The olive baboon (Papio anubis): a potential animal model to study the function of human leukocyte antigen-G (HLA-G)

The human class Ib major histocompatibility complex (MHC) molecule, HLA-G, is unique in its limited polymorphism, high expression in the placenta and generation of multiple transcripts by alternative splicing. The proteins encoded by these transcripts are believed to modulate maternal-fetal immunological relationships during pregnancy. The baboon placenta expresses Paan-AG, a novel MHC molecule that is evolutionarily related to the MHC-A locus but shares unique characteristics with HLA-G. In this brief review, we present evidence suggesting that Paan-AG may be the functional homologue of HLA-G, and propose that the baboon would compromise an excellent animal model for functional studies of HLA-G proteins in human pregnancy.

The prevalence of anti-phospholipid antibodies in a selected population of Kenyan women and development of a non-human primate model

The mechanisms by which anti-phospholipid antibodies (aPLs) may induce pregnancy losses, intrauterine growth retardation and pregnancy-induced hypertension are not clearly understood. Moreover, there is a controversy regarding the possible direct effects of these antibodies on the physiology of the placenta since the target antigens of these antibodies are intracellular antigens and are potentially inaccessible to the antibody. Also, controversy exists regarding the usefulness of the treatment regimens currently available. In this study, we present preliminary data on the prevalence of aPLs in a selected population (n = 80) of Kenyan women visiting Kenyatta National Hospital, Nairobi, Kenya for obstetrical complications including recurrent pregnancy losses. Our results showed approximately 13.8% of the patients were positive for anti-cardiolipin antibodies whereas 33.8% were positive for aPS. Additionally, we screened 72 non-human primates for presence of aPLs and our results showed that the olive baboon (Papio anubis) had the highest prevalence rate (52.2%, n = 23). Overall, our results suggest that the olive baboon may be a suitable animal model for studying the mechanism of action of the anti-phospholipid antibody and pregnancy complications associated with aPLs.

A probe generated by chromosome microdissection, useful for analyzing Y chromosome evolution in Old World monkeys

We isolated a DNA probe, designated MMDYZ1, using a chromosome microdissection technique from the Y chromosome of the Rhesus monkey. The probe obtained from eight whole Y chromosomes shows higher specificity for the Y short arm of the Rhesus monkey, which consists totally of constitutive heterochromatin. Two microclones (MMY#3 and MMY#4) were constructed from the Y-specific primary PCR products. Sequence analysis of these two microclones revealed that both were essentially identical to each other and the sizes were 870 and 686 bp, respectively. From alignment analysis using the Genbank database of primates, the alphoid DNA has the highest affinity with the probe. However, the total composition of this probe has extremely high homology with the Y short arm of the Rhesus monkey, as demonstrated by fluorescence in-situ hybridization (FISH). Comparative FISH-mapping disclosed that this DNA-sequence cluster was located at extremely different sites on the Y chromosome in several species of the Old World monkey. Accordingly, this probe seems to be a high-quality tool, now established for the first time, for investigating Y chromosome evolution of the Old World monkey.

Potential involvement of the immune system in the development of endometriosis

This article presents an overview of immunological factors and their role in the development of endometriosis, with emphasis on inflammatory cytokines, growth and adhesion factors. Although retrograde menstruation is a common phenomenon among women of reproductive age, not all women who have retrograde menstruation develop endometriosis. The development of endometriosis is hypothesised to be a complex process, which may be facilitated by several factors, including the quantity and quality of endometrial cells in peritoneal fluid (PF), increased inflammatory activity in PF, increased endometrial-peritoneal adhesion and angiogenesis, reduced immune surveillance and clearance of endometrial cells, and increased production of autoantibodies against endometrial cells. Potential biomarkers like cytokines and autoantibodies upregulated during development of endometriosis may be useful in the development of a non-surgical diagnostic tool. Although endometriosis can be treated using hormonal suppression, there is need for non-hormonal drugs, which can inhibit the development of endometriosis and alleviate pain or infertility without inhibition of ovulation. New molecules that modulate immune function in endometriosis should be the targets for future research.

Transfected Plasmodium knowlesi produces bioactive host gamma interferon: a new perspective for modulating immune responses to malaria parasites

Transgenic pathogenic microorganisms expressing host cytokines such as gamma interferon (IFN-gamma) have been shown to manipulate host-pathogen interaction, leading to immunomodulation and enhanced protection. Expression of host cytokines in malaria parasites offers the opportunity to investigate the potential of an immunomodulatory approach by generating immunopotentiated parasites. Using the primate malaria parasite Plasmodium knowlesi, we explored the conditions for expressing host cytokines in malaria parasites. P. knowlesi parasites transfected with DNA constructs for expressing rhesus monkey (Macaca mulatta) IFN-gamma under the control of the heterologous P. berghei apical membrane antigen 1 promoter, produced bioactive IFN-gamma in a developmentally regulated manner. IFN-gamma expression had no marked effect on in vitro parasite development. Bioactivity of the parasite-produced IFN-gamma was shown through inhibition of virus cytopathic effect and confirmed by using M. mulatta peripheral blood cells in vitro. These data indicate for the first time that it is feasible to generate malaria parasites expressing bioactive host immunomodulatory cytokines. Furthermore, cytokine-expressing malaria parasites offer the opportunity to analyze cytokine-mediated modulation of malaria during the blood and liver stages of the infection.

Experimental infection of the olive baboon (Paplio anubis) with Plasmodium knowlesi: severe disease accompanied by cerebral involvement

Experimental systems that model some of the complex interactions between parasite and host can be extremely valuable in identifying and developing new prophylactics and therapeutics against human diseases. Because primates have similar immune systems to humans, we have characterized a baboon model for understanding host response to Plasmodium knowlesi. Ten intact olive baboons (Papio anubis) of either sex were experimentally infected with P. knowlesi H strain erythrocytic parasites. The infection in these baboons was either acute or chronic. Animals with acute infection developed multiple system organ dysfunction and cerebral involvement. In chronically infected animals, only the spleen was moderately enlarged. The P. knowlesi parasitemia profile in baboons and rhesus monkeys was comparable. However, some clinical symptoms of the baboons and P. falciparum-infected humans were similar. These studies demonstrate for the first time that P. anubis is a suitable host for P. knowlesi for studying clinical symptoms and pathology.

Effects of khat (Catha edulis) consumption on reproductive functions: a review

OBJECTIVE

To review research findings on the effects of khat (Catha edulis) chewing on reproductive functions.

DATA SOURCES

Retrieval and critical review of relevant articles and abstracts cited in international and local journals, literature searches on Medline and Medchem from 1961 to 2002.

DATA SYNTHESIS

Analysis of published data and limited interviews of regular khat users revealed that khat chewing lowers libido in humans and may also lead to sexual impotence following long term use. In pregnant women, consumption of khat affects growth of foetus by inhibiting utero-placental blood flow and as a consequence, impairs foetal growth.

CONCLUSION

Detailed studies on the effects of khat on reproduction are lacking. However, the limited available data reveal that chewing of khat has a negative impact on human reproductive health. Khat is genotoxic and has teratogenic effects on the foetus if regularly consumed by pregnant mothers. Since low birth weight is a well-established risk factor for both perinatal and young infant death, khat chewing during pregnancy may be one of the factors contributing to infant mortality in communities where khat is commonly chewed. Khat consumption affects the potency of male sexuality by affecting spermatogenesis and plasma testosterone concentration. However, the precise mechanisms by which khat may affect the male reproductive physiology have not been elucidated.

Ectopic splenic nodules in the olive baboon (Papio cynocephalus anubis)

Post-mortem evaluation of a female sub-adult olive baboon (Papio cynocephalus anubis) revealed a case of ectopic spleen anomaly. Three spherical masses characterized the spleen anomaly. The splenic nodules were located on the left upper quadrant of the stomach, at the distal end of the pancreas. The anterior nodule measures 1.2 cm, the middle nodule 1.9 cm and the posterior nodule 1.3 cm in diameter. Normal spleen was not observed in this case. All the three ectopic splenic nodules showed normal histological architecture. A case of ectopic splenic nodules in baboon is important in that the spleen malformation can readily be mistaken for a pathological process.

Future directions in endometriosis research

Future research in endometriosis must focus on pathogenesis studies in the baboon model, the early interactions between endometrial and peritoneal cells in the pelvic cavity at the time of menstruation, and potential differences between eutopic endometrium and myometrium in women with and without endometriosis. More integration is needed between the areas of epidemiology and genetics. Pelvic inflammation in women with endometriosis could be the target for new diagnostic and therapeutic approaches. Important questions remain regarding the relationship between endometriosis and environmental factors. Systemic and extrapelvic manifestations of endometriosis must be analyzed carefully, and better tools are needed to measure quality of life in women with chronic pain caused by endometriosis. Most current evidence supports a causal relationship between endometriosis and subfertility, and the spontaneous progressive nature of endometriosis has been demonstrated in 30% to 60% of patients. Recurrence of endometriosis after classic medical and surgical therapy is a major and underestimated problem, especially in women with advanced disease. Integrated clinical and research teams are needed that combine expert medical, surgical, and holistic care with state-of-the-art research expertise in immunology, endocrinology, and genetics to discover new diagnostic methods and medical treatments for endometriosis.

Baboon placentas express soluble and membrane-bound Paan-AG proteins encoded by alternatively spliced transcripts of the class Ib major histocompatibility complex gene, Paan-AG

The human class Ib major histocompatibility complex (MHC) molecule, HLA-G, is unique in its limited polymorphism, high expression in the placenta and generation of multiple transcripts by alternative splicing. The proteins encoded by these transcripts are believed to modulate maternal-fetal immunological relationships during pregnancy. The baboon placenta contains messages encoded by a novel MHC gene, Paan-AG, which is evolutionarily related to the HLA-A locus, but shares unique characteristics with HLA-G. In this study, we show that the Paan-AG message is alternatively spliced to generate at least seven transcripts. One of these transcripts retains intron 4 and encodes a soluble glycoprotein with three external domains and a unique 21-amino-acid sequence at the carboxyl terminus, similar to soluble HLA-G1. This glycoprotein was detected in first trimester placental villous cytotrophoblast and syncytiotrophoblast, and in extravillous cytotrophoblast cells in the basal plate in term placenta. Four of the transcripts ( Paan-AG1, Paan-AG2, Paan-AG3, Paan-AG4) encode membrane-bound class Ib MHC glycoprotein isoforms. Paan-AG1 protein expression was similar to that of sPaan-AG, while Paan-AG2 protein was not detected in these tissues. The other two transcripts ( Paan-AGx and Paan-AGxi) contain a truncated exon 3 and multiple stop codons. Paan-AG1 and Paan-AGx transcripts were detected in a number of non-placental tissues, but these transcripts contained multiple stop codons. Because of the structural similarities and common features of organ-specific expression and splicing of the message, studies on Paan-AG may be of value in dissecting the functions of the class Ib proteins in human pregnancy.

Plasmodium knowlesi provides a rapid in vitro and in vivo transfection system that enables double-crossover gene knockout studies

Transfection technology for malaria parasites provides a valuable tool for analyzing gene function and correlating genotype with phenotype. Transfection models are even more valuable when appropriate animal models are available in addition to complete in vitro systems to be able to fully analyze parasite-host interactions. Here we describe the development of such a model by using the nonhuman primate malaria Plasmodium knowlesi. Blood-stage parasites were adapted to long-term in vitro culture. In vitro-adapted parasites could re-adapt to in vivo growth and regain wild-type characteristics after a single passage through an intact rhesus monkey. P. knowlesi parasites, either in vitro adapted or in vivo derived, were successfully transfected to generate circumsporozoite protein (CSP) knockout parasites by double-crossover mechanisms. In vitro-transfected and cloned CSP knockout parasites were derived in a time span of only 18 days. Microscopic evaluation of developing oocysts from mosquitoes that had fed on CSP knockout parasites confirmed the impairment of sporozoite formation observed in P. berghei CSP knockout parasites. The P. knowlesi model currently is the only malaria system that combines rapid and precise double-crossover genetic manipulation procedures with complete in vitro as well as in vivo possibilities. This allows for full analysis of P. knowlesi genotype-phenotype relationships and host-parasite interactions in a system closely related to humans.

Endogenous retrovirus sequences expressed in male mammalian reproductive tissues: a review

OBJECTIVES

To review the research findings on the expression of endogenous retroviruses and retroviral-related particles in male mammalian reproductive tissues, and to discuss their possible role in normal cellular events and association with disease conditions in male reproductive tissues.

DATA SOURCES

Published findings on endogenous retrovirus (ERV) expression in vertebrate reproductive tissues.

STUDY SELECTION

Relevant citations on ERVs and male reproduction by research groups worldwide.

DATA EXTRACTION

Literature search on Medline and Pubmed upto the year 2000, and retrieval of relevant articles cited from international and local journals.

DATA SYNTHESIS

Most of the studies demonstrated integrated retroviruses and retroviral-related sequences in human and mouse testis, epididymis and vas deferens. Endogenous retroviruses in human and mice may be associated with normal cellular differentiation and development, and carcinogenesis. In humans, one ERV family, human endogenous retrovirus-K (HERV-K) is abundantly expressed, and is associated with germ cell tumours, while ERV3 env is expressed in normal human testis.

CONCLUSION

The expression of ERVs in male reproductive tissues suggests a possible role in normal and disease conditions involving the testis and epididymis. These speculative functions may include among others spermatogenesis and or sperm maturation or tumour formation. However, further studies need to be carried out to investigate specific roles of ERVs in male reproductive events.

A survey for Cyclospora spp. in Kenyan primates, with some notes on its biology

From March 1999 through August 2000, 511 stool samples collected from 11 different primate species in 10 geographically distinct locations in Kenya, East Africa, were screened for the presence of Cyclospora spp. oocysts. Positive samples (43/102, 42%) were identified in vervet monkeys (Cercopithecus aethiops) in 4 of 4 locations; 19/206 (9%) in yellow and olive baboons (Papio cynocephalus, P. anubis, respectively) in 5 of 5 locations; and 19/76 (25%) in black and white colobus monkeys (Colobus angolensis, C. guereza, respectively) from 2 of 3 locations. DNA sequences obtained from 18 S rRNA coding regions from respective subsets of these positive samples were typed as Cyclospora cercopitheci (samples from Cercopithecus aethiops). Cyclospora papionis (samples from Papio cynocephalus and P. anubis), and Cyclospora colobi (samples from Colobus angolensis and C. guereza). Cyclospora oocysts were not detected in samples collected from patas, highland sykes, lowland sykes, blue sykes, DeBrazza, or red-tailed monkeys. A coded map showing the geographic location of the collected samples is given. Stool samples from 1 troop of vervet monkeys were collected over a 12-mo period. Positive samples ranged between 21 and 63%. These results suggest that there is no strongly marked seasonality evident in Cyclospora infection in monkeys as has been noted in human infection. This is further confirmed by the recovery of positive samples collected from vervet monkeys, baboons, and colobus monkeys at all times of the year during this survey. This absence of seasonality in infection is especially notable because of the extreme weather patterns typical of Kenya, where marked rainy and dry seasons occur. A second noteworthy observation is that the striking host specificity of the Cyclospora species initially described was confirmed in this survey. Baboons were only infected with C. papionis, vervet monkeys with C. cercopitheci, and colobus monkeys with C. colobi, despite geographic overlaps of both the monkey and parasite species and wide geographic distribution of each parasite and monkey host.

Varieties of male circumcision: a study from Kenya

BACKGROUND

Because male circumcision has been linked to a lower risk of HIV infection, it is advocated tentatively as a possible preventive intervention. Most studies, however, have relied on men's self-reports of their circumcision status.

GOAL

To document varied techniques of male circumcision in one area of Kenya and the visible results.

STUDY DESIGN

Researchers interviewed men who had performed or undergone various forms of circumcision. They also did genital observations on a subsample of respondents.

RESULTS

All the men reported undergoing circumcision during adolescence, and most were able to tell which technique was used. According to the circumcisers, in type A, approximately 4 cm of the prepuce is removed; in type B, 1 to 2 cm of the prepuce and some of its inner surface are removed. Types A and B result in the same genital appearance. In type C, 1 to 2 cm of the prepuce and some of the inner surface are removed. The remaining prepuce is slit and suspended below the penile shaft.

CONCLUSIONS

Asking a man "Are you circumcised?" is not sufficient. Classifying his circumcision status requires both a genital examination and an understanding of the precise local surgical techniques used. Even in a small geographic area, considerable variety may exist in the techniques of cutting, removing, altering, or leaving different portions of the foreskin. Each variation may affect the transmission of HIV and other infections.

Endogenous Retroviruses: What risks do they pose in xenotransplant

Endogenous retroviruses are diverse in nature and found in genomes of ; vertebrates examined to date. There is also a spectrum of retrovirus-Iil transposable genetic elements that have been found in plants, fungi, and prokaryotes, which use reverse transcription as a replicative strategy. The presen of these retroviruses in various animal tissues can potentially leads to the spread animal-derived endogenous retroviruses during xenotransplantation. Althouj these retroviruses are generally inactive and non-effective in their hosts, the behavior in an immunocompromised xenograft recipient cannot be predicts There are reports that various non-human primate and pig endogenous retrovirusi can infect and replicate in various human cell lines. There is also concern ovpossible activation of latent viruses, including retroviruses, from xenograft tissue This paper discusses the possible dangers of endogenous viruses to human vi xenotransplantation.

Evaluation of Non-radioactive ELISA assay Kits for Detection of Retroviral Reverse Transcriptase (RT) Activity Associated with Retroviral SIV and HIV

Reverse transcriptase (RT) assay is commonly used to detect enzyme activity associated with retroviral-like particles. Previously, detection of RT activity in virus-infected cultures was done using a radioisotope-based assay system. However, assay systems, which detect the antigen directly(as opposed to antibody ELISA assays), have been developed. For diagnostic purposes, RT activity and p24 antigen capture assays are the two most commonly used methods for detection of retroviral infection. More recently, new non-radioactive assay systems have been developed. In this study, four non-radioactive reverse transcriptase kits were evaluated using samples obtained from a chimeric virus, simian/human immunodeficiency virus (SHIV) and SIV-infected cell cultures. The results showed that the magnesium kit was the most appropriate for detection of SIV and SHIV infection in cell culture supernatants.

Potential risks of viral infections in xenotransplantation

The shortage of cadaveric human organs for transplantation may, be alleviated by the use of xenografts as a therapeutic option for end-stage organ failure. Successful attempts have been made to prevent rejection of xenograft tissues in humans. The potential spread of animal-derived pathogens to the xenograft recipient is a complication of xenotransplantation, which must be addressed. This can be complicated further by, the presence of new pathogens, new clinical syndromes, and altered behaviour of these organisms in the immunocompromised recipient. There is concern over the possible activation of latent viruses, including retroviruses, from xenograft tissues. This paper discusses the possible dangers of transmission of animal viruses to humans via xenotransplantation.

DNA typing of primate major histocompatibility complex (Mhc)-DQA1 locus by PCR and dot blot hybridization

Non-human primates (NHPs) are increasingly utilized as models to investigate different aspects of immune responses against self (autoimmunity) and foreign antigens. These animals provide valuable models for testing the efficacy of candidate vaccines against pathogens such as human immunodeficiency virus (HIV) and also fertility regulating agents (immunocontraceptives). In order to fully understand the effects of vaccination, it may be necessary to elucidate the immunogenetic background of these animals. The major histocompatibility complex (Mhc) molecules play an important role in the generation of effective immune responses. Serological techniques have been used in the identification of human leukocyte antigens (HLA) necessary for cross-matching organs and tissues for transplantation. However, the application of this technique for typing monkey Mhc alleles has been hampered by unavailability of well characterized immunological reagents. Polymerase chain reaction (PCR)-based techniques such as restriction fragment length polymorphism (RFLP) and sequence-specific oligonucleotide probe hybridization (SSOP) have been extensively used for typing HLA-DP, DQ and DR alleles. A commercially available Kit (AmpliTypeR) designed for amplification and typing of HLA DQalpha alleles is routinely used in typing DNA samples for forensic casework. In the present study, we have evaluated this kit for possible application in routine typing of primate DQA1 alleles. Genomic DNA from ten African primate species (23 individuals) was isolated from peripheral blood lymphocytes and polymorphic second exon of DQA1 locus amplified using GH26 and GH27 PCR primers. The PCR products were hybridized on a nylon membrane containing immobilized sequence-specific oligonucleotide probes. Our results show seven of the nine probes hybridizing with primate DQA1 alleles, indicating that typing of equivalent primate alleles can be accomplished at lower stringency conditions. However, it may be necessary to design additional oligonucleotides probes (based on available primate DQA1 sequences) to improve the discriminating power of this kit for use in routine typing of Old World monkey DQA1 alleles.

The prevalence of antibodies to simian T-cell leukaemia/lymphotropic virus (STLV-I) in non-human primate colonies in Kenya

Retroviruses closely related to the human T-cell leukaemia/lymphotrophic virus type I (HTLV-I) have been detected in several, non-human, primate species. These retroviruses are called simian T-lymphotrophic virus type I (STLV-I). Infection with STLV-I has been associated with lymphoma and leukaemia in macaques, baboons, African green monkeys and gorillas. However, no STLV-I infection has been detected in New World primates, although STLV-II has been detected in spider monkeys. When sera from 10 species of non-human primates maintained at the Institute of Primate Research were screened for STLV-I infection, anti-STLV-I antibodies were detected in 12%, 12%, 23% and 38% of the olive baboons, yellow baboons, African green monkeys and lowland Sykes' monkeys, respectively. Western-blot studies confirmed these results. To date, no clinical disease has been linked with STLV-I infection in these colonies. The relatively high prevalence of anti-STLV-I antibodies in these non-human primates offers an opportunity for studies on the transmission, phylogenetic relationships and natural history of STLV-I in primate colonies.