Elimination of GPI2 suppresses glycosylphosphatidylinositol GlcNAc transferase activity and alters GPI glycan modification in Trypanosoma brucei.

Many eukaryotic cell-surface proteins are post-translationally modified by a glycosylphosphatidylinositol (GPI) moiety that anchors them to the cell membrane. The biosynthesis of GPI anchors is initiated in the endoplasmic reticulum by transfer of GlcNAc from UDP-GlcNAc to phosphatidylinositol. This reaction is catalyzed by GPI GlcNAc transferase, a multisubunit complex comprising the catalytic subunit Gpi3/PIG-A as well as at least five other subunits, including the hydrophobic protein Gpi2, which is essential for the activity of the complex in yeast and mammals, but the function of which is not known. To investigate the role of Gpi2, we exploited Trypanosoma brucei (Tb), an early diverging eukaryote and important model organism that initially provided the first insights into GPI structure and biosynthesis. We generated insect-stage (procyclic) trypanosomes that lack TbGPI2 and found that in TbGPI2-null parasites, (i) GPI GlcNAc transferase activity is reduced, but not lost, in contrast with yeast and human cells, (ii) the GPI GlcNAc transferase complex persists, but its architecture is affected, with loss of at least the TbGPI1 subunit, and (iii) the GPI anchors of procyclins, the major surface proteins, are underglycosylated when compared with their WT counterparts, indicating the importance of TbGPI2 for reactions that occur in the Golgi apparatus. Immunofluorescence microscopy localized TbGPI2 not only to the endoplasmic reticulum but also to the Golgi apparatus, suggesting that in addition to its expected function as a subunit of the GPI GlcNAc transferase complex, TbGPI2 may have an enigmatic noncanonical role in Golgi-localized GPI anchor modification in trypanosomes.

Trypanosoma brucei colonizes the tsetse gut via an immature peritrophic matrix in the proventriculus.

The peritrophic matrix of blood-feeding insects is a chitinous structure that forms a protective barrier against oral pathogens and abrasive particles1. Tsetse flies transmit Trypanosoma brucei, which is the parasite that causes human sleeping sickness and is also partially responsible for animal trypanosomiasis in Sub-Saharan Africa. For this parasite to establish an infection in flies, it must first colonize the area between the peritrophic matrix and gut epithelium called the ectoperitrophic space. Although unproven, it is generally accepted that trypanosomes reach the ectoperitrophic space by penetrating the peritrophic matrix in the anterior midgut2-4. Here, we revisited this event using fluorescence- and electron-microscopy methodologies. We show that trypanosomes penetrate the ectoperitrophic space in which the newly made peritrophic matrix is synthesized by the proventriculus. Our model describes how these proventriculus-colonizing parasites can either migrate to the ectoperitrophic space or become trapped within peritrophic matrix layers to form cyst-like bodies that are passively pushed along the gut as the matrix gets remodelled. Furthermore, early proventricular colonization seems to be promoted by factors in trypanosome-infected blood that cause higher salivary gland infections and potentially increase parasite transmission.

Tsetse Fly Transmission Studies of African Trypanosomes.

African trypanosomes are naturally transmitted by bloodsucking tsetse flies in sub-Saharan Africa and these transmission cycles can be reproduced in the laboratory if clean tsetse flies and suitable trypanosomes are available for experiments. Tsetse transmission gives access to more trypanosome developmental stages than are available from in vitro culture, albeit in very small numbers; for example, the sexual stages of Trypanosoma brucei have been isolated from infected tsetse salivary glands, but have not yet been reported from culture. Tsetse transmission also allows for the natural transition between different developmental stages to be studied.Both wild-type and genetically modified trypanosomes have been successfully fly transmitted, and it is possible to manipulate the trypanosome environment inside the fly to some extent, for example, the induction of expression of genes controlled by the Tet repressor by feeding flies with tetracycline.

Proteome-Wide Quantitative Phosphoproteomic Analysis of Trypanosoma brucei Insect and Mammalian Life Cycle Stages.

Mass spectrometry based proteomics allows for the identification and quantification of protein and phosphorylation site abundance on a proteome wide scale. Here we describe the metabolic labeling of cultured Trypanosoma brucei cells in either the bloodstream or procyclic life cycle stage using stable isotope labeling of amino acids in cell culture (SILAC), and the production of samples suitable for analysis by liquid chromatography tandem mass spectrometry. The protocols require little specialist equipment, and they typically enable quantification of over 4500 proteins and 9000 phosphorylation sites.

In Vivo Bioluminescence Imaging to Assess Compound Efficacy Against Trypanosoma brucei.

Traditional animal models for human African trypanosomiasis rely on detecting Trypanosoma brucei brucei parasitemia in the blood. Testing the efficacy of new compounds in these models is cumbersome because it may take several months after treatment before surviving parasites become detectable in the blood. To expedite compound screening, we have used a Trypanosoma brucei brucei GVR35 strain expressing red-shifted firefly luciferase to monitor parasite distribution in infected mice through noninvasive whole-body bioluminescence imaging. This protocol describes the infection and in vivo bioluminescence imaging of mice to assess compound efficacy against T. brucei during the two characteristic stages of disease, the hemolymphatic phase (stage 1) and the encephalitic or central nervous system phase (stage 2).

Trypanosoma brucei infection protects mice against malaria.

Sleeping sickness and malaria are parasitic diseases with overlapping geographical distributions in sub-Saharan Africa. We hypothesized that the immune response elicited by an infection with Trypanosoma brucei, the etiological agent of sleeping sickness, would inhibit a subsequent infection by Plasmodium, the malaria parasite, decreasing the severity of its associated pathology. To investigate this, we established a new co-infection model in which mice were initially infected with T. brucei, followed by administration of P. berghei sporozoites. We observed that a primary infection by T. brucei significantly attenuates a subsequent infection by the malaria parasite, protecting mice from experimental cerebral malaria and prolonging host survival. We further observed that an ongoing T. brucei infection leads to an accumulation of lymphocyte-derived IFN-γ in the liver, limiting the establishment of a subsequent hepatic infection by P. berghei sporozoites. Thus, we identified a novel host-mediated interaction between two parasitic infections, which may be epidemiologically relevant in regions of Trypanosoma/Plasmodium co-endemicity.

A national atlas of tsetse and African animal trypanosomosis in Mali.

BACKGROUND: Tsetse-transmitted trypanosomosis is a deadly, neglected tropical disease and a major challenge for mixed crop-livestock agriculture in sub-Saharan Africa. It is caused by several species of the genus Trypanosoma. Information on the occurrence of tsetse flies and African animal trypanosomosis (AAT) is available for different areas of Mali. However, these data have never been harmonized and centralized, which prevents the development of comprehensive epidemiological maps and constrains an evidence-based planning of control actions. To address this challenge, we created a dynamic geo-spatial database of tsetse and AAT distribution in Mali. METHODS: A digital repository containing epidemiological data collected between 2000 and 2018 was assembled. In addition to scientific publications, the repository includes field datasheets, technical reports and other grey literature. The data were verified, harmonized, georeferenced and integrated into a single spatially-explicit database. RESULTS: For the tsetse component, approximately 19,000 trapping records, corresponding to 6000 distinct trapping locations and 38,000 flies were included in the database. Glossina palpalis gambiensis was the most widespread and abundant species, and it was found in the southern, southern-central and western parts of the country. Glossina tachinoides was only found in the South. Only a few specimens of Glossina morsitans submorsitans were detected. For the AAT component, approximately 1000 survey records were included, corresponding to 450 distinct survey sites and 37,000 tested bovines. AAT was found in all surveyed regions, although data for the tsetse-free North and North-East are lacking. Trypanosoma vivax and Trypanosoma congolense were the dominant species, while Trypanosoma brucei infections were much less numerous. CONCLUSIONS: The atlas of tsetse and AAT in Mali provides a synoptic view of the vector and disease situation at the national level. Still, major geographical gaps affect the North, the North-East and the West, and there is also a severe lack of data over the past five years. Trypanosomosis remains a major animal health problem in Mali. However, despite its prevalence and distribution, monitoring and control activities are presently very limited. Efforts should be made to strengthen the progressive control of AAT in Mali, and the atlas provides a new tool to identify priority areas for intervention.

Evaluation of an alternative indirect-ELISA test using in vitro-propagated Trypanosoma brucei brucei whole cell lysate as antigen for the detection of anti-Trypanosoma evansi IgG in Colombian livestock.

Surra is a zoonotic disease caused by Trypanosoma evansi, affecting the health and production of the livestock significantly. There are several methods to diagnose this disease, which have different principles, sensitivity, and specificity. Among them, the serological techniques using T. evansi as antigen are powerful tools for its epidemiological surveillance. However, they are poorly used due to inefficient in vitro propagation of T. evansi, which requires the use of laboratory animals for antigen production. In the present study, whole cell lysate of T. brucei brucei propagated in vitro was used as an antigen for the detection of anti-T. evansi immunoglobulin G in cattle through an indirect-ELISA. Based on a total of 45 samples from non-infected and 45 samples from T. evansi infected cattle, the sensitivity and specificity were estimated as 100% and 97.7%, respectively. After the validation, serological and molecular surveys were carried out in 710 cattle samples from two endemic Colombian regions (Antioquia and Arauca departments) for T. evansi where molecular prevalences of ˜7.0% were detected through the year and sporadic outbreaks of T. vivax infections have been associated to low prevalence of this species (<1%). A total of 424 (59.7%) samples were positive by indirect-ELISA T. b. brucei, while PCR test for T. evansi and T. vivax, showed 49 (6.9%) and no positive samples, respectively. Interestingly, categories of animals aged>1 year, Bos taurus breed, and those raised under intensive farming system exhibited a higher seroprevalence to T. evansi (P < 0.05). The results displayed a new alternative for antibody detection anti-T. evansi in livestock, using parasites propagated in vitro as antigen, which presents the advantage of higher standardization potential, and avoid the use of live animal for antigen production. A larger availability of this ELISA will generate useful information for a better understanding of the epidemiologic aspects, as well as for the management and control of these diseases in Colombia. However, the ability of the test to detect and/or cross react with T. vivax infections remains to be investigated.

A post-transcriptional respiratome regulon in trypanosomes.

Post-transcriptional regulons coordinate the expression of groups of genes in eukaryotic cells, yet relatively few have been characterized. Parasitic trypanosomatids are particularly good models for studies on such mechanisms because they exhibit almost exclusive polycistronic, and unregulated, transcription. Here, we identify the Trypanosoma brucei ZC3H39/40 RNA-binding proteins as regulators of the respiratome; the mitochondrial electron transport chain (complexes I-IV) and the FoF1-ATP synthase (complex V). A high-throughput RNAi screen initially implicated both ZC3H proteins in variant surface glycoprotein (VSG) gene silencing. This link was confirmed and both proteins were shown to form a cytoplasmic ZC3H39/40 complex. Transcriptome and mRNA-interactome analyses indicated that the impact on VSG silencing was indirect, while the ZC3H39/40 complex specifically bound and stabilized transcripts encoding respiratome-complexes. Quantitative proteomic analyses revealed specific positive control of >20 components from complexes I, II and V. Our findings establish a link between the mitochondrial respiratome and VSG gene silencing in bloodstream form T. brucei. They also reveal a major respiratome regulon controlled by the conserved trypanosomatid ZC3H39/40 RNA-binding proteins.

African trypanosomes.

African trypanosomes cause human African trypanosomiasis and animal African trypanosomiasis. They are transmitted by tsetse flies in sub-Saharan Africa. Although most famous for their mechanisms of immune evasion by antigenic variation, there have been recent important studies that illuminate important aspects of the biology of these parasites both in their mammalian host and during passage through their tsetse fly vector. This Primer overviews current research themes focused on these parasites and discusses how these biological insights and the development of new technologies to interrogate gene function are being used in the search for new approaches to control the parasite. The new insights into the biology of trypanosomes in their host and vector highlight that we are in a 'golden age' of discovery for these fascinating parasites.

Molecular identification of bovine trypanosomes in relation to cattle sources in southwest Nigeria.

Bovine trypanosomosis is a problem in the livestock industry in Nigeria. A longitudinal survey of cattle sampled during the wet and dry seasons was conducted from April 2016 to March 2017. Blood samples were collected by random sampling from 745 cattle in southwest Nigeria and screened for trypanosomes by internal transcribed spacer-polymerase chain reaction (ITS-PCR). Cattle positive for Trypanozoon DNA were further screened with the Rode Trypanozoon antigen type (RoTat) 1.2 PCR and Trypanosoma brucei gambiense glycoprotein (TgsGP) genes for T. evansi and T. b. gambiense respectively. Trypanosome DNA was amplified in 23.8% (95%CI: 20.8-26.9) of cattle with significantly higher prevalence in wet season (95%CI: 22.9-30.8) when compared to the dry season (95%CI: 14.3-23.6). A high prevalence was observed in Fulani cattle farms 54.1% (95%CI: 42.78-64.93%) while the prevalence was lower in institutional farms 14.7% (95%CI: 10.10-20.97%). Trypanosoma vivax was the most prevalent trypanosome observed (11.54% (95%CI: 9.44-14.04%)), followed by T. congolense 8.5% (95%CI: 6.67-10.67%) T. b. brucei 4.8% (95%CI: 3.51-6.62%) and T. evansi 1.74% (95%CI: 1.02-2.96%). Mixed infections were observed in 2.8% (95%CI: 1.85-4.27%) of cattle. Seasonal variation revealed a predominance of T. congolense and T. vivax in wet and dry season, respectively. The high prevalence of Trypanosoma species in cattle indicates a need for expanded surveillance for AAT in southwest Nigeria. Migration, settlement patterns, increased marketing and management types were some of the risk factors identified for AAT.

Remarkable richness of trypanosomes in tsetse flies (Glossina morsitans morsitans and Glossina pallidipes) from the Gorongosa National Park and Niassa National Reserve of Mozambique revealed by fluorescent fragment length barcoding (FFLB).

Trypanosomes of African wild ungulates transmitted by tsetse flies can cause human and livestock diseases. However, trypanosome diversity in wild tsetse flies remains greatly underestimated. We employed FFLB (fluorescent fragment length barcoding) for surveys of trypanosomes in tsetse flies (3086) from the Gorongosa National Park (GNP) and Niassa National Reserve (NNR) in Mozambique (MZ), identified as Glossina morsitans morsitans (GNP/NNR=77.6%/90.5%) and Glossina pallidipes (22.4%/9.5%). Trypanosomes were microscopically detected in 8.3% of tsetse guts. FFLB of gut samples revealed (GNP/NNR): Trypanosoma congolense of Savannah (27%/63%), Kilifi (16.7%/29.7%) and Forest (1.0%/0.3%) genetic groups; T. simiae Tsavo (36.5%/6.1%); T. simiae (22.2%/17.7%); T. godfreyi (18.2%/7.0%); subgenus Trypanozoon (20.2%/25.7%); T. vivax/T. vivax-like (1.5%/5.2%); T. suis/T. suis-like (9.4%/11.9%). Tsetse proboscises exhibited similar species composition, but most prevalent species were (GNP/NNR): T. simiae (21.9%/28%), T. b. brucei (19.2%/31.7%), and T. vivax/T. vivax-like (19.2%/28.6%). Flies harboring mixtures of trypanosomes were common (~ 64%), and combinations of more than four trypanosomes were especially abundant in the pristine NNR. The non-pathogenic T. theileri was found in 2.5% while FFLB profiles of unknown species were detected in 19% of flies examined. This is the first report on molecular diversity of tsetse flies and their trypanosomes in MZ; all trypanosomes pathogenic for ungulates were detected, but no human pathogens were detected. Overall, two species of tsetse flies harbor 12 species/genotypes of trypanosomes. This notable species richness was likely uncovered because flies were captured in wildlife reserves and surveyed using the method of FFLB able to identify, with high sensitivity and accuracy, known and novel trypanosomes. Our findings importantly improve the knowledge on trypanosome diversity in tsetse flies, revealed the greatest species richness so far reported in tsetse fly of any African country, and indicate the existence of a hidden trypanosome diversity to be discovered in African wildlife protected areas.

Molecular prevalence of trypanosome infections in cattle and tsetse flies in the Maasai Steppe, northern Tanzania.

BACKGROUND: African trypanosomosis is a disease of public health and economic importance that poses a major threat to the livelihoods of people living in the Maasai Steppe, where there is a significant interaction between people, livestock and wildlife. The vulnerability of the Maasai people to the disease is enhanced by the interaction of their cattle, which act as vehicles for trypanosomes, and tsetse flies close to wildlife in protected areas. This study was aimed at identification of trypanosome infections circulating in cattle and tsetse flies in order to understand their distribution and prevalence in livestock/wildlife interface areas in the Maasai Steppe. METHODS: A total of 1002 cattle and 886 tsetse flies were sampled from June 2015 to February 2016 in five villages and PCR was conducted to amplify the internal transcribed spacer 1 (ITS1) from trypanosomes. All Trypanosoma brucei-positive samples were further tested for the presence of the serum resistance-associated (SRA) gene found in human-infective trypanosomes using the SRA-LAMP technique. RESULTS: The overall prevalence of trypanosome infections was 17.2% in cattle and 3.4% in tsetse flies. Using a nested PCR, prevalence and abundance of five trypanosome species, Trypanosoma vivax, T. brucei, T. simiae, T. theileri and T. congolense, were determined, which varied with season and location. The highest prevalence of the identified trypanosome species was recorded at the end of wet season with an exception of T. brucei which was high at the beginning of the wet season. No human-infective trypanosomes were detected in both cattle and tsetse fly DNA. CONCLUSIONS: This study confirms that seasonality and location have a significant contribution to the prevalence of trypanosome species in both mammalian and vector hosts. These results are important for designing of community-wide vector and disease control interventions and planning of sustainable regimes for reduction of the burden of trypanosomosis in endemic pastoral areas, such as the Maasai Steppe in northern Tanzania.

Dynamic nuclear polarization facilitates monitoring of pyruvate metabolism in Trypanosoma brucei.

Dynamic nuclear polarization provides sensitivity improvements that make NMR a viable method for following metabolic conversions in real time. There are now many in vivo applications to animal systems and even to diagnosis of human disease. However, application to microbial systems is rare. Here we demonstrate its application to the pathogenic protozoan, Trypanosoma brucei, using hyperpolarized 13C1 pyruvate as a substrate and compare the parasite metabolism with that of commonly cultured mammalian cell lines, HEK-293 and Hep-G2. Metabolic differences between insect and bloodstream forms of T. brucei were also investigated. Significant differences are noted with respect to lactate, alanine, and CO2 production. Conversion of pyruvate to CO2 in the T. brucei bloodstream form provides new support for the presence of an active pyruvate dehydrogenase in this stage.

Ornithine uptake and the modulation of drug sensitivity in Trypanosoma brucei.

Trypanosoma brucei, protozoan parasites that cause human African trypanosomiasis (HAT), depend on ornithine uptake and metabolism by ornithine decarboxylase (ODC) for survival. Indeed, ODC is the target of the WHO "essential medicine" eflornithine, which is antagonistic to another anti-HAT drug, suramin. Thus, ornithine uptake has important consequences in T. brucei, but the transporters have not been identified. We describe these amino acid transporters (AATs). In a heterologous expression system, TbAAT10-1 is selective for ornithine, whereas TbAAT2-4 transports both ornithine and histidine. These AATs are also necessary to maintain intracellular ornithine and polyamine levels in T. brucei, thereby decreasing sensitivity to eflornithine and increasing sensitivity to suramin. Consistent with competition for histidine, high extracellular concentrations of this amino acid phenocopied a TbAAT2-4 genetic defect. Our findings established TbAAT10-1 and TbAAT2-4 as the parasite ornithine transporters, one of which can be modulated by histidine, but both of which affect sensitivity to important anti-HAT drugs.-Macedo, J. P., Currier, R. B., Wirdnam, C., Horn, D., Alsford, S., Rentsch, D. Ornithine uptake and the modulation of drug sensitivity in Trypanosoma brucei.

Plasma ACTH concentration and pituitary gland histo-pathology in rats infected with Trypanosoma brucei brucei.

BACKGROUND: Human African trypanosomiasis is one of the neglected and re-emerging infectious diseases in Africa with over 60 million people being at risk of contracting the disease. OBJECTIVE: To investigate the effects of Trypanosoma brucei brucei infection on secretion of adrenocorticotropic hormone (ACTH) and histology of the pituitary gland and paraventricular nucleus in rats. METHODS: Rats were randomly divided into two groups, control and experimental. Experimental rats were injected intraperitonially with 0.2ml of blood containing 1.0 × 104 live T.b.brucei parasites. Tail blood samples were collected weekly for the determination of plasma concentration of ACTH. The pituitary gland and coronal section of brain were processed histologically and observed microscopically. RESULTS: There was a significant difference (p = 0.0190) in plasma ACTH concentration between the control and experimental rats. Histological alterations were observed in both the pituitary and paraventricular nucleus of experimental rats. CONCLUSION: T.b.brucei infection causes histological changes in both the paraventricular nucleus and pituitary gland in rats. These histological changes could account for the decrease in corticotropin releasing hormone (CRH) and ACTH production in the infected rats.

Further evidence from SSCP and ITS DNA sequencing support Trypanosoma evansi and Trypanosoma equiperdum as subspecies or even strains of Trypanosoma brucei.

The subgenus Trypanozoon includes three species Trypanosoma brucei, Trypanosoma evansi and Trypanosoma equiperdum, which are morphologically identical and indistinguishable even using some molecular methods. In this study, PCR-based single strand conformation polymorphism (PCR-SSCP) was used to analyze the ribosomal DNA of the Trypanozoon species. Data indicate different patterns of ITS2 fragments between T. brucei, T. evansi and T. equiperdum by SSCP. Furthermore, analysis of total ITS sequences within these three members of the subgenus Trypanozoon showed a high degree of homology using phylogenetic analysis but were polyphyletic in haplotype networks. These data provide novel nuclear evidence to further support the notion that T. evansi and T. equiperdum should be subspecies or even strains of T. brucei.

Illuminating the Prevalence of Trypanosoma brucei s.l. in Glossina Using LAMP as a Tool for Xenomonitoring.

BACKGROUND: As the reality of eliminating human African trypanosomiasis (HAT) by 2020 draws closer, the need to detect and identify the remaining areas of transmission increases. Here, we have explored the feasibility of using commercially available LAMP kits, designed to detect the Trypanozoon group of trypanosomes, as a xenomonitoring tool to screen tsetse flies for trypanosomes to be used in future epidemiological surveys. METHODS AND FINDINGS: The DNA extraction method was simplified and worked with the LAMP kits to detect a single positive fly when pooled with 19 negative flies, and the absolute lowest limit of detection that the kits were able to work at was the equivalent of 0.1 trypanosome per ml. The DNA from Trypanosoma brucei brucei could be detected six days after the fly had taken a blood meal containing dead trypanosomes, and when confronted with a range of non-target species, from both laboratory-reared flies and wild-caught flies, the kits showed no evidence of cross-reacting. CONCLUSION: We have shown that it is possible to use a simplified DNA extraction method in conjunction with the pooling of tsetse flies to decrease the time it would take to screen large numbers of flies for the presence of Trypanozoon trypanosomes. The use of commercially-available LAMP kits provides a reliable and highly sensitive tool for xenomonitoring and identifying potential sleeping sickness transmission sites.

Community-based tsetse fly control significantly reduces fly density and trypanosomosis prevalence in Metekel Zone, Northwest, Ethiopia.

African animal trypanosomosis is a great obstacle to livestock production where tsetse flies play a major role. Metekel zone is among the tsetse-infested areas. Community-based tsetse fly and trypanosomosis control using targets was conducted from June 2011 to May 2012 in Metekel zone, Ethiopia, to decrease trypanosomosis and tsetse fly. Cloth screen targets were developed, impregnated with 0.1 % deltamethrin, and deployed alongside rivers by the research team together with the community animal health workers. Monthly parasitological and entomological data were collected, processed, and compared with similar data collected before control. Overall average tsetse fly (Glossina tachinoides) density decreased from 1.13 to 0.18 fly/trap/day after control. The density was decreased in all sites with no significant difference among the sites. However, higher decrements were observed in the dry and late dry seasons by more than 12 and 6 times, respectively. The reduction in overall apparent prevalence of trypanosomosis caused by Trypanosoma congolense, Trypanosoma brucei, and Trypanosoma vivax from 12.14 % before to 3.61 % after control coincides with the tsetse fly reduction. In all the study sites, significant reduction was observed before and after control. The highest decrement was observed in the late dry season when the apparent prevalence was reduced from 7.89 to 1.17 % before and after control, respectively. As this approach is simple, cost-effective, and appropriate for riverine tsetse species, we recommend to be scaled up to other similar places.