Trypanosomatid protozoa in fruit of solanaceae in southeastern Brazil

Fruits of cultivated and indigenous Solanaceae from Southeastern Brazil have been examined for the presence of trypanosomatid flagellates. The 14 species found infected were: Capsicum annum, C. praetermissum, Lycopersicon esculentum, Nicandra physaloides, Physalis angulata, Solanum sp., S. americanum, S. concinnum, S. diflorum, S. erianthum, S. gilo, S. robustum, S. variable and S. viarum. The pentatomid hemipteran Arvelius albopunctatus experimentally transmitted flagellates to fruits of some species. Cultures of flagellates were obtained form fruits of eight species of Salonaceae and from A. albopunctatus.

The Infection Rates of Trypanosomes in Squirrel Monkeys at Two Sites in the Brazilian Amazon

A study was conducted to determine the prevalence of natural infections by trypanosome species in squirrel monkeys: Saimiri sciureus (Linnaeus) and Saimiri ustus (Geoffroy) caught respectively near 2 hydroelectric plants: Balbina, in the State of Amazonas, and Samuel, in the State of Rondônia, Brazil. A total of 165 squirrel monkeys were examined by thick and thin blood smears (BS), haemocultures and xenodiagnosis: 112 monkeys, 67.9%,(being 52.7% with mix infections) were positive to trypanosomes. Four species of trypanosomes were found in monkeys from the 2 areas: Trypanosoma (Tejeraia) rangeli Tejera or T. rangeli-like parasites in 58 squirrel monkeys (35.2%), Trypanosoma (Megatrypanum) minasense Chagas in 55 (33.3%), Trypanosoma (Herpetosoma) saimirii Rodhain or T. saimirii-like parasites in 53 (32.1%) and Trypanosoma (Schizotrypanum) cruzi Chagas in 17 (10.3%). As T. saimirii resembles T. minasense in blood-stream trypomastigotes and T. rangeli in cultural forms and in this survey almost all monkeys presenting trypanosomes morphologically indistinguishable from T. saimirii and/or T. minasense in BS were found through xenodiagnosis and/or haemoculture to be infected by T. rangeli, we suggest that the validity of T. saimirii needs to be evaluated

Morphological Features of Trypanosomes from Squirrel Monkeys from the Brazilian Amazon

A morphometric analysis of blood trypomastigotes identified as Trypanosoma minasense, T. saimirii, and T. rangeli harbored by squirrel monkeys from the Brazilian Amazon was performed. Additionally, morphological and biological comparative analyses were conducted of T. saimirii-like and T. rangeli development forms from haemoculture and xenodiagnosis. Illustrations are given of blood trypomastigotes as well as of developing flagellates in triatomine and axenic culture. Mean values of blood trypomastigotes of T. saimirii differ statistically from those of T. rangeli in only two out of ten morphological characters measured, and ranges overlapped. The developing forms of T. saimrii-like parasites were essentially identical in both xenodiagnosis and haemoculture to those of T. rangeli. Trypanosomes confirmed as T. rangeli were transmitted to mice by the bites of the great majority of triatomines that fed on T. saimirii-like infected monkeys. We conclude that, based on morphology and on the development in triatomine bugs and haemoculture, T. saimirii should not be considered a distinct species. We therefore propose T. saimirii to be a junior synonym of T. rangeli

Parasite Genotypically Related to a Monoxenous Trypanosomatid of Dog's Flea Causing Opportunistic Infection in an HIV Positive Patient

An HIV positive patient presenting a clinical picture of visceral leishmaniasis co-infection was submitted to a bone marrow aspiration after admission to hospital. Amastigotes forms were seen in the bone marrow aspirate and the parasite grew in culture as promastigotes. Molecular analyses showed that the flagellates isolated did not belong to the genera Leishmania, Trypanosoma or Sauroleishmania. It was not possible to establish infection in laboratory animals. In vitro culture of mouse peritoneal macrophages revealed the invasion of the host cells by the flagellates and their killing 48 hr after infection. Opportunistic infection with an insect trypanosomatid was suspected. Further hybridization analyses against a pannel of different monoxenous and heteroxenous trypanosomatids showed kDNA cross-homology with Leptomonas pulexsimulantis a trypanosomatid found in the dog's flea

Biochemical characterization of a trypanosomatid isolated from the plant Amaranthus retroflexus

A protozoan flagelate has recently been isolated from Amaranthus retroflexus. This plant grows near economically important crops in southeastern Spain, which are known to be parasitized by Phytomonas spp. The present study focuses on the characterization of the energy metabolism of this new isolate. These flagellates utilize glucose efficiently as their primary energy source, although they are unable to completely degrade it. They excrete ethanol, acetate, glycine, and succinate in lower amount, as well as ammonium. The presence of glycosomes was indicated by the early enzymes of the glycolytic pathway, one enzyme of the glycerol pathway (glycerol kinase), and malate dehydrogenase. No evidence of a fully functional citric-acid cycle was found. In the absence of catalase activity, these flagellates showed significant superoxide dismutase activity located in the glycosomal and cytosolic fractions. These trypanosomes, despite being morphologically and metabolically similar to other Phytomonas isolated from the same area, showed significant differences, suggesting that they are phylogenetically different species.

Molecular adaptability of nucleoside diphosphate kinase b from trypanosomatid parasites: stability, oligomerization and structural determinants of nucleotide binding

Nucleoside diphosphate kinases play a crucial role in the purine-salvage pathway of trypanosomatid protozoa and have been found in the secretome of Leishmania sp., suggesting a function related to host-cell integrity for the benefit of the parasite. Due to their importance for housekeeping functions in the parasite and by prolonging the life of host cells in infection, they become an attractive target for drug discovery and design. In this work, we describe the first structural characterization of nucleoside diphosphate kinases b from trypanosomatid parasites (tNDKbs) providing insights into their oligomerization, stability and structural determinants for nucleotide binding. Crystallographic studies of LmNDKb when complexed with phosphate, AMP and ADP showed that the crucial hydrogen-bonding residues involved in the nucleotide interaction are fully conserved in tNDKbs. Depending on the nature of the ligand, the nucleotide-binding pocket undergoes conformational changes, which leads to different cavity volumes. SAXS experiments showed that tNDKbs, like other eukaryotic NDKs, form a hexamer in solution and their oligomeric state does not rely on the presence of nucleotides or mimetics. Fluorescence-based thermal-shift assays demonstrated slightly higher stability of tNDKbs compared to human NDKb (HsNDKb), which is in agreement with the fact that tNDKbs are secreted and subjected to variations of temperature in the host cells during infection and disease development. Moreover, tNDKbs were stabilized upon nucleotide binding, whereas HsNDKb was not influenced. Contrasts on the surface electrostatic potential around the nucleotide-binding pocket might be a determinant for nucleotide affinity and protein stability differentiation. All these together demonstrated the molecular adaptation of parasite NDKbs in order to exert their biological functions intra-parasite and when secreted by regulating ATP levels of host cells.

Secretory pathway of trypanosomatid parasites

The Trypanosomatidae comprise a large group of parasitic protozoa, some of which cause important diseases in humans. These include Tryanosoma brucei (the causative agent of African sleeping sickness and nagana in cattle), Trypanosoma cruzi (the causative agent of Chagas' disease in Central and South America), and Leishmania spp. (the causative agent of visceral and [muco]cutaneous leishmaniasis throughout the tropics and subtropics). The cell surfaces of these parasites are covered in complex protein- or carbohydrate-rich coats that are required for parasite survival and infectivity in their respective insect vectors and mammalian hosts. These molecules are assembled in the secretory pathway. Recent advances in the genetic manipulation of these parasites as well as progress with the parasite genome projects has greatly advanced our understanding of processes that underlie secretory transport in trypanosomatids. This article provides an overview of the organization of the trypanosomatid secretory pathway and connections that exist with endocytic organelles and multiple lytic and storage vacuoles. A number of the molecular components that are required for vesicular transport have been identified, as have some of the sorting signals that direct proteins to the cell surface or organelles it? the endosome-vacuole system. Finally, the subcellular organization of the major glycosylation pathways in these parasites is reviewed. Studies on these highly divergent eukaryotes provide important insights into the molecular processes underlying secretory transport that arose very early in eukaryotic evolution. They also reveal unusual or novel aspects of secretory), transport and protein glycosylation that may be exploited in developing new antiparasite drugs.

The infectivity of single flagellates of Trypanosoma cruzi

Single organisms of Trypanosoma cruzi of the virulent Peru strain were isolated by direct visualisation and were injected peritoneally into CFI mice. Single trypanomastigotes of different morphology and from different sources (mouse blood, in vitro cufture and bug faeces) were used. Single trypanomastigotes from mouse blood caused parasitaemia and fataiity in a high percentage of mice. This was true irrespective of the morphology (broad or narrow form) of the trypano mastigo tec. Single organisms of the culture forms were also capable of causing infection, although these were less infectious than single trypanomastigotes obtained from mouse blood or the reduviid bug. The difficulties attendant on the performance of the cloning technique are discussed and some indication is given of how these problems can be overcome.

Flagellates in the Malpighian tubules of laboratory-bred Lutzomyia longipalpis fed on a hamster experimentally infected with Leishmania mexicana amazonensis

As a preparatory stage for a study aiming at identifying the species and subspecies of local Leishmania in naturally infected sandflies through immunoradiometric assay with monoclonal antibodies, we tried to obtain experimental infections of phlebotomines with well characterized stocks of parasites, in order to test the effectiveness of the method.

From a mono to a digenetic life-cycle: how was the jump for flagellates of the family trypanosomatidae?

It has been found that species of the digenetic genus Trypanosoma as well as species of monogenetic trypanosomatids of insects can grow in the lumen of the scent glands of opossums reproducing the cycle they perform in the intestinal tract of their insect hosts. Based on these findings, speculations are made on the incompletely known cycles of many mammalian trypanosomes and on the evolution of the family Trypanosomatidae.

The trypanosomatid evolution workshop London School of Hygiene and Tropical Medicine

The trypanosome evolution workshop, a joint meeting of the University of Exeter and the London School of Hygiene and Tropical Medicine, focused on topics relating to trypanosomatid and vector evolution. The meeting, sponsored by The Wellcome Trust, The Special Programme for Research and Training in Tropical Disease of World Health Organization and the British Section of the Society of Protozoologists, brought together an international group of experts who presented papers on a wide range of topics including parasite and vector phylogenies, molecular methodology and relevant biogeographical data.

Insect trypanosomatids: the need to know more

Of ten recognized trypanosomatid genera, only two -- pathogenic Trypanosoma and Leishmania -- have been actively investigated for any length of time while the plant flagellates -- Phytomonas -- have recently begun to attract attention due to their role as agricultural parasites. The remaining genera that comprise parasites associated with insects have been largely neglected except for two or three containing popular isolates. This publication reviews current knowledge of trypanosomatids from insects.