susceptibility for transmission, identification of receptor molecules as well as molecular mechanisms of the transmission process are intensely investigated. Current knowledge let us to assume that inapparent stages of prion infection pretend a (not existing) species barrier. This inapparent infection preceeds overt disease and, thus, most re-search focuses on the development of highly sensitive assay systems for detection of minute amounts of pathological prionprotein in suspected cases. Inapparence also should warn us to underestimate BSE or human vCJD cases; at present, 124 in Europe and one probable case in Hongkong (7 March 2002). Whether BSE had spread to other parts of the world by animal nutrition components or meat can neither be excluded nor confirmed at this time. New data on transmission and consequences of BSE for the human population are summarized in this review.

Lack of simian immunodeficiency virus (SIV) specific IgA response in the intestine of SIV infected rhesus macaques

BACKGROUND

Little is known about secretory immunity-the major defence mechanism at mucosal surfaces-in human immunodeficiency virus (HIV) infected patients, especially in the early stages of the disease.

AIMS

The aim of the study was to analyse mucosal immunoglobulin production and simian immunodeficiency virus (SIV) specific antibody response in the intestinal mucosa during the course of SIV infection in comparison with serum and saliva.

ANIMALS AND METHODS

IgG, IgA, and IgM concentrations were determined in supernatants of short term cultured duodenal biopsies, serum, and saliva from SIV infected rhesus macaques (n=8) and controls (n=2) by ELISA at defined times before and after infection. Specific antibodies to SIV were detected by western blot and/or dot blot analysis. In addition, rectal swabs from two uninfected and 12 SIV infected rhesus macaques (seven without and five with enteritis) were analysed for albumin and IgG concentrations.

RESULTS

An increase in total intestinal IgG and a decrease in IgA were observed. SIV specific IgG or IgA responses were detectable as early as one week after SIV infection in the serum of seven of eight animals. In contrast, intestinal SIV specific IgG production was detected only four weeks after infection in six of eight animals, and intestinal SIV specific IgA was not produced in the intestine at any time point. In saliva, the secretory component on SIV specific IgA was only detected in one animal at week 24 after infection. Enteritis is frequent in SIV infected animals and results in a significant increase in albumin and IgG secretion into the intestinal lumen.

CONCLUSION

Despite modest quantitative changes in mucosal immunglobulin production there was a total lack of SIV specific IgA synthesis in the intestine during SIV infection. This lack or disturbed secretory SIV specific IgA response at mucosal surfaces may explain the rapid and high HIV/SIV replication in this compartment. In addition, our investigations indicate secretion of serum proteins into intestinal fluids during SIV infection. Previous investigations using intestinal secretions or swabs for analysing quantitative and specific immunglobulins therefore should be interpreted with caution.

[Primates as experimental animals]

The term "primates" comprises a varied group of animals, consisting of more than 250 different species. The close evolutionary relationship to man resulted in the use of nonhuman primates as subjects of study for scientists from different research fields. In biomedical research the use of primates is restricted to questions which cannot be answered by animals with less developed physiological senses. Primates play an important role in infectious disease research, as many pathogens relevant to humans can be transferred to selected primate species. In the last few decades this applied especially for HIV-infections of man, viral hepatitides, herpesvirus infections and for quite a long time for agents of transmissible spongiform encephalopathies, too. In neurobiology, primates play an outstanding role due to the morphological-structural and functional resemblance of their CNS to that of man. Due to new developments in biomedicine, in particular in the field of gene therapeutics, it has to be expected that primates will have to be used also in future as animal models for the welfare of human health.

SIV-associated lymphomas in rhesus monkeys (Macaca mulatta) in comparison with HIV-associated lymphomas

A retrospective study was performed to characterize malignant lymphomas of 16 Simian immunodeficiency virus (SIV)-infected rhesus monkeys (Macaca mulatta), 2-9 years of age, on the basis of clinical data, histologic and immunophenotypic results, and cell death indices compiled with the TdT-mediated X-duTP nick end labeling method. We particularly focused on providing immunohistochemical evidence of expression products of EBNA2, Bc12, c-Myc, P21, P53, and Bc16. Results were compared with data from the literature on human HIV-associated lymphomas. According to the updated Kiel classification, the lymphomas were classified as 11 centroblastic lymphomas, three immunoblastic lymphomas, one Burkitt-like lymphoma, and one immunocytoma. Using antibodies to CD20, the B-cell origin of tumor cells was demonstrated. SIV antigen was not demonstrated in the tumor cells. Infection with rhesus lymphocryptovirus was present in 94% of the monkeys. Lymphomas revealed expression of Bc12 in 15/16 (94%), c-Myc in 14/16 (88%), P21 in 10/ 16 (63%), P53 in 12/16 (75%), and Bc16 in 1/16 (6%) monkeys. This study provided evidence that the expression of these gene products, which are thought to play an important role in cell proliferation and apoptosis in HIV- and non-HIV-associated lymphomas, are also involved in the pathogenesis of lymphomas in SIV-infected rhesus monkeys. A tentative relationship between the described gene products and the cell death indices was established for the expression of Bc12. The present primate model represents a suitable animal model for studying the pathogenesis of AIDS-associated lymphomas.

Three spontaneous lymphomas in a colony of cotton-top tamarins (Saguinus oedipus)

Cotton-top tamarins are well known for their prevalence to idiopathic colitis and adenocarcinomas. At the same time, information on the incidence of spontaneous lymphomas in this highly endangered species is rare. Records, 212 in total, of cotton-top tamarins (Saguinus oedipus) necropsied at the German Primate Centre between 1979 and 1998 were viewed to establish the prevalence of lymphoid neoplasms. Neoplastic lymphoid cell growth was mentioned in three necropsy records. Immunohistology was performed in all three cases on the remaining formalin-fixed, paraffin-embedded tissue using antibodies against CD20, CD3, lysozyme, Ki-67, IgM, IgG, kappa, lambda and EBNA-2. Combining histological and immunohistological results, the lymphomas could be differentiated into two low-grade T-cell lymphomas and one high-grade multicentric polymorphic B-cell lymphoma. This corresponds to a 1.4% incidence of lymphomas in our cotton-top tamarin population over a period of 19 years. Although frozen material was not available and virological testing could not be carried out, clinical or histological evidence did not support an aetiological role of Herpes (H.) saimiri, H. ateles, simian T-cell leukaemia virus type 1 (STLV-1) or Epstein-Barr-related herpesvirus in any of these cases. The lymphomas were considered to be spontaneous.

Expression of the simian Epstein-Barr virus-encoded latent membrane protein-1 in malignant lymphomas of SIV-infected rhesus macaques

During the course of simian immunodeficiency virus (SIV) infection, nearly 15% of rhesus macaques (Macaca mulatta) and up to 40% of cynomolgus macaques (Macaca fascicularis) developed SIV-associated non-Hodgkin's lymphomas. Most of these malignant lymphomas harbored lymphocryptoviruses, which are closely related to the human Epstein-Barr virus (EBV; Herpesvirus M. mulatta and Herpesvirus M. fascicularis). To characterize the oncogenic role of simian EBV infection for lymphomagenesis during SIV infection, expression of the EBV-encoded latent membrane protein-1 (LMP-1) was analyzed in malignant lymphomas of SIV-infected rhesus macaques. Nine seropositive rhesus macaques suffering from B-cell lymphomas during the late phase of SIV infection were euthanized. Latency stages of EBV infection within malignant lymphomas and simian EBV-infected lymphoblastoid cell lines (LCL8664, H50) were characterized by analyzing expression of the EBV-encoded nuclear antigens EBNA-1, EBNA-2, and small RNAs EBER1/2. In parallel, the presence of viral LMP-1 transcripts was assessed by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization. Results were compared with findings in AIDS-associated malignant lymphomas in two patients infected with human immunodeficiency virus (HIV)-1. Rhesus macaques developed high-grade B-cell lymphomas of the centroblastic (five of nine), immunoblastic (two of nine), centroblastic-centrocytic (one of nine), and Burkitt-like (one of nine) subtypes within 18-29 months postinfection with SIV(mac)251/32H. The presence of Herpesvirus M. mulatta was detected in eight of nine cases. Transcription of the viral oncogene LMP-1 could be demonstrated within the simian EBV-infected cell lines as well as in four of nine SIV-associated malignant lymphomas. These four cases and both of the HIV-1-related non-Hodgkin's lymphomas expressed the full spectrum of latent EBV gene products (LMP-1, EBER1/2, EBNA-1, EBNA-2) and were thus classified as latency type III stages of EBV infection. Simian EBV infection was demonstrated in 90% of lymphomas in SIV-infected rhesus macaques. Analysis of LMP-1 expression suggests an important role for this viral oncogene in the pathogenesis of both SIV and HIV-1-associated malignant lymphomas.

Analysis of potential porcine endogenous retrovirus (PERV) transmission in a whole-organ xenotransplantation model without interfering microchimerism

The question whether porcine xenografts can lead to porcine endogenous retrovirus (PERV) infection of recipients is critical for the evaluation of the safety of pig-to-man xenotransplantation. Unfortunately, polymerase chain reaction (PCR)-based analysis of potential PERV infections in nonhuman-primate whole-organ xenotransplantation models is hampered by false positive results due to chimeric porcine cells. To avoid the inherent analytical problem of xenomicrochimerism, we developed a non-life-supporting pig-to-primate kidney xenotransplantation model: porcine kidneys were transplanted, whereas the functioning recipient kidneys remained in situ. Subsequent to rejection (after 2 hours to 15 days), xenografts were removed, and recipients remained alive for up to 287 days. Immunosuppressive therapy based on cyclophosphamide, cyclosporine, and steroids was maintained for 28 days after transplantation. Using appropriate PCR assays, xenochimerism was found in tissue samples and partly even in peripheral blood leukocytes (PBLs) while the porcine kidneys were in situ. After graft removal, xenochimerism was no longer detectable, thus allowing analysis for possible PERV transmission.

First outbreak of callitrichid hepatitis in Germany: genetic characterization of the causative lymphocytic choriomeningitis virus strains

Callitrichid hepatitis (CH) is a highly fatal, rodent-borne zoonosis of New World primates (family Callitrichidae) caused by lymphocytic choriomeningitis virus (LCMV). It is unclear whether virulence in Callitrichidae is associated with specific genetic or phylogenetic markers of the virus as only a partial S RNA sequence of a single CH-associated isolate is known. In a period of 10 months, three pygmy marmosets (Cebuella pygmaea) and one Goeldi's monkey (Callimico goeldii) died from CH in a German zoo. LCMV was most likely transmitted by wild mice. Infection was associated with characteristic histopathological lesions in liver, brain, and lymphoid tissue. Virus sequences from all callitrichids and a captured mouse were > or =99.2% identical. LCMV strains from a pygmy marmoset and the Goeldi's monkey were isolated in cell culture and the 3.4-kb S RNA was completely sequenced. Both strains differed considerably in their genetic and phylogenetic characteristics from known LCMV strains, including the previously described CH-associated strain. These data show that CH is widespread and can be caused by distantly related LCMV strains.

Callitrichid nutrition and food sensitivity

Captive callitrichids are prone to developing intestinal problems. Their captive and natural diets differ enormously, and diet has been suggested to play a major role in wasting marmoset syndrome. Proteins in wheat, soy and milk are included in callitrichid diets of most colonies and have been linked to an immune reaction in Saguinus oedipus and Callithrix jacchus. In the present study of 23 males and females of the two species, wheat protein was tested but soy and milk products were excluded. One group had wheat and the other had rice in their diet. Blood samples and biopsies from the colon were taken. Results showed changes in the colon and an immune reaction to gliadin, a wheat protein related to coeliac disease in humans. A further immune reaction was also observed. Suggestions for further study and exclusion of cereal in the diet of these small, New World primates are discussed.

Cellular and humoral immune response in progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is a fatal, demyelinating disease caused by JC virus (JCV) in patients with severe immunosuppression. We studied the JCV-specific cellular and humoral immune response in 7 healthy donors (HD), 6 human immunodeficiency virus-1 (HIV-1)-infected patients without PML (HIV), 4 HIV-1-negative patients with PML (PML), and 8 HIV-1-positive patients with PML (HIV/PML). As antigens, recombinant virus-like particles of the major structural protein VP1 (VP1-VLP) of JCV, tetanus toxoid (TT), or the mitogen phytohemagglutinin (PHA) were used. Proliferation of peripheral blood mononuclear cells (PBMC) after stimulation with the VP1-VLP was significantly suppressed in PML and HIV/PML patients compared to HD. After antigen stimulation the production of interferon-gamma (IFN-gamma) was reduced in PML, in HIV/PML, and in HIV patients. The production of interleukin-10 (IL-10), however, was elevated in HIV/PML patients. Neither proliferation nor cytokine production correlated with the presence of JCV DNA in PBMC. The immunoglobulin G serum antibody titer to the VP1-VLP was slightly elevated in HIV, elevated in PML, and highly elevated in HIV/PML patients compared to HD. The development of PML appears to coincide with a general impairment of the Th1-type T-helper cell function of cell-mediated immunity.

Experimental Helicobacter pylori infection of rhesus macaques (Macaca mulatta)

The aim of the present study was to establish an animal model for Helicobacter pylori (H. pylori) infection at the German Primate Centre in rhesus monkeys (Macaca mulatta). During the experiments the susceptibility of three animals to different H. pylori strains of human origin was tested. In a follow-up study gastric biopsies from three different sites were investigated in regular intervals using microbiological, histological, electron microscopical and molecular biological methods to evaluate the presence of bacterial colonization and the occurrence of gastritis. It was possible to establish a persistent experimental infection. The rather long follow-up period of 18 months offered the possibility to demonstrate a permanent H. pylori infection in the gastric mucosa of the test animals. The three animals have now been successfully colonized with H. pylori for 18 months and presented a chronic active gastritis confirmed by microbiological and histological methods. By molecular typing, the identity of the isolates recovered from the animals was shown. It was possible to demonstrate that one infection strain outcompeted the second one. Taken together, prerequisites exist for making use of an attractive and useful animal model in rhesus monkeys especially for long term observations.

Immunohistochemical detection of simian immunodeficiency virus (SIV) in rectal mucosa of experimentally infected rhesus macaques (Macaca mulatta)

Experimental simian immunodeficiency virus (SIV) infection is the most appropriate animal model for human HIV infection. Eight male rhesus monkeys (Macaca mulatta) were intravenously or intrarectally infected with SIVmac251/MPBMC to comparatively investigate the distribution and spread of the virus within the rectum during the course of the disease. SIV-positive cells were immunohistochemically detected in rectal biopsies obtained at days 3 and 7 and week 2, 4 and 12 postinfection. SIV-expressing cells were detected for the first time at one week after experimental infection and were present in the lamina propria and lymph follicles. Numbers of positive cells per individual animal varied strongly in time, with a more rapid rise in animals with rapid progression of the disease. Differences were not observed between intravenous and intrarectal infection. Our observations support the significance of the intestinal tract as target organ in initial pathogenesis of SIV infection.

Homozygosity for a conserved Mhc class II DQ-DRB haplotype is associated with rapid disease progression in simian immunodeficiency virus-infected macaques: results from a prospective study

In human immunodeficiency virus type 1 (HIV-1)-infected individuals, disease progression varies considerably. This is also observed after experimental infection of macaques with simian immunodeficiency virus (SIV). Major histocompatibility complex (MHC) genes may influence disease progression in both species. Homozygosity for Mhc-Mamu (Macaca mulatta)-DQB1*0601 was previously identified to be associated with rapid disease progression in SIV-infected macaques. To validate the association of this genotype with disease progression, a prospective study was carried out. Six unrelated monkeys homozygous for Mamu-DQB1*0601 and DRB1*0309-DRB*W201 and 6 heterozygous monkeys were infected with SIVmac. Five of the homozygous and only 1 of the heterozygous monkeys died rapidly after infection, with manifestations of AIDS. These results were validated by a retrospective survival analysis of 71 SIV-infected monkeys. The identified DQ-DRB genotype is frequent among monkeys of different breeding colonies and allows a fairly reliable selection before infection of monkeys predisposed for rapid disease progression.

Acute vascular rejection is associated with systemic complement activation in a pig-to-primate kidney xenograft model

The introduction of h-DAF transgenic porcine organs into pre-clinical pig-to-primate discordant xenotransplantation has led to complete and reliable abrogation of hyperacute xenograft rejection (HAR). Despite additional heavy immunosuppression however, most xenografts are still lost due to acute vascular rejection (AVR), with current treatment protocols being of only limited value. In a life-supporting model of pig-to-primate kidney transplantation, unmodified (n=8) or h-DAF-transgenic (n=9) porcine kidneys were transplanted into cynomolgus monkeys under cyclophosphamide (CyP), cyclosporine and low-dose steroid immunosuppression. Longest recipient survival was 11 days in the control group and 68 days in the h-DAF transgenic group. Stable initial graft function with recipient survival >4 days was generated in eight animals (two controls and six transgenics). In these animals, plasma complement levels were analyzed during ongoing AVR. Compared with baseline levels, a two-fold increase in C3a levels and a four-fold increase in sC5b-9 levels were measured. In parallel to systemic complement activation, increased deposition of C3 and C5b-9 along with massive staining for recipient IgM immunoglobulins was detected in the xenografts on immunohistochemistry. We conclude that acute vascular xenograft rejection of porcine kidneys in cynomolgus monkeys is associated with classical pathway complement activation following binding of induced recipient anti-porcine antibodies. This complement activation can be observed despite membrane bound expression of human complement regulators in the porcine xenografts. Therefore, additional short-term fluid phase complement inhibition seems necessary for the future development of protocols designed for treatment of AVR in the pig-to-primate combination.

Long-term follow-up study on SIV intestinal proviral load in rhesus macaques

After experimental infection with simian immunodeficiency virus (SIV), intestinal endoscopy proved to be an easily tolerated, minimal invasive procedure to obtain biopsies from the gastrointestinal tract of rhesus macaques during all stages of disease. As the GI tract is affected by many opportunistic infections and immunological impairment after SIV/human immunodeficiency virus (HIV) infection, knowledge on the proviral load is an important parameter for a better understanding of disease pathogenesis. In this paper, we describe the set-up and evaluation of a quantitative competitive polymerase chain reaction (PCR) and the quantification of SIV intestinal proviral load in a long-term follow-up study of eight rhesus monkeys (Macaca mulatta) after two different routes of virus inoculation. A SIV-specific signal could be detected as early as day 3 after infection. Of 143 biopsies from the follow-up study, 85.3% showed a positive PCR. DNA copy numbers ranged from 300 to 15,000 molecules per 100,000 cells. No significant influence of the inoculation route could be shown on either proviral load or survival time, but higher SIV proviral load was associated with a more rapid progression to disease. Therefore, the amount of proviral load in intestinal biopsies may be an important prognostic value for the further course of the disease.

Phenotype, intestinal morphology, and survival of homozygous and heterozygous endothelin B receptor--deficient (spotting lethal) rats

BACKGROUND/PURPOSE

Spotting lethal (sl) rats, a model for Hirschsprung's disease, recently have been found to carry a deletion in the endothelin B (ET(B)) gene, causing functional lack of ET(B) receptors. The ET(B) receptor mediates, together with and in counterbalance to the ET(A) receptor, endothelin actions on vessels, cell proliferation, and migration. The authors investigated the effect of homozygosity (sI/sI) or heterozygosity (+/sl) on phenotype, intestinal morphology, and survival.

METHODS

Weight, circumference, and serum albumin were measured. Histological tests of major organs and immunoperoxidase reaction for Peripherin, glial fibrillary acid protein (GFAP), and S-100 in small and large intestine were performed. Peripherin-immunostained sections of colon and jejunum were analyzed morphometrically. Screening for sepsis included search for enterocolitis, bacterial infection, endotoxin, and iNOS mRNA.

RESULTS

Sl/sl rats died within 4 weeks of life, showing an early and a later death group. Serum albumin levels were decreased in sl/sl rats, whereas signs of sepsis were rare. Immunostaining uncovered alterations in nerve and glial cells in the whole gut of sl/sl rats, and to a subtle degree also in +/sl rats, which appear clinically normal. Morphometric quantification yielded statistically significant alterations in sl/sl rats only. No obvious abnormalities were found in other organs.

CONCLUSIONS

Sl/sl rats die from malnutrition rather than sepsis, too early for ischemic complications to occur. Rats of the later death group are a suitable model for studying the ET8 receptor in vivo. Subtle abnormalities in the enteric nervous system of heterozygous rats underline the critical role of the "gene dose" for functional compensation.

Morphologic and immunophenotypic characteristics of malignant lymphomas in SIV-infected rhesus macaques

Eight cases of extranodal non-Hodgkin's lymphoma in simian immunodeficiency virus (SIV)-infected rhesus macaques, aged 4-9 years, were phenotypically and immunologically characterized, using the updated Kiel classification, in order to determine both the differences and the similarities between these types of lymphoma in immunodeficient rhesus macaques (Macaca mulatta) and man. The high-grade malignant tumors were of B-cell origin, with a predilection for extranodal growth in viscera and periorbital tissues. Immunophenotypical characterization showed that the monkey lymphomas were similar in many aspects to human immunodeficiency virus-associated lymphomas. The number of Ki67 positive cells varied from case to case and ranged from 50 to 90%. A serological screening for the simian equivalent of the Epstein-Barr virus (sEBV) by immunofluorescence assay revealed a prevalence of 92% of the sEBV antibodies in our cohort. The presence of Ebstein-Barr virus nuclear antigen (EBNA-2) could be demonstrated by immunohistochemistry in four out of eight cases. In situ hybridization revealed the presence of small EBV-encoded RNAs (EBER-1, EBER-2) in six of the eight cases. Further studies should define the precise role of herpesvirus infection for lymphomagenesis in SIV-induced immunodeficiency.