Isolation of salivarian trypanosomes from man and other mammals using DEAE-cellulose

Toll-like receptor 9 signaling is associated with immune responses to Trypanosoma brucei infection

Trypanosoma brucei, a causative agent of human and animal trypanosomiasis, regularly switches its major surface antigen to avoid elimination by the immune system. Toll-like receptor 9 (TLR9) is a key modulator for resistance to host-infective trypanosomes; however, the underlying molecular mechanism remains indistinct. Thus, we first approached the issue using Tlr9-mutant mice that render them non-responsive to TLR9 agonists. After infection, T cells in the spleens of Tlr9-mutant mice were analyzed by flow cytometry and a reduction in CD8+, CD4+ T, and NKT cells was observed in Tlr9-mutant mice compared to WT mice. We further found that the responses of inflammatory cytokines in the sera were reduced in Tlr9-mutant mice after T. brucei infection. The underlying molecular mechanism was that T. b. brucei DNA activated TLR9, which consequently upregulated the expression of p38 and ERK/MAPK, resulting in host resistance to trypanosome infection. In conclusion, these findings provide novel insights into the TLR9-mediated host responses to trypanosome infection.

Molecular, immunological, and physiological evidences of a sphingosine-activated plasma membrane Ca2+-channel in Trypanosoma equiperdum

The hemoparasite Trypanosoma equiperdum belongs to the Trypanozoon subgenus and includes several species that are pathogenic to animals and humans in tropical and subtropical areas across the world. As with all eukaryotic organisms, Ca2+ is essential for these parasites to perform cellular processes thus ensuring their survival across their life cycle. Despite the established paradigm to study proteins related to Ca2+ homeostasis as potential drug targets, so far little is known about Ca2+ entry into trypanosomes. Therefore, in the present study, the presence of a plasma membrane Ca2+-channel in T. equiperdum (TeCC), activated by sphingosine and inhibited by verapamil, is described. The TeCC was cloned and analyzed using bioinformatic resources, which confirmed the presence of several domains, motifs, and a topology similar to the Ca2+ channels found in higher eukaryotes. Biochemical and confocal microscopy assays using antibodies raised against an internal region of human L-type Ca2+ channels indicate the presence of a protein with similar predicted molar mass to the sequence analyzed, located at the plasma membrane of T. equiperdum. Physiological assays based on Fura-2 signals and Mn2+ quenching performed on whole parasites showed a unidirectional Ca2+ entry, which is activated by sphingosine and blocked by verapamil, with the distinctive feature of insensitivity to nifedipine and Bay K 8644. This suggests a second Ca2+ entry for T. equiperdum, different from the store-operated Ca2+ entry (SOCE) previously described. Moreover, the evidence presented here for the TeCC indicates molecular and pharmacological differences with their mammal counterparts, which deserve further studies to evaluate the potential of this channel as a drug target.

Long-term antitrypanosomal effect of quinapyramine sulphate-loaded oil-based nanosuspension in T. evansi-infected mouse model

The goal of the present work consisted of the formulation development and evaluation of quinapyramine sulphate (QS)-loaded long-acting oil-based nanosuspension for improved antitrypanosomal effect. QS was transformed into a hydrophobic ionic complex using anionic sodium cholate (Na.C). The complex was characterized by FTIR, DSC, and XRD. Oil-based nanosuspension was prepared by dispersing the QS-Na.C complex in thixotropically thickened olive oil. The nanoformulation was found to be cytocompatible (82.5 ± 5.87% cell viability at the minimum effective concentration [MEC]) in THP-1 cell lines and selectively trypanotoxic (p < 0.0001). The pharmacokinetic studies of QS-Na.C complex-loaded oily nanosuspension showed 13.54-fold, 7.09-fold, 1.78-fold, and 17.35-fold increases in t1/2, AUC0-∞, Vz/F, and MRT0-ꝏ, respectively, as compared to free QS. Moreover, a 7.08-fold reduction in plasma clearance was observed after the treatment with the optimized formulation in Wistar rats. Furthermore, treatment with QS-Na.C complex-loaded oily nanosuspension (7.5 mg/kg) in T. evansi-infected mice model showed the absence of parasitaemia for more than 75 days after the treatment during in vivo efficacy studies. The efficacy of the treatment was assessed by observation of blood smear and PCR assay for DNA amplification. To conclude, our findings suggest that the efficient delivery of QS from the developed QS-Na.C complex-loaded oily nanosuspension could be a promising treatment option for veterinary infections against trypanosomiasis.

Suramin action in African trypanosomes involves a RuvB-like DNA helicase

Suramin is one of the oldest drugs in use today. It is still the treatment of choice for the hemolymphatic stage of African sleeping sickness caused by Trypanosoma brucei rhodesiense, and it is also used for surra in camels caused by Trypanosoma evansi. Yet despite one hundred years of use, suramin's mode of action is not fully understood. Suramin is a polypharmacological molecule that inhibits diverse proteins. Here we demonstrate that a DNA helicase of the pontin/ruvB-like 1 family, termed T. brucei RuvBL1, is involved in suramin resistance in African trypanosomes. Bloodstream-form T. b. rhodesiense under long-term selection for suramin resistance acquired a homozygous point mutation, isoleucine-312 to valine, close to the ATP binding site of T. brucei RuvBL1. The introduction of this missense mutation, by reverse genetics, into drug-sensitive trypanosomes significantly decreased their sensitivity to suramin. Intriguingly, the corresponding residue of T. evansi RuvBL1 was found mutated in a suramin-resistant field isolate, in that case to a leucine. RuvBL1 (Tb927.4.1270) is predicted to build a heterohexameric complex with RuvBL2 (Tb927.4.2000). RNAi-mediated silencing of gene expression of either T. brucei RuvBL1 or RuvBL2 caused cell death within 72 h. At 36 h after induction of RNAi, bloodstream-form trypanosomes exhibited a cytokinesis defect resulting in the accumulation of cells with two nuclei and two or more kinetoplasts. Taken together, these data indicate that RuvBL1 DNA helicase is involved in suramin action in African trypanosomes.

"Lysis and Concentration Technique" improves the parasitological diagnosis of Trypanosoma vivax

The "Lysis and Concentration Technique" (LCTe) involves lysing red blood cells and concentrating parasites to increase the chances of visualization in low parasitemia and in scenarios of evaluators with less knowledge. The lysis of red blood cells reduced the time of diagnosis by 21 s, showing that the effect produced by the treatment is comparable to the effect of the experience in parasitological examination. In addition, the concentration of parasites was 39.18% higher for slides with high parasitemia and 131.03% for slides with low parasitemia in relation to the standard slide. LCTe proved to be inexpensive, with a total cost of approximately US$0.07 per slide made, which allows it to be easily implemented in most laboratories.

The developmental hierarchy and scarcity of replicative slender trypanosomes in blood challenges their role in infection maintenance

The development of Trypanosoma brucei in its mammalian host is marked by a distinct morphological change as replicative "slender" forms differentiate into cell cycle arrested "stumpy" forms in a quorum-sensing-dependent manner. Although stumpy forms dominate chronic infections at the population level, the proportion of replicative parasites at the individual cell level and the irreversibility of arrest in the bloodstream are unclear. Here, we experimentally demonstrate that developmental cell cycle arrest is definitively irreversible in acute and chronic infections in mice. Furthermore, analysis of replicative capacity and single-cell transcriptome profiling reveal a temporal hierarchy, whereby cell cycle arrest and appearance of a reversible stumpy-like transcriptome precede irreversible commitment and morphological change. Unexpectedly, we show that proliferating parasites are exceptionally scarce in the blood after infections are established. This challenges the ability of bloodstream trypanosomes to sustain infection by proliferation or antigenic variation, these parasites instead being overwhelmingly adapted for transmission.

Validation of in vitro-produced and freeze-dried whole cell lysate antigens for ELISA Trypanosoma evansi antibody detection in camels

Trypanosoma evansi is a blood parasite responsible for surra in mammals, with a high impact in camels and horses. The WOAH-recommended reference method for detecting immunoglobulin G directed against T. evansi is ELISA, using whole cell lysate antigens (WCLAs). WCLAs are prepared with T. evansi produced in laboratory rodents, separated from blood cells using DE-cellulose anion exchange chromatography. As parasite lysates are fragile, antigens are preserved frozen pending use. For these reasons and others, T. evansi WCLAs are not commercially available. They are produced in small quantities, in a limited number of specialized laboratories, and they require a reliable and expensive cold chain for their shipment. In this study, we assessed and validated in vitro production of T. evansi and lyophilization of WCLAs in comparison with the reference method using frozen WCLAs prepared with parasites produced in rodents. Using a set of 400 samples monthly collected from 12 naturally infected camels followed-up for 1384 days, and two batches of referenced serum samples (infected, n = 12; non-infected, n = 15), statistical studies on qualitative and semi-quantitative results of the ELISAs did not show any significant difference when comparing the four combinations of parasites produced in vivo or in vitro, and frozen or freeze-dried WCLSAs. A repeatability study (28 repeats in 9 serum samples) was fully satisfying (p-value = 0.055). With the more convenient in vitro-produced freeze-dried WCLAs it was possible to: (i) avoid the ethical concern of in vivo production, (ii) improve the standardization of antigen production, (iii) secure antigen preservation during shipment and (iv) save a considerable amount of money (DE52-cellulose and dry-ice cold chain being avoided). Additional studies with other Trypanosoma spp are required for further extending ELISA to regional laboratories in enzootic areas, especially in view of the current progress in the "Progressive Control Pathway" (PCP) for trypanosomes in Africa.

Type-I like metalloproteinase in the venom of the West African saw-scaled carpet viper (Echis ocellatus) has anti-trypanosomal activity against African trypanosomes

African trypanosomiasis is an infectious disease caused by hemoparasites of the genus Trypanosoma and remains a major health problem in Africa - killing around 4000 people and animals worth an estimated $5 billion, annually. The absence of a vaccine and satisfactory drug against African trypanosomiasis (AT) necessitates the continued search for new chemotherapy options. Owing to the rich biochemical diversity in snake venom, it has recently become a source of therapeutic peptides that are being explored for the development of novel drug candidates for diverse ailments such as cancers and infectious diseases. To explore this, Echis ocellatus venom (EOV) was investigated for the presence of an anti-Trypanosoma factor, with the subsequent aim to isolate and identify it. Crude EOV was collected and tested in vitro on the bloodstream form (BSF) i.e. long and slender morphological form of Trypanosoma brucei and T. congolense. This initial testing was followed by a sequential anti-trypanosomal assay guided purification of EOV using ethanol precipitation, distillation, and ion exchange (IEX) chromatography to obtain the active trypanocidal component. The purified anti-Trypanosoma factor, estimated to be a 52-kDa protein on SDS-PAGE, was subjected to in-gel trypsin digestion and 2D RP HPLC-MS/MS to identify the protein. The anti-Trypanosoma factor was revealed to be a zinc-dependent metalloproteinase that contains the HEXXHXXGXXH adamalysin motif. This protein may provide a conceptual framework for the possible design of a safe and effective anti-trypanosomal peptide for the treatment of AT.

Expression kinetics of cytokines and the humoral antibody response concerning short-term protection induced by radiation-attenuated Trypanosoma evansi in bovine calves

'Surra', an economically important disease of livestock, is caused by the parasitic blood protozoon Trypanosoma evansi. Both innate and adaptive immunity contribute to the protection against this infection. T-helper cells play a crucial role in the antibody-mediated clearance of T. evansi. We present here the data on the kinetics of expression of important Th1, Th2 and Th17 cytokines, vis-a-vis the dynamics of humoral response in bovine calves following immunization with γ-radiation-attenuated live T. evansi and later challenged with homologous virulent T. evansi. Significant upregulation of the pro-inflammatory Th1 and Th17 cytokines was correlated with the IgG2-mediated protection in the immunized bovine calves post-challenge. The calves were immunized with 5 × 10⁶ 500 Gy γ-radiation-attenuated live T. evansi (horse isolate) thrice at 15 days intervals through the subcutaneous route and subsequently, challenged with 1 × 10³ virulent T. evansi on day 50. Significantly high serum IgG (1:1600) and IgM (1:800) titres were recorded on week 2 PC, whereas the peak serum IgG2 titre (1:800) was recorded on week 6 PC. Significant upregulation of IFN-γ, TNF, IL-1β, and IL-2 was recorded between days 1 to 3 PC, while the same for IL-17 was recorded on day 14 PC. The immunized calves were free from parasitemia post-challenge and were clinically healthy till the end of the experiment. Significant upregulation of IL-10 and IL-4 transcripts and a corresponding increase of serum IgG1 titre in the placebo group helped patency of the parasite in an anti-inflammatory environment and clinical exacerbation of the disease. The expression of the important Th1 cytokines was crucial for antibody-mediated short-term protection against a lethal challenge of T. evansi in cattle.

Trypanosoma evansi secretome carries potential biomarkers for Surra diagnosis

Trypanosoma evansi is a parasite that is phylogenetically close to Trypanosoma brucei and is the causative agent of a disease known as surra. Surra is responsible for a high mortality rate in livestock and large economic losses in the Americas, Africa, and Asia. This work aimed to analyze in vitro secreted proteins from T. evansi and identify potential treatment and diagnostic biomarkers for surra diagnosis. Two groups were used. In one group the parasites were purified using a DEAE-Cellulose column and maintained in a secretion medium while in the other group the parasites were not purified. Each group was further divided to be maintained at either 37 °C or 27 °C. We identified 246 proteins through mass spectrometry and found that the temperature appears to modulate protein secretion. We found minimal variations in the protein pools from pure and non-purified sets. We observed an emphasis on proteins associated to vesicles, glycolysis, and cellular homeostasis through the enrichment of GO. Also, we found that most secretome proteins share homologous proteins with T. b. brucei, T. b. gambiense, T. vivax, T. equiperdum, and T. b. rhodesiense secretome but unique T. evansi epitopes with potential biomarkers for surra diagnosis were detected. SIGNIFICANCE: Trypanosoma evansi is a parasite of African origin that is phylogenetically close to Trypanosoma brucei. As with other trypanosomatids and blood parasites, its infection causes non-pathognomonic symptoms, which makes its diagnosis difficult. One great problem is the fact that no diagnostic test differentiates between Trypanosoma equiperdum and T. evansi, which is a problem in South America and Asia, and Africa. Thus, it is urgent to study the biochemistry of the parasite to discover proteins that can be used for differential diagnosis or be possible therapeutic targets. In addition, the study of the secretome can point out proteins that are used by the parasite in its interactions with the host, helping to understand the progression of the disease.

Exploring the potential of invariable surface glycoprotein (ISG65) as promising antigen for diagnosis of Trypanosoma evansi infection

Trypanosoma evansi, a hemoflagellate protozoan, leads to wasting disease, surra in livestock animals causing huge economic losses. Currently, the preferred assay for surra diagnosis is whole cell lysate (WCL) based ELISA, which requires the use of rodents for WCL preparation. To avoid use of laboratory animals, we used recombinant DNA technology to express T. evansi invariable surface glycoprotein (ISG) in E. coli. The potential of recombinant ISG65 (rISG65) as a diagnostic antigen was investigated in immunoblot and indirect ELISA using experimentally infected equine serum samples from 0 to 84 days post infection. The results indicated that rISG65 reacted with horse T. evansi positive serum giving two bands of approximately 48 kDa and 96 kDa. T. evansi-specific antibodies were detected as early as 10 and 14 days post infection using immunoblot and indirect ELISA, respectively using rISG65 antigen. No cross-reactivity was observed in ELISA and immunoblot with different serum samples of equines positive for Equine herpesvirus 1, Burkholderia mallei, and Theileria equi infections. Several immunoreactive regions were observed between 30 and 100 kDa in T. evansi isolate of horse origin indicating the existence of multiple copies of ISG protein in a single trypanosome. The recombinant ISG has proven to be good candidate antigen to be used in ELISA for serodiagnosis of T. evansi infection in different animals.

PAG3 promotes the differentiation of bloodstream forms in Trypanosoma brucei and reveals the evolutionary relationship among the Trypanozoon trypanosomes

Introduction

Trypanosoma brucei, T. evansi and T. equiperdum are members of the subgenus Trypanozoon and are highly similar morphologically and genetically. The main differences between these three species are their differentiation patterns in the hosts and the role of vectors in their life cycles. However, the mechanisms causing these differences are still controversial.

Methods

PAG3 gene was accessed by PCR amplification in 26 strains of Trypanozoon and sequences were then analyzed by BLAST accompanied with T. evansitype B group. RNA interference and CRISPR/Cas9 were used for revealing possible role of PAG3 in slender to stumpy transformation.

Results

The procyclin associated gene 3 (PAG3) can be found in the pleomorphicspecies, T.brucei, which undergoes differentiation of slender forms to the stumpy form. This differentiation process is crucial for transmission to the tsetse fly vector. However, a homologue of PAG3 was not detected in either T. evansi or in the majority of T. equiperdum strains which are allmonomorphic. Furthere xperiments in T. brucei demonstrated that, when PAG3 was down-regulated or absent, there was a significant reduction in the differentiation from slender to stumpy forms.

Conclusion

Therefore, we conclude that PAG3 is a key nuclear gene involved in the slender to stumpy differentiation pathway of T.brucei in the mammalian host. Loss of this gene might also offer a simple evolutionary mechanism explaining why T. evansi and some T. equiperdum have lost the ability to differentiate and have been driven to adapt to transmission cycles that by pass the tsetse vector or mechanical contact.

Trypanosoma evansi RoTat 1.2 variant surface antigen mimotopes selected by panning of the random peptide phage-display library against monoclonal antibodies

Mimotope peptides of native antigens are valuable for diverse applications such as diagnostics, therapeutics and modern vaccine design. Here, we report for the first time the selection and identification of peptide mimotopes of Trypanosoma evansi RoTat 1.2 variant surface glycoprotein (VSG) for their potential uses in surra diagnostics and multi-epitope vaccine research. First, we produced the mouse monoclonal antibodies (mAbs), designated as 2E11 (IgG1) and 1C2 (IgG1), against the antigens in T. evansi RoTat 1.2 lysates. We then used 2E11 mAb to immunoprecipitate the target antigen. The immunoprecipitated antigen was then identified to be the VSG by mass spectrometry. Both 2E11 and 1C2 mAbs reacted with the VSG in immunoblots. The surface plasmon resonance immunosensors developed with both the mAbs detected VSG in the parasite lysates as well as in the rodent sera. Further, the mAbs were biotinylated and used in three rounds of panning to select peptide mimotopes from the random peptide phage display library (PhD-12; New England Biolabs, USA). The phage clones selected against each mAb were amplified and tested by phage capture ELISA for specificity. The peptide coding regions of the selected phages were sequenced and the protein blast search of the deduced amino acid sequences was performed by accessing the non-redundant protein database at https://blast.ncbi.nlm.nih.gov/. The conformational B epitope prediction of the selected mimotope sequences was done by using 3D Pepitope algorithms accessed at: http://pepitope.tau.ac.il/. The potential applications of the selected mimotopes in surra diagnostics and research are being explored.

Deep kinetoplast genome analyses result in a novel molecular assay for detecting Trypanosoma brucei gambiense-specific minicircles

The World Health Organization targeted Trypanosoma brucei gambiense (Tbg) human African trypanosomiasis for elimination of transmission by 2030. Sensitive molecular markers that specifically detect Tbg type 1 (Tbg1) parasites will be important tools to assist in reaching this goal. We aim at improving molecular diagnosis of Tbg1 infections by targeting the abundant mitochondrial minicircles within the kinetoplast of these parasites. Using Next-Generation Sequencing of total cellular DNA extracts, we assembled and annotated the kinetoplast genome and investigated minicircle sequence diversity in 38 animal- and human-infective trypanosome strains. Computational analyses recognized a total of 241 Minicircle Sequence Classes as Tbg1-specific, of which three were shared by the 18 studied Tbg1 strains. We developed a minicircle-based assay that is applicable on animals and as specific as the TgsGP-based assay, the current golden standard for molecular detection of Tbg1. The median copy number of the targeted minicircle was equal to eight, suggesting our minicircle-based assay may be used for the sensitive detection of Tbg1 parasites. Annotation of the targeted minicircle sequence indicated that it encodes genes essential for the survival of the parasite and will thus likely be preserved in natural Tbg1 populations, the latter ensuring the reliability of our novel diagnostic assay.

Trypanosoma brucei histones are heavily modified with combinatorial post-translational modifications and mark Pol II transcription start regions with hyperacetylated H2A

Trypanosomes diverged from the main eukaryotic lineage about 600 million years ago, and display some unusual genomic and epigenetic properties that provide valuable insight into the early processes employed by eukaryotic ancestors to regulate chromatin-mediated functions. We analysed Trypanosoma brucei core histones by high mass accuracy middle-down mass spectrometry to map core histone post-translational modifications (PTMs) and elucidate cis-histone combinatorial PTMs (cPTMs). T. brucei histones are heavily modified and display intricate cPTMs patterns, with numerous hypermodified cPTMs that could contribute to the formation of non-repressive euchromatic states. The Trypanosoma brucei H2A C-terminal tail is hyperacetylated, containing up to five acetylated lysine residues. MNase-ChIP-seq revealed a striking enrichment of hyperacetylated H2A at Pol II transcription start regions, and showed that H2A histones that are hyperacetylated in different combinations localised to different genomic regions, suggesting distinct epigenetic functions. Our genomics and proteomics data provide insight into the complex epigenetic mechanisms used by this parasite to regulate a genome that lacks the transcriptional control mechanisms found in later-branched eukaryotes. The findings further demonstrate the complexity of epigenetic mechanisms that were probably shared with the last eukaryotic common ancestor.

Immunopathology and Trypanosoma congolense parasite sequestration cause acute cerebral trypanosomiasis

Trypanosoma congolense causes a syndrome of variable severity in animals in Africa. Cerebral trypanosomiasis is a severe form, but the mechanism underlying this severity remains unknown. We developed a mouse model of acute cerebral trypanosomiasis and characterized the cellular, behavioral, and physiological consequences of this infection. We show large parasite sequestration in the brain vasculature for long periods of time (up to 8 hr) and extensive neuropathology that associate with ICAM1-mediated recruitment and accumulation of T cells in the brain parenchyma. Antibody-mediated ICAM1 blocking and lymphocyte absence reduce parasite sequestration in the brain and prevent the onset of cerebral trypanosomiasis. Here, we establish a mouse model of acute cerebral trypanosomiasis and we propose a mechanism whereby parasite sequestration, host ICAM1, and CD4⁺ T cells play a pivotal role.

Isolation and in vitro cultivation of Trypanosoma evansi Thai strains

Trypanosoma evansi is a flagellate protozoan parasite responsible for "surra." To generate T. evansi antigens for serodiagnosis, parasites are generally propagated in laboratory animals before isolation. The alternation of animal models using axenic cultivation systems to produce trypomastigotes of various Trypanosoma species is currently available but has never been applied in Thailand. The isolation protocol for separation of live T. evansi trypomastigotes from animal blood components before in vitro cultivation has not been clearly documented. This study focused on validation of trypomastigote isolation method, in vitro cultivation of T. evansi Thai strains, and its virulence ability in vivo. In this study, two strains of T. evansi collected from Thailand were used. Trypanosoma evansi trypomastigotes were propagated in mice, and three different isolation methods, including: low-speed centrifugation, high-speed centrifugation, and ion exchange chromatography using diethylaminoethyl (DEAE) cellulose (or DE52), were compared. Four solutions of in vitro cultivation media, two different in vitro cultivation containers, and different trypomastigote densities for initiation of in vitro culture were compared. Virulence test using in vitro-adapted parasite for 100 days was conducted in vivo. The results showed that the DE52 isolation method was suitable for separation of live T. evansi trypomastigotes from animal blood components before conducting in vitro cultivation. Trypanosoma evansi Thai strains were successfully cultivated and multiplied in HMI-9 Solution I using 25 cm² flasks and 12-well plates. The parasite was growing slowly at the initiation of in vitro culture for 15-16 days, and then rapidly increased to 10, 20, 50, 100, and 200 folds, approximately. The doubling times were varied from 11.95 ± 8 h to 41.18 ± 4.29 h in vitro. The maximum densities have reached from 0.14 × 10⁶ to 4.63 × 10⁶ trypomastigotes/ml. Virulence test showed that the in vitro-cultivated T. evansi was virulent in mice. In conclusion, T. evansi Thai strains were successfully isolated and cultivated in vitro for the first time. The isolation and in vitro cultivation protocols were clearly provided. The benefit of using the in vitro cultivation system helps in the production of T. evansi antigen, and replacing the use of experimental animals. It is also useful for the development of diagnostic tests in the future.

Analysis of the epidemiological variables associated with a high prevalence of bovine surra in the Chhattisgarh state of India

Trypanosoma evansi, a unicellular haemoflagellate, causes surra in bovines and other economically important livestock species. We report here the epidemiological variables associated with the high prevalence of T. evansi infection in cattle in the plain agro-climatic zone of Chhattisgarh state, India. A total of 920 blood and sera samples were tested by a combination of parasitological, molecular and serodiagnostic tests. An overall prevalence of T. evansi was recorded as 4.57% (95% CI: 3.22-5.92%), 6.09% (95% CI: 4.54-7.63%), 63.91% (95% CI: 60.81-67.01%) and 55.33% (95% CI: 52.12-58.54%) by direct microscopy, PCR, ELISA and IFAT, respectively. The Chi-Square test established a significant correlation between the prevalence of T. evansi and the season, breed and place of the study, while the association with the gender and age of the animals was insignificant. The analysis of the prevalence ratio revealed a significant association of the breed, season and place of study with the prevalence of T. evansi. As per PR _observed, the prevalence was 1.63 times higher in summer and 1.68 times higher in the rainy season than in the winter (reference season). The prevalence was higher in all the districts as compared to Rajnandgaon (reference district). The prevalence ratio in Sahiwal and HF cross-breed cattle was significantly higher than the Gir breed of cattle (reference). Durg district recorded the highest prevalence of surra, and the difference was significant. The medium IFAT titre, determined in a large number of sera collected from Durg, predicted a higher incidence of trypanosomosis in that district. Since T. evansi has a broad host range, the study predicted that a large population of livestock in Chhattisgarh state were at high risk of T. evansi infection. Treatment of the subclinically and clinically infected animals with selective curative drugs, such as diminazene aceturate, isometamidium chloride or the combination of quinapyramine sulphate and quinapyramine chloride, could help restore productivity and help in containing the infection.

A review on the diagnosis of animal trypanosomoses

This review focuses on the most reliable and up-to-date methods for diagnosing trypanosomoses, a group of diseases of wild and domestic mammals, caused by trypanosomes, parasitic zooflagellate protozoans mainly transmitted by insects. In Africa, the Americas and Asia, these diseases, which in some cases affect humans, result in significant illness in animals and cause major economic losses in livestock. A number of pathogens are described in this review, including several Salivarian trypanosomes, such as Trypanosoma brucei sspp. (among which are the agents of sleeping sickness, the human African trypanosomiasis [HAT]), Trypanosoma congolense and Trypanosoma vivax (causing “Nagana” or animal African trypanosomosis [AAT]), Trypanosoma evansi (“Surra”) and Trypanosoma equiperdum (“Dourine”), and Trypanosoma cruzi, a Stercorarian trypanosome, etiological agent of the American trypanosomiasis (Chagas disease). Diagnostic methods for detecting zoonotic trypanosomes causing Chagas disease and HAT in animals, as well as a diagnostic method for detecting animal trypanosomes in humans (the so-called “atypical human infections by animal trypanosomes” [a-HT]), including T. evansi and Trypanosoma lewisi (a rat parasite), are also reviewed. Our goal is to present an integrated view of the various diagnostic methods and techniques, including those for: (i) parasite detection; (ii) DNA detection; and (iii) antibody detection. The discussion covers various other factors that need to be considered, such as the sensitivity and specificity of the various diagnostic methods, critical cross-reactions that may be expected among Trypanosomatidae, additional complementary information, such as clinical observations and epizootiological context, scale of study and logistic and cost constraints. The suitability of examining multiple specimens and samples using several techniques is discussed, as well as risks to technicians, in the context of specific geographical regions and settings. This overview also addresses the challenge of diagnosing mixed infections with different Trypanosoma species and/or kinetoplastid parasites. Improving and strengthening procedures for diagnosing animal trypanosomoses throughout the world will result in a better control of infections and will significantly impact on “One Health,” by advancing and preserving animal, human and environmental health.

The Occurrence of Malignancy in Trypanosoma brucei brucei by Rapid Passage in Mice

Pleomorphic Trypanosoma brucei are best known for their tightly controlled cell growth and developmental program, which ensures their transmissibility and host fitness between the mammalian host and insect vector. However, after long-term adaptation in the laboratory or by natural evolution, monomorphic parasites can be derived. The origin of these monomorphic forms is currently unclear. Here, we produced a series of monomorphic trypanosome stocks by artificially syringe-passage in mice, creating snapshots of the transition from pleomorphism to monomorphism. We then compared these artificial monomorphic trypanosomes, alongside several naturally monomorphic T. evansi and T. equiperdum strains, with the pleomorphic T. brucei. In addition to failing to generate stumpy forms in animal bloodstream, we found that monomorphic trypanosomes from laboratory and nature exhibited distinct differentiation patterns, which are reflected by their distinct differentiation potential and transcriptional changes. Lab-adapted monomorphic trypanosomes could still be induced to differentiate, and showed only minor transcriptional differences to that of the pleomorphic slender forms but some accumulated differences were observed as the passages progress. All naturally monomorphic strains completely fail to differentiate, corresponding to their impaired differentiation regulation. We propose that the natural phenomenon of trypanosomal monomorphism is actually a malignant manifestation of protozoal cells. From a disease epidemiological and evolutionary perspective, our results provide evidence for a new way of thinking about the origin of these naturally monomorphic strains, the malignant evolution of trypanosomes may raise some concerns. Additionally, these monomorphic trypanosomes may reflect the quantitative and qualitative changes in the malignant evolution of T. brucei, suggesting that single-celled protozoa may also provide the most primitive model of cellular malignancy, which could be a primitive and inherent biological phenomenon of eukaryotic organisms from protozoans to mammals.

Method for Isolation of Myxozoan Proliferative Stages from Fish at High Yield and Purity: An Essential Prerequisite for In Vitro, In Vivo and Genomics-Based Research Developments

Myxozoans are a diverse group of microscopic cnidarian parasites and some representatives are associated with important diseases in fish, in both marine and freshwater aquaculture systems. Research on myxozoans has been largely hampered by the inability to isolate myxozoan parasites from their host tissues. In this study, we developed and optimized a method to isolate the myxozoan proliferative stages of different size and cellularity from fish blood, using DEAE-cellulose ion exchange chromatography. We optimized several parameters and obtained 99–100% parasite purity, as well as high survival and infectivity. Using polyclonal pan-carp blood cell-specific antibodies, we further developed a rapid cytometric assay for quantification of the proliferative stages, not only in highly concentrated DEAE-C isolates but also in dilute conditions in full blood. Early developmental stages of myxozoans are key to parasite proliferation, establishment, and pathology in their hosts. The isolation of these stages not only opens new possibilities for in vivo and in vitro studies, but also for obtaining purified DNA and protein extracts for downstream analyses. Hence, we provide a long-desired tool that will advance the functional research into the mechanisms of host exploitation and immune stimulation/evasion in this group, which could contribute greatly to the development of therapeutic strategies against myxozoans.

Polymerase Spiral Reaction (PSR) as a novel rapid colorimetric isothermal point of care assay for detection of Trypanosoma evansi genomic DNA

Polymerase spiral reaction (PSR) opens new avenues for specific diagnosis of pathogens known for cryptic infection at field level and its application is still unexplored in the field of parasitology. The present study aimed to explore and optimize colorimetric based PSR technique for the detection of Trypanosoma evansi in the blood of the host by targeting the 196bp Invariable Surface Glycoprotein (ISG) gene of Trypanosoma evansi. The specificity of the test was determined against Theileria equi, Theileria annulata, Babesia caballi, Burkholderia mallei and Equine herpes virus. The T. evansi DNA was extracted from purified parasites and serially diluted from 2.8ng to 2.8 × 10^-8 pg. The detection limit of PSR was found to be as low as 2.8 × 10^-6 pg of T. evansi DNA, which will aid in detection of Surra infection. The duration of reaction for determination of result of field sample is 1h and result can be read by naked eyes. In addition, PSR assay was also performed on DNA extracted from 28 field equine samples; out of which 1 was found positive by microscopy and ISG-196 targeted PCR assay and 2 were recorded positive by PSR assay. Data generated shows colorimetric PSR is convenient, rapid, sensitive and specific tool for diagnosis and monitoring of Surra infection in livestock at field level. Further, visual PSR assay has wide scope for application in government policies aimed at detection of early infection, sub-clinical cases, drug-efficacy studies, control and elimination of Surra organism from livestock animals.

Free-ranging pigs identified as a multi-reservoir of Trypanosoma brucei and Trypanosoma congolense in the Vavoua area, a historical sleeping sickness focus of Côte d'Ivoire

Background

The existence of an animal reservoir of Trypanosoma brucei gambiense (T. b. gambiense), the agent of human African trypanosomiasis (HAT), may compromise the interruption of transmission targeted by World Health Organization. The aim of this study was to investigate the presence of trypanosomes in pigs and people in the Vavoua HAT historical focus where cases were still diagnosed in the early 2010’s.

Methods

For the human survey, we used the CATT, mini-anion exchange centrifugation technique and immune trypanolysis tests. For the animal survey, the buffy coat technique was also used as well as the PCR using Trypanosoma species specific, including the T. b. gambiense TgsGP detection using single round and nested PCRs, performed from animal blood samples and from strains isolated from subjects positive for parasitological investigations.

Results

No HAT cases were detected among 345 people tested. A total of 167 pigs were investigated. Free-ranging pigs appeared significantly more infected than pigs in pen. Over 70% of free-ranging pigs were positive for CATT and parasitological investigations and 27–43% were positive to trypanolysis depending on the antigen used. T. brucei was the most prevalent species (57%) followed by T. congolense (24%). Blood sample extracted DNA of T. brucei positive subjects were negative to single round TgsGP PCR. However, 1/22 and 6/22 isolated strains were positive with single round and nested TgsGP PCRs, respectively.

Discussion

Free-ranging pigs were identified as a multi-reservoir of T. brucei and/or T. congolense with mixed infections of different strains. This trypanosome diversity hinders the easy and direct detection of T. b. gambiense. We highlight the lack of tools to prove or exclude with certainty the presence of T. b. gambiense. This study once more highlights the need of technical improvements to explore the role of animals in the epidemiology of HAT.

Significant efforts to control human African trypanosomiasis (HAT) since the 1990’s have drastically reduced the prevalence of the disease. Its elimination as a public health problem is being achieved. World Health Organization now targets the interruption of transmission for 2030. However, potential animal reservoirs of Trypanosoma brucei gambiense (T. b. gambiense), the main agent of HAT, may compromise this ambitious objective. It is the case in the Vavoua historical focus in Côte d’Ivoire where HAT cases were still diagnosed in the early 2010’s. During a study conducted in this area, we scrutinized the trypanosomes circulating in pigs and people sharing the same environment using serological, immunological, parasitological and molecular tools. No HAT cases were detected. We showed that T. brucei s.l. and T. congolense actively circulated in free-ranging pigs. Even if no tools were sensitive and specific enough to unambiguously identify T. b. gambiense directly from biological samples, six isolated strains from pigs positive for trypanosomes were amplified for TgsGP, the only currently accepted T. b. gambiense specific molecular marker. The apparent discrepancies between the presence of T. b. gambiense in pigs despite the absence of human cases is discussed. These results stress the need for an efficient “molecular toolbox” to easily detect and identify T. b. gambiense in any animal it may infect.

Novel protein candidates for serodiagnosis of African animal trypanosomosis: Evaluation of the diagnostic potential of lysophospholipase and glycerol kinase from Trypanosoma brucei

African trypanosomosis, a parasitic disease caused by protozoan parasites transmitted by tsetse flies, affects both humans and animals in sub-Saharan Africa. While the human form (HAT) is now limited to foci, the animal form (AAT) is widespread and affects the majority of sub-Saharan African countries, and constitutes a real obstacle to the development of animal breeding. The control of AAT is hampered by a lack of standardized and easy-to used diagnosis tools. This study aimed to evaluate the diagnostic potential of TbLysoPLA and TbGK proteins from Trypanosoma brucei brucei for AAT serodiagnosis in indirect ELISA using experimental and field sera, individually, in combination, and associated with the BiP C-terminal domain (C25) from T. congolense. These novel proteins were characterized in silico, and their sequence analysis showed strong identities with their orthologs in other trypanosomes (more than 60% for TbLysoPLA and more than 82% for TbGK). TbLysoPLA displays a low homology with cattle (<35%) and Piroplasma (<15%). However, TbGK shares more than 58% with cattle and between 45–55% with Piroplasma. We could identify seven predicted epitopes on TbLysoPLA sequence and 14 potential epitopes on TbGK. Both proteins were recombinantly expressed in Escherichia coli. Their diagnostic potential was evaluated by ELISA with sera from cattle experimentally infected with T. congolense and with T.b. brucei, sera from cattle naturally infected with T. congolense, T. vivax and T.b. brucei. Both proteins used separately had poor diagnostic performance. However, used together with the BiP protein, they showed 60% of sensitivity and between 87–96% of specificity, comparable to reference ELISA tests. In conclusion, we showed that the performance of the protein combinations is much better than the proteins tested individually for the diagnosis of AAT.

African animal trypanosomiasis (AAT) is an endemic disease in sub-Saharan Africa that hinders the development of livestock production on the continent. The control of the disease is based on chemotherapy, vector control and diagnosis. Misuse, as well as the continuous/regular use of a limited number of anti-trypanosomal drugs, is responsible for the appearance of increasingly drug-resistant strains of trypanosomes. In terms of serological diagnosis, the most efficient test at present suffers from a lack of reagent standardization. Unfortunately, even the most promising candidates fail due to low sensitivity in primately or chronically infected animals. Based on this observation it seems obvious that diagnosis must be revisited. In this study we evaluated the diagnostic potential of two Trypanosoma brucei proteins, TbLysoPLA and TbGK, in indirect ELISA for antibody detection. To provide a proof of concept that the judicious association of immunoreactive proteins could improve the sensitivity and specificity of tests based on recombinant antigens, we used these molecules alone and then in combination, associated or not with the BiP protein of T. congolense. The evaluation in serological diagnosis showed that the two proteins used separately had a poor performance. However, when used together with the BiP protein, they showed a sensitivity of 60% and a specificity between 87 and 96%, comparable to the reference tests. It shows for the first time that the performance of protein combinations is much better than that of the proteins tested individually for the diagnosis of AAT.

An enzyme-mediated bioorthogonal labeling method for genome-wide mapping of 5-hydroxymethyluracil

DNA 5-hydroxymethyluracil (5hmU) is a thymine modification existing in the genomes of various organisms. The post-replicative formation of 5hmU occurs via hydroxylation of thymine by ten-eleven translocation (TET) dioxygenases in mammals and J-binding proteins (JBPs) in protozoans, respectively. In addition, 5hmU can also be generated through oxidation of thymine by reactive oxygen species or deamination of 5hmC by cytidine deaminase. While the biological roles of 5hmU have not yet been fully explored, determining its genomic location will highly assist in elucidating its functions. Herein, we report a novel enzyme-mediated bioorthogonal labeling method for selective enrichment of 5hmU in genomes. 5hmU DNA kinase (5hmUDK) was utilized to selectively install an azide (N₃) group or alkynyl group into the hydroxyl moiety of 5hmU followed by incorporation of the biotin linker through click chemistry, which enabled the capture of 5hmU-containing DNA fragments via streptavidin pull-down. The enriched fragments were applied to deep sequencing to determine the genomic distribution of 5hmU. With this established enzyme-mediated bioorthogonal labeling strategy, we achieved the genome-wide mapping of 5hmU in Trypanosoma brucei. The method described here will allow for a better understanding of the functional roles and dynamics of 5hmU in genomes.

Protein Lactylation Critically Regulates Energy Metabolism in the Protozoan Parasite Trypanosoma brucei

Lysine lactylation has been recognized as a novel post-translational modification occurring on histones. However, lactylation in non-histone proteins, especially in proteins of early branching organisms, is not well understood. Energy metabolism and the histone repertoire in the early diverging protozoan parasite Trypanosoma brucei, the causative agent of African trypanosomiasis, markedly diverge from those of conventional eukaryotes. Here, we present the first exhaustive proteome-wide investigation of lactylated sites in T. brucei. We identified 387 lysine-lactylated sites in 257 proteins of various cellular localizations and biological functions. Further, we revealed that glucose metabolism critically regulates protein lactylation in T. brucei although the parasite lacks lactate dehydrogenase. However, unlike mammals, increasing the glucose concentration reduced the level of lactate, and protein lactylation decreased in T. brucei via a unique lactate production pathway. In addition to providing a valuable resource, these foregoing data reveal the regulatory roles of protein lactylation of trypanosomes in energy metabolism and gene expression.

No more cold-chain failures, using dehydrated reagents in ELISA antibody-detection against animal trypanosomes of African origin

Animal trypanosomoses due to trypanosomes of African origin (ATAO), mainly caused by Trypanosoma congolense type Savannah (TCS), T. brucei brucei (TBB), T. vivax (TV), and T. evansi, are widespread diseases that affect domestic and wild mammals and have a huge economic impact. ATAO clinical suspicions are usually confirmed by parasitological and molecular methods, while sero-epidemiological surveys are generally carried out using the OIE-recommended ELISA method based on whole cell lysate soluble antigens (WCLSA) from purified trypanosomes; this reagent is usually stored frozen. With a view to expanding this ELISA test, we assessed, standardized, and validated the use of dehydrated rather than frozen WCLSA and serum samples. For the three ELISA assays (TV, TCS & TBB), a repeatability study revealed no significant difference between repeats. The results obtained using frozen rather than freeze-dried antigen and serum strongly correlated for Pearson's correlation values (>0.93) and Lin's measure ("very good" to "excellent"). Reproducibility was robust, with Pearson's correlation values >0.97 for inter technician effects, and 0.87 (TV) to 0.97 (TBB & TCS) for inter-laboratory tests; their combination was "very satisfactory" to "excellent" according to Lin's measure and there was no impact on qualitative test results. Dehydrated reagents offer the advantage of shipment at room temperature, allowing the secured provision of reagents to regional laboratories. Together with a compendium of standard diagnostic protocols for ATAO (/OIE), dehydrated reagents will enable the serological diagnosis of ATAO at regional level in endemic countries. This very welcome improvement in the context of the Progressive Control Pathway for trypanosomes, recently launched by African countries, will possibly be extended to Latin America in the near future.

African Trypanosomiasis: Extracellular Vesicles Shed by Trypanosoma brucei brucei Manipulate Host Mononuclear Cells

African trypanosomiasis or sleeping sickness is a zoonotic disease caused by Trypanosoma brucei, a protozoan parasite transmitted by Glossina spp. (tsetse fly). Parasite introduction into mammal hosts triggers a succession of events, involving both innate and adaptive immunity. Macrophages (MΦ) have a key role in innate defence since they are antigen-presenting cells and have a microbicidal function essential for trypanosome clearance. Adaptive immune defence is carried out by lymphocytes, especially by T cells that promote an integrated immune response. Like mammal cells, T. b. brucei parasites release extracellular vesicles (TbEVs), which carry macromolecules that can be transferred to host cells, transmitting biological information able to manipulate cell immune response. However, the exact role of TbEVs in host immune response remains poorly understood. Thus, the current study examined the effect elicited by TbEVs on MΦ and T lymphocytes. A combined approach of microscopy, nanoparticle tracking analysis, multiparametric flow cytometry, colourimetric assays and detailed statistical analyses were used to evaluate the influence of TbEVs in mouse mononuclear cells. It was shown that TbEVs can establish direct communication with cells of innate and adaptative immunity. TbEVs induce the differentiation of both M1- and M2-MΦ and elicit the expansion of MHCI⁺, MHCII⁺ and MHCI⁺MHCII⁺ MΦ subpopulations. In T lymphocytes, TbEVs drive the overexpression of cell-surface CD3 and the nuclear factor FoxP3, which lead to the differentiation of regulatory CD4⁺ and CD8⁺ T cells. Moreover, this study indicates that T. b. brucei and TbEVs seem to display opposite but complementary effects in the host, establishing a balance between parasite growth and controlled immune response, at least during the early phase of infection.

Trypanosoma brucei Lipophosphoglycan Induces the Formation of Neutrophil Extracellular Traps and Reactive Oxygen Species Burst via Toll-Like Receptor 2, Toll-Like Receptor 4, and c-Jun N-Terminal Kinase Activation

Trypanosoma brucei brucei is the causative agent of African animal trypanosomosis, which mainly parasitizes the blood of the host. Lipophosphoglycan (LPG), a polymer anchored to the surface of the parasites, activates the host immune response. In this study, we revealed that T. brucei LPG stimulated neutrophils to form neutrophil extracellular traps (NETs) and release the reactive oxygen species (ROS). We further analyzed the involvement of toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) and explored the activation of signaling pathway enzymes in response to LPG stimulation. During the stimulation of neutrophils by LPG, the blockade using anti-TLR2 and anti-TLR4 antibodies reduced the phosphorylation of c-Jun N-terminal kinase (JNK), the release of DNA from the NETs, and the burst of ROS. Moreover, the addition of JNK inhibitor and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor exhibited similar effects. Our data suggest that T. brucei LPG activates the phosphorylation of JNK through TLR2 and TLR4 recognition, which causes the formation of NETs and the burst of ROS.

Divergent metabolism between Trypanosoma congolense and Trypanosoma brucei results in differential sensitivity to metabolic inhibition

Animal African Trypanosomiasis (AAT) is a debilitating livestock disease prevalent across sub-Saharan Africa, a main cause of which is the protozoan parasite Trypanosoma congolense. In comparison to the well-studied T. brucei, there is a major paucity of knowledge regarding the biology of T. congolense. Here, we use a combination of omics technologies and novel genetic tools to characterise core metabolism in T. congolense mammalian-infective bloodstream-form parasites, and test whether metabolic differences compared to T. brucei impact upon sensitivity to metabolic inhibition. Like the bloodstream stage of T. brucei, glycolysis plays a major part in T. congolense energy metabolism. However, the rate of glucose uptake is significantly lower in bloodstream stage T. congolense, with cells remaining viable when cultured in concentrations as low as 2 mM. Instead of pyruvate, the primary glycolytic endpoints are succinate, malate and acetate. Transcriptomics analysis showed higher levels of transcripts associated with the mitochondrial pyruvate dehydrogenase complex, acetate generation, and the glycosomal succinate shunt in T. congolense, compared to T. brucei. Stable-isotope labelling of glucose enabled the comparison of carbon usage between T. brucei and T. congolense, highlighting differences in nucleotide and saturated fatty acid metabolism. To validate the metabolic similarities and differences, both species were treated with metabolic inhibitors, confirming that electron transport chain activity is not essential in T. congolense. However, the parasite exhibits increased sensitivity to inhibition of mitochondrial pyruvate import, compared to T. brucei. Strikingly, T. congolense exhibited significant resistance to inhibitors of fatty acid synthesis, including a 780-fold higher EC50 for the lipase and fatty acid synthase inhibitor Orlistat, compared to T. brucei. These data highlight that bloodstream form T. congolense diverges from T. brucei in key areas of metabolism, with several features that are intermediate between bloodstream- and insect-stage T. brucei. These results have implications for drug development, mechanisms of drug resistance and host-pathogen interactions.

A store-operated Ca2+-entry in Trypanosoma equiperdum: Physiological evidences of its presence

The Trypanosomatidae family encompasses many unicellular organisms responsible of several tropical diseases that affect humans and animals. Livestock tripanosomosis caused by Trypanosoma brucei brucei (T. brucei), Trypanosoma equiperdum (T. equiperdum) and Trypanosoma evansi (T. evansi), have a significant socio-economic impact and limit animal protein productivity throughout the intertropical zones of the world. Similarly, to all organisms, the maintenance of Ca²⁺ homeostasis is vital for these parasites, and the mechanism involved in the intracellular Ca²⁺ regulation have been widely described. However, the evidences related to the mechanisms responsible for the Ca²⁺ entry are scarce. Even more, to date the presence of a store-operated Ca²⁺ channel (SOC) has not been reported. Despite the apparent absence of Orai and STIM-like proteins in these parasites, in the present work we demonstrate the presence of a store-operated Ca²⁺-entry (SOCE) in T. equiperdum, using physiological techniques. This Ca²⁺-entry is induced by thapsigargin (TG) and 2,5-di-t-butyl-1,4-benzohydroquinone (BHQ), and inhibited by 2-aminoethoxydiphenyl borate (2APB). Additionally, the use of bioinformatics techniques allowed us to identify putative transient receptor potential (TRP) channels, present in members of the Trypanozoon family, which would be possible candidates responsible for the SOCE described in the present work in T. equiperdum.

Bioinformatics and expression analysis of the Xeroderma Pigmentosum complementation group C (XPC) of Trypanosoma evansi in Trypanosoma cruzi cells

Nucleotide excision repair (NER) acts repairing damages in DNA, such as lesions caused by cisplatin. Xeroderma Pigmentosum complementation group C (XPC) protein is involved in recognition of global genome DNA damages during NER (GG-NER) and it has been studied in different organisms due to its importance in other cellular processes. In this work, we studied NER proteins in Trypanosoma cruzi and Trypanosoma evansi, parasites of humans and animals respectively. We performed three-dimensional models of XPC proteins from T. cruzi and T. evansi and observed few structural differences between these proteins. In our tests, insertion of XPC gene from T. evansi (TevXPC) in T. cruzi resulted in slower cell growth under normal conditions. After cisplatin treatment, T. cruzi overexpressing its own XPC gene (TcXPC) was able to recover cell division rates faster than T. cruzi expressing TevXPC gene. Based on these tests, it is suggested that TevXPC (being an exogenous protein in T. cruzi) interferes negatively in cellular processes where TcXPC (the endogenous protein) is involved. This probably occurred due interaction of TevXPC with some endogenous molecules or proteins from T.cruzi but incapacity of interaction with others. This reinforces the importance of correctly XPC functioning within the cell.

Epidemiology of Trypanosomiasis in Wildlife-Implications for Humans at the Wildlife Interface in Africa

While both human and animal trypanosomiasis continue to present as major human and animal public health constraints globally, detailed analyses of trypanosome wildlife reservoir hosts remain sparse. African animal trypanosomiasis (AAT) affects both livestock and wildlife carrying a significant risk of spillover and cross-transmission of species and strains between populations. Increased human activity together with pressure on land resources is increasing wildlife–livestock–human infections. Increasing proximity between human settlements and grazing lands to wildlife reserves and game parks only serves to exacerbate zoonotic risk. Communities living and maintaining livestock on the fringes of wildlife-rich ecosystems require to have in place methods of vector control for prevention of AAT transmission and for the treatment of their livestock. Major Trypanosoma spp. include Trypanosoma brucei rhodesiense, Trypanosoma brucei gambiense, and Trypanosoma cruzi, pathogenic for humans, and Trypanosoma vivax, Trypanosoma congolense, Trypanosoma evansi, Trypanosoma brucei brucei, Trypanosoma dionisii, Trypanosoma thomasbancrofti, Trypanosma elephantis, Trypanosoma vegrandis, Trypanosoma copemani, Trypanosoma irwini, Trypanosoma copemani, Trypanosoma gilletti, Trypanosoma theileri, Trypanosoma godfreyi, Trypansoma simiae, and Trypanosoma (Megatrypanum) pestanai. Wildlife hosts for the trypansomatidae include subfamilies of Bovinae, Suidae, Pantherinae, Equidae, Alcephinae, Cercopithecinae, Crocodilinae, Pteropodidae, Peramelidae, Sigmodontidae, and Meliphagidae. Wildlife species are generally considered tolerant to trypanosome infection following centuries of coexistence of vectors and wildlife hosts. Tolerance is influenced by age, sex, species, and physiological condition and parasite challenge. Cyclic transmission through Glossina species occurs for T. congolense, T. simiae, T. vivax, T. brucei, and T. b. rhodesiense, T. b. gambiense, and within Reduviid bugs for T. cruzi. T. evansi is mechanically transmitted, and T. vixax is also commonly transmitted by biting flies including tsetse. Wildlife animal species serve as long-term reservoirs of infection, but the delicate acquired balance between trypanotolerance and trypanosome challenge can be disrupted by an increase in challenge and/or the introduction of new more virulent species into the ecosystem. There is a need to protect wildlife, animal, and human populations from the infectious consequences of encroachment to preserve and protect these populations. In this review, we explore the ecology and epidemiology of Trypanosoma spp. in wildlife.

Diminazene resistance in Trypanosoma congolense is not caused by reduced transport capacity but associated with reduced mitochondrial membrane potential

Trypanosoma congolense is a principal agent causing livestock trypanosomiasis in Africa, costing developing economies billions of dollars and undermining food security. Only the diamidine diminazene and the phenanthridine isometamidium are regularly used, and resistance is widespread but poorly understood. We induced stable diminazene resistance in T. congolense strain IL3000 in vitro. There was no cross-resistance with the phenanthridine drugs, melaminophenyl arsenicals, oxaborole trypanocides, or with diamidine trypanocides, except the close analogs DB829 and DB75. Fluorescence microscopy showed that accumulation of DB75 was inhibited by folate. Uptake of [³ H]-diminazene was slow with low affinity and partly but reciprocally inhibited by folate and by competing diamidines. Expression of T. congolense folate transporters in diminazene-resistant Trypanosoma brucei brucei significantly sensitized the cells to diminazene and DB829, but not to oxaborole AN7973. However, [³ H]-diminazene transport studies, whole-genome sequencing, and RNA-seq found no major changes in diminazene uptake, folate transporter sequence, or expression. Instead, all resistant clones displayed a moderate reduction in the mitochondrial membrane potential Ψm. We conclude that diminazene uptake in T. congolense proceed via multiple low affinity mechanisms including folate transporters; while resistance is associated with a reduction in Ψm it is unclear whether this is the primary cause of the resistance.

TatD DNases of African trypanosomes confer resistance to host neutrophil extracellular traps

African trypanosomatid parasites escape host acquired immune responses through periodic antigenic variation of their surface coat. In this study, we describe a mechanism by which the parasites counteract innate immune responses. Two TatD DNases were identified in each of Trypanosoma evansi and Trypanosoma brucei. These DNases are bivalent metal-dependent endonucleases localized in the cytoplasm and flagella of the parasites that can also be secreted by the parasites. These enzymes possess conserved functional domains and have efficient DNA hydrolysis activity. Host neutrophil extracellular traps (NETs) induced by the parasites could be hydrolyzed by native and recombinant TatD DNases. NET disruption was prevented, and the survival rate of parasites was decreased, in the presence of the DNase inhibitor aurintricarboxylic acid. These data suggest that trypanosomes can counteract host innate immune responses by active secretion of TatD DNases to degrade NETs.

Physiological and proteomic profiles of Trypanosoma brucei rhodesiense parasite isolated from suramin responsive and non-responsive HAT patients in Busoga, Uganda

Human African Trypanosomiasis (HAT) is a disease of major economic importance in Sub-Saharan Africa. The HAT is caused by Trypanosoma brucei rhodesiense (Tbr) parasite in eastern and southern Africa, with suramin as drug of choice for treatment of early stage of the disease. Suramin treatment failures has been observed among HAT patients in Tbr foci in Uganda. In this study, we assessed Tbr parasite strains isolated from HAT patients responsive (Tbr EATRO-232) and non-responsive (Tbr EATRO-734) to suramin treatment in Busoga, Uganda for 1) putative role of suramin resistance in the treatment failure 2) correlation of suramin resistance with Tbr pathogenicity and 3) proteomic pathways underpinning the potential suramin resistance phenotype in vivo. We first assessed suramin response in each isolate by infecting male Swiss white mice followed by treatment using a series of suramin doses. We then assessed relative pathogenicity of the two Tbr isolates by assessing changes pathogenicity indices (prepatent period, survival and mortality). We finally isolated proteins from mice infected by the isolates, and assessed their proteomic profiles using mass spectrometry. We established putative resistance to 2.5 mg/kg suramin in the parasite Tbr EATRO-734. We established that Tbr EATRO-734 proliferated slower and has significantly enriched pathways associated with detoxification and metabolism of energy and drugs relative to Tbr EATRO-232. The Tbr EATRO-734 also has more abundantly expressed mitochondrion proteins and enzymes than Tbr EATRO-232. The suramin treatment failure may be linked to the relatively higher resistance to suramin in Tbr EATRO-734 than Tbr EATRO-232, among other host and parasite specific factors. However, the Tbr EATRO-734 appears to be less pathogenic than Tbr EATRO-232, as evidenced by its lower rate of parasitaemia. The Tbr EATRO-734 putatively surmount suramin challenges through induction of energy metabolism pathways. These cellular and molecular processes may be involved in suramin resistance in Tbr.

Comparative pathology of experimental infection with four isolates of Trypanosoma evansi in Wistar albino Rats

In the present study, pathological changes due to experimental infection with four isolates of T. evansi were studied in rats to know the pathogenicity. Male Wistar albino rats (140) were divided in five groups of 28 rats each (4 isolate groups and 1 control group). Each rat was infected with 1×105 T. evansi from buffalo, dog, leopard and lion isolates and normal saline in control group by intraperitoneal route. Four rats were sacrificed on Day 1 (D1) to D7 post infection in each group and collected blood was for microscopic examination and tissues for pathology. Blood smear examination revealed presence of trypanosomes on D3, D4, D5 and D5 in buffalo, dog, leopard and lion isolates, respectively. All the T. evansi infected rats showed hypoglycaemia and increased blood urea nitrogen in serum. Rats showed clinical signs with dullness, lethargy and hunched back on D7. Liver showed vacuolar degeneration, congestion of blood vessels and infiltration of mononuclear cells on D7 in buffalo, dog, lion isolates, and no changes in leopard isolate infected rats. Kidney, spleen, lung and testis revealed pathological changes in buffalo and dog isolates. Trypanosomes were present in the endocardium of heart in buffalo isolate infected rats. Immunohistopathology revealed presence of trypanosome antigens in the blood vessels of liver, and spleen. Thus, based on trypanosome counts, serum glucose, blood urea nitrogen and pathological changes, there was variation between these isolates and revealed pathogenicity in ascending order as leopard, lion, dog and buffalo isolates in rats.

Serum proteomic signature of Trypanosoma evansi -infected mice for identification of potential biomarkers

Trypanosoma evansi is the agent of "surra," a trypanosomosis endemic in many areas worldwide. Trypanosoma proteins released/secreted during infection are attractive biomarkers for disease detection and monitoring. Using liquid chromatography-tandem mass spectrometry (LC-MS/MS), we performed a comprehensive analysis of the serum proteome of mice infected with T.evansi and detected changes in the abundance of parasite and host serum proteins during infection. Following bioinformatics analysis, 30 T. evansi proteins were identified in the mice serum including known targets such as pyruvate kinase 1, β-tubulin, actin A, heat shock protein 70, and cyclophilin A. We also identified two exclusive VSG epitopes which are novel putative biomarker targets. In addition, upregulation of 31 mouse proteins, including chitinase-like protein 3 and monocyte differentiation antigen CD14, were observed. Identification of parasite-specific biomarkers in the host serum is critical for the development of reliable serological/ assays for differential diagnosis.

Selenocysteine in Trypanosoma evansi: Identification of the Genes selb, selc, seld, pstk, seltryp and the Selenophosphate Synthetase Protein

Selenoproteins have been described in all three domains of life and their function has been mainly associated with oxidative stress defense. Canonical elements required for selenoprotein production have been identified in members of the kinetoplastid group supporting the existence of a complete selenocysteine synthesis pathway in these organisms. Currently, nothing is known regarding the selenocysteine pathway in Trypanosoma evansi. In this study, we identified the expression of the elements selB, selC, selD, PSTK and selTRYP at the mRNA level in T. evansi. All translated proteins (selD, PSTK, selTRYP and selB) have the domains predicted and higher identity with Trypanosoma brucei. gambiense. The selenophosphate synthetase protein was localized in the cytoplasm. Our results support the existence of an active selenocysteine pathway in T. evansi.

Evaluation of buffered Trypanosoma evansi antigen and rapid serum agglutination test (BA/Te) for the detection of anti-T. evansi antibodies in horses in Brazil

Surra is an infectious disease caused by Trypanosoma evansi, which affects a large number of domestic and wild animal species. Infection control is based on rapid diagnosis followed by treatment of sick animals. This study aimed to evaluate a buffered T. evansi antigen and rapid serum agglutination test (BA/Te) for the detection of anti-T. evansi antibodies in serum samples of horses. For this purpose, 445 serum samples from horses were evaluated and the results compared with the diagnosis by CATT/T. evansi. Our data show a sensitivity of 92%, specificity of 91% and a degree of agreement kappa (κ) of 0.82 (95% CI: 0.771–0.877, P < 0.01) between BA/Te and CATT/T. evansi. Antigen specificity was also evaluated against reactive serum for other infectious agents circulating in equine herds. In conclusion, our findings show that BA/Te has the potential to be a practical and quick screening method for the detection of anti-T. evansi antibodies in horses.

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New reliable, cheap, fast, and practical serum agglutination test for surra.

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Specific to Trypanosoma evansi when tested against serum samples from animals positive for other infectious agents in equines.

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High specificity and sensitivity in agreement with CATT/T. evansi.

Reversible phosphorylation of a protein from Trypanosoma equiperdum that exhibits homology with the regulatory subunits of mammalian cAMP-dependent protein kinases

Homologous proteins of the cAMP-dependent protein kinase (PKA) regulatory and catalytic subunits have been identified in Trypanosoma equiperdum (TeqR-like and TeqC-like, respectively). Partially purified TeqR-like from parasites isolated in the presence of glucose migrated as an apparent 55 kDa/57 kDa polypeptide doublet when separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, a single polypeptide of 57 kDa was obtained when parasites were deprived of glucose, a condition that has been shown to activate a TeqC-like enzyme. As revealed by immunoblots using anti-phospothreonine antibodies, the 57 kDa band corresponded to a form of TeqR-like that was phosphorylated in threonine residues. TeqR-like phosphorylation was reversible since the level of phospho-TeqR-like decreased once glucose was readded to glucose starved-parasites. Dephospho- and phospho-TeqR-like proteins are monomers with native molecular masses of 54.93-57.41 kDa, Stokes radii of 3.42-3.37 nm, and slightly asymmetric shapes (frictional ratio f/fo = 1.36-1.32). A protein kinase of ∼40 kDa was also partially purified from glucose deprived-trypanosomes, which corresponded to the TeqC-like enzyme by its ability to phosphorylate kemptide, its inhibition by PKA-specific inhibitors, and its immunorecognition by anti-PKA catalytic subunit antibodies. TeqR-like and TeqC-like did not coelute following anion-exchange chromatography, revealing that these proteins are not associated forming a complex in T. equiperdum. Yet, when TeqR-like was incubated in vitro with TeqC-like in the presence of Mg²⁺ and ATP, the 55 kDa dephospho form of the 55kDa/57 kDa polypeptide doublet of TeqR-like was converted into the 57 kDa phospho form, demonstrating that TeqR-like is a substrate for TeqC-like.

Disorder and partial folding in the regulatory subunit hinge region of Trypanosoma brucei protein kinase A: The C-linker portion inhibits the parasite's protein kinase A

Microbial pathogens, such as Trypanosoma brucei, have an enormous impact on global health and economic systems. Protein kinase A of T. brucei is an attractive drug target as it is an essential enzyme which differs significantly from its human homolog. The hinge region of this protein's regulatory domain is vital for enzymatic function, but its conformation is unknown. Here, the secondary structure of this region has been characterized using NMR and CD spectroscopies. More specifically, three overlapping peptides corresponding to residues T187-I211, G198-Y223 and V220-S245 called peptide 1, peptide 2 and peptide 3, respectively, were studied. The peptide 1 and peptide 2 are chiefly unfolded; only low populations (<10%) of α-helix were detected under the conditions studied. In contrast, the peptide 3 contains a long α-helix whose population is significantly higher; namely, 36% under the conditions studied. Utilizing the dihedral φ and ψ angles calculated on the basis of the NMR data, the conformation of the peptide 3 was calculated and revealed an α-helix spanning residues E230-N241. This α-helix showed amphiphilicity and reversible unfolding and refolding upon heating and cooling. Most fascinating, however, is its capacity to inhibit the activity of the catalytic domain of Trypanosoma equiperdum protein kinase A even though it is quite distinct from the canonical inhibitor motif. Based on this property, we advance that peptoids based on the peptide 3 α-helix could be novel leads for developing anti-trypanosomal therapeutics.

An Unbiased Immunization Strategy Results in the Identification of Enolase as a Potential Marker for Nanobody-Based Detection of Trypanosoma evansi

Trypanosoma evansi is a widely spread parasite that causes the debilitating disease “surra” in several types of ungulates. This severely challenges livestock rearing and heavily weighs on the socio-economic development in the affected areas, which include countries on five continents. Active case finding requires a sensitive and specific diagnostic test. In this paper, we describe the application of an unbiased immunization strategy to identify potential biomarkers for Nanobody (Nb)-based detection of T. evansi infections. Alpaca immunization with soluble lysates from different T. evansi strains followed by panning against T. evansi secretome resulted in the selection of a single Nb (Nb11). By combining Nb11-mediated immuno-capturing with mass spectrometry, the T. evansi target antigen was identified as the glycolytic enzyme enolase. Four additional anti-enolase binders were subsequently generated by immunizing another alpaca with the recombinant target enzyme. Together with Nb11, these binders were evaluated for their potential use in a heterologous sandwich detection format. Three Nb pairs were identified as candidates for the further development of an antigen-based assay for Nb-mediated diagnosis of T. evansi infection.

Comparison of serological and molecular tests for detection of Trypanosoma evansi in domestic animals from Ghardaïa district, South Algeria

Trypanosoma evansi (T. evansi) is a hemoflagellate parasite that affects a broad range of mammalian hosts and that causes a disease called surra. Diagnosis of surra based on clinical symptoms alone is inaccurate. Therefore, a variety of serological and molecular diagnostic tests are used to assist in the detection of T. evansi infections. The aim of this study was to compare the diagnostic performance of four serological tests (CATT/T.evansi, immune trypanolysis, ELISA with purified variant surface glycoprotein RoTat 1.2 and with whole cell lysate) and two molecular PCR tests targeting sequences within the ribosomal genes locus (ITS1 TD PCR and 18S qPCR). Tests were carried out on blood samples from 161 dromedary camels, 93 horses, 129 goats, 168 sheep, 127 bovines and 76 dogs. Latent class analysis was carried out to calculate the sensitivity and specificity of each diagnostic test. Cohen's Kappa test was used to assess the concordance between the different diagnostic tests. Overall positivity rates observed with the serological tests were as follows: 3.1 % with CATT/T.evansi, 4.9 % with ELISA/RoTat 1.2, 3.4 % with ELISA/whole lysate and 2.0 % with immune trypanolysis (TL). Among the 754 samples tested with the molecular tests, 1.7 % were positive with 18S qPCR and 1.3 % with ITS1 TD PCR. Cohen's Kappa test showed agreement ranging from fair to substantial (k = 0.2-0.8) between serological diagnostic tests. However, it showed a perfect agreement (k = 0.868) between molecular diagnostic tests. Latent class analysis showed that all serological tests were 100 % sensitive, in contrast to the molecular tests with 47 % sensitivity. All tests, though, were highly specific (≥ 97 %). Given the persistence of circulating antibodies after cure, detectable by serological tests, it is recommend combining a serological and a molecular diagnostic test for accurate diagnosis of infection with T. evansi in domestic animals.

Evaluation of the Immunoprotective Potential of Recombinant Paraflagellar Rod Proteins of Trypanosoma evansi in Mice

Trypanosomosis, caused by Trypanosoma evansi, is an economically significant disease of livestock. Systematic antigenic variation by the parasite has undermined prospects for the development of a protective vaccine that targets the immunodominant surface antigens, encouraging exploration of alternatives. The paraflagellar rod (PFR), constituent proteins of the flagellum, are prominent non-variable vaccine candidates for T. evansi owing to their strategic location. Two major PFR constituent proteins, PFR1 (1770bp) and PFR2 (1800bp), were expressed using Escherichia coli. Swiss albino mice were immunized with the purified recombinant TePFR1 (89KDa) and TePFR2 (88KDa) proteins, as well as with the mix of the combined proteins at equimolar concentrations, and subsequently challenged with virulent T. evansi. The PFR-specific humoral response was assessed by ELISA. Cytometric bead-based assay was used to measure the cytokine response and flow cytometry for quantification of the cytokines. The recombinant TePFR proteins induced specific humoral responses in mice, including IgG1 followed by IgG2a and IgG2b. A balanced cytokine response induced by rTePFR 1 and 2 protein vaccination associated with extended survival and improved control of parasitemia following lethal challenge. The observation confirms the immunoprophylactic potential of the covert antigens of T. evansi.

High-Throughput Sequencing for Trypanosome Transcriptome Characterization

High-throughput sequencing of cDNA (RNASeq) is now the method of choice for analysis of transcriptomes. This chapter details important considerations in the design of RNASeq experiments for kinetoplastids grown in culture or experimental animals. It contains protocols for obtaining parasites from rodents, and for removal of rRNA from total RNA. In addition, custom pipelines for sequence alignment, and for data analysis and visualization, are described.

TLR-2 and MyD88-Dependent Activation of MAPK and STAT Proteins Regulates Proinflammatory Cytokine Response and Immunity to Experimental Trypanosoma congolense Infection

It is known that Trypanosoma congolense infection in mice is associated with increased production of proinflammatory cytokines by macrophages and monocytes. However, the intracellular signaling pathways leading to the production of these cytokines still remain unknown. In this paper, we have investigated the innate receptors and intracellular signaling pathways that are associated with T. congolense-induced proinflammatory cytokine production in macrophages. We show that the production of IL-6, IL-12, and TNF-α by macrophages in vitro and in vivo following interaction with T. congolense is dependent on phosphorylation of mitogen-activated protein kinase (MAPK) including ERK, p38, JNK, and signal transducer and activation of transcription (STAT) proteins. Specific inhibition of MAPKs and STATs signaling pathways significantly inhibited T. congolense-induced production of proinflammatory cytokines in macrophages. We further show that T. congolense-induced proinflammatory cytokine production in macrophages is mediated via Toll-like receptor 2 (TLR2) and involves the adaptor molecule, MyD88. Deficiency of MyD88 and TLR2 leads to impaired cytokine production by macrophages in vitro and acute death of T. congolense-infected relatively resistant mice. Collectively, our results provide insight into T. congolense-induced activation of the immune system that leads to the production of proinflammatory cytokines and resistance to the infection.