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Sent on Wednesday, 2011 Sep 21Search kinetoplastids OR kinetoplastid OR Kinetoplastida OR "trypanosoma brucei" OR leishmania OR brucei OR leishmaniasis OR "African trypanosomiasis"
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| PubMed Results |
| 1. | PLoS Negl Trop Dis. 2011 Sep;5(9):e1323. Epub 2011 Sep 13.Luciferase-Expressing Leishmania infantum Allows the Monitoring of Amastigote Population Size, In Vivo, Ex Vivo and In Vitro.Michel G, Ferrua B, Lang T, Maddugoda MP, Munro P, Pomares C, Lemichez E, Marty P.SourceUniversité de Nice-Sophia Antipolis, Faculté de Médecine, Nice, France. AbstractHere we engineered transgenic Leishmania infantum that express luciferase, the objectives being to more easily monitor in real time their establishment either in BALB/c mice-the liver and spleen being mainly studied-or in vitro. Whatever stationary phase L. infantum promastigotes population-wild type or engineered to express luciferase-the parasite burden was similar in the liver and the spleen at day 30 post the intravenous inoculation of BALB/c mice. Imaging of L. infantum hosting BALB/C mice provided sensitivity in the range of 20,000 to 40,000 amastigotes/mg tissue, two tissues-liver and spleen-being monitored. Once sampled and processed ex vivo for their luciferin-dependent bioluminescence the threshold sensitivity was shown to range from 1,000 to 6,000 amastigotes/mg tissue. This model further proved to be valuable for in vivo measurement of the efficiency of drugs such as miltefosine and may, therefore, additionally be used to evaluate vaccine-induced protection. |
| 2. | PLoS Negl Trop Dis. 2011 Sep;5(9):e1310. Epub 2011 Sep 13.High-throughput analysis of synthetic peptides for the immunodiagnosis of canine visceral leishmaniasis.Faria AR, Costa MM, Giusta MS, Grimaldi G Jr, Penido ML, Gazzinelli RT, Andrade HM.SourceDepartamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brasil. AbstractBACKGROUND:Visceral leishmaniasis is the most severe form of leishmaniasis. Approximately 20% of zoonotic human visceral leishmaniasis worldwide is caused by Leishmania infantum, which is also known as Leishmania chagasi in Latin America, and disease incidence is increasing in urban and peri-urban areas of the tropics. In this form of disease, dogs are the main reservoirs. Diagnostic methods used to identify Leishmania infected animals are not able to detect all of the infected ones, which can compromise the effectiveness of disease control. Therefore, to contribute to the improvement of diagnostic methods for canine visceral leishmaniasis (CVL), we aimed to identify and test novel antigens using high-throughput analysis. METHODOLOGY/PRINCIPAL FINDINGS:Immunodominant proteins from L. infantum were mapped in silico to predict B cell epitopes, and the 360 predicted peptides were synthesized on cellulose membranes. Immunoassays were used to select the most reactive peptides, which were then investigated with canine sera. Next, the 10 most reactive peptides were synthesized using solid phase peptide synthesis protocol and tested using ELISA. The sensitivity and specificity of these peptides were also compared to the EIE-LVC Bio-Manguinhos kit, which is recommended by the Brazilian Ministry of Health for use in leishmaniasis control programs. The sensitivity and specificity of the selected synthesized peptides was as high as 88.70% and 95.00%, respectively, whereas the EIE-LVC kit had a sensitivity of 13.08% and 100.00% of specificity. Although the tests based on synthetic peptides were able to diagnose up to 94.80% of asymptomatic dogs with leishmaniasis, the EIE-LVC kit failed to detect the disease in any of the infected asymptomatic dogs. CONCLUSIONS/SIGNIFICANCE:Our study shows that ELISA using synthetic peptides is a technique with great potential for diagnosing CVL; furthermore, the use of these peptides in other diagnostic methodologies, such as immunochromatographic tests, could be beneficial to CVL control programs. |
| 3. | PLoS Negl Trop Dis. 2011 Sep;5(9):e1296. Epub 2011 Sep 13.Serological Markers of Sand Fly Exposure to Evaluate Insecticidal Nets against Visceral Leishmaniasis in India and Nepal: A Cluster-Randomized Trial.Gidwani K, Picado A, Rijal S, Singh SP, Roy L, Volfova V, Andersen EW, Uranw S, Ostyn B, Sudarshan M, Chakravarty J, Volf P, Sundar S, Boelaert M, Rogers ME.SourceBanaras Hindu University, Varanasi, India. AbstractBACKGROUND:Visceral leishmaniasis is the world' second largest vector-borne parasitic killer and a neglected tropical disease, prevalent in poor communities. Long-lasting insecticidal nets (LNs) are a low cost proven vector intervention method for malaria control; however, their effectiveness against visceral leishmaniasis (VL) is unknown. This study quantified the effect of LNs on exposure to the sand fly vector of VL in India and Nepal during a two year community intervention trial. METHODS:As part of a paired-cluster randomized controlled clinical trial in VL-endemic regions of India and Nepal we tested the effect of LNs on sand fly biting by measuring the antibody response of subjects to the saliva of Leishmania donovani vector Phlebotomus argentipes and the sympatric (non-vector) Phlebotomus papatasi. Fifteen to 20 individuals above 15 years of age from 26 VL endemic clusters were asked to provide a blood sample at baseline, 12 and 24 months post-intervention. RESULTS:A total of 305 individuals were included in the study, 68 participants provided two blood samples and 237 gave three samples. A random effect linear regression model showed that cluster-wide distribution of LNs reduced exposure to P. argentipes by 12% at 12 months (effect 0.88; 95% CI 0.83-0.94) and 9% at 24 months (effect 0.91; 95% CI 0.80-1.02) in the intervention group compared to control adjusting for baseline values and pair. Similar results were obtained for P. papatasi. CONCLUSIONS:This trial provides evidence that LNs have a limited effect on sand fly exposure in VL endemic communities in India and Nepal and supports the use of sand fly saliva antibodies as a marker to evaluate vector control interventions. |
| 4. | PLoS Pathog. 2011 Sep;7(9):e1002229. Epub 2011 Sep 8.Restoration of IFNγR Subunit Assembly, IFNγ Signaling and Parasite Clearance in Leishmania donovani Infected Macrophages: Role of Membrane Cholesterol.Sen S, Roy K, Mukherjee S, Mukhopadhyay R, Roy S.SourceDivision of Infectious Diseases and Immunology, Indian Institute of Chemical Biology, Council of Scientific and Industrial Research, Kolkata, India. AbstractDespite the presence of significant levels of systemic Interferon gamma (IFNγ), the host protective cytokine, Kala-azar patients display high parasite load with downregulated IFNγ signaling in Leishmania donovani (LD) infected macrophages (LD-MØs); the cause of such aberrant phenomenon is unknown. Here we reveal for the first time the mechanistic basis of impaired IFNγ signaling in parasitized murine macrophages. Our study clearly shows that in LD-MØs IFNγ receptor (IFNγR) expression and their ligand-affinity remained unaltered. The intracellular parasites did not pose any generalized defect in LD-MØs as IL-10 mediated signal transducer and activator of transcription 3 (STAT3) phosphorylation remained unaltered with respect to normal. Previously, we showed that LD-MØs are more fluid than normal MØs due to quenching of membrane cholesterol. The decreased rigidity in LD-MØs was not due to parasite derived lipophosphoglycan (LPG) because purified LPG failed to alter fluidity in normal MØs. IFNγR subunit 1 (IFNγR1) and subunit 2 (IFNγR2) colocalize in raft upon IFNγ stimulation of normal MØs, but this was absent in LD-MØs. Oddly enough, such association of IFNγR1 and IFNγR2 could be restored upon liposomal delivery of cholesterol as evident from the fluorescence resonance energy transfer (FRET) experiment and co-immunoprecipitation studies. Furthermore, liposomal cholesterol treatment together with IFNγ allowed reassociation of signaling assembly (phospho-JAK1, JAK2 and STAT1) in LD-MØs, appropriate signaling, and subsequent parasite killing. This effect was cholesterol specific because cholesterol analogue 4-cholestene-3-one failed to restore the response. The presence of cholesterol binding motifs [(L/V)-X(1-5)-Y-X(1-5)-(R/K)] in the transmembrane domain of IFNγR1 was also noted. The interaction of peptides representing this motif of IFNγR1 was studied with cholesterol-liposome and analogue-liposome with difference of two orders of magnitude in respective affinity (K(D): 4.27×10(-9) M versus 2.69×10(-7) M). These observations reinforce the importance of cholesterol in the regulation of function of IFNγR1 proteins. This study clearly demonstrates that during its intracellular life-cycle LD perturbs IFNγR1 and IFNγR2 assembly and subsequent ligand driven signaling by quenching MØ membrane cholesterol. |
| 5. | Iran J Immunol. 2011 Sep;8(3):150-8.Validation of a β-ME ELISA for Detection of Anti Leishmania donovani Antibodies in Eastern Sudan.Abass E, Mahamoud A, Mansour D, Mohebali M, El Harith A.SourceProfessor emeritus of Microbiology, Ahfad University for Women, Omdurman, Sudan, e-mail: harith17@yahoo.com. AbstractBackground: A β-mercaptoethnol (β-ME)-treated promastigote antigen of L. donovani was successfully employed in direct agglutination test (DAT) for the diagnosis of visceral leishmaniasis (VL). Objective: The β-ME-treated antigen was further incorporated into an enzyme-linked immunosorbent assay set-up (β-ME ELISA) and evaluated for VL diagnosis against outcome of reference freeze-dried DAT (FD-DAT) and rK39 strip test (RKT) commercial kits. Methods: Two-hundred and ninety-two sera from patients with high VL suspicion of whom 105 had confirmed L. donovani infection were tested. Results: Relatively higher sensitivities of 93.3% (95% CI: 88.4-98.2) and 92.4% (95% CI: 87.3-97.5) were determined for β-ME ELISA and FD-DAT as compared to 83.8% (95% CI: 76.7-90.8) for RKT. Of 73 VL sera that scored maximum absorbance values (>0.81) in β-ME ELISA, 66 (90.4%) tested at the highest agglutination titres (>1:51200) in FD-DAT as did 56 (76.7%) also at comparable reaction intensities (3 + colour intensity) in RKT. Compared with FD-DAT (94.7%, 95% CI: 91.5-97.9) or RKT (93.0%, 95% CI: 89.3-96.6), lower specificity was estimated for β-ME ELISA (90.4%, 95% CI: 86.1-94.6). Based both on positive and negative microscopy for L. donovani in organ aspirates of all VL suspects enrolled (292), significantly higher correlation (p<0.01, 0.919) was established between β-ME ELISA and FD-DAT than between β-ME ELISA and RKT (p<0.01, 0.824). Taking into calculation the combined estimates of sensitivity, specificity, positive and negative predictive values, higher agreement (94.8%) was determined between total performance of β-ME ELISA and FD-DAT than between that of β-ME ELISA and RKT (90.7%). Conclusion: Based on results and merits discussed, we recommend application of this β-ME ELISA both for diagnosis of VL at laboratory level and confirmation of results obtained with DAT or RKT in the field. |
| 6. | Ann Trop Med Parasitol. 2011 Jul;105(5):373-83.Evaluation of TNF-α, IL-4, and IL-10 and parasite density in spleen and liver of L. (L.) chagasi naturally infected dogs.DE F Michelin A, Perri SH, De Lima VM.SourceUniversidade Estadual Paulista, Via de Acesso Professor Paulo Donato Castellane s/n ZIP 14884- 900, Jaboticabal, Sa˜o Paulo, Brazil. AbstractDogs are the main domestic reservoirs of L. (L.) chagasi. Once in the vertebrate host, the parasite can cause visceral leishmaniasis, which can also be transmitted to humans. Cytokines are key elements of the host immune response against Leishmania spp. To investigate whether tumor necrosis factor (TNF)-α, interleukin (IL)-4 and IL-10 are associated with pattern infection in dogs, these cytokines were quantified in the spleen and liver of dogs naturally infected with L. (L.) chagasi, with or without clinical manifestations, and their levels were correlated with the parasite load verified in these organs. A total of 40 adult dogs naturally infected with L. (L.) chagasi were assessed, together with 12 uninfected control dogs. Samples from spleen and liver were used to determine the cytokine levels by capture ELISA and for quantifying parasite load by real-time PCR. Statistical analysis was performed using the minimum Chi square method and group means were compared using the Tukey test. TNF-α, IL-4 and IL-10 levels in infected dogs were higher than in control groups; the liver was the main cytokine-producing organ during infection. The level of splenic TNF-α showed correlation with parasite load and may represent an important marker for infection process evolution, with the participation of IL-10. These results may contribute to a clearer understanding of the immune response in dogs infected with L. (L.) chagasi, which may lead to the development of prophylactic or preventive measures for these animals. |
| 7. | Parasite Immunol. 2011 Sep 19. doi: 10.1111/j.1365-3024.2011.01334.x. [Epub ahead of print]Evaluation of an ELISA assay for canine leishmaniasis immunodiagnostic using recombinant proteins.de Souza CM, Silva ED, Ano Bom AP, Bastos RC, Nascimento HJ, Silva Junior JG.SourceLaboratório de Tecnologia Diagnóstica, Instituto de Tecnologia em Imunobiológicos, Fundação Oswaldo Cruz, RJ, Brazil Laboratório de Macromoléculas, Instituto de Tecnologia em Imunobiológicos, Fundação Oswaldo Cruz, RJ, Brazil. AbstractThe present work describes the isolation and purification of two Leishmania chagasi (= syn. Leishmania infantum) recombinant proteins, rLci2B and rLci1A, and their use in the development of an immunoassay for the diagnostic of canine leismaniasis. After protein expression and cell disruption, rLci2B was purified by immobilized metal affinity chromatography followed by size exclusion chromatography, whereas rLci1A, expressed as an inclusion body, was treated with urea and purified by anion exchange chromatography. Homogeneities were ascertained by denaturing gel electrophoresis (MW (rLci2B) = 46370; MW(rLci1A) = 88400), isoelectric focusing (pI (rLci2B) = 5.91; pI (rLci1A) = 6.01) and western blot. An indirect ELISA assay was developed using the purified antigens rLci2B and rLci1A and a leismaniasis canine serum panel (n = 256). The ELISA showed 100% sensitivity and 95% specificity for rLci2B and 96% sensitivity and 92% specificity for rLci1A. The purified proteins did not present cross-reactivity with sera from dogs infected with Trypanosoma caninum, Babesia canis and Ehrlichia canis. Cross-reaction was verified with sera from dogs infected with Leishmania braziliensis (11.7% for rLci2B and 2.9% for rLci1A). Based on ELISA results it is suggested the use of rLci2B and rLci1A as antigens in an alternative serological assay for diagnostic of canine leishmania. Copyright © 2011 Blackwell Publishing Ltd. |
| 8. | Anal Chem. 2011 Sep 19. [Epub ahead of print]Towards Global Metabolomics Analysis with Liquid Chromatography-Mass Spectrometry: Improved Metabolite Identification by Retention Time Prediction.Creek DJ, Jankevics A, Breitling R, Watson DG, Barrett MP, Burgess KE.AbstractMetabolomics is an emerging field of postgenomic biology concerned with comprehensive analysis of small molecules in biological systems. However, difficulties associated with the identification of detected metabolites currently limit its application. Here we demonstrate that a retention time prediction model can improve metabolite identification on a hydrophilic interaction chromatography - high resolution mass spectrometry metabolomics platform. A Quantitative Structure Retention Relationship (QSRR) model, incorporating six physicochemical variables in a multiple-linear regression based on 120 authentic standard metabolites, shows good predictive ability for retention times of a range of metabolites (cross-validated R2 = 0.82 and mean squared error = 0.14). The predicted retention times improved metabolite identification by removing 40% of the false identifications that occurred with identification by accurate mass alone. The importance of this procedure was demonstrated by putative identification of 690 metabolites in extracts of the protozoan parasite Trypanosoma brucei, thus allowing identified metabolites to be mapped onto an organism-wide metabolic network, providing opportunities for future studies of cellular metabolism from a global systems biology perspective. |
| 9. | Vet Parasitol. 2011 May 31;178(1-2):9-14. Epub 2011 Jan 11.Activities of adenine nucleotide and nucleoside degradation enzymes in platelets of rats infected by Trypanosoma evansi.Oliveira CB, Da Silva AS, Vargas LB, Bitencourt PE, Souza VC, Costa MM, Leal CA, Moretto MB, Leal DB, Lopes ST, Monteiro SG.SourceDepartment of Microbiology and Parasitology, Universidade Federal de Santa Maria, Brazil. camilabelmontevet@yahoo.com.br AbstractNucleotide and nucleoside-degrading enzymes, such as nucleoside triphosphate diphosphohydrose (NTPDase), 5'-nucleotidase and adenosine deaminase (ADA) are present in the surface membranes of platelets, involved in clotting disturbances of Trypanosoma evansi-infected animals. Thus, this study was aimed at evaluating the activities of these enzymes in platelets of rats experimentally infected with T. evansi. Animals were divided into four groups, according to the level of parasitemia. Blood samples were collected on days 3 (group A: at the beginning of parasitemia), 5 (group B: high parasitemia) and 15 (group C: chronic infection), post-infection. Group D (control group) was composed of non-infected animals for platelet count, separation and enzymatic assays. Animals from groups A and B showed marked thrombocytopenia, but platelet count was not affected in chronically infected rats. NTPDase, 5'-nucleotidase and ADA activities decreased (p<0.05) in platelets from rats of groups A and B, when compared to the control group. In group C, only NTPDase and 5'-nucleoside activities decreased (p<0.001). The correlations between platelet count and nucleotide/nucleoside hydrolysis were positive and statistically significant (p<0.05) in groups A and B. Platelet aggregation was decreased in all infected groups, in comparison to the control group (p<0.05). It is concluded that the alterations observed in the activities of NTPDase, 5'-nucleotidase and ADA in platelets of T. evansi-infected animals might be related to thrombocytopenia, that by reducing the number of platelets, there was less release of ATP and ADP. Another possibility being suggested is that changes have occurred in the membrane of these cells, decreasing the expression of these enzymes in the cell membrane. Copyright © 2011 Elsevier B.V. All rights reserved. |
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