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At least 1,243 records · Page 69Linked to original sources
PubMed2003

Clinical Toxoplasma gondii, Hammondia heydorni, and Sarcocystis spp. infections in dogs.

Concurrent infections with coccidians Toxoplasma gondii, Sarcocystis spp., and a Hammondia heydorni-like parasite were identified in tissues of three littermate pups on a Kelpie dog breeding farm in Australia. In total, 20 pups in four litters had died following vaccination with an attenuated distemper virus vaccine. Toxoplasma gondii tachyzoites were identified immunohistochemically in tissues of two dogs. Sarcocystis sp. sporocysts were seen in the intestinal lamina propria of two dogs. Asexual and sexual stages of H. heydorni-like parasite were found in enterocytes of the small intestine of two dogs. Ultrastructural development of schizonts and gamonts of this parasite is described. None of the protozoa in these dogs reacted with antibodies to Neospora caninum. Feeding of uncooked tissue of sheep was considered to be the likely source of infection for these coccidians in dogs.

Animal Feed↗
PubMed2004

Immune response to Toxoplasma gondii.

Oral-route infection with Toxoplasma gondii sporozoites or tachyzoites leads to the rapid spread of quick-replicating cytolytic tachyzoites throughout the whole body. Toxoplasma easily crosses the blood-retina, encephalic and placental barriers. The acute phase of this infection lasts for less than around ten days. The parasite causes a very strong type-1 response focused on the interferon-gamma secreted by the T lymphocytes. This immune response limits the tissue extension of the parasite, ensuring the survival of the host, but, paradoxically, also aiding the survival of the parasite by converting it into a bradyzoite, an intracellular quiescent resistant form persisting in the muscle and brain tissues.

Acute Disease↗
PubMed2004

[Intra-cellular signal pathway and synthesis of prostaglandin E2 during invasion of macrophage by Toxoplasma gondii].

OBJECTIVE: To investigate the signal transduction pathway of arachidonic acid (AA) and prostaglandin E2 (PGE2) synthesis in macrophage invaded by Toxoplasma gondii. METHODS: Synthesis of AA and PGE2, expression of COX-2 mRNA and protein following stimulation infection by Toxoplasma gondii were evaluated in RAW264.7 cells by ELISA, RT-PCR and Western blotting after treatment with calcium channel blocker verapamil, chelator of extracellular calcium EGTA and inhibitor of CaM trifluoperazine (TFP), selective PKC inhibitor H7. RESULTS: Production of AA and PGE2 induced by tachyzoite was significantly inhibited by EGTA, TFP and BAPTA/AM, and the PGE2 production was inhibited by H7, with a reduced expression of COX-2 mRNA and protein in a dose-dependent manner. CONCLUSION: The parasite down-regulates macrophage functions by affecting PKC signaling pathways, and triggers a biochemical cascade whose signals ultimately conduct to the secretion of immunosuppressive molecules PGE2.

Animals↗
PubMed2004

Molecular modifications of host cells by Toxoplasma gondii.

Toxoplasma gondii, the etiological agent of toxoplasmosis, is an Apicomplexa obligate intracellular protozoan parasite, which is able to infect any nucleated cell of numerous endothermic vertebrates. The combined abilities to actively penetrate host cells and perfectly control the fate of the parasite-containing vacuole (parasitophorus vacuole, PV) contribute to the remarkable global success of Toxoplasma as an intracellular parasite. Very broad host range and the relative ease of growth both in cell cultures in vitro and in vivo suggest that the parasite is able to manipulate the host cell apoptotic machinery. The article describes different aspects of host-parasite interplay focusing on molecular modifications of infected host cells.

Animals↗
PubMed2004

The modulation of transferrin receptors level on mouse macrophages and fibroblasts by Toxoplasma gondii.

Macrophage-mediated early nonspecific immunological response is an important part of the immunity against intracellular parasite Toxoplasma gondii. The immunological functions of macrophages are closely connected with iron metabolism and acquiring of iron mainly from transferrin by the receptor-mediated endocytosis. The level of specific transferrin receptors can be modulated by different soluble exogenous and endogenous factors and also by microbial pathogens. The goal of our study was to determine the influence of T. gondii infection and toxoplasma lysate antigen (TLA) on the expression level of transferrin receptors (TfRs) on mouse macrophages and fibroblasts which can serve as host cells for the parasite replication. The level of TfRs was measured using CELISA assay. Strong down-regulation of the receptors level, started about 18 hours after infection of macrophages with a high number of freshly harvested tachyzoites T. gondii. Stimulation of the mouse cells with TLA antigen did not cause any changes in TfRs expression. In our studies we did not observe any differences in the TfRs level on mouse fibroblasts even after incubation with high concentrations of TLA antigen or inoculation with a high number of tachyzoites.

Animals↗
PubMed1992

The prevalence of toxoplasma antibodies in swine sera in Finland.

A total of 1847 swine sera obtained from the 10 largest abattoirs slaughtering swine in Finland were examined by ELISA for toxoplasma antibodies. The sample represented 0.64% of the total number of swine slaughtered in these abattoirs over a period of 2 months. The prevalence of toxoplasma antibodies in swine sera was 2.5%.

Abattoirs↗
PubMed1991

Synergistic role of CD4+ and CD8+ T lymphocytes in IFN-gamma production and protective immunity induced by an attenuated Toxoplasma gondii vaccine.

BALB/c mice vaccinated with a temperature-sensitive mutant (TS-4) of Toxoplasma gondii develop complete resistance to lethal challenge with a highly virulent toxoplasma strain (RH). This immunity is known to be dependent on IFN-gamma synthesis. In vitro and in vivo T cell depletions were performed in order to identify the subsets responsible for both protective immunity and IFN-gamma production. When stimulated with crude tachyzoite Ag in vitro, CD4+ cells from vaccinated mice produced high levels of TH1 cytokines (IL-2 and IFN-gamma) but not TH2 cytokines (IL-4 and IL-5). CD8+ cells, in contrast, produced less IFN-gamma and no detectable IL-2. Nevertheless, they could be induced to synthesize IFN-gamma when exposed in culture to exogenous IL-2. In vivo treatment with anti-CD4 plus anti-CD8 or anti-IFN-gamma antibodies during challenge infection completely abrogated resistance to T. gondii. In contrast, treatment with anti-CD4 alone failed to reduce immunity, whereas anti-CD8 treatment partially decreased vaccine-induced resistance. These results suggest that although IFN-gamma and IL-2-producing CD4+ lymphocytes are induced by vaccination, IFN-gamma-producing CD8+ T cells are the major effectors of immunity in vivo. Nevertheless, CD4+ lymphocytes appear to play a synergistic role in vaccine-induced immunity, probably through the augmentation of IFN-gamma synthesis by the CD8+ effector cells. This hypothesis is supported by the observation that when giving during vaccination, as opposed to after challenge, anti-CD4 antibodies are capable of blocking protective immunity.

Animals↗
PubMed2006

[Study on the methods for detection of Toxoplasma antigen].

A sandwich ELISA was established with monoclonal antibody as detecting antibody and rabbit anti-Toxoplasma polyclonal antibody as capturing antibody. ABC (avidin-biotin-peroxidase complex)-ELISA and immuno-PCR were also used to detect different concentrations of Toxoplasma antigen. The lowest concentration of antigen to be detected by sandwich ELISA, ABC-ELISA and immuno-PCR was 0. 6 microg/ml, 0. 075 microg/ml and 0.1 ng/ml respectively. The immuno-PCR shows a much higher sensitivity than the other two methods.

Animals↗
PubMed2003

[The prevalence of anti-Toxoplasma gondii antibodies among abattoir workers in Lublin].

Abattoir workers are occupationally exposed to Toxoplasma gondii by the contact with raw meat. One hundred and seven abattoir workers from the Meat Factory in Lublin were examined for the presence of anti-Toxoplasma antibodies. Sixty-one blood donors were also tested as the reference group. Sera from workers and referents were tested by direct agglutination with 2-mercaptoethanol (DA-2ME), and also by ELFA IgG and ELFA IgM tests (Vidas Toxo IgM, Vidas Toxo IgG, bioMerieux, France). In the workers group, out of 107 tested sera, 70 were found positive (65.4%). The highest percentage of seropositive results was found in the Cured Meat Division--76.2%. In the Meat Production Division 66.6% of seropositive results were found, and in the Slaughter Division--46.1%. Three persons with the presence of IgM antibodies were found in the Cured Meat Division. In the reference group, 34 out of 61 sera (55.7%) were positive. The difference in seropositivity between Cured Meat Division workers and reference group was statistically significant (p < 0.05). The high percentage of seropositive reactions among the workers of Cured Meat Division and the presence of persons in early stage of invasion suggest an increased risk of exposure to T. gondii in this section.

Abattoirs↗
PubMed2001

[Prevalence of Toxoplasma gondii and analysis of specific immunoglobulins concentration in serum of women during the reproductive period in a sample of Włocławek population].

The aim of the study, from 1996 to 1999, was to investigate the serological course of prevalence Toxoplasma gondii in 985 women of procreation period. In non - pregnant women the incidence of Toxoplasma gondii specific IgG was significantly higher (59.0 +/- 1.9%) than in pregnant women (43.4 +/- 2.8%). Specific IgM was less frequent (from 1.47 +/- 1.02% to 1.76 +/- 0.66%).

Abortion, Spontaneous↗
PubMed2001

[Detection of Toxoplasma gondii DNA by PCR in mother's blood, amniotic fluid and child's blood in selected cases of pathological pregnancy].

Prenatal screening of Toxoplasma gondii infection is controversial. The diagnosis is based on serological tests detecting IgM and IgG antibodies against T. gondii, but interpretation of these tests results is often confusing. It is commonly made retrospectively when serological screening indicates a possibility of recent infection. Most women have antibodies against T. gondii and serial testing is required only in monitoring of pregnancies where initial screening is negative. The introduction of Polymerase Chain Reaction (PCR) assay for detection of Toxoplasma gondii DNA in selected cases of pathologic pregnancies has permitted a more accurate and faster diagnosis of congenital toxoplasmosis infections.

Adult↗
PubMed1991

Human T cell clone identifies a potentially protective 54-kDa protein antigen of Toxoplasma gondii cloned and expressed in Escherichia coli.

Protective immunity against Toxoplasma gondii is recognized to be cell mediated and IFN-gamma is considered to be the major mediator of resistance. Thus, protective Ag of the parasite must induce IFN-gamma-producing T cells. In order to identify such Ag, we have constructed a T. gondii cDNA library in the cloning/expression vector lambda gt11, screened this library with a pool of sera of immune donors, and further screened the set of selected recombinant Ag using, as probe, a T. gondii-reactive T-cell clone (TCC) derived from an infected/immune individual and producing a high level of IFN-gamma. One recombinant Ag was shown to induce TCC proliferation and was characterized. The corresponding mature T. gondii Ag has an apparent molecular mass of 54 kDa and the sequence of the cDNA clone suggests that it is membrane associated. The epitope defined by the TCC on this Ag was found to be present in three Toxoplasma strains independently of their phenotype (virulent or cyst forming). Recognition of this Ag by the TCC was shown to be restricted by HLA-DPw4, the most frequent allele in the Caucasian population (approximately 40%). The use of this Ag as a vaccine component is proposed.

Amino Acid Sequence↗
PubMed1975

The prevalence of entamoeba histolytica and Toxoplasma gondii antibodies in Central Java, Indonesia.

Sera collected from people living along the slopes of Mt. Merapi and Mt. Merbabu (900-1900 m) in Boyolali Regency, Central Java, Indonesia were tested by indirect hemagglutination tests for antibodies to Entamoeba histolytica and Toxoplasma gondii. A total of 695 sera from 439 males and 256 females, 2 to 75 years of age were tested for amoebiasis and 17.6% had positive antibody titers of 1:128 or greater. The prevalence of antibodies was the same for males and females and increased with age. The seropositivity rate for Toxoplasma gondii antibodies among 438 males and 255 females was 2% at titers of 1:256 or greater. The prevalence was higher in females (2.7%) than in males (1.6%), and was highest in the oldest age groups.

Adolescent↗
PubMedDate not supplied

[Isolation of Toxoplasma gondii from peritoneal exudate and organs of mice with experimental infection].

UNLABELLED: Peritoneal exudates and organs from 53 male albino mice, experimentally infected by Toxoplasma gondii were studied, 21 at the acute phase of infection, and 32 at the chronic phase. Peritoneal inoculations were made with 0.5 ml of peritoneal exudates (tachyzoites), or brain macerates (cysts) of previously infected mice. Direct examinations of peritoneal exudates (tachyzoites) were realized between 3 to 12 days post-inoculation, and in brain (cysts) after 10 days post-inoculation . Organs macerates were inoculated in new mice, for the parasite recovering, from exudates or from brains. At the acute infection (3 to 12 days) the positivity at the direct examination was: peritoneal exudate 19/19, lung 12/14, muscle 6/9, heart 4/9 and brain 1/3. After inoculation: peritoneal exudate 5/5, heart 9/9, lung 13/13, muscles 14/17 and brain 2/2. Then, there were 9 new positive organs. At the chronic infection, between 10 and 495 days, the positivity was, at direct examination: brain 28/32, heart 0/4 and muscle 0/4. After inoculation: brain 6/6, heart 14/29 and muscle 16/26. After that a new positive mouse was detected, which leads to 29 the positivity for all mice, or 90.6%. Finally the positivity for the acute phase was: peritoneal exudate 19/19 (100%), heart 15/17 (88.5%), muscle 12/14 (85.7%), lung 14/14 (100%) and brain 2/3 (66.6%). For the chronic phase: brain 28/32 (87.5%), muscle 16/28 (57.1%) and heart 14/31 (45.1%). At the end of experience, at the 495th day, the brain still presented large cysts by direct examination and also the heart and muscle were positives after inoculation. CONCLUSIONS: 1st) on mice the Toxoplasma gondii remained for 495 days, mainly on the brain, but also on heart and muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

[Antibody titer to Toxoplasma gondii in uveitis of toxoplasmosis and other origin].

The diagnostic value of toxoplasma serology in ocular toxoplasmosis is a controversial issue. Some authors feel that a positive titer indicates nothing more than that the patient had been exposed to Toxoplasma gondii at some stage. Even if in most cases the diagnosis is based on the morphological findings on the fundus, it might sometimes be useful to have an additional serologic evaluation. In a retrospective study we compared the level of antitoxoplasmosis antibodies (measured in a complement fixation test and an immunofluorescence test) in 75 patients with clinically proven ocular toxoplasmosis and 146 patients with uveitis of other origin. In our results we showed that the incidence of positive titers and antibody levels are significantly higher in patient with ocular toxoplasmosis than in other uveitis patient (chi 2-test, Mann-Whitney Willcoxon test, p = 0.05). There was no significant difference between antibody levels in patients with anterior uveitis, posterior uveitis or panuveitis of nontoxoplasmotic origin. No correlation between the antibody levels and amount of retinochorioidal fundus lesions could be found. Based on our results, we conclude that in cases where fundus findings are compatible with ocular toxoplasmosis and a complement fixation or immunefluorescence test is positive, specific antitoxoplasmotic therapy should be started.

Animals↗
PubMed1991

[Activation of the latent Toxoplasma infection and cyst formation in mice].

Latent Toxoplasma infection in mice inoculated with the low virulent Beverley strain (BEV) and avirulent Fukaya strain (FUK) was reactivated by prednisolone administration. Parasitaemia reappeared and the organism could be continuously isolated from the lymph nodes by mouse passage. No distinct decrease in specific antibody levels was observed when the sera were assayed by dye test and latex agglutination test. A significant increase in the number of brain cysts in infected mice was noted at the third week of infection while the challenge infection and steroid immunosuppression treatment resulted in an enhancement of cyst formation. A hypothesis was, therefore, proposed that the cyst formation in tissues might be regulated by the immune response of infected host to Toxoplasma infection.

Animals↗
PubMed1991

Pathological changes in the brains of mice infected with Toxoplasma gondii: a histological, immunocytochemical and ultrastructural study.

The pathological changes in the brains of mice infected with T. gondii were studied at various intervals between 7 days and 22 months post-infection using histology, immunocytochemistry and electron microscopy. Initially, a few single parasites were observed (day 7) but necrotic lesions and microglial and inflammatory nodules rapidly appeared (9-I4 days). The majority of the lesions between days 9 and I4 contained proliferating toxoplasma and early cyst formation but from 2I days onwards the vast majority of nodules contained neither parasites nor Toxoplasma antigen. Intact intracellular cysts persisted throughout the period of study eliciting no host response. A generalized meningoencephalitis developed by day II and persisted with varying degrees of severity throughout the 22 months studied. At first, the inflammatory cells consisted of lymphocytes and monocyte/macrophages but during the chronic phase plasma cells predominated. In chronic infections, the number of microglial/inflammatory nodules was relatively constant with only a few containing toxoplasmic material resulting from recent cyst rupture. A few brains contained small nodules of dystrophic calcification. This study shows that in these asymptomatic animals, the major feature is perivascular cuffing by mononuclear cells and localized microglial/inflammatory nodules. After the development of the chronic state, there is no obvious increase or decrease in the severity of the pathological changes with time.

Animals↗
PubMed1991

[Epidemiological findings of Toxoplasma gondii infections of humans in the area of Cottbus].

Using the indirect fluorescence antibody test (IFAT) results concerning the infection of people by Toxoplasma in dependence on age, sex, settlement area and consumption of raw meat in the region of (State Brandenburg) Cottbus are represented as well as on frequency of primoinfections during pregnancy. Infections by Toxoplasma have been found out in 35.6 of 100 cases (n = 3665). With 39.2% women are infected more often than men with 27.1%. Probands of the urbane settlement area show with 37.9% (n = 3402) an higher degree of the infections than probands living in the country with 30.9% (n = 2656). Consumption of raw meat increases the risk of an infection significant. The frequency of primoinfections - found by prospective study with 22559 pregnant women - is placed by 6%, that of connatale infections by 2.6%.

Adolescent↗