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At least 1,369 records · Page 76Linked to original sources
PubMed1996

[Detection of specific toxoplasma class A antibodies: a comparison of diagnostic usefulness of commercially available diagnostic kits].

Diagnostic significance of the presence of specific anti-Toxoplasma gondii IgA antibodies was discussed with particular reference to the cases of congenital toxoplasmosis and infections in pregnant women. Furthermore, the possibilities of testing for anti-Toxoplasma IgA antibodies with commercially available diagnostic kits were presented. From amongst the examined 5 diagnostic kits, Platelia Toxo IgA and ISAGA Plus IgA/IgM showed the highest sensitivity and specificity.

Animals↗
PubMed1997

Heat shock protein 65 induced by gammadelta T cells prevents apoptosis of macrophages and contributes to host defense in mice infected with Toxoplasma gondii.

We previously reported that gammadelta T cells mediate the expression of endogenous heat shock protein 65 (HSP65) in macrophages of mice with acquired resistance against infection with Toxoplasma gondii. We show here that HSP65 contributes to protective immunity by preventing apoptosis of infected macrophages. Macrophages of BALB/c mice, which readily acquired resistance to T. gondii infection with the low virulence Beverley strain, strongly expressed HSP65, and only a few of these macrophages underwent apoptosis. On the other hand, the BALB/c mice were susceptible to the infection with the high virulence RH strain of T. gondii; their macrophages did not express HSP65 and did undergo apoptosis. Mice depleted of gammadelta T cells using a mAb specific for TCR-gammadelta became highly susceptible to infection even with the Beverley strain. In these mice, HSP65 expression was markedly suppressed, and their infected macrophages died via apoptosis. Apoptosis was induced in cultured macrophages or macrophage cell lines after infection in vitro with the RH strain, whereas apoptosis was prevented when HSP65 was induced in these cells, before infection, by activation with IFN-gamma and TNF-alpha. However, apoptosis associated with infection by T. gondii RH strain was not prevented when HSP65 synthesis was inhibited by introducing an antisense oligonucleotide for this protein into the cells before activation with IFN-gamma plus TNF-alpha. Thus, HSP65 appears to contribute to immunity by preventing the apoptosis of infected macrophages, and the high virulence Toxoplasma appears to have mechanisms that allow these organisms to evade the host defense system by interfering with HSP65 expression.

Animals↗
PubMed1997

Oocyst-induced murine toxoplasmosis: life cycle, pathogenicity, and stage conversion in mice fed Toxoplasma gondii oocysts.

The development of sporozoites to tachyzoites and bradyzoites was studied in mice after feeding 1-7.5 x 10(7) Toxoplasma gondii oocysts. Within 2 hr after inoculation (HAI), sporozoites had excysted and penetrated the small intestinal epithelium. At 2 HAI, most sporozoites were in surface epithelial cells and in the lamina propria of the ileum, and by 8 HAI, T. gondii was also seen in mesenteric lymph nodes. At 12 HAI, sporozoites had divided into 2 tachyzoites in the lamina propria of the small intestine. By 48 HAI, there was a profuse growth of tachyzoites in the intestine and mesenteric lymph nodes of mice fed 7.5 x 10(7) oocysts. Parasites had disseminated via the blood and lymph to other organs by 4 days after inoculation (DAI). Toxoplasma gondii was first isolated from peripheral blood at 4 HAI. Tissue cysts were visible histologically in the brain at 8 DAI. By using immunohistochemical staining with anti-bradyzoite-specific (BAG-5 antigen) serum, BAG-5-positive organisms were first seen at 5 DAI in the intestine and at 8 DAI in the brain. Using the bioassay in cats, bradyzoites were first detected in mouse tissues between 6 and 7 DAI, and they were found in intestines before they were found in the brain. Cats fed murine tissues containing bradyzoites shed oocysts in their feces with a short (< 10 days) prepatent period, whereas cats fed tissues containing tachyzoites did not shed oocysts within 3 wk. Using a pepsin-digestion procedure and mouse bioassay, bradyzoites were first detected in brain tissue at 7 DAI and in many organs of mice at 51 and 151 DAI. Individual bradyzoites, small and large tissue cysts, and tachyzoites were seen in the brains of mice at 87 and 236 DAI.

Animals↗
PubMed1998

Vaccination of mice with Neospora caninum: response to oral challenge with Toxoplasma gondii oocysts.

Neospora caninum is a protozoan parasite that can cause severe disease in mammals. Two experiments were conducted to examine the effects of subcutaneous (s.c.) vaccination with Hank's balanced salt solution (HBSS), 1 x 10(5) N. caninum NC-1 strain tachyzoites or 1 x 10(5) Toxoplasma gondii TS-4 strain tachyzoites on challenge oral infections in mice with sporulated VEG strain T. gondii oocysts (1 X 10(3) oocysts exp. 1 and 5 x 10(3) oocysts exp. 2). An additional study, experiment 3, evaluated s.c. challenge with 2.5 X 10(3) tachyzoites of the highly virulent RH strain of T. gondii after vaccination with HBSS, NC-1 tachyzoites, or TS-4 tachyzoites. Mice vaccinated with NC-1 strain tachyzoites survived significantly (P < 0.05) longer than mice given HBSS in experiment 1, but not in experiments 2 and 3. Mice vaccinated with TS-4 strain tachyzoites survived significantly longer than HBSS-vaccinated mice in experiments 1, 2, and 3 and significantly longer than mice vaccinated with the NC-1 strain in experiments 2 and 3. Toxoplasma gondii tissue cyst numbers were significantly lower for mice vaccinated with TS-4 strain tachyzoites than mice vaccinated with HBSS or the NC-1 strain tachyzoites in experiment 1. No difference was observed in tissue cyst numbers in mice vaccinated with HBSS or NC-1 strain tachyzoites in experiment 1. No HBSS-vaccinated mice survived experiment 2, and the numbers of T. gondii tissue cysts were significantly lower for mice vaccinated with the TS-4 strain tachyzoites compared to NC-1 strain tachyzoites. No HBSS- or NC-1-vaccinated mice survived RH strain challenge in experiment 3. Results of these experiments indicate that infection with N. caninum provides some protection against fatal oral infection with T gondii oocysts of a moderately pathogenic strain but not tachyzoites of a highly pathogenic strain. The protection provided by N. caninum is much less than that provided by previous exposure to T. gondii, and the numbers of tissue cysts in the brains of mice are not significantly (P > 00.5) lowered.

Animals↗
PubMedDate not supplied

[An immunochemical study of the antigens from Toxoplasma gondii tachyzoites obtained in different cultivation systems].

The protein composition and immunochemical properties of Toxoplasma gondii tachyzoites cultured on Vero cells and on mice were studied. Despite the fact that the main components of both preparations were shown to be proteins with molecular weights of 47, 34, 24, and 22 kDa, Toxoplasma-infected human sera antibodies interact mainly with the antigens of 66, 62, 57, 42, 38, 37, 36, 31, and 24 kDa. Comparing efficiency of enzyme immunoassay using the antigens of the tachyzoites obtained in different culture systems showed that the preparation of cultured Vero cells is similar to those of peritoneal exudates from infected mice and may be successfully used for the detection of antitoxoplasma antibodies in the sera of infected subjects.

Animals↗
PubMed1976

Prevalence of Toxoplasma gondii antibodies in wild and domestic animals in northern California.

Wild and domestic animals from 3 geographic-climatologic areas in northern California were tested for antibodies against Toxoplasma gondii. A total of 2,796 serum samples representing 37 species of wild mammals, 35 species of wild birds, and 5 species of domestic animals were tested by the indirect hemagglutination test. Of 1,174 wild mammal serums tested, 10.8% were positive, which compared with 14.7% of the 1,221 domestic mammal serums. Of 229 wild carnivores tested, 45% were seropositive, including 69% of 86 bobcats, 28% of 58 coyotes, 48% of 25 raccoons, 27% of 26 gray foxes, 22% of 32 striped skunks, a civet cat, and a mink. Serologic evidence of infection was found in 38% of 47 rural domestic cats, but none of the 7 dogs tested was seropositive. Of 160 murid rodents (rats and house mice) in rural habitats, 4% were seropositive, which compared with 2% of 399 cricetine rodents (mostly deer mice) collected from wilderness habitats. Seven percent of 56 wild Artiodactyla (deer and feral pigs) were seropositive, which compared with 15% of 1,048 domestic sheep tested. Of 401 birds tested, 3.5% had antibodies against T gondii. The highest prevalence of antibodies among birds was in crows (14%). Toxoplasma was isolated from 1 raven, by mouse inoculation. In general, the highest prevalence of seropositive carnivores, rodents, and sheep was in the coastal region below 100 ft elevation, where the weather is cool and damp for much of the year. In the central valley the highest prevalence among sheep was in areas under irrigation. The prevalence of antibodies was lowest in the mountain areas, where climatologic extremes prevail at various seasons of the year.

Animals↗
PubMed1995

[The identification and isolation of Toxoplasma gondii antigens].

It is know that 30% of AIDS patients may develop toxoplasmic encephalitis in an advanced stage of the disease. This study was conducted to investigate the presence of antigens to Toxoplasma gondii in the urine of patients infected by human immunodeficiency virus, group IV, who presenting with acute toxoplasmosis. These proteins were identified by electrophoresis in polyacrylamide gels, in the presence of sodium dodecyl sulfate in reduction conditions with the subsequent transfer to nitrocellulose sheets. Finally, they were isolated by affinity chromatography. Proteins with molecular weights nearly 66 and 61 KD were identified in the samples studied. Results obtained from this study highlights the presence of Toxoplasma gondii circulating antigens in patient presenting with AIDS and toxoplasmic encephalitis. The detection of these antigens in the urine of patients would be a very useful tool for the diagnosis of the acute infection by this protozoon.

AIDS-Related Opportunistic Infections↗
PubMed1997

[Preliminary application of PCR to curative effect assessment of chemotherapy against experimental acute infection of Toxoplasma gondii in mice].

Treatment with pyrimethamine and sulfamethoxazolum combination administered via intragastric route, was started 2 hours after each mouse received an intraperitoneal injection of a lethal inoculum of 5 x 10(3) tachyzoites of RH strain toxoplasma gondii and the therapy was lasted for 52 days. Combined therapy of the two drugs resulted in 83.3% survival rate in mice. PCR and the conventional mouse inoculation (MI) were compared for their validity as an curative effect assessing method. The positive rates of PCR and MI were 63.64% and 18.18%, respectively. The results suggest that PCR can be used in studies involving drug screening and curative effect assessment of anti-Toxoplasma chemotherapy in vivo. In addition, the results indicated that longer course of treatment against toxoplasmosis is required in clinical practice.

Animals↗
PubMed1998

Toxoplasma gondii antibody in pregnant women with and without HIV infection.

One thousand two hundred pregnant women were examined for Toxoplasma gondii antibody with the objective of identifying the prevalence and risk factors of the disease. By using Sabin-Feldman Dye test, the prevalence of IgG to Toxoplasma gondii was 13.2%. In this study 19 cases (1.6%) were anti-HIV seropositive. Between HIV-seropositive and HIV-seronegative pregnant women, antibody rates to T. gondii were 21.1% and 13.1% respectively, however, the statistical comparison could not be done due to the very few subjects in the former group (n=4). Concerning the risk factors, among those who had no cat in their house, the prevalence of T. gondii antibody were significantly different between under-cooked and properly-cooked meat consumers (19.5%; and 9.6%; odds ratio=2.28, 95% confidence interval). And when under-cooked meat consumers were excluded, the antibody to T. gondii between two groups (having and not-having cat in the house) were also found the significantly different (31.8% and 19.3%; odd ratio=1.96, 95% confidence interval). In conclusion, consuming under-cooked meat and having a cat in the house, both are risk factors of transmission of toxoplasmosis. Further study with more subjects in HIV-infected pregnant women who had antibody to T. gondii, will be helpful for confirmation of the difference with respect to the non HIV-infected group.

Adult↗
PubMed1998

[Simultaneous occurrence of Toxoplasma gondii and Borrelia burgdorferi antibodies in patients with suspected toxoplasmosis or borreliosis].

In 1995-1997 the frequency of concurrent antibodies against Toxoplasma gondii and Borrelia burgdorferi was assessed in two groups of patients with different clinical symptoms. In 485 subjects the dermatological form (erythema migrans) of borreliosis was suspected, 877 subjects had clinical symptoms suggesting the nodular form of toxoplasmosis. The group of 485 subjects with suspected borreliosis comprised 199 (41%) subjects with the diagnosis confirmed by the serological finding and 286 (59%) subjects were serologically negative. During concurrent examination for toxoplasmosis a statistically significantly higher incidence of antitoxoplasmatic antibodies was recorded in patients with suspected borreliosis but without detected antibodies against Borrelia burgdorferi (29%) than in the group with both types of antibodies (11.5%), p < 0.001. The expected values of the incidence of antibodies against Toxoplasma gondii in the population (25%) were however not substantially surpassed by the actual values. In the group of 877 patients with suspected toxoplasmosis there were 114 subjects (13%) with acute toxoplasmosis, 300 subjects (34%) with anamnestic titres suggesting the chronic form of infection and 463 (53%) subjects where the infection with toxoplasmosis was not confirmed by serological tests. In the whole group, regardless whether the acute or chronic form of infection was involved, but also in the group without antitoxoplasmatic antibodies a significantly elevated number of subjects with antiborrelia antibodies (18-25%) was recorded as compared with the expected values of the incidence of antibodies against Borrelia burgdorferi in the population (10%), p < 0.001. In the discussion the authors deal with the possible causes of these phenomena.

Adolescent↗
PubMed1978

Toxoplasma antibodies and spontaneous abortion.

One hundred and fifty-two women with spontaneous abortion were investigated by hemagglutination (HA) and immunofluorescence antibody (IFA) tests for toxoplasmosis. In 48 cases, quantitive immunoglobulin (Ig) studies and mouse inoculation with gestational material were performed. Positive toxoplasma antibody titers were observed in 62 cases (40.8%) using HA and in 52 cases (38.2%) using IFA. This prevalence was significantly higher than that observed in 80 normal women who served as controls. Toxoplasma gondii was isolated in two cases. No correlation was found between antibody titers and IgG, IgM or IgA levels. We conclude that toxoplasmosis should be considered as the cause of abortion when a patient's antibody titer exceeds 1:256.

Abortion, Spontaneous↗
PubMed1979

Effect of gonadectomy and oestrogen administration on the response of lymph-node post-capillary venules to infection with Toxoplasma gondii.

The effects of gonadectomy and oestrogen administration on the response of lymph-node post-capillary venules to infection with Toxoplasma gondii have been studied in mice. The endothelial cells of the post-capillary venules were significantly higher in the female than in the male controls. Oophorectomy had no significant effect while orchidectomy increased the height of the cells. However, hexoestrol administration resulted in a rise of the height to maximum levels in the female and in the male gonadectomised animals. The endothelial cells of male and female control and gonadectomised mice were higher after infection with Toxoplasma while in the infected hexoestrol-treated animals, lower cells were seen. The number of lymphocytes passing through the post-capillary venule wall was increased by gonadectomy and decreased by hexoestrol administration in both sexes. The same pattern was seen in the infected groups. The influence of sex hormones on the post-capillary venules and its possible contribution to the differences seen in the immune response between the two sexes is discussed.

Animals↗
PubMed1992

Analysis of the electroretinogram in toxoplasma retinochorioiditis.

The decision to use therapy in toxoplasma retinochorioiditis depends on the location of the active lesion and the presence of vitreous activity. In eyes with dense vitreous clouding it can be difficult to see whether the macular region is involved or not. In theory the localisation of a lesion can be estimated on the basis of the flash ERG. The standard flash electroretinogram was recorded in 23 patients with inactive toxoplasma retinochorioiditis lesions in the retina. In 17 cases a lesion was present within the central 12 degrees of the visual field, 8 of these had a reduced photopic ERG. In 15 patients lesions were found outside the central 12 degrees, in 8 of whom the scotopic ERG was reduced. We conclude that the ERG can be of use in indicating the scar location in patients with dense vitreous clouding.

Adolescent↗
PubMed1984

Toxoplasma infection and response to novelty in mice.

Three groups of mice were infected with Toxoplasma and used for behavioral testing using a Y-maze. One group was infected when adult and two groups congenitally, one of these born to dams infected during gestation, the other to dams chronically infected prior to mating. In an initial habituation period each mouse was exposed to a black arm and stem of the maze, entrance to a white arm being blocked by a transparent door. In a subsequent free-choice trial both arms were black and the mouse was free to explore all parts of the maze. During both periods infected mice were more active than controls. Infected mice engaged in less grooming behavior indicative of less approach-avoidance conflict than controls prior to entry into a choice arm at the beginning of the free-choice trial. Infected mice spent more time in the familiar than in the novel (previously blocked) arm during the free-choice trial; conversely, uninfected mice spent more time in the novel than in the familiar arm. It is suggested that the reported behavioural changes would lead to dissemination of the infection in the environment by ultimately making infected mouse intermediate hosts more susceptible to predation by domestic cats, the definitive hosts of Toxoplasma.

Animals↗
PubMed1985

The influence of congenital Toxoplasma infection on the spontaneous running activity of mice.

Home-cage running-wheel activity of mice congenitally infected with Toxoplasma was recorded over 24 days. Infected mice were consistently more active than uninfected controls over the entire testing period. This finding extends previous studies and indicates that such increased activity levels occur not only in novel but also in familiar environments, and suggests that congenital toxoplasmosis tends to render mice "hyperactive'. If such behavioural alterations occur in wild mice, it is likely that infected mouse intermediate hosts would be more susceptible to predation by cats, the definitive hosts of Toxoplasma.

Animals↗
PubMed1996

Classification system and case definitions of Toxoplasma gondii infection in immunocompetent pregnant women and their congenitally infected offspring. European Research Network on Congenital Toxoplasmosis.

Classification systems and case definitions provide the foundations upon which clinical and epidemiological studies are based. The European Research Network on Congenital Toxoplasmosis acknowledged the lack of such a system or definitions within its field of interest and established a working group to address the issue. Congenital Toxoplasma gondii infection was defined as occurring in four separate patient groups: pregnant women, fetuses, infants, and individuals > 1 year of age. The likelihood of Toxoplasma gondii infection was separated into five mutually exclusive categories: definite, probable, possible, unlikely, and not infected. Inclusion within a specific category is dependent upon the case definition, which is in turn derived from criteria based on serological, parasitological, and clinical information. Notes are included within the classification not only to clarify the definitions, but also to improve the reliability and quality of diagnosis. The goal is to construct a system that encompasses all aspects of congenital toxoplasmosis, which is applicable to different countries and health services, suitable for large epidemiological studies, aids the diagnosis and management of individual cases, and lends itself to computerisation.

Female↗
PubMed1992

Cotrimoxazole therapy of Toxoplasma gondii encephalitis in AIDS patients.

Twenty-four consecutive HIV-positive patients affected by Toxoplasma gondii encephalitis received trimethoprim-sulfamethoxazole (cotrimoxazole) as acute-phase treatment. Two dosage regimens of cotrimoxazole were used: 40 mg/kg/day (12 patients) or 120 mg/kg/day (12 patients) of total compound (trimethoprim plus sulfamethoxazole). Clinical and radiological responses to treatment were evaluated, and the product-limit method for survival data analysis was used. Eighteen of 24 patients showed both a clinical and radiological response (75% response rate). There were no differences in response rates between patients receiving the two dosage regimens of cotrimoxazole. Adverse reaction consisted of leukopenia (two cases) and skin rash (three cases) which led to the discontinuation of the drug in one case. These results suggest that a randomized, controlled clinical trial should be carried out comparing cotrimoxazole versus sulfadiazine-pyrimethamine in AIDS patients with Toxoplasma gondii encephalitis.

Acquired Immunodeficiency Syndrome↗
PubMed1982

The course of Plasmodium berghei infection in mice latently infected with Toxoplasma gondii.

The course of infection with 2 different virulent strains of Plasmodium berghei was investigated in mice latently infected with Toxoplasma gondii. When given the highly virulent ANKA strain of P. berghei all Toxoplasma-infected mice died but the survival time was prolonged. After infection with the less virulent strain K 173 mice could survive the subsequent infection. In these cases levels of parasitemia depended upon the duration of the T. gondii infection. Mice infected for about 6 weeks with T. gondii showed maximum protection.

Animals↗