Predicting the long-term impact of rotavirus vaccination in 112 countries from 2006 to 2034: A transmission modeling analysis

Rotavirus vaccination has been shown to reduce rotavirus burden in many countries, but the long-term magnitude of vaccine impacts is unclear, particularly in low-income countries. We use a transmission model to estimate the long-term impact of rotavirus vaccination on deaths and disability adjusted life years (DALYs) from 2006 to 2034 for 112 low- and middle-income countries. We also explore the predicted effectiveness of a one- vs two- dose series and the relative contribution of direct vs indirect effects to overall impacts. To validate the model, we compare predicted percent reductions in severe rotavirus cases with the percent reduction in rotavirus positivity among gastroenteritis hospital admissions for 10 countries with pre- and post-vaccine introduction data. We estimate that vaccination would reduce deaths from rotavirus by 49.1 % (95 % UI: 46.6-54.3 %) by 2034 under realistic coverage scenarios, compared to a scenario without vaccination. Most of this benefit is due to direct benefit to vaccinated individuals (explaining 69-97 % of the overall impact), but indirect protection also appears to enhance impacts. We find that a one-dose schedule would only be about 57 % as effective as a two-dose schedule 12 years after vaccine introduction. Our model closely reproduced observed reductions in rotavirus positivity in the first few years after vaccine introduction in select countries. Rotavirus vaccination is likely to have a substantial impact on rotavirus gastroenteritis and its mortality burden. To sustain this benefit, the complete series of doses is needed.

Rotavirus diarrhoea hospitalizations among children under 5 years of age in Nigeria, 2011-2016

BACKGROUND

The high burden of rotavirus acute gastroenteritis (AGE) is well documented among children under 5 years of age, with the majority of mortality occurring in developing countries. Nigeria ranked second worldwide in the number of rotavirus deaths in 2013. As Nigeria plans to introduce rotavirus vaccine soon, a pre-vaccine documentation of rotavirus disease burden is necessary to determine vaccine impact.

METHODS

Routine rotavirus surveillance was conducted during 2011-2016 in 3 sentinel sites in Nigeria using the standard WHO protocol. Children under 5 years of age hospitalized for acute gastroenteritis were enrolled and demographic, clinical and outcome data were collected. A stool sample was subsequently obtained and tested for human rotavirus antigen using the Enzyme-linked immunosorbent assay (ELISA).

RESULTS

2694 children with acute gastroenteritis were enrolled during January 2011 to December 2016; of these, 1242 (46%) tested positive for rotavirus. Among the rotavirus positive cases, 66% and 94% were younger than 12 months and 24 months respectively. Marked peaks in rotavirus positivity were seen in January of each year. Vomiting, and use of oral and intravenous fluids occurred more often in rotavirus positive cases as compared to rotavirus negative cases.

CONCLUSION

The high prevalence of rotavirus disease highlights the need for urgent introduction of rotavirus vaccine in Nigeria. Additionally, this study provides pre-vaccine introduction disease-burden data that will serve as a baseline for rotavirus vaccine impact-assessment once vaccine has been introduced in the national immunization program.

Sustained impact of rotavirus vaccine on rotavirus hospitalisations in Lusaka, Zambia, 2009-2016

BACKGROUND

Monovalent rotavirus vaccine (RV1) was introduced in Lusaka in February 2012 and rolled out countrywide in November 2013 in the routine Expanded Programme on Immunisation and administered at 6 and 10 weeks with no catch up dose. Reported here is the monitoring of rotavirus acute gastroenteritis hospitalisations at the University Teaching Hospital, Lusaka, Zambia as part of efforts to document the impact of rotavirus vaccine.

METHODS

Children <5 years hospitalised for acute gastroenteritis (AGE) from January 2009 to December 2016 were recruited into the rotavirus disease burden active surveillance and had their stools tested for rotavirus by enzyme immunoassay. We compared rotavirus-associated AGE hospitalisations of the pre-vaccine era (2009-2011) with the post-rotavirus vaccine introduction period (2013-2016).

RESULTS

With the increase in RV1 coverage in Lusaka, rotavirus AGE declined significantly from 40% of diarrhoea hospitalisation in the pre-vaccine era to 29% of diarrhoea hospitalisation in the post-vaccine era (p < 0.001) in children <5 years. After a decreasing trend in rotavirus positivity from 2013 to 2015, positivity increased to 37% in 2016. However, the post-vaccine years (2012-2016) saw substantial decline in the number tested (median decline: 34% (range: 20-43%)) and the number of positive results (median decline: 52% (range: 30-65%).

CONCLUSION

A sustained and significant decline in rotavirus AGE hospitalisations was observed in children <5 years since the introduction of RV1 in Lusaka, Zambia. Despite an increase in rotavirus positivity in 2016, the total number of children enrolled and the number of rotavirus positive children remained below baseline. The reason for the increase in rotavirus positivity in 2016 is unknown but could be due to an accumulation of susceptible children and the shifting of disease to children of older age groups. This finding underscores the need for continued monitoring of rotavirus vaccine impact.

Rotavirus strain diversity in Eastern and Southern African countries before and after vaccine introduction

BACKGROUND

The African Rotavirus Surveillance Network has been detecting and documenting rotavirus genotypes in the African sub-continent since 1998 in anticipation of the rollout of rotavirus vaccination in routine Expanded Programme on Immunisation. This paper reports distribution of the rotavirus strains circulating in 15 Eastern and Southern African (ESA) countries from 2010-2015 as part of active World Health Organization (WHO) rotavirus surveillance, and investigates possibility of emergence of non-vaccine or unusual strains in six selected countries post-vaccine introduction.

MATERIAL AND METHODS

Stool samples were collected from children <5 years of age presenting with acute gastroenteritis at sentinel hospitals pre- and post-rotavirus vaccine introduction. Samples were tested for group A rotavirus using an enzyme immunoassay by the national and sentinel laboratories. At the WHO Rotavirus Regional Reference Laboratory in South Africa, molecular characterisation was determined by PAGE (n = 4186), G and P genotyping (n = 6447) and DNA sequencing for both G and P types (n = 400).

RESULTS

The six-year surveillance period demonstrated that 23.8% of the strains were G1P[8], followed by G2P[4] (11.8%), G9P[8] (10.4%), G12P[8] (4.9%), G2P[6] (4.2%) and G3P[6] (3.7%) in 15 ESA countries. There was no difference in circulating strains pre- and post-rotavirus vaccine introduction with yearly fluctuation of strains observed over time. Atypical rotavirus G and P combinations (such as G1P[4], G2P[8], G9P[4] and G12P[4]) that might have arisen through inter-genogroup or inter-genotypes reassortment were detected at low frequency (2%). Close genetic relationship of African strains were reflected on the phylogenetic analysis, strains segregated together to form an African cluster in the same lineages/sub-lineage or monophyletic branch.

CONCLUSION

There has been considerable concern about strain replacement post-vaccine introduction, it was not clear at this early stage whether observed cyclical changes of rotavirus strains were due to vaccine pressure or this was just part of natural annual fluctuations in the six ESA countries, long-term surveillance is required.

Impact of rotavirus vaccine on all-cause diarrhea and rotavirus hospitalizations in Madagascar

BACKGROUND

Rotavirus vaccine was introduced into the Extended Program on Immunization in Madagascar in May 2014. We analyzed trends in prevalence of all cause diarrhea and rotavirus hospitalization in children <5years of age before and after vaccine introduction and assessed trend of circulating rotavirus genotypes at Centre Hospitalier Universitaire Mère Enfant Tsaralalàna (CHU MET).

METHODS

From January 2010 to December 2016, we reviewed the admission logbook to observe the rate of hospitalization caused by gastroenteritis among 19619 children <5years of age admitted at the hospital. In June 2013-December 2016, active rotavirus surveillance was also conducted at CHUMET with support from WHO. Rotavirus antigen was detected by EIA from stool specimen of children who are eligible for rotavirus gastroenteritis surveillance at sentinel site laboratory and rotavirus positive specimens were further genotyped at Regional Reference Laboratory by RT-PCR.

RESULTS

Diarrhea hospitalizations decreased after rotavirus vaccine introduction. The median proportion of annual hospitalizations due to diarrhea was 26% (range: 31-22%) before vaccine introduction; the proportion was 25% the year of vaccine introduction, 17% in 2015 and 16% in 2016. Rotavirus positivity paralleled patterns observed in diarrhea. Before vaccine introduction, 56% of stool specimens tested positive for rotavirus; the percent positive was 13% in 2015, 12% in 2016. Diverse genotypes were detected in the pre-vaccine period; the most common were G3P[8] (n=53; 66%), G2P[4] (n=12; 15%), and G1P[8] (n=11; 14%). 6 distinct genotypes were found in 2015; the most common genotype was G2P[4] (n=10; 67%), the remaining, 5, G12[P8], G3[P8], G1G3[P4], G3G12[P4][P8] and G1G3[NT] had one positive specimen each.

CONCLUSIONS

Following rotavirus vaccine introduction all-cause diarrhea and rotavirus-specific hospitalizations declined dramatically. The most common genotypes detected in the pre-vaccine period were G3P[8] and G2P[4] in 2015, the post vaccine period.

Norovirus GII.17 Predominates in Selected Surface Water Sources in Kenya

In this study, the prevalence and genotypes of noroviruses (NoVs) in selected water sources from rural, urban and refugee settings in Kenya were investigated. Ten litres each of river, household and borehole water was collected in rural (Mboone River), urban (Nairobi and Mutoine River) and refugee (Dadaab refugee camp) settings. NoVs were recovered from the water samples by a glass wool adsorption-elution technique and/or PEG/NaCl precipitation. Nucleic acid was extracted using the automated MagNA Pure platform. NoVs were detected with singleplex real-time reverse transcription-polymerase chain reaction assays and characterised by nucleotide sequence analysis. NoVs were detected in 63% (25/40) of the selected water samples comprising GII (42.5%), GI (2.5%) and mixed GI/GII (17.5%) positive samples. The prevalence of NoVs in the Mutoine River (urban area) was higher than in the Mboone River (rural area) (P = 0.0013). Noroviruses GI.1, GI.3, GI.9, GII.4, GII.6, GII.12, GII.16 and GII.17 were identified, with GII.17 accounting for 76% (16/21) of the typed strains. The NoV GII.17 predominance differs to other studies in Africa and further surveillance of NoVs in clinical and environmental settings is required to clarify/elucidate this observation. As information regarding NoVs in Kenyan water sources is limited this report provides valuable new data on NoV genotypes circulating in environmental water sources and the surrounding communities in Kenya.

Novel genital alphapapillomaviruses in baboons (Papio hamadryas anubis) with cervical dysplasia

Genital Alphapapillomavirus (αPV) infections are one of the most common sexually transmitted human infections worldwide. Women infected with the highly oncogenic genital human papillomavirus (HPV) types 16 and 18 are at high risk for development of cervical cancer. Related oncogenic αPVs exist in rhesus and cynomolgus macaques. Here the authors identified 3 novel genital αPV types (PhPV1, PhPV2, PhPV3) by PCR in cervical samples from 6 of 15 (40%) wild-caught female Kenyan olive baboons (Papio hamadryas anubis). Eleven baboons had koilocytes in the cervix and vagina. Three baboons had dysplastic proliferative changes consistent with cervical squamous intraepithelial neoplasia (CIN). In 2 baboons with PCR-confirmed PhPV1, 1 had moderate (CIN2, n = 1) and 1 had low-grade (CIN1, n = 1) dysplasia. In 2 baboons with PCR-confirmed PhPV2, 1 had low-grade (CIN1, n = 1) dysplasia and the other had only koilocytes. Two baboons with PCR-confirmed PhPV3 had koilocytes only. PhPV1 and PhPV2 were closely related to oncogenic macaque and human αPVs. These findings suggest that αPV-infected baboons may be useful animal models for the pathogenesis, treatment, and prophylaxis of genital αPV neoplasia. Additionally, this discovery suggests that genital αPVs with oncogenic potential may infect a wider spectrum of non-human primate species than previously thought.

The detection of enteric viruses in selected urban and rural river water and sewage in Kenya, with special reference to rotaviruses

AIM

To determine the occurrence of eight human enteric viruses in surface water and sewage samples from different geographical areas in Kenya.

METHODS AND RESULTS

Enteric viruses were recovered from the water and sewage sources by glass-wool adsorption elution and/or polyethylene glycol/NaCl precipitation and detected by singleplex real-time and conventional PCR and reverse transcriptase-PCR assays. One or more enteric viruses were detected in nearly all sewage and river water samples except the urban Mbagathi River. The VP7 (G types) and the VP4 (P types) of the rotaviruses (RV) were characterized by multiplex nested PCR methods. The G and P types could be determined in 95·5% of the RV strains, respectively. Mixed G types were detected with G12 and G1 predominating, and unusual G types, G5 and G10, were present. P[4] predominated in the urban Karen sewage samples, while P[8] predominated in the urban and rural streams.

CONCLUSIONS

The high prevalence of RVs in surface water highlights the importance of assessing the water sources used for domestic purposes for viral contamination.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study demonstrates the benefit of environmental surveillance as an additional tool to determine the epidemiology of RVs and other enteric viruses circulating in a given community.

Vaginal histological changes of the baboon during the normal menstrual cycle and pregnancy

BACKGROUND

A baboon, a non-human primate, is phylogenetically close to human and has been used to study in detail aspects of reproductive physiology that cannot be studied in humans for ethical reasons.

OBJECTIVE

To determine the histological changes in baboon vagina associated with cyclic variations during normal menstrual cycle.

SETTING

The experiments were carried out at Institute of Primate Research (IPR), Karen, Nairobi, Kenya.

SUBJECTS

Nine adult healthy female olive baboons were used in this study. These baboons were monitored over a period of one year and found to have regular menstrual cycles. The vaginal biopsies were taken at different menstrual stages, fixed in 10% formalin and processed to evaluate histological changes.

RESULTS

Observation of the histological sections of the biopsies by light microscopy showed that there were histological changes associated with cyclic variations in female olive baboon. During the luteal phase, menstrual phase and pregnancy the squamous epithelium was very thin. The layer gradually thickens throughout the proliferative phase and was thickest during the ovulation period.

CONCLUSION

The changes in squamous epithelium suggest that the baboon vagina undergoes histological changes throughout the menstrual cycle which may be associated with hormonal variations. The data from this study also suggest that olive baboon is a good model for investigating possible effects of hormonal contraceptives on vaginal epithelium and the mechanism of female heterosexual transmission of HIV.

Feline non-repetitive mitochondrial DNA control region database for forensic evidence

The domestic cat is the one of the most popular pets throughout the world. A by-product of owning, interacting with, or being in a household with a cat is the transfer of shed fur to clothing or personal objects. As trace evidence, transferred cat fur is a relatively untapped resource for forensic scientists. Both phenotypic and genotypic characteristics can be obtained from cat fur, but databases for neither aspect exist. Because cats incessantly groom, cat fur may have nucleated cells, not only in the hair bulb, but also as epithelial cells on the hair shaft deposited during the grooming process, thereby generally providing material for DNA profiling. To effectively exploit cat hair as a resource, representative databases must be established. The current study evaluates 402 bp of the mtDNA control region (CR) from 1394 cats, including cats from 25 distinct worldwide populations and 26 breeds. Eighty-three percent of the cats are represented by 12 major mitotypes. An additional 8.0% are clearly derived from the major mitotypes. Unique sequences are found in 7.5% of the cats. The overall genetic diversity for this data set is 0.8813±0.0046 with a random match probability of 11.8%. This region of the cat mtDNA has discriminatory power suitable for forensic application worldwide.

Delivering new malaria drugs through grassroots private sector

OBJECTIVE

To demonstrate that micro-franchising system is an effective way of improving access to effective health care such as the introduction of first line antimalarias in populations living in underserved rural areas in Kenya.

DESIGN

A descriptive study.

SETTING

Child and family wellness (CFW) micro-franchised nurse run clinics in Kenya.

RESULTS

In 2007, 39.3% of RDTs carried out were positive for malaria. All malaria positive (RDTs and microscopy) patients received artemether lumefantrine (AL) according to their weight in accordance with the Government approved treatment guidelines. During the same period a total of 3,248 community members were reached with malaria information, however, community expectations took longer to change as patients demanded AL even when the malaria diagnosis was negative. Initially, this led to the dispensing of other antimalarials to patients with malaria like symptoms even with a negative test. This demand decreased with more community education on the importance of the tests. Engaging the private sector though with challenges proved feasible and appropriate in accessing malaria treatment based on clinical diagnosis supported by RDTs to confirm the diagnosis instead of presumptive treatment based on fever. This led to a reduction of antimalarial prescriptions by more than 50%, implying better patient care, rational drug use as well as cost savings on malaria treatment.

CONCLUSION

A micro-franchising system is an effective and sustainable way of improving access to effective health care by populations living in underserved rural areas of Africa. With appropriate supportive training and supervision, the system can adapt to changes in treatment guidelines and to new regimens.

Nonhuman primate models for translational research in endometriosis

Endometriosis, defined as the ectopic presence of endometrial-like cells, is associated with infertility and pelvic pain in women. Whereas pathogenesis and spontaneous evolution of endometriosis are still poorly understood, recurrences after surgical therapy or after medical treatment are common. Spontaneous endometriosis occurs only in women and in nonhuman primates (NHPs). Inbred rhesus monkeys kept in colonies offer an attractive preclinical model to study the inheritance of spontaneous endometriosis. Baboons with spontaneous or induced endometriosis appear to be the best NHP model to study pathogenesis, pathophysiology, spontaneous evolution and new medical treatment options. In baboons, induction of endometriosis after intrapelvic injection of menstrual endometrium leads to biological changes in peritoneal cavity and in endometrium. This induction process may allows the study of cause-effect relationships which may lead to the discovery of new biomarkers for the development of new non-invasive diagnostic tests and drugs that may prevent or treat endometriosis.

Baboon serum is superior to human or bovine serum albumin for baboon sperm capacitation and zona binding

BACKGROUND

Baboon in vitro fertilization requires capacitated sperm inappropriate media. In this study, we compared the effect of baboon serum (Bas), human serum albumin (HSA) and bovine serum albumin (BSA) on baboon sperm capacitation.

METHODS

Five males (n = 5) were electroejaculated and 43 oocytes retrieved from super-ovulated female baboons (n = 10). Each sperm sample was assessed for initial motility and concentration before and after swim-up. For swim-up, each sperm sample was incubated separately in Biggers-Whitten-Whittingham media containing either BaS, HSA, BSA or without protein supplementation (control). After swim-up, each sperm aliquot was incubated with two to three oocytes. The number of sperm bound to the zona was evaluated after overnight incubation.

RESULTS

Sperm motility and zona binding was significantly higher after capacitation in media supplemented with BaS than in HSA or BSA or in media without protein supplementation (P < 0.05).

CONCLUSION

Baboon serum is superior to HSA or BSA for baboon sperm capacitation and zona binding.

Enzootic simian piroplasm (Entopolypoides macaci ) in wild-caught Kenyan non-human primates

BACKGROUND

Three species of non-human primates comprising African green monkeys (AGMs), (Cercopithecus aethiops, n = 89), Syke's monkeys (Cercopithecus mitis, n = 60) and olive baboons (Papio cynocephalus anubis, n = 30), were screened for Entopolypoides macaci.

METHODS

Observation of blood smears prepared from these animals revealed E. macaci infection rate of 42.7% in AGMs, 35% in Syke's monkeys and 33.3% in baboons.

RESULTS

Gender infection rate was 38.2% in females and 29% in males. Statistically, there was no significant difference in infection rates between the monkey species and sexes (P > 0.05). Subsequent indirect immuno fluorescent antibody test supported the morphological appearance of E. macaci observed by microscopy. Sera from infected animals reacted positively (1:625) with E. macaci antigen, but not to Babesia bigemina or B. bovis antigen at 1:125 titer.

CONCLUSION

This study has revealed high prevalence of E. macaci infection in all three widely distributed Kenyan non-human primates. With the continued use of these animals as models for human parasitic diseases, the presence of this highly enzootic parasite should be noted.

Molecular characterisation of the rotavirus strains prevalent in Maua, Meru North, Kenya

BACKGROUND

Rotavirus is the most common cause of severe infantile diarrhoea disease in infants and young children below five years worldwide. Rotavirus is associated with high cases of morbidity and mortality and it is estimated that up to 650,000 deaths in young children occur annually in the less developed countries and approximately 150,000-200,000 deaths occur in Africa alone.

OBJECTIVE

To characterise the circulating rotavirus strains in Maua, Meru North district, Kenya.

DESIGN

A prospective study to investigate and characterise rotavirus serotypes/genotypes and electropherotypes in infants and children with severe diarrhoea hospitalised and/or attending the outpatient department of Maua Methodist Hospital during the period April 2004 to September 2005.

SETTING

Maua Methodist Hospital, Meru North, Kenya.

SUBJECTS

Faecal samples were collected from 135 infants and children with acute diarrhoea and were screened first for the presence of human Group A rotavirus antigen using commercially available enzyme linked immunosorbent assay kit (ELISA). The positive samples were evaluated by sodium dodecyl polycrylamide gel electrophoresis (SDS-PAGE) to determine the viral RNA electropherotype profile. Rotavirus strains were also genotyped using reverse transcriptase polymerase chain reaction (RT-PCR) of the VP7 gene.

RESULTS

Assay of these samples with commercial ELISA showed that 17.8% (24/135) were positive for group A rotavirus antigen. Twenty of these ELISA positive samples were also analysed by SDS-PAGE of which 75% (15/20) gave detectable electropherotype pattern with the long electropherotype being predominant 80.0% (12/15) followed by the short RNA profile 20.0% (2/ 15). Seventeen of the ELISA positive samples were genotyped for VP7 and the results showed that G9 was the most predominant genotype comprising 47.1% (8/17) followed by G8 29.4% (5/17), GI 17.4% (3/17) and the mixed genotype was G8/G9 5.9% (1/17). Most patients with rotavirus infection were of the age of 3 - 60 months, with 79% being less than 18 months old.

CONCLUSION

The overall prevalence of rotavirus infection in young children with diarrhoea hospitalised and/or attending the out-patient department of Maua Methodist Hospital was 17.8% with the predominant serotype being G9. These results show that rotavirus plays an important role in severe viral diarrhoea in young children in Maua Meru North district, Kenya. Furthermore, this high G9 rotavirus prevalence in Kenya may require vaccine trials to be held in Kenya so as to determine the efficacy of new rotavirus vaccine candidates that do not include the G9 serotype.

Evidence for expression of endogenous retroviral sequences on primate reproductive tissues and detection of cross-reactive ERVS antigens in the baboon ovary: a review

OBJECTIVE

To review recent research findings on the specific expression of endogenous retroviral sequences (ERVS) in reproductive tissues and their possible physiological roles. ERVS have been implicated in several biological events such as induction of resistance to exogenous retrovirus invasion, involvement in placental trophoblast formation, sperm maturation and differentiation; and stimulation of local immunosuppression to protect the foetus from immunological attack.

DATA SOURCES

Critical review of relevant articles and abstracts cited in international and local journals, literature searches on Medline and Medchem up to 2005.

DATA SYNTHESIS

Retroviruses have been implicated in the induction of tumour and immunological disorders. Over the years, endogenous retroviruses (ERVs) and retroviral elements have been detected in the genome of many vertebrate species, including primates. The evidence for the presence of retroviruses in the primate tissues such as the placenta, ovary, breast, testis and epididymis has been documented using electron microscopic studies. Retrovirus-like particles were found budding from the basal membrane of syncytiotrophoblasts, as well as in tumour cell lines in embryonic carcinoma or teratocarcinomas. Apart from their pathological effects, recent evidence suggests that these ERVs may play useful roles in normal physiological events.

RESULTS

Recent studies indicate the expression of endogenous retroviruses in the testis, epididymis, placenta and breast. However, limited data exist on the detection of ERVs in the ovary. Overall, the precise functions for ERVs in these tissues are not well understood. In the testis and epididymis, speculative functions may include among others spermatogenesis and/or sperm maturation (differentiation) whereas in placenta they are possibly associated with trophoblast fusion and locally induced immunosuppression to protect the foetus from immunological attack. Experiments in our laboratory have indicated restricted expression of retroviral antigens including baboon endogenous retroviral proteins (BERV), ERV-3, HIV-1 gp41 and HERV-K env in the baboon ovary.

CONCLUSION

ERVs are specifically expressed in different mammalian reproductive tissues and may have unique physiological roles.

Treatment with anti-TNF monoclonal antibody (c5N) reduces the extent of induced endometriosis in the baboon

BACKGROUND

Inflammatory cytokines, including interleukin (IL)-1, IL-6, IL-8 and tumour necrosis factor-alpha (TNF-alpha), are important in the pathogenesis of endometriosis. We assessed the efficacy of anti-TNF monoclonal antibody (mAb, c5N), known to prevent induced endometriosis in baboons, in reducing established endometriosis in baboons.

METHODS

This prospective, randomized, blinded, controlled study was conducted in baboons at the Institute of Primate Research (IPR), Nairobi, Kenya. Endometriosis was induced in 18 adult female baboons (Papio anubis) with regular menstrual cycles and a normal pelvis; the extent of endometriosis was documented by videolaparoscopy 25 days later. The baboons were then randomly assigned to receive a single infusion of either placebo (n=7, 5 ml/kg) or c5N (n=11, 5 mg/kg). Follow-up laparoscopy was performed 25 days later to document any differences in the number, surface area and estimated volume of lesions between the two groups and between the first and the second laparoscopies in each group. Representative biopsies of at least one endometriotic lesion per baboon were obtained at the final laparoscopy.

RESULTS

Significant reductions in total surface area, estimated total volume of endometriotic lesions and both number and surface area of red lesions were observed after treatment with c5N, but not after placebo treatment, when compared to the initial laparoscopy. Conversely, a significant increase in the number of typical and red lesions was observed after placebo treatment when compared to the initial laparoscopy. Neither c5N nor placebo treatment affected the menstrual cycle.

CONCLUSION

In baboons with induced endometriosis, anti-TNF-mAb (c5N) treatment significantly reduced the extent of endometriosis, mainly due to reducing both the number and surface area of red lesions. These findings suggest that anti-TNF-mAb therapy may have therapeutic potential for active peritoneal endometriosis.

Validation of real-time RT-PCR assays for mRNA quantification in baboons

Real-time RT-PCR has been used widely, both in fundamental research and in clinical diagnostics, for instance for quantification of RNA levels in human tissues and tissue biopsies. In the present study we provide a strategy to validate primers/probes for real-time RT-PCR quantification of baboon samples. The method is based on the TaqMan system and uses primers/probes that have been designed and validated for human real-time RT-PCR. A prerequisite for the accuracy of this strategy is a similar amplification efficiency between human and baboon PCR reactions. We propose two different methods, i.e. by calculating PCR efficiencies from the slope of a dilution curve or by using the linear regression method, to compare the amplification efficiency between human and baboon samples. In conclusion, by performing a simple validation experiment, real-time PCR assays based on human sequences, which are easily available, can be applied for analysis of baboon samples.

Human group C rotaviruses identified in Kenya

BACKGROUND

Rotavirus is associated with acute infantile gastro-enteritis in infants and young children worldwide. Rotavirus is associated with the high cases of morbidity and mortality and it is estimated that up to 650,000 deaths in young children occur annually in the less developed countries. Approximately a quarter of these deaths occur in African children yet minimal data exist on the circulating rotavirus strains in Africa.

OBJECTIVE

To characterise the circulating rotavirus strains in Kenya.

DESIGN

A prospective study to investigate rotavirus infection in infants and young children with acute diarrhoea in different areas of Kenya. Between September 2001 and February 2002, 119 faecal specimens were collected from children aged between 1 and 60 months with acute infantile gastro-enteritis.

SETTING

Faecal samples were collected from clinics around Nairobi and its suburbs including Karen, Ngong, Ongata Rongai.

SUBJECTS AND METHODS

Faecal samples were collected from 119 infants and young children with diarrhoea and were analysed by commercial ELISA and polyacrylamide gel electrophoresis (SDS-PAGE) to identify possible non-group A rotaviruses. Extraction of any potential rotavirus double-stranded RNA from faeces and characterisation by SDS-PAGE showed the presence of human group C rotaviruses.

RESULTS

Examination of these samples with a commercial ELISA assay for the presence of group A rotavirus antigen showed that 13 specimens (11%) were positive. An analysis of all stool specimens was performed by polyacrylamide gel electrophoresis to identify possible non-group A rotaviruses. Extraction of any potential rotavirus double-stranded RNA from faeces and characterisation by SDS-PAGE showed the presence of human group C rotaviruses.

CONCLUSION

This is the first report of group C rotaviruses in Kenya. Further studies are underway to continue the surveillance of rotavirus strains in Kenya; as this information will be useful in planning rotavirus vaccine trials in Africa.

Human endogenous retrovirus-R (ERV 3) env-like antigens expressed in baboon testes and epididymides

BACKGROUND

A substantial component of the vertebrate genome comprise of retrovirus-related sequences named as endogenous retroviruses (ERVs). The role of these ERV-related sequences in the biological processes of the host species is still unknown. However, they have been associated with tumourigenesis, autoimmune diseases and placental morphogenesis in primates.

OBJECTIVE

To determine the expression of ERVs in male baboon reproductive tissues.

DESIGN

The testes and other reproductive tissues from sexually immature and mature male olive baboons (Papio anubis) were investigated for the expression of endogenous retrovirus-related particles. Immunohistochemical staining was performed using antibodies raised against human immunodeficiency virus (HIV)-1/2, simian immunodeficiency virus (SIV) and human ERVs. Biochemical properties were determined by western blot, and reverse transcriptase (RTase) activity in epididymal spermatozoa, ejaculate spermatozoa and seminal fluid was evaluated.

SETTING

Institute of Primate Research, Nairobi, Kenya.

RESULTS

ERV3 env-like antigens were detected on spermatogenic cells in mature baboon testes and on epididymal spermatozoa. Similarly, antigens cross-reactive with antibodies to HIV structural and envelope glycoproteins were expressed in mature and juvenile baboon testes. In addition, reverse transcriptase activity was detected in ejaculate spermatozoa, seminal fluid and epididymal spermatozoa.

CONCLUSION

These results indicate that retroviral-related genes were expressed in normal male baboon testes and spermatozoa, similar to humans. The functions of these ERVs in vertebrates remains unclear.

Serological detection of adenoviruses in non-human primates maintained in a colony in Kenya

BACKGROUND

Adenoviruses are known to cause several human diseases including acute febrile respiratory syndromes, epidemic conjunctivitis and gastroenteritis. These diseases associated with adenovirus infection affect adults and are usually more severe in infants and children. Forty-seven human adenoviruses serotypes have so far been identified adenovirus. The diversity of these viruses has delayed progress on vaccine development due to difficulties in identifying appropriate vaccine targets. To date, limited studies have been done to determine the prevalence of adenovirus infection in non-human primates with the goal of developing a non-human primate model that can be used to study the mechanisms of infection.

OBJECTIVE

To determine the prevalence of enteric adenovirus infection in Kenyan non-human primates.

DESIGN

A prospective study to investigate the prevalence of enteric andenovirus infection in captive non-human primates maintained in a colony.

SETTING

Faecal samples were collected from monkeys trapped from different geographical areas of Kenya and also from the ones maintained in a colony at the Institute of Primate Research (IPR), Kenya.

SUBJECTS

Ninety four faecal samples were collected from three species of non-human primates consisting of various ages and sex. Samples were collected from monkeys trapped from different geographical areas of Kenya and also from the ones maintained in a colony at the Institute of Primate Research (IPR), Kenya. All the faecal samples were screened for presence of adenoviruses using a commercial antigen-capture enzyme immunoassay (EIA) kit, this is an enzyme-linked immunosorbent assay (ELISA) kit designed for diagnosis of human enteric adenoviruses in stool samples.

RESULTS

The highest prevalence of adenoviruses, detected by EIA kit, was in olive baboons (Papio anubis, 52.9%), followed by vervet monkeys (Cercopithecus aethiops, 48.9%) and the yellow baboons (Papio cynocephalus, 18.8%). Sub-grouping within each species (based on age and sex) indicated no significant differences (p > 0.05) in adenovirus infection signifying equal susceptibility. The prevalence of adenoviruses in vervet monkeys that were also Simian Immunodeficiency virus (SIV) seropositive was determined and shown to be 63.2%.

CONCLUSION

The results of this study indicate that adenovirus infection is prevalent among non-human primates in Kenya. These findings suggest that cross species transmission in Kenyan non-human primates may be a common occurrence and there is a possibility of zoonotic transmission of adenoviruses. Furthermore, our results highlight the potential of using these non-human primates as models for testing safety and efficacy of candidate adenovirus vaccines prior to clinical trials in humans.

The prevalence of endometriosis among African-American and African-indigenous women

Endometriosis is gynaecological disorder, characterized by the growth of endometrial tissue outside the uterine cavity. It is the most common cause of pelvic pain and occurs in 20-25% of women with infertility. Although Sampson first described endometriosis in 1927, studies on the prevalence of endometriosis among African women are still lacking. The current thinking is that endometriosis rarely affects women from the African origin. However, in African-American women in the USA, endometriosis is one of the commonest indications for major gynaecological surgery and hysterectomy, and is associated with long hospital stay and high hospital charges. There is also some evidence that endometriosis is more commonly found in African-American patients from private practice than in African-American patients treated in public hospitals. The prevalence of endometriosis in African-indigenous women with infertility seems low, possibly due to a different life style (early pregnancy, increased risk for PID and blocked Fallopian tubes) and due to lack of laparascopic facilities and specific training of African gynecologists to diagnose ascites caused by endometriosis appear to be more frequently observed in African-indigenous of African-American women than in women with other ethnic backgrounds.

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.

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.

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.

Molecular characterisation of a putative endogenous retrovirus cDNA isolated from human placental tissue

The human genome comprises of abundant DNA sequences related to endogenous retroviruses (ERV) and a variety of solitary long terminal repeats (LTRs). Substantial numbers of intact retroviral particles have been detected by electron microscopy in normal human placental villous tissue particularly in syncytiotrophoblast. Understanding the molecular structure, organisation and distribution of these ERV sequences may lead to elucidation of their possible dual function at the foetal-maternal interface; proliferation and differentiation of cytotrophoblast and induction of local pregnancy-associated immune suppression thus allowing survival of the foetal allograft. In this study, antibody probes were used to screen a human placental expression library and cDNA clones isolated were characterized by polymerase chain reaction, Southern blot hybridisation, DNA cloning and partial nucleotide sequencing. A specific 1.7kb-cDNA clone was isolated from a human placental expression library. Further characterisation showed this clone represents a single copy gene, approximately 9-10kb and did not hybridise to the env region of ERV3 human endogenous retrovirus. The 1.7kb-cDNA clone may represent a provirus co-expressed with cellular sequences.

Characterization of antigens expressed in normal baboon trophoblast and cross-reactive with HIV/SIV antibodies

Electron microscopic studies have revealed the presence of endogenous retroviral (ERV) particles in normal primate placental tissues. These particles have ultrastructural similarities to type C retroviral particles and are mainly associated with the trophoblast. In normal human placental tissues, they have antigenic similarity with exogenous retroviruses, such as the human immunodeficiency virus (HIV), and may have a role to play in the regulation of cellular gene expression, syncytiotrophoblast formation or pregnancy-related immunosuppression. In this study, a panel of antibodies (polyclonal and monoclonal antibodies) against viral proteins (anti-HIV and anti-SIV) and endogenous retroviral (ERV) proteins were assessed by immunohistochemistry and immunoblotting, for their cross-reactivity with ERV particles isolated from normal baboon placental tissues. The antibodies (anti-HERV-K RT, anti-ERV3 env, anti-HIV-1 p17, anti-HIV-2 gp120) reacted positively with the syncytiotrophoblast and each antibody recognized one or two proteins of molecular weights (MW) 38, 58 or 64 kDa present in the baboon placental villous tissues and SIV-infected molt-4 Cl8 cells, but not in uninfected cells. The results of this study confirm the specific expression of retroviral cross-reactive antigens in normal baboon placental tissues and suggest placental cellular proteins may have antigenic similarity with those recognized by anti-HIV/SIV antibodies. The role of these retroviral-related proteins expressed at the maternal-fetal interface remain unclear.

Immunohistochemical localization of retroviral-related antigens expressed in normal baboon placental villous tissue

Endogenous retroviral particles (ERVs) have been detected in the genome of all eukaryotes. They are generally non-pathogenic except in mice where they have been found to induce tumors and immunological disorders. The ERVs have morphological features consistent with type-C retroviral particles and are commonly expressed in normal placental villous tissues. ERVs may have a role in the regulation of placental gene expression, syncytiotrophoblast formation, or pregnancy-related immunosuppression. In this study, well-characterized antibodies (monoclonal and polyclonal antibodies) raised against retroviral proteins (anti-HIV and anti-SIV) and endogenous retroviral (ERV) particles were assessed for their cross-reactivity (by using immunohistochemistry) with normal baboon placental and other adult tissues. The monoclonal antibodies to exogenous retroviral proteins (anti-HIV-2 gp120, anti-HIV-1 gp41, anti-SIVmac p27, anti-HIV-1 RT, and anti-HIV-2 core protein) showed specific immunohistochemical reactivity with the syncytiotrophoblast. Antibodies to endogenous retroviral gene products (anti-ERV3 env, anti-HERV-K RT, and anti-HERV-K env) also reacted in a similar manner and did not cross-react with other adult tissues. These studies have shown that retroviral-cross-reactive proteins are expressed in baboon placental syncytiotrophoblast and may have a role to play at the feto-maternal interface.

Expression of endogenous retroviral genes in germ cells and embryonic tissues in primates

The presence of endogenous retroviral sequences (ERVs) in vertebrate genomes is well documented. ERVs have been found to be generally inactive and non-infective except in certain pathological conditions. However, baboon endogenous rectrovirus (BaEV) has been shown to be infective in vitro, and ERV particles have been isolated from normal placental villous tissues of most primates. These particles have ultra-structural features similar to type C retroviruses and are cross-reactive with antibodies to exogenous retroviruses such as HIV. Their function is not yet known. This review examines their possible role in modulation of the immune system during pregnancy and in the syncytiotrophoblast in primates.

Characterisation of retroviral-related antigens expressed in normal baboon placental tissues

The genomes of all eukaryotes contain multiple copies of DNA sequences that are related to sequences found in infectious retroviruses. Endogenous retroviruses (ERVs) are generally non-pathogenic although they have been implicated in the induction of tumours and immunological disorders. The ERVs have morphological features consistent with type-C retroviral particles and are expressed in normal placental tissue in most mammals. They have antigenic similarity with exogenous retroviruses such as HIV-1 and may have a role to play in the regulation of cellular gene expression, syncytiotrophoblast formation or pregnancy-related immunosuppression. Some of the human endogenous retroviruses have been well-characterised. Among the non-human primates, the baboon endogenous virus (BaEV) is the only endogenous retrovirus so far which has been shown to be effective in vitro. The entire nucleotide sequence of BaEV has been determined. It has been shown to have a chimeric genomic structure of about 8 kb long. BaEV particle expression in placental tissues has been demonstrated using electron microscopy. However, to date, very little work has been done to evaluate the expression of retroviral-related antigens in normal baboon tissues. In this study, mouse polyclonal antibodies were produced against isolated baboon placental ERV particles and characterised using immunohistochemistry and immunoblotting techniques. Most of the anti-BERV antibodies displayed specific immunoperoxidase staining on placental syncytiotrophoblast and cross-reacted with exogenous retroviral proteins on immunoblot analyses. Reverse transcriptase (RTase) activity associated with sucrose gradient-purified placental retroviral-like particles were also demonstrated. These studies indicate that endogenous retroviral particles are expressed in baboon placental villous tissue and suggest retroviral proteins may play an immunomodulatory role at the maternal-foetal interface.

Analysis of primate major histocompatibility complex (MHC)-DQA1 locus by PCR-single strand conformation polymorphism (SSCP)

Major histocompatibility complex (Mhc) gene products play an important role in the immune responses against pathogens and autoimmunity, disease resistance and transplantation. Non-human primates (NHPs) are increasingly being utilized as models to test the safety and efficacy of candidate vaccines. Mhc typing of NHPs is an important component of the vaccine trial studies and in the investigations of any associations between Mhc alleles and disease. Routine typing of primate Mhc alleles has been hampered by unavailability of well characterised immunological reagents. In this study, we have used PCR amplification and SSCP for screening polymorphisms in the primate DQA1 locus. Using this technique, 9 African primate species (36 individuals) were analyzed. Ten individuals showed three or four electrophoretic band patterns and the rest two-band patterns indicating this technique can be used to discriminate homozygous and heterozygous individuals prior to DNA sequencing. This method may also be used to screen primates for Mhc-DQA1 allelic polymorphism. However, practical application of this technique for routine typing of primate Mhc-DQA1 alleles depends on availability of adequate nucleotide sequence information.