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1.
The objective of the research was to test the hamster for a model of transmission of congenital toxoplasmosis. A non-invasive method for the diagnosis of pregnancy in hamsters was designed, with a specificity and a sensitivity of 70.2 and 94.7%, respectively (n = 168). Of 32 females with a chronic toxoplasma infection, 3 transmitted Toxoplasma congenitally during their first pregnancy, but not during the subsequent pregnancy. Congenital transmission rates of infections initiated during pregnancy with 2 stages of 2 strains of Toxoplasma were in the range of 33 to 100% of the 76 females inoculated. Only 1 of 17 females transmitted the parasite exclusively via milk. It was concluded that the hamster is a promising species for a model of transmission of congenital toxoplasmosis. 相似文献
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D.J.P. Ferguson 《International journal for parasitology》2009,39(8):871-869
The first clue to the elucidation of the complete life cycle of Toxoplasma gondii was the identification of an infectious form in cat faeces that could be transmitted orally and could survive in the external environment for extended periods. This personal review describes the scientist (W.M. Hutchison) and the background to the initial discovery and covers the period to the complete elucidation of the life cycle of T. gondii. 相似文献
4.
Érica S. Martins-Duarte Wanderley de Souza Rossiane C. Vommaro 《Experimental parasitology》2010,124(4):466-469
Toxoplasma gondii is an important opportunistic pathogen affecting immunocompromised patients with AIDS. Toxoplasmic encephalitis is responsible for high morbidity and mortality. In this study, we investigated the activity of the antifungals fluconazole (FLZ) and itraconazole (ITZ) against T. gondii in mice infected with the Me49 strain. As previously reported for ITZ, FLZ also demonstrated a selective effect against T. gondii in vitro; the IC50 values obtained for FLZ were 8.9 μM and 3.1 μM after 24 h and 48 h of treatment, respectively. A 10-day treatment of mice with orally or intraperitoneally administered 20 mg/kg/day FLZ showed a significant survival difference compared to untreated mice. The administration of 20 mg/kg/day ITZ significantly reduced the brain cyst burden compared to untreated mice but did not exert significant protection against death. The results obtained in this work are rather promising as ITZ and FLZ are safe and low-cost drugs available on the market. 相似文献
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Konstantinos I. Terpsidis Margarita G. Papazahariadou Nikolaos G. Papaioannou Ioannis Th. Theodoridis 《Experimental parasitology》2009,121(3):238-241
Toxoplasma gondii is a protozoan parasite that is globally widespread and infects man and animals. With the aim of studying the influence of toxoplasmosis on male reproductive parameters, we investigated sperm motility, concentration and morphology of male rats experimentally infected by T. gondii. The GT F1 strain of T. gondii tissue cysts were fed at a dose of 5 × 103 tissue cysts per rat by oral gavage in an experimental group of 42 healthy adult male Wistar rats, while 42 male rats were used as controls. On days 10, 20, 30, 40, 50 and 60 post-inoculation (p.i.) 7 rats from each group were anesthetized. The body weight of each animal was recorded, then epididymis and testes were immediately removed, weighed and semen evaluation was undertaken. Weight of the right epididymis was significantly decreased on day 30 p.i., sperm motility was significantly decreased on days 10, 20, 30, 40, 50 and 60 p.i. and sperm concentration was significantly decreased on days 10, 30, 40 and 60 p.i. A marked increase of sperm abnormalities was noticed on days 30 and 40 p.i. No pathological lesions were detected either in the pituitary gland or the testes. In this study it was found that toxoplasmosis can affect main reproductive parameters in male rats, which are the most predictive of their fertilizing capacity. 相似文献
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Izabela J. Swierzy Maisalreem Muhammad Jana Kroll Anja Abelmann Astrid M. Tenter Carsten G.K. Lüder 《International journal for parasitology》2014
Toxoplasma gondii infects virtually any nucleated cell type of warm-blooded animals and humans including skeletal muscle cells (SkMCs). Infection of SkMCs by T. gondii, differentiation from the highly replicative tachyzoites to dormant bradyzoites and tissue cyst formation are crucial for parasite persistence in muscle tissue. These processes are also prerequisites for one of the major routes of transmission to humans via undercooked or cured meat products. Evidence obtained in vitro and in vivo indicates that SkMCs are indeed a preferred cell type for tissue cyst formation and long-term persistence of T. gondii. This raises intriguing questions about what makes SkMCs a suitable environment for parasite persistence and how the SkMC–T. gondii interaction is regulated. Recent data from our laboratory show that differentiation of SkMCs from myoblasts to syncytial myotubes, rather than the cell type itself, is critical for parasite growth, bradyzoite formation and tissue cyst maturation. Myotube formation is accompanied by a permanent withdrawal from the cell cycle, and the negative cell cycle regulator cell division autoantigen (CDA)-1 directly or indirectly promotes T. gondii stage conversion in SkMCs. Moreover, host cell cycle regulators are specifically modulated in mature myotubes, but not myoblasts, following infection. Myotubes also up-regulate the expression of various pro-inflammatory cytokines and chemokines after T. gondii infection and they respond to IFN-γ by exerting potent anti-parasitic activity. This highlights that mature myotubes are active participants rather than passive targets of the local immune response to T. gondii which may also govern the interaction between SkMCs and the parasite. 相似文献
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Sandia B. Pezerico Helio Langoni Aristeu V. Da Silva Rodrigo C. Da Silva 《Experimental parasitology》2009,123(2):168-177
Toxoplasma gondii infection is common worldwide and highly important to pregnant women as it can be transmitted to the fetus via the placenta. This study aimed at evaluating the prevention of placental transmission in two different strains after chronic infection with each one of the strains. A BALB/c mice model was inoculated 30 days before breeding (immunization) and re-infected 12 and 15 days after pregnancy (challenge). Seven experimental groups were assayed: G1: ME49-immunization (type II), M7741-challenge (type III); G2: M7741-immunization, ME49-challenge; G3, ME49-immunization; G4: M7741-immunization; G5: ME49-challenge; G6: M7741-challenge; G7: saline solution inoculation. Serology, mouse bioassay, PCR and RLFP of the uterus, placenta and fetus were performed to determine the congenital transmission of the strains challenged after chronic infection. IgG T. gondii antibodies were detected in G1, G2, G3 and G4, but not in G5, G6 and G7. All animals of G5 and G6 were IgM-positive. Congenital infection was not detected by bioassay and PCR. Nonetheless, placentas from G3 and G4 resulted positive but no corresponding fetal infection was detected. G1 and G2 did not show the genotype of the strain challenged during pregnancy, only those of chronic infection. Thus, the chronically infected BALB/c mice showed no re-infection after inoculation with another strain during pregnancy. Further studies with different parasite loads and different mice lineages are needed. 相似文献
8.
In this study, human sera reactivity against nine peptides derived from the Toxoplasma gondii P30 protein was assessed by ELISA in patients with different clinical forms of toxoplasmosis. Same as has been reported in mice, sera from congenital, ocular and chronic asymptomatic toxoplasmosis patients recognized more strongly peptides from the protein’s carboxy-terminus, being peptide 2017 (amino acids 301-320) the one most strongly recognized by sera from patients with ocular toxoplasmosis. Serum samples collected from 13 patients without ocular infection, 13 with inactive chorioretinal scars, 6 with active ocular infection and 10 seronegative individuals were then screened for anti-2017 IgG. Peptide 2017 was recognized by all patients’ samples but not by sera from T. gondii-seronegative individuals. No statistically significant differences were found between the absorbance levels of groups with and without lesions or with active or inactive ocular lesions, as determined by ANOVA. 相似文献
9.
Urszula Liwak 《Experimental parasitology》2009,122(2):155-161
Toxoplasma gondii, an intracellular parasite, has two distinctive growth stages, namely rapidly growing tachyzoites and slowly growing bradyzoites. Here we report a unique physiological function of the last committed glycolytic enzyme of T. gondii, lactate dehydrogenase (TgLDH), which is present in two isoforms and expressed in a stage-specific manner. TgLDH1 is present in tachyzoites while TgLDH2 is found in bradyzoites. Using clonal transgenic parasites over-expressing either TgLDH1 or TgLDH2, we showed that the enzymatic activity, growth, and virulence of tachyzoites were unaffected by the presence of the recombinant protein. Interestingly, under alkaline conditions the presence of the recombinant TgLDH proteins increased the differentiation, as detected by the formation of cyst structures in vitro, while green fluorescent protein did not. The differentiation enhancement of the recombinant TgLDH1 and TgLDH2 strongly suggests that TgLDH1 and TgLDH2 have an important physiological function, in addition to being glycolytic enzymes and differentiation markers. 相似文献
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Ana Camejo Daniel A. Gold Diana Lu Kiva McFetridge Lindsay Julien Ninghan Yang Kirk D.C. Jensen Jeroen P.J. Saeij 《International journal for parasitology》2014
The rhoptries are key secretory organelles from apicomplexan parasites that contain proteins involved in invasion and modulation of the host cell. Some rhoptry proteins are restricted to the posterior bulb (ROPs) and others to the anterior neck (RONs). As many rhoptry proteins have been shown to be key players in Toxoplasma invasion and virulence, it is important to identify, understand and characterise the biological function of the components of the rhoptries. In this report, we identified putative novel rhoptry genes by identifying Toxoplasma genes with similar cyclical expression profiles as known rhoptry protein encoding genes. Using this approach we identified two new rhoptry bulb (ROP47 and ROP48) and one new rhoptry neck protein (RON12). ROP47 is secreted and traffics to the host cell nucleus, RON12 was not detected at the moving junction during invasion. Deletion of ROP47 or ROP48 in a type II strain did not show major influence in in vitro growth or virulence in mice. 相似文献
11.
The kinetics of Toxoplasma gondii infection reactivation in the brain and muscles was analyzed in this study to determine the preferred tissue by the parasite during immunosuppression. Two groups of Wistar rats (G1 and G2) were inoculated with 104 bradyzoites of BTU10 strain (genotype I), p.o., and other two groups (G3 and G4) were inoculated with 0.9% saline solution. G2 and G4 were immunosuppressed with dexamethasone (DXM) and hydrocortisone sodium succinate (HSS). The presence of antibodies was researched in all groups through modified agglutination test (MAT) on days 0 and 21 p.i., and brain and muscle tissues of the rats were bioassayed in mice. G2 rats died at approximately 19.2 days after drug treatment, while G1 rats survived. The reactivation was initially observed in G1 brain and G2 muscles. Thus, the initial reactivation in muscles after immunosuppression allows doctors to save precious time to control the evolution of reactivated infection, preventing brain damage to the host. 相似文献
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Toxoplasma gondii, the etiological agent of toxoplasmosis, is an obligate intracellular protozoan parasite that infects a variety of mammals including humans. In an attempt to find new antigen-adjuvant combinations that enhance the immunogenicity of antigen candidates for toxoplasma vaccines, we analyzed the potent protection in mice immunized with recombinant protein ROP18 when co-administered with ginsenoside Re, a most important component isolated from Panax ginseng. All immunized mice produced specific anti-rROP18 immunoglobulins, with high levels of IgG antibody and a mixed IgG1/IgG2a response, with predominance of IgG1 production. The cellular and humoral immune responses were associated with the production of IFN-γ and IL-4 cytokines respectively. Vaccinated mice displayed a significantly increased survival time compared with control mice which died within 6 days of challenge with RH strain. Our data demonstrate that by addition of ginsenoside Re, the rROP18 triggered a stronger humoral and cellular response against T. gondii, and that Re is a promising vaccine adjuvant against toxoplasmosis, deserves further evaluation and development. 相似文献
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Jean François Dubremetz David J.P. Ferguson 《International journal for parasitology》2009,39(8):883-893
In many ways the history of the discovery of the life cycle of Toxoplasma gondii and the development of biological electron microscopy progressed in parallel through the 1950s and 1960s. Although Toxoplasma was discovered in 1908, it was only in the 1950s that the extent of the infection in humans and domestic animals was realised and work was undertaken to elucidate its life cycle (reviewed elsewhere in this edition). The development of ultrastructural techniques and their application to biological systems including Toxoplasma developed over the same period. This resulted in a synergistic effect with the re-classification of previously unrelated parasites within a single phylum, the Apicomplexa, which was based on the ultrastructural appearances of the infectious stages. This review will describe the central role played by electron microscopy and Toxoplasma in the developments associated with this progress. 相似文献
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Yenisey Alfonso Narciso Jiménez Alberto J. Dorta-Contreras Virginia Capó Olga Pomier 《Experimental parasitology》2009,122(3):203-46
Highly active antiretroviral therapy (HAART) has decreased the incidence of opportunistic infections in the central nervous system (CNS) in AIDS patients. However, toxoplasmic encephalitis (TE) still represents the most common cerebral mass lesion in patients infected with human immunodeficiency virus (HIV). The aim of this study was to evaluate nested PCR-B1 using cerebrospinal fluid (CSF) to detect Toxoplasma gondii DNA for the diagnosis of TE. A total of 114 samples were evaluated, and 33/44 samples from patients with TE were positive by PCR (sensitivity 75%), demonstrating the diagnostic usefulness of PCR technique. PCR-B1 products were analyzed by restriction fragment length polymorphism (RFLP) in 30 samples. Only type I allele at B1 was identified in these samples according banding patterns. This is the first report of evaluation of S1-AS1/S2-AS2 set of primers in more than 100 clinical samples as well as the first genotyping study of T. gondii in Cuba. 相似文献
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It is very difficult to define an endocytic system in Toxoplasma gondii. The parasite does not appear to take up exogenous materials via classical endocytosis. The presence of Rab5 and Rab7, classical markers of endocytic compartments, and their decoration of endomembranous structures suggest, however, that an endosomal-like system may operate. Additionally, new findings reveal that dynamin and the transmembrane type-I receptor sortilin are involved in the biogenesis of T. gondii micronemes and rhoptries, unique apical secretory organelles required for parasite migration and host–cell invasion, manipulation and egress. Evidence suggests that the parasite uses an endosomal-like system to traffic and sort proteins to rhoptries and micronemes via the endoplasmic reticulum and Golgi. In this review, I discuss recent findings suggesting that T. gondii and other apicomplexans have reduced their endosomal system and repurposed the evolutionarily conserved regulators of the system to build the apical secretory organelles. This review is also intended to serve as a resource for future investigations of apicomplexan biology and evolution. 相似文献
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P. Escoffier J.C. Jeanny C. Marinach-Patrice L. Jonet W. Raoul F. Behar-Cohen L. Paris J.F. Dubremetz D. Mazier 《Experimental parasitology》2010,126(2):259-262
Ocular toxoplasmosis is the principal cause of posterior uveitis and a leading cause of blindness. Animal models are required to improve our understanding of the pathogenesis of this disease. The method currently used for the detection of retinal cysts in animals involves the observation, under a microscope, of all the sections from infected eyes. However, this method is time-consuming and lacks sensitivity. We have developed a rapid, sensitive method for observing retinal cysts in mice infected with Toxoplasma gondii. This method involves combining the flat-mounting of retina - a compromise between macroscopic observation and global analysis of this tissue - and the use of an avirulent recombinant strain of T. gondii expressing the Escherichia coli β-galactosidase gene, visually detectable at the submacroscopic level. Single cyst unilateral infection was found in six out of 17 mice killed within 28 days of infection, whereas a bilateral infection was found in only one mouse. There was no correlation between brain cysts number and ocular infection. 相似文献
17.
The cosmopolitan parasitic pathogen Toxoplasma gondii is capable of infecting essentially any warm-blooded vertebrate worldwide, including most birds and mammals, and establishes chronic infections in one-third of the globe’s human population. The success of this highly prevalent zoonosis is largely the result of its ability to propagate both sexually and clonally. Frequent genetic exchanges via sexual recombination among extant parasite lineages that mix in the definitive felid host produces new lines that emerge to expand the parasite’s host range and cause outbreaks. Highly successful lines spread clonally via carnivorism and in some cases sweep to pandemic levels. The extent to which sexual reproduction versus clonal expansion shapes Toxoplasma’s current, global population genetic structure is the central question this review will attempt to answer. 相似文献
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John C. Boothroyd 《International journal for parasitology》2009,39(8):935-946
This article is an attempt to identify the most significant highlights of Toxoplasma research over the last 25 years. It has been a period of enormous progress and the top 25 most significant advances, in the view of this author, are described. These range from the bench to the bedside and represent a tremendous body of work from countless investigators. And, having laid out so much that has been discovered, it is impossible not to also reflect on the challenges that lie ahead. These, too, are briefly discussed. Finally, while every effort has been made to view the field as a whole, the molecular biology background of the author almost certainly will have skewed the relative importance attached to past and future advances. Despite this, it is hoped that the reader will agree with, or at least not disagree too strongly with, most of the choices presented here. 相似文献
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Marco Antônio G.B. Gomes Gabriela M. Carreira Daniela P.V. Souza Paulo Marcos R. Nogueira Edésio J.T. de Melo Edmilson J. Maria 《Comptes rendus biologies》2013,336(4):203-206
Toxoplasmosis is a neglected disease, with an estimated occurrence of one-third of the population worldwide. Research in medicinal chemistry has for some years been pursuing the development of new drugs against toxoplasmosis, because current treatments cause serious side effects in the patient. The use of thiosemicarbazones as an alternative option for the treatment of various diseases has been published in recent years, due to their, among others, anticancer, antimalarial, antitrypanosomal, antibacterial, and antitoxoplasmosis activities, the latter being the subject of this study, which is based upon biological analyses and tests of the response of Toxoplasma gondii in the presence of thiosemicarbazones. 相似文献
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N. Parameswaran N. Sundar M. Johnson M.E. Grigg 《International journal for parasitology》2010,40(6):635-111
Australia is geographically isolated and possesses a remarkable diversity of wildlife species. Marsupials are highly susceptible to infection with the cosmopolitan parasite Toxoplasma gondii. Of 46 marsupials screened for T. gondii by multilocus PCR-DNA sequencing at polymorphic genes (B1, SAG3, GRA6, GRA7), 12 were PCR-positive; the majority (67%; 9/12) were infected by non-archetypal Type II-like or atypical strains. Six novel alleles were detected at B1, indicating greater diversity of genotypes than previously envisaged. Two isolates lethal to marsupials, were avirulent to mice. The data support the conclusion that Australia’s isolation may have favoured the persistence of non-archetypal ancestral genotypes. 相似文献