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Sent on Wednesday, 2010 Mar 10Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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| 1. | Eur J Immunol. 2010 Mar 8. [Epub ahead of print]IL-18, but not IL-15, contributes to the IL-12-dependent induction of NK cell effector functions by Leishmania infantum in vivo.Haeberlein S, Sebald H, Bogdan C, Schleicher U.Microbiology Institute - Clinical Microbiology, Immunology and Hygiene, Friedrich-Alexander-University Erlangen-Nuremberg and University Clinic of Erlangen, Erlangen, Germany. Activation of NK cells is a hallmark of infections with intracellular pathogens. We previously showed that the protozoan parasite Leishmania infantum triggered a rapid NK cell response in mice that required TLR9-positive myeloid DC and IL-12, but no IFN-alpha/beta. Here, we investigated whether IL-15 or IL-18 mediate the activity of IL-12 or function as independent activators of NK cells. In contrast to earlier studies that described IL-15 as crucial for NK cell priming in response to TLR ligands, the expression of IFN-gamma, FasL, perforin and granzyme B by NK cells in L. infantum-infected mice was completely preserved in the absence of IL-15, whereas the proliferative capacity of NK cells was lower than in WT mice. IFN-gamma secretion, cytotoxicity and FasL expression of NK cells from infected IL-18(-/-) mice were significantly reduced compared to controls, but, unlike IL-12, IL-18 was not essential for NK cell effector functions. Part of the NK cell-stimulatory effect of IL-12 was dependent on IL-18. We conclude that IL-15 is not functioning as a universal NK cell priming signal and that IL-18 contributes to the NK cell response in visceral leishmaniasis. The cytokine requirements for NK cell activation appear to differ contingent upon the infectious pathogen. |
| PMID: 20213736 [PubMed - as supplied by publisher] | |
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| 2. | Eur J Immunol. 2010 Mar 8. [Epub ahead of print]Murine visceral leishmaniasis: IgM and polyclonal B-Cell activation lead to disease exacerbation.Deak E, Jayakumar A, Cho KW, Goldsmith-Pestana K, Dondji B, Lambris JD, McMahon-Pratt D.Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, CT, USA. In visceral leishmaniasis, the draining lymph node (DLN) is the initial site for colonization and establishment of infection after intradermal transmission by the sand fly vector; however, little is known about the developing immune response within this site. Using an intradermal infection model, which allows for parasite visceralization, we have examined the ongoing immune responses in the DLN of BALB/c mice infected with L. infantum. Although not unexpected, at early times post-infection there is a marked B cell expansion in the DLN, which persists throughout infection. However, the characteristics of this response were of interest; as early as day 7 post-infection, polyclonal antibodies (TNP, OVA, chromatin) were observed and the levels appeared comparable to the specific anti-leishmania response. Although B-cell-deficient J(h)D BALB/c mice are relatively resistant to infection, neither B-cell-derived IL-10 nor B-cell antigen presentation appear to be primarily responsible for the elevated parasitemia. However, passive transfer and reconstitution of J(h)D BALB/c with secretory immunoglobulins, (IgM or IgG; specific or non-specific immune complexes) results in increased susceptibility to L. infantum infection. Further, J(h)D BALB/c mice transgenetically reconstituted to secrete IgM demonstrated exacerbated disease in comparison to wild type BALB/c mice as early as 2 days post-infection. Evidence suggests that complement activation (generation of C5a) and signaling via the C5aR (CD88) is related to the disease exacerbation caused by IgM rather than cytokine levels (IL-10 or IFN-gamma). Overall these studies indicate that polyclonal B cell activation, which is known to be associated with human visceral leishmaniasis, is an early and intrinsic characteristic of disease and may represent a target for therapeutic intervention. |
| PMID: 20213734 [PubMed - as supplied by publisher] | |
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| 3. | J Infect Dev Ctries. 2010 Mar 8;4(2):114-7.Compararative evaluation of rK9, rK26 and rK39 antigens in the serodiagnosis of Indian visceral leishmaniasis.Mohapatra TM, Singh DP, Sen MR, Bharti K, Sundar S.Dept.of Microbiology, Inst.of Medical Sciences, BHU, Varanasi, India. tmmohapatra2000@yahoo.com. BACKGROUND: This study was designed for comparative evaluation of two relatively newer recombinant hydrophilic antigens, rK9 and rK26 of Leishmania chagasi along with rK39 (a 39-aminoacid-repetitive immunodominant B-cell epitope of kinesin-related antigen from L. chagasi) and crude soluble antigen (CSA) for the serodiagnosis of Indian visceral leishmaniasis (VL) patients by quantitative ELISA. METHODOLOGY: In the present study a total of 80 subjects comprising of 55 confirmed VL cases and 25 endemic controls (EC) were subjected to ELISA using four different antigens, namely rK9, rK26, rK39 and CSA (derived from Leishmania donovani promastigotes). RESULTS: Sensitivity was as follows: 78% (95%CI 63-100%) for rK9, 38% (95%CI 28-59%) for rK26, 100% for rK39, and 80% (95% CI 65-100%) for CSA. The specificity of rK9, rK26, rK39 and CSA was found to be 84% (95%CI 61-100%), 80% (95%CI 56-100%), 96% (95%CI 75-100%) and 72% (95%CI 49-100%), respectively. CONCLUSIONS: rK39 was observed to be the most suitable antigen as compared to rK26 and rK9 whereas rK9 performed better than rK26. Hence rK9 antigen may either be used as an adjunct to rK39 for accurate diagnosis of VL or may be used in the absence or non-availability of rK39 antigen for the serodiagnosis. |
| PMID: 20212344 [PubMed - in process] | |
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| 4. | Exp Parasitol. 2010 Apr;124(4):386-93. Epub 2009 Dec 23.Trypanosoma rangeli: differential expression of ecto-phosphatase activities in response to inorganic phosphate starvation.Dick CF, Dos-Santos AL, Fonseca-de-Souza AL, Rocha-Ferreira J, Meyer-Fernandes JR.Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitária, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil. In this work, we showed that living cells of Trypanosoma rangeli express different ecto-phosphatase activities in response to different inorganic phosphate (Pi) concentrations in the culture medium. The ecto-phosphatase activity from T. rangeli grown at low-Pi concentration was inhibited by the increase of the pH, while the ecto-phosphatase of the cells grown at high Pi concentration was not modulated by the change of the pH of the medium. Okadaic acid inhibited only the ecto-phosphatase activity from cells grown at low-Pi concentration but not the ecto-phosphatase activity from cells grown at high-Pi concentration. Accordingly, phosphatase activity from T. rangeli grown at low Pi concentration was able to hydrolyze P-serine and P-threonine at high rate but not P-tyrosine. The phosphatase activity from T. rangeli grown at high-Pi concentration was able to hydrolyze P-serine, P-threonine and P-tyrosine with the same rate. The addition of anterior midgut homogenate of Rhodnius prolixus on the epimastigotes suspension inhibited the enzyme activity of T. rangeli grown at low-Pi concentration. On the other hand, anterior midgut homogenate had no effect in the ecto-phosphatase of T. rangeli maintained at high-Pi concentration. Altogether, the results described here indicate that ecto-phosphatase activities hydrolyzing phosphorylated compounds present in the extracellular medium of T. rangeli are regulated by the external Pi concentration. Copyright 2010 Elsevier Inc. All rights reserved. |
| PMID: 20034491 [PubMed - indexed for MEDLINE] | |
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| 5. | Glycobiology. 2009 Dec;19(12):1462-72. Epub 2009 Aug 20.Sorting of phosphoglucomu tase to glycosomes in Trypanosoma cruzi is mediated by an internal domain.Penha LL, Sant'Anna CB, Mendonça-Previato L, Cunha-e-Silva NL, Previato JO, Lima AP.Instituto de Biofísica Carlos Chagas Filho, Centro de Ciências da Saúde, Bloco G, Universidade Federal do Rio de Janeiro, 21 944 970, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, Brazil. Trypanosoma cruzi relies on highly galactosylated molecules as virulence factors and the enzymes involved in sugar biosynthesis are potential therapeutic targets. The synthesis of UDP-galactose in T. cruzi requires the activity of phosphoglucomutase (PGM), the enzyme that catalyzes the interconversion of glucose-6-phosphate and glucose-1-phosphate. Several enzymes that participate in carbohydrate metabolism in trypanosomes are confined to specialized peroxisome-like organelles called glycosomes. The majority of glycosomal proteins contain peroxisome-targeting signals (PTS) at the COOH- or at the amino-terminus, which drive their transport to glycosomes. We had previously identified the T. cruzi PGM gene (TcPGM) and demonstrated that it encodes a functional enzyme. Here, we show that, in contrast to yeast and mammalian cells, TcPGM resides in glycosomes of the parasite. However, no classical PTS1 or PTS2 motif is present in its sequence. We investigated glycosomal targeting by generating T. cruzi cell lines expressing different domains of TcPGM fused to the green fluorescent protein (GFP). The analysis of the subcellular localization of fusion proteins revealed that an internal targeting signal of TcPGM, residing between amino acid residues 260 and 380, is capable of targeting GFP to glycosomes. These results demonstrate that, in T. cruzi, PGM import into glycosomes is mediated by a novel non-PTS domain that is located internally in the protein. |
| PMID: 19696235 [PubMed - indexed for MEDLINE] | |
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| 6. | PLoS Negl Trop Dis. 2009;3(3):e392. Epub 2009 Mar 17.The population structure of Glossina palpalis gambiensis from island and continental locations in Coastal Guinea.Solano P, Ravel S, Bouyer J, Camara M, Kagbadouno MS, Dyer N, Gardes L, Herault D, Donnelly MJ, De Meeûs T.CIRDES/IRD UMR 177 IRD-CIRAD, Bobo-Dioulasso, Burkina Faso. solano@ird.bf BACKGROUND: We undertook a population genetics analysis of the tsetse fly Glossina palpalis gambiensis, a major vector of sleeping sickness in West Africa, using microsatellite and mitochondrial DNA markers. Our aims were to estimate effective population size and the degree of isolation between coastal sites on the mainland of Guinea and Loos Islands. The sampling locations encompassed Dubréka, the area with the highest Human African Trypanosomosis (HAT) prevalence in West Africa, mangrove and savannah sites on the mainland, and two islands, Fotoba and Kassa, within the Loos archipelago. These data are discussed with respect to the feasibility and sustainability of control strategies in those sites currently experiencing, or at risk of, sleeping sickness. PRINCIPAL FINDINGS: We found very low migration rates between sites except between those sampled around the Dubréka area that seems to contain a widely dispersed and panmictic population. In the Kassa island samples, various effective population size estimates all converged on surprisingly small values (10<N(e)<30) that suggest either a recent bottleneck, and/or other biological or ecological factors such as strong variance in the reproductive success of individuals. CONCLUSION/SIGNIFICANCE: Whatever their origin, the small effective population sizes suggest high levels of inbreeding in tsetse flies within the island samples in marked contrast to the large diffuse deme in Dubréka zones. We discuss how these genetic results suggest that different tsetse control strategies should be applied on the mainland and islands. PMCID: PMC2652410 |
| PMID: 19290038 [PubMed - indexed for MEDLINE] | |
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| 7. | PLoS Negl Trop Dis. 2009;3(3):e387. Epub 2009 Mar 3.Influence of Ecto-nucleoside triphosphate diphosphohydrolase activity on Trypanosoma cruzi infectivity and virulence.Santos RF, Pôssa MA, Bastos MS, Guedes PM, Almeida MR, Demarco R, Verjovski-Almeida S, Bahia MT, Fietto JL.Núcleo de Pesquisa em Ciências Biológicas Universidade Federal de Ouro Preto, Minas Gerais, Brazil. BACKGROUND: The protozoan Trypanosoma cruzi is the causative agent of Chagas disease. There are no vaccines or effective treatment, especially in the chronic phase when most patients are diagnosed. There is a clear necessity to develop new drugs and strategies for the control and treatment of Chagas disease. Recent papers have suggested the ecto-nucleotidases (from CD39 family) from pathogenic agents as important virulence factors. In this study we evaluated the influence of Ecto-Nucleoside-Triphosphate-Diphosphohydrolase (Ecto-NTPDase) activity on infectivity and virulence of T. cruzi using both in vivo and in vitro models. METHODOLOGY/PRINCIPAL FINDINGS: We followed Ecto-NTPDase activities of Y strain infective forms (trypomastigotes) obtained during sequential sub-cultivation in mammalian cells. ATPase/ADPase activity ratios of cell-derived trypomastigotes decreased 3- to 6-fold and infectivity was substantially reduced during sequential sub-cultivation. Surprisingly, at third to fourth passages most of the cell-derived trypomastigotes could not penetrate mammalian cells and had differentiated into amastigote-like parasites that exhibited 3- to 4-fold lower levels of Ecto-NTPDase activities. To evidence the participation of T. cruzi Ecto-NTPDase1 in the infective process, we evaluated the effect of known Ecto-ATPDase inhibitors (ARL 67156, Gadolinium and Suramin), or anti-NTPDase-1 polyclonal antiserum on ATPase and ADPase hydrolytic activities in recombinant T. cruzi NTPDase-1 and in live trypomastigotes. All tests showed a partial inhibition of Ecto-ATPDase activities and a marked inhibition of trypomastigotes infectivity. Mice infections with Ecto-NTPDase-inhibited trypomastigotes produced lower levels of parasitemia and higher host survival than with non-inhibited control parasites. CONCLUSIONS/SIGNIFICANCE: Our results suggest that Ecto-ATPDases act as facilitators of infection and virulence in vitro and in vivo and emerge as target candidates in chemotherapy of Chagas disease. PMCID: PMC2644763 |
| PMID: 19255624 [PubMed - indexed for MEDLINE] | |
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| 8. | Glycoconj J. 2009 Nov;26(8):915-21.Proteomic scale high-sensitivity analyses of GPI membrane anchors.Mehlert A, Ferguson MA.Division of Biological Chemistry and Drug Discovery, College of Life Sciences, Wellcome Trust Biocentre, University of Dundee, Dundee DD1 5EH, UK. Glycosylphosphatidylinositol (GPI) anchored proteins are ubiquitous in eukaryotic cells. Earlier analysis methods required large amounts of purified protein to elucidate the structure of the GPI. This paper describes methods for analyzing GPIs on a 'proteomic' scale. Partially purified proteins may be run on sodium dodecyl sulphate polyacrylamide gel electrophoresis and then blotted onto a polyvinylidene difluoride (PVDF) membrane. Following identification of the protein the piece of PVDF may be subjected to various chemical treatments, which are specific for GPI structures. The first method uses gas chromatography-mass spectrometry and it enables the presence of a GPI anchor to be confirmed. The second method depends on the cleavage of phosphate bonds and permits the carbohydrate structure to be elucidated by electrospray or matrix assisted laser desorption ionization-time of flight mass spectrometry. The final method described uses deamination of the glucosamine residue to release the lipid moiety for analysis by mass spectrometry. PMCID: PMC2791486 |
| PMID: 18330699 [PubMed - indexed for MEDLINE] | |
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