Trypanosoma Research Articles

Efficacy and Mechanisms of α-Solasonine-and α-Solamargine-Induced Cytolysis on Two Strains of Trypanosoma cruzi

Two genetically diverse strains of Trypanosoma cruzi were tested in vitro for susceptibility to the solanum-derived triglycoside alkaloids solasonine and solamargine. Cytolytic assays were performed on epimastigotes (EMs) and bloodstream form trypomastigotes (BSFs) lifecycle stages by using serial dilutions of each alkaloid. Each alkaloid effectively lysed both lifecycle stages, although solasonine routinely required higher concentrations to induce similar results. EMs demonstrated greater resistance to cytolysis than BSFs at equal concentrations of either alkaloid. No significant resistance could be correlated to parasite strain. The reported synergistic cytolytic effects observed upon compounding solasonine and solamargine together were also tested. We failed to identify any cytolytic synergism in cultures of EMs or BSFs. The role of rhamnose-binding proteins (RBPs) in mediating cytolysis was investigated through competitive inhibition experiments. The addition of exogenous L: -rhamnose to the media failed to reduce parasite attrition independent of the parasite lifecycle stage. Based on these results, we suggest the mechanisms involved in cytolysis of T. cruzi by solasonine and solamargine are largely independent of rhamnose receptor-specific interactions. We propose that attrition likely involves less-specific carbohydrate interactions, which lead to the formation and intercalation of sterol complexes into the parasite plasma membrane.

Response of microminerals in serum of sheep infected with Trypanosoma congolense

Twenty (20) Yankassa sheep ages between 12-18 months were infected with fresh stock of Trypanosoma congolense isolated from a cow. Animals were grouped into three; groups A and B were infected while group C served as uninfected controls. Samples between the infected and the uninfected controls showed a high significant levels of calcium (Ca) and iron (Fe) (P 0.05). Generally, values of the contemporaneously uninfected sheep were significantly lower for calcium and iron and higher for phosphorus and copper. Therefore, the increase in concentrations of calcium, iron and phosphorus may suggest that they could have a role in the pathogenesis of trypanosomosis due to T. congolense. Key words: Yankassa sheep, microminerals, T. congolense, pathogensis.

Scoparia dulcis reduces the severity of Trypanosoma brucei-induced hyperlipidaemia in the rabbit

We investigated the effect of oral administration of the herb, Scoparia dulcis, onTrypanosoma brucei-induced changes in plasma lipid profile in rabbits over a period of twenty eight days. Results obtained show that infection with T. bruceiresulted in significant increases in plasma total cholesterol, trriacylglycerol, and low density lipoprotein (LDL)-cholesterol, while the level of high density lipoprotein (HDL)-cholesterol was also significantly reduced. Further comparative analysis of data revealed that these lesions were significantly less severe (p<0.05), in the infected and treated group relative to their untreated counterparts. However, the precise mechanism underlying the plasma lipid modulating effects of the herb is still a matter of speculations. Key words: Scoparia dulcis, Trypanosoma brucei, cholesterol, triacylglycerol lipoproteins.

Role of TbALG3 in N‐linked glycosylation of Trypanosoma brucei

Role of TbALG3 in N‐linked glycosylation of Trypanosoma brucei

Combined contribution of TbAT1 and TbMRPA to drug resistance in Trypanosoma brucei (Short communication)

Combined contribution of TbAT1 and TbMRPA to drug resistance in Trypanosoma brucei (Short communication)

Co-infection with Trypanosoma brucei brucei prevents experimental autoimmune encephalomyelitis in DBA/1 mice through induction of suppressor APCs

The immune system has co-evolved with the infectious agents that challenge it, and in response pathogens have developed different mechanisms to subvert host immunity. A wealth of evidence suggests that infections are important components in the development of a functional immune system, and understanding the modulation of the host immune system by pathogens may offer new therapeutic strategies in a non-infectious setting. We investigated how infection with the protozoan parasite Trypanosoma brucei brucei (Tbb) modulates the autoimmune response to recombinant myelin oligodendrocyte glycoprotein (rMOG) in DBA/1 mice. Mice harbouring a Tbb infection did not develop experimental autoimmune encephalomyelitis (EAE) induced by immunization with rMOG in CFA, an animal model for the human autoimmune disease multiple sclerosis. Additionally, mice infected with the parasite at the time of immunization or 1 week later developed less severe EAE than uninfected controls. Protected mice displayed a markedly diminished rMOG-specific proliferation and IFNgamma production in lymph node cells and had correspondingly low titres of serum anti-rMOG IgG. Antigen-presenting cells (APCs) from spleens of Tbb-infected mice presented rMOG less efficiently to rMOG-specific T cells in vitro than did splenic APCs from uninfected mice and could also inhibit antigen-specific proliferation in control in vitro cultures. This suppressive effect is at least in part due to increased release of IL-10. Transfer of splenic APCs from Tbb-infected mice into mice immunized with rMOG-CFA 7 days previously abrogated disease significantly. These findings indicate that infections can prevent autoimmunity and that APCs might be used as immunomodulants.

Endocytosis, Sorting and Exocytosis of the GPI-anchored VSG in Trypanosoma brucei

Endocytosis, Sorting and Exocytosis of the GPI-anchored VSG in <i>Trypanosoma brucei</i>

TbMP81 is required for RNA editing in Trypanosoma brucei.

Most mitochondrial mRNAs are edited in Trypano soma brucei by a series of steps that are catalyzed by a multienzyme complex that is in its initial stages of characterization. RNA interference (RNAi)-mediated repression of the expression of TbMP81, a zinc finger protein component of the complex, inhibited growth of bloodstream and insect forms, and blocked in vivo RNA editing. This repression preferentially inhibited insertion editing compared with deletion editing in vitro. It resulted in reduced specific endoribonucleolytic cleavage and a greater reduction of U addition and associated RNA ligation activities than U removal and associated RNA ligation activities. The repressed cells retained 20S editing complexes with several demonstrable proteins and adenylatable TbMP52 RNA ligase, but adenlyatable TbMP48 was not detected. Elimination of TbMP48 by RNAi repression did not inhibit cell growth or in vivo editing in either bloodstream or procyclic forms. These results indicate that TbMP81 is required for RNA editing and suggest that the editing complex is functionally partitioned.

Basic cell biology of Trypanosoma cruzi.

The paper reviews basic aspects of the biology of Trypanosoma cruzi emphasizing the following topics: (a) developmental stages of the life cycle in the vertebrate and invertebrate hosts; (b) the cytoskeleton of the protozoan, especially the sub-pellicular microtubules; (c) the flagellum, emphasizing its attachment to the protozoan body through specialized junctions; (d) the kinetoplast-mitochondrion complex, describing its structural organization and the replication of the kinetoplast-DNA; (e) the peroxisome (glycosome) and its role in the metabolism of the cell; (f) the acidocalcisome, describing its morphology, biochemistry and functional role; (g) the cytostome and the endocytic pathway; (h) the organization of the endoplasmic reticulum-Golgi complex; (i) the nucleus, describing its structural organization during interphase and division, and (j) basic aspects of the process of interaction of the parasite with host cells.

Trypanosoma cruzi: infection patterns in intact and athymic mice of susceptible and resistant genotypes.

Inbred strains of mice inoculated with the T cruzi Y strain behaved as susceptible (A/J, C3H/HeN), intermediate (BALB/c) or relatively resistant (C57BL/6) with respect to the magnitude of parasitaemia and mortality rate. C57BL/10 mice were susceptible in relation to parasitaemia but resistant when mortality was analyzed. Infection with T cruzi CL strain presented the same results, except for C57BL/6 which behaved as susceptible mice. Athymic mice of various backgrounds revealed no differences in susceptibility, presenting the same dramatic parasitaemia, tissue colonization pattern and no inflammatory reaction in any of the tissues studied. Infection of euthymic and athymic BALB/c mice elicited the production of parasite-specific antibodies, which reached similar levels on the first 9 days but differed after day 13. Serum transfer experiments in BALB/c mice did not show great differences in parasitaemia but altered T. cruzi polymorphism reducing the slender forms in athymic mice. Histopathology of athymic BALB/c mice showed the same tissue tropism when infected either with T cruzi Y or CL strain.

Bovine trypanosomosis due to Trypanosoma vivax in the German Bush province, Bolivia

Trypanosoma vivax es un hemoparasito encontrado en la region de la mosca tse-tse en Africa. Sin embargo, el se ha difundido a otras partes de Africa, Centro-America, Sud-America, Indias Occidentales e Islas Mauricio. Este trabajo es un relato de la primera occurencia de T. vivax en la provincia de German Bush, Bolivia. T. vivax fue identificado en 45% de los 80 bovinos examinados por el test de microhematocrito. Los sintomas clinicos observados fueran fiebre, anemia, abortos, emagrecimiento progresivo, perdida substancial de peso en tiempo corto y emaciacion progresiva y linfonodos aumentados. Lo resultados de este estudio sugieren que la difusion acelerada de T. vivax podrian representar un serio impacto a la economia de la region

Anti-Trypanosoma cruzi immunoglobulin G1 can be a useful tool for diagnosis and prognosis of human Chagas' disease.

Two functionally distinct antibodies, categorized as conventional serology antibodies (CSA) and lytic antibodies (LA) have been described in Chagas' disease, based on their ability to bind to fixed epimastigotes (EPI) or live trypomastigotes (TRYPO), respectively. In this study, the profile of immunoglobulin G (IgG) subclasses of CSA and LA were analyzed by flow cytometry using serum samples from chronic chagasic patients with the indeterminate (IND), cardiac (CARD), and digestive (DIG) clinical forms of the disease. The results were expressed as percentage of positive fluorescent parasites (PPFP) for each sample. CSA showed a higher PPFP than LA for all samples. At serum dilutions between 1:256 and 1:2,048, IgG1 anti-EPI was able to distinguish chagasic from nonchagasic individuals. Different profiles of IgG subclasses were observed for CSA and LA. IgG1 and IgG2 were the main subclasses in CSA, whereas IgG1 and IgG3 were the predominant ones in LA. The reactivity of IgG2 anti-EPI was greater in IND and CARD than in DIG patients. Furthermore, a low level of IgG1 and IgG3 LA was associated with most of the CARD patients. On the other hand, a high level of IgG1 LA was associated with most of the IND patients. In summary, our findings indicate the potential of IgG1 anti-EPI for serological diagnosis of Chagas' disease, providing further evidence for a protective role of LA, and show that IgG1 anti-live Trypanosoma cruzi TRYPO may be used to predict the risk of cardiac damage in Chagas' disease.

Amplification of a Specific Repetitive DNA Sequence for Trypanosoma rangeli Identification and Its Potential Application in Epidemiological Investigations

Vargas, N., Souto, R. P., Carranza, J. C., Vallejo, G. A., and Zingales, B. 2000. Amplification of a specific repetitive DNA sequence for Trypanosoma rangeli identification and its potential application in epidemiological investigations. Experimental Parasitology 96, 147– 159. Trypanosoma rangeli can infect humans as well as the same domestic and wild animals and triatomine vectors infected by Trypano soma cruzi in Central and South America. This overlapping distribution complicates the epidemiology of American trypanosomiasis due to the cross-reactivity between T. rangeli and T. cruzi antigens and the pres ence of conserved DNA sequences in these parasites. We have isolated a T. rangeli-specific DNA repetitive element which is represented in approximately 103 copies per parasite genome and is distributed in several chromosomal bands. The 542-bp nucleotide sequence of this element, named P542, was determined and a PCR assay was standard ized for its amplification. The sensitivity of the assay is high, allowing the detection of one tenth of the DNA content of a single parasite. The presence of the P542 element was confirmed in 11 T. rangeli isolates from mammalian hosts and insect vectors originating from several countries in Latin America. Negative amplification was ob served with different T. cruzi strains and other trypanosomatids. The potential field application of the P542 PCR assay was investigated in simulated samples containing T. rangeli and/or T. cruzi and intestinal tract and feces of Rhodnius prolixus. Epidemiological studies were conducted in DNA preparations obtained from the digestive tracts of 12 Rhodnius colombiensis insects collected in a sylvatic area in Colombia. Positive amplification of the P542 element was obtained in 9/12 insects. We have also compared in the same samples the diagnostic performance of two PCR assays for the amplification of the variable domain of minicircle kinetoplast DNA (kDNA) and of the large subunit (LSU) of the ribosomal RNA gene of T. cruzi and T. rangeli. Data indicate that the kDNA PCR assay does not allow diagnosis of mixed infections in most insects. On the other hand, the PCR assay of the LSU RNA gene showed lower sensitivity in the detection of T. rangeli than the PCR assay of the P542 element. It is predicted that the use of sensitive detection techniques will indicate that the actual distribution of T. rangeli in America is wider than presumed.

Regulated exocytosis and trypanosome invasion: the unexpected link

Regulated exocytosis and trypanosome invasion: the unexpected link

MGE-PCR: a novel approach to Trypanosome epidemiology

MGE-PCR: a novel approach to Trypanosome epidemiology

The evolution of minicircles and guide RNAs in Trypanosomes

The evolution of minicircles and guide RNAs in Trypanosomes

T-cell repertoire analysis in acute and chronic human Chagas' disease: differential frequencies of Vbeta5 expressing T cells.

Here, we analysed the use of Vbeta-TCR regions by CD4+ and CD8+ T cells from acute and chronic chagasic patients using flow cytometry. We determined the Vbeta expression in cells freshly isolated from patients, as well as after in vitro stimulation with antigens derived from epimastigote (EPI) or trypomastigote (TRYPO) forms of Trypanosoma cruzi. Analysis of Vbeta-TCR expression of T cells freshly isolated from patients showed a decrease in Vbeta5 expression in the CD4+ T-cell population from acutely infected individuals, whereas CD4+Vbeta5+ T cells were found to be increased in chronic patients with the cardiac, but not indeterminate, clinical form. After culturing peripheral blood mononuclear cells (PBMC) from chronic patients with EPI or TRYPO, we found that both antigenic preparations led to a preferential expansion of CD4+Vbeta5+ T cells. EPI stimulation also led to the expansion of CD8+Vbeta5+ T cells, whereas TRYPO led to the expansion of this cell population only if PBMC were from cardiac and not indeterminate patients. We observed that TRYPO stimulation led to an increase in the frequency of CD4+Vbeta17+ T cells in cultures of PBMC from indeterminate patients, whereas an increase in the frequency of CD8+Vbeta17+ T cells was found upon TRYPO stimulation of PBMC from cardiac patients. Despite this increase in the frequency of Vbeta17+ T-cell populations upon TRYPO stimulation, the same antigenic preparation led to a much higher expansion of Vbeta5+ T cells. These results show a differential expression of Vbeta5-TCR in cells freshly isolated from chagasic patients in different stages of the disease and that parasite-specific antigens stimulate a portion of the T-cell repertoire with preferential usage of Vbeta5-TCR.

First isolation of Trypanosoma theileri in Sicilian cattle.

First isolation of Trypanosoma theileri in Sicilian cattle.

A survey of congenital Chagas' disease, carried out at three health institutions in São Paulo City, Brazil.

The congenital transmission of Chagas' disease was evaluated in 57 pregnant women with Chagas' disease and their 58 offspring. The patients were selected from three Health Institutions in São Paulo City. The maternal clinical forms of Chagas' disease were: indeterminate (47.4%), cardiac (43.8%) and digestive (8.8%); 55 were born in endemic areas and two in São Paulo City. The transmission of Chagas' disease at fetal level was confirmed in three (5.17%) of the 58 cases studied and one probably case of congenital Chagas' disease. Two infected infants were born to chagasic women with HIV infection and were diagnosed by parasitological assays (microhematocrit, quantitative buffy coat-QBC or artificial xenodiagnosis). In both cases the placenta revealed T. cruzi and HIV p24 antigens detected by immunohistochemistry. In one case, a 14-week old abortus, the diagnosis of congenital T. cruzi infection was confirmed by immunohistochemistry. The other probable infection, a 30-week old stillborn, the parasites were found in the placenta and umbilical cord. The Western blot method using trypomastigote excreted/secreted antigens of T. cruzi (TESA) was positive for IgG antibodies in 54/55 newborns and for IgM in 1/55 newborns. One of the two newborns with circulating parasites had no detectable IgG or IgM antibodies. The assessment of IgG antibodies in the sera of pregnant women and their newborns was performed by ELISA using two different T. cruzi antigens: an alkaline extract of epimastigotes (EAE) and trypomastigote excreted/secreted antigens (TESA). The analysis showed a linear correlation between maternal and newborn IgG antibody titers at birth.

Entamoeba histolytica: a eukaryote with trypanothione metabolism instead of glutathione metabolism.

Entamoeba histolytica is a human pathogen that lacks the capacity to synthesize glutathione but can incorporate it, from the growth media or presumably from the human host, to form trypanothione [N(1), N(8)-bis(glutathionyl)-spermidine conjugate]. This novel thiol compound has previously been found in trypanosomatids, as has its precursor glutathionyl-spermidine, which was originally detected in Escherichia coli. Previously we showed the presence of these two thiol compounds in extracts from cultures of Entamoeba histolytica HK9. Here we report that when Entamoeba histolytica HK9 is grown in a culture medium that lacks glutathione (treated with the enzyme gamma-glutamyl transpeptidase), trypanothione is not formed, although the trophozoites can continue dividing for at least 60 h but at 25% lower cell density. The finding of a trypanothione metabolism in Entamoeba histolytica raises many questions: one concerns the possibility of a phylogenetic relationship, in this respect, with trypanosomatids such as Trypanosoma cruzi, T. brucei and Crithidia fasciculata; another concerns its role in cell metabolism; a third concerns it possible use as a target for a rational drug design strategy against this parasite.