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1.
Torriceli Souza Thé Renata Siqueira Portella Marcos Lázaro Guerreiro Sonia Gumes Andrade 《Memórias do Instituto Oswaldo Cruz》2013,108(6):691-698
Acute infection with Trypanosoma cruzi results in intense
myocarditis, which progresses to a chronic, asymptomatic indeterminate form. The
evolution toward this chronic cardiac form occurs in approximately 30% of all
cases of T. cruzi infection. Suppression of delayed type
hypersensitivity (DTH) has been proposed as a potential explanation of the
indeterminate form. We investigated the effect of cyclophosphamide (CYCL)
treatment on the regulatory mechanism of DTH and the participation of heart
interstitial dendritic cells (IDCs) in this process using BALB/c mice
chronically infected with T. cruzi. One group was treated with
CYCL (20 mg/kg body weight) for one month. A DTH skin test was performed by
intradermal injection of T. cruzi antigen (3 mg/mL) in the
hind-footpad and measured the skin thickness after 24 h, 48 h and 72 h. The skin
test revealed increased thickness in antigen-injected footpads, which was more
evident in the mice treated with CYCL than in those mice that did not receive
treatment. The thickened regions were characterised by perivascular infiltrates
and areas of necrosis. Intense lesions of the myocardium were present in
three/16 cases and included large areas of necrosis. Morphometric evaluation of
lymphocytes showed a predominance of TCD8 cells. Heart IDCs were immunolabelled
with specific antibodies (CD11b and CD11c) and T. cruzi
antigens were detected using a specific anti-T. cruzi antibody.
Identification of T. cruzi antigens, sequestered in these cells
using specific anti-T. cruzi antibodies was done, showing a
significant increase in the number of these cells in treated mice. These results
indicate that IDCs participate in the regulatory mechanisms of DTH response to
T. cruzi infection. 相似文献
2.
3.
In this study, we evaluated the long-term efficacy of a two-component subunit vaccine against Trypanosoma cruzi infection. C57BL/6 mice were immunized with TcG2/TcG4 vaccine delivered by a DNA-prime/Protein-boost (D/P) approach and challenged with T. cruzi at 120 or 180 days post-vaccination (dpv). We examined whether vaccine-primed T cell immunity was capable of rapid expansion and intercepting the infecting T. cruzi. Our data showed that D/P vaccine elicited CD4+ (30-38%) and CD8+ (22-42%) T cells maintained an effector phenotype up to 180 dpv, and were capable of responding to antigenic stimulus or challenge infection by a rapid expansion (CD8>CD4) with type 1 cytokine (IFNγ+ and TFNα+) production and cytolytic T lymphocyte (CTL) activity. Subsequently, challenge infection at 120 or 180 dpv, resulted in 2-3-fold lower parasite burden in vaccinated mice than was noted in unvaccinated/infected mice. Co-delivery of IL-12- and GMCSF-encoding expression plasmids provided no significant benefits in enhancing the anti-parasite efficacy of the vaccine-induced T cell immunity. Booster immunization (bi) with recombinant TcG2/TcG4 proteins 3-months after primary vaccine enhanced the protective efficacy, evidenced by an enhanced expansion (1.2-2.8-fold increase) of parasite-specific, type 1 CD4+ and CD8+ T cells and a potent CTL response capable of providing significantly improved (3-4.5-fold) control of infecting T. cruzi. Further, CD8+T cells in vaccinated/bi mice were predominantly of central memory phenotype, and capable of responding to challenge infection 4-6-months post bi by a rapid expansion to a poly-functional effector phenotype, and providing a 1.5-2.3-fold reduction in tissue parasite replication. We conclude that the TcG2/TcG4 D/P vaccine provided long-term anti-T. cruzi T cell immunity, and bi would be an effective strategy to maintain or enhance the vaccine-induced protective immunity against T. cruzi infection and Chagas disease. 相似文献
4.
Daniel Sousa-Rocha Mariana Thomaz-Tobias Larissa Figueiredo Alves Diniz Priscila Silva Sampaio Souza Phileno Pinge-Filho Karina Alves Toledo 《PloS one》2015,10(10)
Neutrophils release fibrous traps of DNA, histones, and granule proteins known as neutrophil extracellular traps (NETs), which contribute to microbicidal killing and have been implicated in autoimmunity. The role of NET formation in the host response to nonbacterial pathogens is not well-understood. In this study, we investigated the release of NETs by human neutrophils upon their interaction with Trypanosoma cruzi (Y strain) parasites. Our results showed that human neutrophils stimulated by T. cruzi generate NETs composed of DNA, histones, and elastase. The release occurred in a dose-, time-, and reactive oxygen species-dependent manner to decrease trypomastigote and increase amastigote numbers of the parasites without affecting their viability. NET release was decreased upon blocking with antibodies against Toll-like receptors 2 and 4. In addition, living parasites were not mandatory in the release of NETs induced by T. cruzi, as the same results were obtained when molecules from its soluble extract were tested. Our results increase the understanding of the stimulation of NETs by parasites, particularly T. cruzi. We suggest that contact of T. cruzi with NETs during Chagas’s disease can limit infection by affecting the infectivity/pathogenicity of the parasite. 相似文献
5.
Everton Falc?o de Oliveira Aline Etelvina Casaril Nathália Lopes Fontoura Mateus Paula Guerra Murat Wagner Souza Fernandes Elisa Teruya Oshiro Alessandra Gutierrez de Oliveira Eunice Aparecida Bianchi Galati 《Memórias do Instituto Oswaldo Cruz》2015,110(8):1051-1057
Studies on natural infection by Leishmania spp of sandflies
collected in endemic and nonendemic areas can provide important information on the
distribution and intensity of the transmission of these parasites. This study sought
to investigate the natural infection by Leishmaniain wild female
sandflies. The specimens were caught in the city of Corumbá, state of Mato Grosso do
Sul (Brazil) between October 2012-March 2014, and dissected to investigate
flagellates and/or submitted to molecular analysis to detect
Leishmania DNA. A total of 1,164 females (77.56% of which were
Lutzomyia cruzi) representing 11 species were investigated using
molecular analysis; 126 specimens of Lu. cruziwere dissected and
also submitted to molecular analysis. The infection rate based on the presence of
Leishmania DNA considering all the sandfly species analysed was
0.69%; only Leishmania (Leishmania) amazonensis was identified in
Lu. cruzi by the molecular analysis. The dissections were
negative for flagellates. This is the first record of the presence of L. (L.)
amazonensis DNA in Lu. cruzi, and the first record of
this parasite in this area. These findings point to the need for further
investigation into the possible role of this sandfly as vector of this parasite. 相似文献
6.
Veruska Nogueira de Brito Arleana do Bom Parto Ferreira de Almeida Luciano Nakazato Rosemere Duarte Cladson de Oliveira Souza Valéria Régia Franco Sousa 《Memórias do Instituto Oswaldo Cruz》2014,109(7):899-904
Visceral leishmaniasis (VL) in Brazil is transmitted by the phlebotomine
Lutzomyia longipalpis and in some midwestern regions by
Lutzomyia cruzi. Studies of the phlebotomine fauna, feeding
habits and natural infection rate by Leishmania contribute to
increased understanding of the epidemiological chain of leishmaniases and their
vectorial capacity. Collections were performed in Jaciara, state of Mato Grosso from
2010-2013, during which time 2,011 phlebotomines (23 species) were captured (68.70%
Lu. cruzi and 20.52% Lutzomyia whitmani).
Lu. cruzi females were identified by observing the shapes of the
cibarium (a portion of the mouthpart) and spermatheca, from which samples were
obtained for polymerase chain reaction to determine the rates of natural infection.
Engorged phlebotomines were assessed to identify the blood-meal host by ELISA. A
moderate correlation was discovered between the number of Lu. cruzi
and the temperature and the minimum rate of infection was 6.10%. Twenty-two females
were reactive to the antisera of bird (28%), dog (3.30%) and skunk (1.60%). We
conclude that Lu. cruzi and Lu. whitmani have
adapted to the urban environment in this region and that Lu. cruzi
is the most likely vector of VL in Jaciara. Moreover, maintenance of
Leishmania in the environment is likely aided by the presence of
birds and domestic and synanthropic animals. 相似文献
7.
Ailin Lepletier Vinicius Frias de Carvalho Patricia Machado Rodrigues e Silva Silvina Villar Ana Rosa Pérez Wilson Savino Alexandre Morrot 《PLoS neglected tropical diseases》2013,7(11)
We have previously shown that experimental infection caused by Trypanosoma cruzi
is associated with changes in the hypothalamus-pituitary-adrenal axis. Increased glucocorticoid (GC)
levels are believed to be protective against the effects of acute stress during infection but result
in depletion of CD4+CD8+ thymocytes by apoptosis, driving to thymic
atrophy. However, very few data are available concerning prolactin (PRL), another stress-related
hormone, which seems to be decreased during T. cruzi infection. Considering the
immunomodulatory role of PRL upon the effects caused by GC, we investigated if intrathymic
cross-talk between GC and PRL receptors (GR and PRLR, respectively) might influence T.
cruzi-induced thymic atrophy. Using an acute experimental model, we observed changes in
GR/PRLR cross-activation related with the survival of CD4+CD8+
thymocytes during infection. These alterations were closely related with systemic changes,
characterized by a stress hormone imbalance, with progressive GC augmentation simultaneously to PRL
reduction. The intrathymic hormone circuitry exhibited an inverse modulation that seemed to
counteract the GC-related systemic deleterious effects. During infection, adrenalectomy protected
the thymus from the increase in apoptosis ratio without changing PRL levels, whereas an additional
inhibition of circulating PRL accelerated the thymic atrophy and led to an increase in
corticosterone systemic levels. These results demonstrate that the PRL impairment during infection
is not caused by the increase of corticosterone levels, but the opposite seems to occur.
Accordingly, metoclopramide (MET)-induced enhancement of PRL secretion protected thymic atrophy in
acutely infected animals as well as the abnormal export of immature and potentially autoreactive
CD4+CD8+ thymocytes to the periphery. In conclusion, our findings
clearly show that Trypanosoma cruzi subverts mouse thymus homeostasis by altering
intrathymic and systemic stress-related endocrine circuitries with major consequences upon the
normal process of intrathymic T cell development. 相似文献
8.
Cristiane Varella Lisboa Rafael Veríssimo Monteiro Andreia Fonseca Martins Samantha Cristina das Chagas Xavier Valdirene dos Santos Lima Ana Maria Jansen 《Memórias do Instituto Oswaldo Cruz》2015,110(3):394-402
Here, we present a review of the dataset resulting from the 11-years follow-up of
Trypanosoma cruzi infection in free-ranging populations of
Leontopithecus rosalia (golden lion tamarin) and
Leontopithecus chrysomelas (golden-headed lion tamarin) from
distinct forest fragments in Atlantic Coastal Rainforest. Additionally, we present
new data regarding T. cruzi infection of small mammals (rodents and
marsupials) that live in the same areas as golden lion tamarins and characterisation
at discrete typing unit (DTU) level of 77 of these isolates. DTU TcII was found to
exclusively infect primates, while TcI infected Didelphis aurita and
lion tamarins. The majority of T. cruzi isolates derived from
L. rosalia were shown to be TcII (33 out 42) Nine T.
cruzi isolates displayed a TcI profile. Golden-headed lion tamarins
demonstrated to be excellent reservoirs of TcII, as 24 of 26 T.
cruzi isolates exhibited the TcII profile. We concluded the following:
(i) the transmission cycle of T. cruzi in a same host species and
forest fragment is modified over time, (ii) the infectivity competence of the golden
lion tamarin population fluctuates in waves that peak every other year and (iii) both
golden and golden-headed lion tamarins are able to maintain long-lasting infections
by TcII and TcI. 相似文献
9.
Felipe Gazos-Lopes Mauricio M. Oliveira Lucas V. B. Hoelz Danielle P. Vieira Alexandre F. Marques Ernesto S. Nakayasu Marta T. Gomes Nasim G. Salloum Pedro G. Pascutti Tha?s Souto-Padrón Robson Q. Monteiro Angela H. Lopes Igor C. Almeida 《PLoS neglected tropical diseases》2014,8(8)
Background
Trypanosoma cruzi is the causative agent of the life-threatening Chagas disease, in which increased platelet aggregation related to myocarditis is observed. Platelet-activating factor (PAF) is a potent intercellular lipid mediator and second messenger that exerts its activity through a PAF-specific receptor (PAFR). Previous data from our group suggested that T. cruzi synthesizes a phospholipid with PAF-like activity. The structure of T. cruzi PAF-like molecule, however, remains elusive.Methodology/Principal findings
Here, we have purified and structurally characterized the putative T. cruzi PAF-like molecule by electrospray ionization-tandem mass spectrometry (ESI-MS/MS). Our ESI-MS/MS data demonstrated that the T. cruzi PAF-like molecule is actually a lysophosphatidylcholine (LPC), namely sn-1 C18:1(delta 9)-LPC. Similar to PAF, the platelet-aggregating activity of C18:1-LPC was abrogated by the PAFR antagonist, WEB 2086. Other major LPC species, i.e., C16:0-, C18:0-, and C18:2-LPC, were also characterized in all T. cruzi stages. These LPC species, however, failed to induce platelet aggregation. Quantification of T. cruzi LPC species by ESI-MS revealed that intracellular amastigote and trypomastigote forms have much higher levels of C18:1-LPC than epimastigote and metacyclic trypomastigote forms. C18:1-LPC was also found to be secreted by the parasite in extracellular vesicles (EV) and an EV-free fraction. A three-dimensional model of PAFR was constructed and a molecular docking study was performed to predict the interactions between the PAFR model and PAF, and each LPC species. Molecular docking data suggested that, contrary to other LPC species analyzed, C18:1-LPC is predicted to interact with the PAFR model in a fashion similar to PAF.Conclusions/Significance
Taken together, our data indicate that T. cruzi synthesizes a bioactive C18:1-LPC, which aggregates platelets via PAFR. We propose that C18:1-LPC might be an important lipid mediator in the progression of Chagas disease and its biosynthesis could eventually be exploited as a potential target for new therapeutic interventions. 相似文献10.
Esther Bettiol Marie Samanovic Andrew S. Murkin Jayne Raper Frederick Buckner Ana Rodriguez 《PLoS neglected tropical diseases》2009,3(2)
The development of new drugs against Chagas disease is a priority since the currently available medicines have toxic effects, partial efficacy and are targeted against the acute phase of disease. At present, there is no drug to treat the chronic stage. In this study, we have optimized a whole cell-based assay for high throughput screening of compounds that inhibit infection of mammalian cells by Trypanosoma cruzi trypomastigotes. A 2000-compound chemical library was screened using a recombinant T. cruzi (Tulahuen strain) expressing β-galactosidase. Three hits were selected for their high activity against T. cruzi and low toxicity to host cells in vitro: PCH1, NT1 and CX1 (IC50: 54, 190 and 23 nM, respectively). Each of these three compounds presents a different mechanism of action on intracellular proliferation of T. cruzi amastigotes. CX1 shows strong trypanocidal activity, an essential characteristic for the development of drugs against the chronic stage of Chagas disease where parasites are found intracellular in a quiescent stage. NT1 has a trypanostatic effect, while PCH1 affects parasite division. The three compounds also show high activity against intracellular T. cruzi from the Y strain and against the related kinetoplastid species Leishmania major and L. amazonensis. Characterization of the anti–T. cruzi activity of molecules chemically related to the three library hits allowed the selection of two compounds with IC50 values of 2 nM (PCH6 and CX2). These values are approximately 100 times lower than those of the medicines used in patients against T. cruzi. These results provide new candidate molecules for the development of treatments against Chagas disease and leishmaniasis. 相似文献
11.
Ligia Cristina Kalb Souza Rosana Elisa Gon?alves Gon?alves Pinho Carla Vanessa de Paula Lima Stênio Perdig?o Fragoso Maurilio José Soares 《Memórias do Instituto Oswaldo Cruz》2013,108(5):631-636
Heteroxenic and monoxenic trypanosomatids were screened for the
presence of actin using a mouse polyclonal antibody produced against the entire
sequence of the Trypanosoma cruzi actin gene, encoding a 41.9
kDa protein. Western blot analysis showed that this antibody reacted with a
polypeptide of approximately 42 kDa in the whole-cell lysates of parasites
targeting mammals (T. cruzi, Trypanosoma
brucei and Leishmania major), insects
(Angomonas deanei, Crithidia fasciculata,
Herpetomonas samuelpessoai and Strigomonas
culicis) and plants (Phytomonas serpens). A single
polypeptide of approximately 42 kDa was detected in the whole-cell lysates of
T. cruzi cultured epimastigotes, metacyclic trypomastigotes
and amastigotes at similar protein expression levels. Confocal microscopy showed
that actin was expressed throughout the cytoplasm of all the tested
trypanosomatids. These data demonstrate that actin expression is widespread in
trypanosomatids. 相似文献
12.
Raquel Tayar Nogueira Alanderson Rocha Nogueira Mirian Claudia Souza Pereira Maurício Martins Rodrigues Patrícia Cristina da Costa Neves Ricardo Galler Myrna Cristina Bonaldo 《PloS one》2013,8(3)
Chagas’ disease is a major public health problem affecting nearly 10 million in Latin America. Despite several experimental vaccines have shown to be immunogenic and protective in mouse models, there is not a current vaccine being licensed for humans or in clinical trial against T. cruzi infection. Towards this goal, we used the backbone of Yellow Fever (YF) 17D virus, one of the most effective and well-established human vaccines, to express an immunogenic fragment derived from T. cruzi Amastigote Surface Protein 2 (ASP-2). The cDNA sequence of an ASP-2 fragment was inserted between E and NS1 genes of YF 17D virus through the construction of a recombinant heterologous cassette. The replication ability and genetic stability of recombinant YF virus (YF17D/ENS1/Tc) was confirmed for at least six passages in Vero cells. Immunogenicity studies showed that YF17D/ENS1/Tc virus elicited neutralizing antibodies and gamma interferon (IFN-γ) producing-cells against the YF virus. Also, it was able to prime a CD8+ T cell directed against the transgenic T. cruzi epitope (TEWETGQI) which expanded significantly as measured by T cell-specific production of IFN-γ before and after T. cruzi challenge. However, most important for the purposes of vaccine development was the fact that a more efficient protective response could be seen in mice challenged after vaccination with the YF viral formulation consisting of YF17D/ENS1/Tc and a YF17D recombinant virus expressing the TEWETGQI epitope at the NS2B-3 junction. The superior protective immunity observed might be due to an earlier priming of epitope-specific IFN-γ-producing T CD8+ cells induced by vaccination with this viral formulation. Our results suggest that the use of viral formulations consisting of a mixture of recombinant YF 17D viruses may be a promising strategy to elicit protective immune responses against pathogens, in general. 相似文献
13.
Chiung-Kuang Chen Patricia S. Doyle Liudmila V. Yermalitskaya Zachary B. Mackey Kenny K. H. Ang James H. McKerrow Larissa M. Podust 《PLoS neglected tropical diseases》2009,3(2)
Background
The two front-line drugs for chronic Trypanosoma cruzi infections are limited by adverse side-effects and declining efficacy. One potential new target for Chagas'' disease chemotherapy is sterol 14α-demethylase (CYP51), a cytochrome P450 enzyme involved in biosynthesis of membrane sterols.Methodology/Principal Finding
In a screening effort targeting Mycobacterium tuberculosis CYP51 (CYP51Mt), we previously identified the N-[4-pyridyl]-formamide moiety as a building block capable of delivering a variety of chemotypes into the CYP51 active site. In that work, the binding modes of several second generation compounds carrying this scaffold were determined by high-resolution co-crystal structures with CYP51Mt. Subsequent assays against the CYP51 orthologue in T. cruzi, CYP51Tc, demonstrated that two of the compounds tested in the earlier effort bound tightly to this enzyme. Both were tested in vitro for inhibitory effects against T. cruzi and the related protozoan parasite Trypanosoma brucei, the causative agent of African sleeping sickness. One of the compounds had potent, selective anti–T. cruzi activity in infected mouse macrophages. Cure of treated host cells was confirmed by prolonged incubation in the absence of the inhibiting compound. Discrimination between T. cruzi and T. brucei CYP51 by the inhibitor was largely based on the variability (phenylalanine versus isoleucine) of a single residue at a critical position in the active site.Conclusions/Significance
CYP51Mt-based crystal structure analysis revealed that the functional groups of the two tightly bound compounds are likely to occupy different spaces in the CYP51 active site, suggesting the possibility of combining the beneficial features of both inhibitors in a third generation of compounds to achieve more potent and selective inhibition of CYP51Tc. 相似文献14.
Lisvane Silva Paes Brian Suárez Mantilla Flávia Menezes Zimbres Elisabeth Mieko Furusho Pral Patrícia Diogo de Melo Erich B. Tahara Alicia J. Kowaltowski Maria Carolina Elias Ariel Mariano Silber 《PloS one》2013,8(7)
Over the past three decades, L-proline has become recognized as an important metabolite for trypanosomatids. It is involved in a number of key processes, including energy metabolism, resistance to oxidative and nutritional stress and osmoregulation. In addition, this amino acid supports critical parasite life cycle processes by acting as an energy source, thus enabling host-cell invasion by the parasite and subsequent parasite differentiation. In this paper, we demonstrate that L-proline is oxidized to Δ1-pyrroline-5-carboxylate (P5C) by the enzyme proline dehydrogenase (TcPRODH, E.C. 1.5.99.8) localized in Trypanosoma cruzi mitochondria. When expressed in its active form in Escherichia coli, TcPRODH exhibits a Km of 16.58±1.69 µM and a Vmax of 66±2 nmol/min mg. Furthermore, we demonstrate that TcPRODH is a FAD-dependent dimeric state protein. TcPRODH mRNA and protein expression are strongly upregulated in the intracellular epimastigote, a stage which requires an external supply of proline. In addition, when Saccharomyces cerevisiae null mutants for this gene (PUT1) were complemented with the TcPRODH gene, diminished free intracellular proline levels and an enhanced sensitivity to oxidative stress in comparison to the null mutant were observed, supporting the hypothesis that free proline accumulation constitutes a defense against oxidative imbalance. Finally, we show that proline oxidation increases cytochrome c oxidase activity in mitochondrial vesicles. Overall, these results demonstrate that TcPRODH is involved in proline-dependant cytoprotection during periods of oxidative imbalance and also shed light on the participation of proline in energy metabolism, which drives critical processes of the T. cruzi life cycle. 相似文献
15.
Fabiana Lopes Rocha André Luiz Rodrigues Roque Juliane Saab de Lima Carolina Carvalho Cheida Frederico Gemesio Lemos Fernanda Cavalcanti de Azevedo Ricardo Corassa Arrais Daniele Bilac Heitor Miraglia Herrera Guilherme Mour?o Ana Maria Jansen 《PloS one》2013,8(7)
Little is known on the role played by Neotropical wild carnivores in the Trypanosoma cruzi transmission cycles. We investigated T. cruzi infection in wild carnivores from three sites in Brazil through parasitological and serological tests. The seven carnivore species examined were infected by T. cruzi, but high parasitemias detectable by hemoculture were found only in two Procyonidae species. Genotyping by Mini-exon gene, PCR-RFLP (1f8/Akw21I) and kDNA genomic targets revealed that the raccoon (Procyon cancrivorus) harbored TcI and the coatis (Nasua nasua) harbored TcI, TcII, TcIII-IV and Trypanosoma rangeli, in single and mixed infections, besides four T. cruzi isolates that displayed odd band patterns in the Mini-exon assay. These findings corroborate the coati can be a bioaccumulator of T. cruzi Discrete Typing Units (DTU) and may act as a transmission hub, a connection point joining sylvatic transmission cycles within terrestrial and arboreal mammals and vectors. Also, the odd band patterns observed in coatis’ isolates reinforce that T. cruzi diversity might be much higher than currently acknowledged. Additionally, we assembled our data with T. cruzi infection on Neotropical carnivores’ literature records to provide a comprehensive analysis of the infection patterns among distinct carnivore species, especially considering their ecological traits and phylogeny. Altogether, fifteen Neotropical carnivore species were found naturally infected by T. cruzi. Species diet was associated with T. cruzi infection rates, supporting the hypothesis that predator-prey links are important mechanisms for T. cruzi maintenance and dispersion in the wild. Distinct T. cruzi infection patterns across carnivore species and study sites were notable. Musteloidea species consistently exhibit high parasitemias in different studies which indicate their high infectivity potential. Mesocarnivores that feed on both invertebrates and mammals, including the coati, a host that can be bioaccumulator of T. cruzi DTU’s, seem to take place at the top of the T. cruzi transmission chain. 相似文献
16.
17.
Carlos H Ni?o Nicolás Forero-Baena Luis E Contreras Diana Sánchez-Lancheros Katherine Figarella María H Ramírez 《Memórias do Instituto Oswaldo Cruz》2015,110(7):890-897
The intracellular parasite Trypanosoma cruzi is the aetiological
agent of Chagas disease, a public health concern with an increasing incidence rate.
This increase is due, among other reasons, to the parasite''s drug resistance
mechanisms, which require nicotinamide adenine dinucleotide (NAD+).
Furthermore, this molecule is involved in metabolic and intracellular signalling
processes necessary for the survival of T. cruzi throughout its life
cycle. NAD+ biosynthesis is performed by de novo and
salvage pathways, which converge on the step that is catalysed by the enzyme
nicotinamide mononucleotide adenylyltransferase (NMNAT) (enzyme commission
number: 2.7.7.1). The identification of the NMNAT of T.
cruzi is important for the development of future therapeutic strategies
to treat Chagas disease. In this study, a hypothetical open reading frame (ORF) for
NMNAT was identified in the genome of T. cruzi. The corresponding
putative protein was analysed by simulating structural models. The ORF was amplified
from genomic DNA by polymerase chain reaction and was further used for the
construction of a corresponding recombinant expression vector. The expressed
recombinant protein was partially purified and its activity was evaluated using
enzymatic assays. These results comprise the first identification of an NMNAT in
T. cruzi using bioinformatics and experimental tools and hence
represent the first step to understanding NAD+ metabolism in these
parasites. 相似文献
18.
Rafael Alberto Martínez-Díaz Alexandra Ibá?ez-Escribano Jesús Burillo Lorena de las Heras Gema del Prado M Teresa Agulló-Ortu?o Luis F Julio Azucena González-Coloma 《Memórias do Instituto Oswaldo Cruz》2015,110(5):693-699
Artemisia absinthium is an aromatic and medicinal plant of
ethnopharmacological interest and it has been widely studied. The use ofA.
absinthium based on the collection of wild populations can result in
variable compositions of the extracts and essential oils (EOs). The aim of this paper
is the identification of the active components of the vapour pressure (VP) EO from a
selected and cultivated A. absinthiumSpanish population (T2-11)
against two parasitic protozoa with different metabolic pathways: Trypanosoma
cruzi andTrichomonas vaginalis. VP showed activity on
both parasites at the highest concentrations. The chromatographic fractionation of
the VP T2-11 resulted in nine fractions (VLC1-9). The chemical composition of the
fractions and the antiparasitic effects of fractions and their main compounds suggest
that the activity of the VP is related with the presence
oftrans-caryophyllene and dihydrochamazulene (main components of
fractions VLC1 and VLC2 respectively). Additionally, the cytotoxicity of VP and
fractions has been tested on several tumour and no tumour human cell lines. Fractions
VLC1 and VLC2 were not cytotoxic against the nontumoural cell line HS5, suggesting
selective antiparasitic activity for these two fractions. The VP and fractions
inhibited the growth of human tumour cell lines in a dose-dependent manner. 相似文献
19.
Rosiane V. da Silva Aparecida D. Malvezi Leonardo da Silva Augusto Danielle Kian Vera Lúcia H. Tatakihara Lucy M. Yamauchi Sueli F. Yamada-Ogatta Luiz V. Rizzo Sergio Schenkman Phileno Pinge-Filho 《PloS one》2013,8(7)
Mice infected with Trypanosoma cruzi, the agent of Chagas disease, rapidly develop anemia and thrombocytopenia. These effects are partially promoted by the parasite trans-sialidase (TS), which is shed in the blood and depletes sialic acid from the platelets, inducing accelerated platelet clearance and causing thrombocytopenia during the acute phase of disease. Here, we demonstrate that oral immunization of C57BL/6 mice with Phytomonas serpens, a phytoflagellate parasite that shares common antigens with T. cruzi but has no TS activity, reduces parasite burden and prevents thrombocytopenia and leukopenia. Immunization also reduces platelet loss after intraperitoneal injection of TS. In addition, passive transfer of immune sera raised in mice against P. serpens prevented platelet clearance. Thus, oral exposure to P. serpens attenuates the progression of thrombocytopenia induced by TS from T. cruzi. These findings are not only important for the understanding of the pathogenesis of T. cruzi infection but also for developing novel approaches of intervention in Chagas disease. 相似文献
20.
Alcione Silva de Carvalho Kelly Salom?o Solange Lisboa de Castro Taline Ramos Conde Helena Pereira da Silva Zamith Ernesto Raúl Caffarena Belinda Suzette Hall Shane Robert Wilkinson Núbia Boechat 《Memórias do Instituto Oswaldo Cruz》2014,109(3):315-323
Megazol (7) is a 5-nitroimidazole that is highly active against Trypanosoma
cruzi and Trypanosoma brucei, as well as drug-resistant
forms of trypanosomiasis. Compound 7 is not used clinically due to its mutagenic and
genotoxic properties, but has been largely used as a lead compound. Here, we compared
the activity of 7 with its 4H-1,2,4-triazole bioisostere (8) in
bloodstream forms of T. brucei and T. cruzi and
evaluated their activation by T. brucei type I nitroreductase
(TbNTR) enzyme. We also analysed the cytotoxic and genotoxic
effects of these compounds in whole human blood using Comet and fluorescein
diacetate/ethidium bromide assays. Although the only difference between 7 and 8 is
the substitution of sulphur (in the thiadiazole in 7) for nitrogen (in the triazole
in 8), the results indicated that 8 had poorer antiparasitic activity than 7 and was
not genotoxic, whereas 7 presented this effect. The determination of Vmax indicated
that although 8 was metabolised more rapidly than 7, it bounds to the
TbNTR with better affinity, resulting in equivalent kcat/KM
values. Docking assays of 7 and 8 performed within the active site of a homology
model of the TbNTR indicating that 8 had greater affinity than
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