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At least 19 recordsLinked to original sources
PubMed1999

Role of Toxoplasma gondii HSP70 and Toxoplasma gondii HSP30/bag1 in antibody formation and prophylactic immunity in mice experimentally infected with Toxoplasma gondii.

Production of antibodies against Toxoplasma gondii (T. gondii)-derived stress proteins, T. gondii HSP70 (T.g.HSP70) and T.g.HSP30/bagl, in C57BL/6 and BALB/c mice perorally infected with cysts of the avirulent Fukaya strain of T. gondii was analyzed. Production of anti-T.g.HSP70 IgG antibodies was transient, whereas production of anti-T.g.HSP30/bag1 IgG antibodies persisted after infection in both C57BL/6 and BALB/c mice. C57BL/6 mice, a susceptible strain, predominantly produced IgG antibodies specific for T.g.HSP70, whereas BALB/c mice, a resistant strain, predominantly produced IgG antibodies specific for T.g.HSP30/bag1, after T. gondii infection. Immunization with rT.g.HSP30/bag1 enhanced, whereas immunization with rT.g.HSP70 reduced host protective immunity against T. gondii infection with a cyst-forming avirulent strain, Fukaya, and a virulent strain, RH.

Animals↗
PubMed1993

Vaccination of mice with the protective F3G3 antigen of Toxoplasma gondii activates CD4+ but not CD8+ T cells and induces Toxoplasma specific IgG antibody.

A major cytoplasmic Toxoplasma gondii (T. gondii) antigen recognized by monoclonal antibody F3G3 (F3G3-Ag), as well as two surface antigens recognized by monoclonal antibodies 2G11 and 1E11 respectively (2G11-Ag; 1E11-Ag), were isolated from crude Toxoplasma sonicates using affinity chromatography. Purified F3G3-Ag induced long term protection against Toxoplasma infection in mice and induced Toxoplasma specific IgG antibody. CD4+ but not CD8+ T cells from immune animals proliferated and produced IL-2 upon restimulation with either Toxoplasma sonicate or F3G3-Ag in vitro. Furthermore, CD4+ T cells from mice immunized with F3G3-Ag responded to purified 2G11- and 1E11-Ag. In contrast, CD4+ T cells from mice immunized with 2G11-Ag responded to Toxoplasma sonicate and 2G11-Ag, but not to F3G3- or 1E11-Ag. The results may indicate that the protective F3G3-Ag shares immunogenic epitopes present also on 2G11- and 1E11-Ag, since the F3G3-Ag used for the vaccination did not contain detectable amounts of 2G11- or 1E11-Ag, and none of the antigens displayed any mitogenicity. Taken together the results show that the cytoplasmic F3G3-Ag of T. gondii induces CD4+ T helper cells, Toxoplasma specific IgG antibodies and long term protection against Toxoplasma infection, but does not induce detectable sensitization of the CD8+ T cell compartment.

Animals↗
PubMed1981

Microbicidal activity of toxoplasma immune beagle plasma and lymphokines to toxoplasma multiplication in host cells.

In beagles infected with Toxoplasma tachyzoites, IgM and IgG humoral antibodies appeared on the early period of infection as the expression of the humoral antibody response. IgM antibody was no longer observed after 16 days, however, IgG antibody persisted maintaining high titers up to the last day of the experiment. When challenged on the 13th day postinfection, IgG antibody levels were boosted, however, IgM levels did not show any change at all. Lymphokines obtained from spleen cells collected 10, 30, 100 and 300 days postinfection showed a gradual increase in the ability to inhibit Toxoplasma multiplication in normal canine monocytes accordingly compared to the control which showed no inhibition at all. Toxoplasma lysate antigen was injected intravenously to hyperimmuned dog 2 wk after rechallenge. Plasma collected 24 hr after injection inhibited markedly Toxoplasma multiplication. No change in the microbicidal activity was found when plasma was absorbed with anti-canine IgG compared to the unabsorbed one. The results therefore indicated that the substance inhibiting Toxoplasma multiplication in canine monocytes existing in plasma is not derived from antibodies specific for Toxoplasma but as a Toxoplasma growth inhibitory factor (Toxo-GIF) or a similar substance. The plasma obtained also showed antiviral activity of interferon type II and was found to increase in the circulation 6 hr after Toxoplasma lysate antigen injection.

Animals↗
PubMed1980

Delayed hypersensitivity to Toxoplasma and unrelated antigens in Toxoplasma-infected mice: induction and elicitation of delayed-type hypersensitivity by antigen-pulsed macrophages.

Delayed-type hypersensitivity (DTH) to Toxoplasma and unrelated antigens in Toxoplasma-infected BALB/c mice was investigated by the radioisotopic uptake method of Vadas et al. (Int. Arch. Allergy Appl. Immunol. 49: 670-692, 1975). DTH became positive on day 30 of infection and remained positive during chronic infection. The expression of DTH in mice infected with the relatively avirulent C37 strain of the parasite paralleled the Toxoplasma antibody response as detected by the Sabin-Feldman dye test. Mice sensitized with Toxoplasma, keyhole limpet hemocyanin, or sheep erythrocytes during the acute or chronic phase of Toxoplasma infection showed a DTH reaction similar to that of uninfected sensitized controls. No parasite antigens could be detected by immunofluorescence techniques on the surface of Toxoplasma-infected cells. When killed organisms were added to the cell cultures, specks of fluorescence appeared on cells containing intracellular parasites as well as on cells without intracellular organisms. That the antigens may be present in or on macrophages in a form readily recognizable by T cells is suggested by experiments in which we demonstrated that injection of uninfected normal macrophages pulsed with Toxoplasma-soluble antigens into the ears of chronically infected mice elicited a DTH reaction comparable to that observed when 10(6) Formalin-fixed tachyzoites were used as the test antigen. When macrophages pulsed with Toxoplasma antigen were used in attempts to induce DTH in naive uninfected mice, the intensity of the reaction was similar to that observed in infected mice.

Animals↗
PubMed1976

Pinocytic rates of macrophages from mice immunized against Toxoplasma gondii and macrophages stimulated to inhibit toxoplasma in vitro.

The rate of pinocytosis by macrophages when measured by uptake of horseradish peroxidase was significantly reduced during toxoplasma infection of the cells in vitro when the macrophages were from toxoplasma-immune mice and when control cells were stimulated in vitro to inhibit toxoplasma multiplication. There was, however, no direct correlation between reduced pinocytosis in this model and inhibition or enhancement of toxoplasma multiplication. We conclude that a reduced pinocytic rate is a feature of the unstimulated toxoplasma-immune macrophage, but this change in rate alone does not correlate with the cell's ability to inhibit toxoplasma. In addition, we observed that enhanced pinocytosis as seen in the elicited macrophage was not a requirement for inhibition of toxoplasma multiplication.

Animals↗
PubMed1984

Delayed secondary immune response in mice immunized with Toxoplasma antigens and its effect for protection against Toxoplasma gondii.

Primary immune response by mice immunized with Toxoplasma peritoneal exudate (PE) was produced slowly at a low level. To induce high Toxoplasma antibodies, mice should be boostered after the primary immune response reached the peak in 4 weeks or later. Immunization of mice with PE alone in 4 weeks could suppress the growth of Toxoplasma but could not accomplish protection. Two of 9 mice immunized with PE in complete Freund's adjuvant (CFA), and 16 of 27 mice immunized with PE containing Toxoplasma ( ToxoPE ) in CFA were protected against a challenge of 1 X 10(3) Toxoplasma, RH strain. The mice surviving to the challenge showed complete protection against a rechallenge of higher dose, 1 X 10(6) RH strain. Their ascites were very high in LA titer and would be a great source for obtaining high titer antibodies to Toxoplasma without contamination of host serum components. Biological characters of Toxoplasma, RH strain, in chronic infection of mice are discussed.

Animals↗
PubMed1987

Presence of high concentrations of circulating Toxoplasma antigens during acute Toxoplasma infection in athymic nude mice.

In mice infected with an avirulent strain of Toxoplasma gondii, circulating Toxoplasma antigens were detectable in the sera during weeks 1 to 3 of infection by a simple agglutination test that uses latex particles coated with anti-Toxoplasma antibodies. An infection in athymic nude mice resulted in high agglutination titers in the anti-Toxoplasma antibody-coated latex particle test and the absence of anti-Toxoplasma antibodies in sera during the acute phase, suggesting that the detection of circulating Toxoplasma antigens is a good tool for the diagnosis of acute toxoplasmosis, especially in severely immunocompromised hosts.

Animals↗
PubMed1995

[Detection of Toxoplasma antigens and antibodies in mice infected with different strains of Toxoplasma gondii].

This study aims to assess the possible strain-dependent variations in detection of Toxoplasma antigens and antibodies. The virulent RH strain or avirulent Beverley strain of T. gondii were injected into mice, intraperitoneally, and their antigens, antibodies and parasites were identified from the blood or tissues; liver, brain and spleen by ELISA, Western blot and PCR. In mice infected with RH strain, circulating antigens and parasitemia were first detected from 2 days after infection, and Toxoplasma DNA were found in the blood, liver, brain and spleen from 3 days after infection. It was impossible to detect specific IgM and IgG antibodies to T. gondii, and any specific band was not found by Western blot. In mice infected with Beverley strain, circulating antigens were detected between day 10 and day 35. The Toxoplasma DNA was found in the blood and liver from day 15 until day 60, and in the brain from day 20. But Toxoplasma DNA in the spleen were mainly detected between day 10 and day 30. The IgM antibodies were first appeared on day 10 post-infection, and were noted obviously increased between day 15 and 25. The IgG antibodies were first detected on day 15, and showed progressively increased titers. The antibody binding bands were specific according to infection period. Sera from mice infected with Beverley strain reacted mainly with the antigen of 27.5-kDa and 32.5-kDa. In conclusion, mice infected with RH strain revealed Toxoplasma antigens strongly, but not antibodies. However, mice infected with Beverley strain revealed both the Toxoplasma antigens and antibodies. The present results showed that immune responses are different between avirulent and virulent T. gondii.

Animals↗
PubMed1981

Mouse spleen cell-derived toxoplasma growth inhibitory factor: its effect on toxoplasma multiplication in the mouse kidney cells.

When Toxoplasma tachyzoites were inoculated into normal kidney cell monolayers, they multiplied in the cells and further causing cell rupture. However, when Toxoplasma immune lymphokines (LKs) was added to normal kidney cells, the intracellular multiplication of the tachyzoites was inhibited remarkably; particularly, in the case in which the tachyzoites were exposed to immune fresh serum prior to inoculation into the cells. Toxoplasma growth inhibitory factor (Toxo-GIF) in LKs, with a m.w. of 30,000 to 40,000 was found to be contained in LKs-II or MIF-I fraction after Sephadex G-100 gel filtration. LKs collected from Balb/c mice inhibited tachyzoite multiplication in ICR-JCL normal mice kidney cells, suggesting that LKs activity did not show mouse-strain specificity. In contrast, the addition of Toxoplasma immune serum to infected cells had no effect on the intracellular multiplication of Toxoplasma and also did not prevent cell-to-cell spread. However, when extracellular tachyzoites were exposed to Toxoplasma immune fresh or heat-inactivated immune serum, especially to the former, at 37 degrees C for 30 min, their active penetration into the kidney cells were extremely inhibited and their subsequent multiplication in the cells were almost totally inhibited within 24 h as compared with those exposed to normal serum.

Animals↗
PubMedDate not supplied

Immune response to Toxoplasma gondii in man. I. Common idiotypic determinants of toxoplasma-specific human antibodies.

A rabbit antiserum against human anti-toxoplasma antibodies was prepared. The rabbit antiserum was made antiidiotypic by extensive absorption. It bound 70% of radio-labelled autologous antibodies. The same antiidiotypic antiserum bound to varying degrees, three out of four other anti-toxoplasma antibodies isolated from different individuals. Inhibition experiments, using 24 human sera containing varying amounts of antibodies, showed that about 60% of them cross-reacted with the antiidiotypic antiserum, indicating that some common determinants were present on human anti-toxoplasma antibodies. F(ab')2 fragments of antiidiotypic immunoglobulin revealed about 8% idiotype-positive (id+) cells among toxoplasma-induced blasts obtained from toxoplasma-sensitized normal donors.

Animals↗
PubMed1988

Western blot analysis of the antibody response of patients with AIDS and toxoplasma encephalitis: antigenic diversity among Toxoplasma strains.

We used immunoblotting to ascertain if toxoplasma encephalitis in disease caused by the human immunodeficiency virus (HIV) could be diagnosed by the appearance of characteristic antibodies recognizing specific Toxoplasma antigens. The profile of antibodies to Toxoplasma was examined in human serum and cerebrospinal fluid from patients with chronic and acute toxoplasmosis with or without HIV infection. Many Toxoplasma antigens were recognized by all sera; the majority were presumably surface proteins, as determined by 125I labeling. All sera recognized antigens at 38, 35, 28, and 26 kilodaltons. No specific antibody or pattern of antibodies distinguished between groups of patients. A 120-kilodalton antigen recognized by sera from Atlanta was not, however, seen in most sera from New York. Study of the recognition of the antigens of different strains of Toxoplasma gondii (RH, C56, T100) by the same human sera demonstrated strain-specific antigenic differences. These strain variations may account for the antibody diversity among the patients studied.

Acquired Immunodeficiency Syndrome↗
PubMed1981

Immunohistological study of the anatomic relationship of toxoplasma antigens to the inflammatory response in the brains of mice chronically infected with Toxoplasma gondii.

The relationship of toxoplasma antigen(s) to the origin and long-term persistence of the mononuclear cell inflammatory infiltrate that is present in the brains of mice chronically infected with Toxoplasma gondii was studied by using the peroxidase-antiperoxidase immunohistochemical staining technique. C3H/Km mice were infected with the avirulent C37 strain of T. gondii and sequentially sacrificed over the ensuing 107 days. Comparable sections of each brain were prepared for routine light microscopy. Antisera to toxoplasma made in rabbits were used for immunohistological staining, and adjacent slides were also stained with conventional histological stains. The peroxidase-antiperoxidase stain demonstrated toxoplasma tissue cysts, tachyzoites, and intra- and extracellular antigen-antibody reaction products. Early infection was characterized by small tight clusters of free tachyzoites gaining access to brain substance in the absence of an inflammatory response. Once there was disruption of neural parenchyma, a mononuclear cellular infiltrate rapidly ensued. After the first days of infection, mononuclear cells were always present in all infected brains and were anatomically associated with some component of toxoplasma antigen(s). The histological picture of late infection suggested that recurrent episodes of hematogenous dissemination of tachyzoites occurred in infected mice and that such episodes were at least partially responsible for persistence of an antigenic stimulus.

Animals↗
PubMed1983

Toxoplasma gondii: microassay to differentiate toxoplasma inhibiting factor and interleukin 2.

Using a sensitive, economical, and reproducible microassay, the relationship of toxoplasma inhibiting factor to interleukin 2 has been examined. The assay developed took advantage of the observation that (1) Toxoplasma gondii tachyzoites replicated efficiently in the murine monocytic cell line, RAW 264; (2) treatment of RAW 264 cells with toxoplasma inhibiting factor prevented intracellular replication of the parasite to an extent similar to that observed with identical treatment of freshly isolated murine peritoneal exudate cells; and (3) [3H]uracil incorporation was an efficacious means to quantify replication (or inhibition of replication) of tachyzoites within the cell line. Although toxoplasma inhibiting factor and interleukin 2 were both present in the same lectin- and antigen-stimulated splenocyte supernatant fluids, results from microassays strongly suggested that the molecules were two distinct entities.

Animals↗
PubMed1991

Toxoplasma encephalitis of immunocompetent and nude mice: immunohistochemical characterisation of Toxoplasma antigen, infiltrates and major histocompatibility complex gene products.

The experimental infection of immunocompetent and immunodeficient athymic mice with an avirulent encephalitogenic Toxoplasma strain (DX strain) was employed to study the ensuing encephalitic process by use of histological and immunocytochemical methods. In the acute phase of the infection Toxoplasma cysts and tachyzoites were accompanied by an infiltrate composed of macrophages, CD4+ and CD8+ T cells. In the chronic stage a granulomatous encephalitis developed. In contrast to immunocompetent NMRI mice, athymic nude NMRI mice died 3 weeks post-infection because of a generalized toxoplasmosis with predominant involvement of the brain. A salient feature of murine Toxoplasma encephalitis was up-regulation of class I and II major histocompatibility complex (MHC) gene products. Class I antigen was widely expressed on microglial cells and astrocytes. Class II antigen was only expressed on microglial cells despite a considerable astrogliosis. Our results indicate a differential expression of MHC-determined antigens on brain cells in acute and chronic murine Toxoplasma encephalitis.

Animals↗
PubMedDate not supplied

Evaluation of the Eiken latex agglutination test for anti-Toxoplasma antibodies and seroprevalence of Toxoplasma infection among factory workers in Addis Ababa, Ethiopia.

Sera from 170 factory workers aged 18-45 years enrolled in a pilot study of human immunodeficiency virus 1 (HIV-1) infection in Addis Ababa, Ethiopia, were screened for anti-Toxoplasma immunoglobulin G antibodies by the Sabin-Feldman test (reference standard) and the Eiken latex agglutination test (under evaluation for use in developing countries). Based on the Sabin-Feldman test, the prevalence of anti-Toxoplasma antibodies was 80.0% (95% confidence interval 73.9-86.1%). The sensitivity and specificity of the Eiken latex agglutination test were 96.3% and 97.1%, respectively, showing its validity for the detection of anti-Toxoplasma antibodies. The prevalence of antibodies did not differ between individuals infected and uninfected with HIV-1 (74.2% versus 83.3%, P > 0.05). However, antibody titres were higher in HIV-infected persons than in those who were uninfected (P < 0.001). Based on these findings, we expect that toxoplasmic encephalitis will be a common opportunistic infection among HIV-infected Ethiopians, and chemoprophylaxis with co-trimoxazole may be beneficial to those with low CD4+ T cell counts. The prognostic significance of high titres of anti-Toxoplasma antibodies remains to be established among Ethiopian HIV-infected individuals.

Adolescent↗
PubMed1987

Correlation between release of reactive oxygen intermediates and inhibition of Toxoplasma multiplication in mouse peritoneal and alveolar macrophages and kidney cells after in vitro incubation with Obioactin, lonomycin A, muramyl dipeptide, lipopolysaccharide or Toxoplasma lysate antigen.

The inhibition of Toxoplasma multiplication inside cells does not correlate with an enhanced release of oxygen intermediates except in the case of peritoneal macrophages treated with Obioactin. The inhibition observed in alveolar macrophages treated with Obioactin, in kidney cells treated with Obioactin or lonomycin A and in peritoneal macrophages treated with lonomycin A was not accompanied by an increment of release of oxygen intermediates. Lipopolysaccharide (LPS) and muramyl dipeptide (MDP) enhanced the release of toxic oxygen intermediates in peritoneal macrophages, but did not have any toxoplasmacidal effect. Adenosine triphosphate (ATP) content increased during Obioactin, MDP or Toxoplasma lysate antigen (TLA) treatment. The actual oxygen consumption of the peritoneal macrophages treated with Obioactin increased dose dependently, but that of TLA-, lonomycin A- or MDP-treated cells did not change. These results suggest that the relationship between the intracellular killing of Toxoplasma protozoa and the release of oxygen intermediates differs according to the cells and/or the stimuli, and that the cellular mechanism of Toxoplasma killing in the peritoneal macrophages treated with Obioactin involves an energy-dependent mechanism.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1985

Antitumor effect of intralesional injection with formalin-fixed Toxoplasma gondii organisms on Lewis lung carcinoma in Toxoplasma-infected mice.

The antitumor effect of formalin-fixed Toxoplasma organisms (f-Tp) as an immunostimulant was examined in Toxoplasma-infected female C57BL/6 mice using a syngeneic Lewis lung carcinoma (3LL). Toxoplasma-infected mice, intradermally inoculated with the tumor cells mixed with 10(5), 10(6) or 10(7) f-Tp, developed a marked antitumor effect, inhibition of tumor growth and prolongation of life-span, in direct relation to the strength of the delayed-type hypersensitivity (DTH) reaction induced by f-Tp. The antitumor effect could also be observed even if an intralesional injection with f-Tp was performed 1, 3 or 5 days after the tumor inoculation. In a control, the injection with 2.5 X 10(6) live Mycobacterium bovis (BCG) in BCG-sensitized mice induced a significant antitumor effect, only when the BCG was injected in the mixture of tumor cells. These results demonstrate that the injection with f-Tp can induce a potent antitumor activity in mice with Toxoplasma infection.

Animals↗
PubMed1983

Immune response to Toxoplasma gondii. I. Toxoplasma-specific proliferation response of peripheral blood lymphocytes from patients with toxoplasmosis.

Peripheral blood leukocytes (PBL) from patients with toxoplasmosis were shown to be highly responsive to in vitro stimulation with Toxoplasma gondii extract as measured by incorporation of [3H]methylated thymidine. Analysis of Toxoplasma-specific proliferative cells in PBL by using monoclonal antibodies specific for human T cell subsets revealed that the Toxoplasma-specific proliferation response of PBL from the patients was mediated by Leu 1, Leu 3a positive cells, that is, helper/inducer T cells. Tests for the Toxoplasma-specific proliferation response may provide a readily available method for the diagnosis of congenital toxoplasmosis, especially during the newborn period.

Antibodies, Monoclonal↗