[Toxoplasma gondii: 2 cases of recontamination in immune patients].
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Adult↗
Biomedical subjects
B Fortier
Publications and source records attributed to B Fortier.
[Prevention and treatment of materno-fetal toxoplasmosis].
Preventing congenital toxoplasmosis is fundamental, and in France screening tests for primary infection are obligatory for pregnant women. All nonimmunized women should be encouraged to follow good dietary and general health rules until delivery. Nevertheless, the risk of seroconversion does exist but can be detected early through monthly serum tests. Spiramycin as initial treatment of maternal primary infection is an essential step in preventing parasite transmission to the fetus. Fetal antitoxoplasmosis antibodies and indirect signs of congenital abnormalities should be detected early by amniotic fluid and fetal blood tests before echographic evidence confirms the diagnosis. Pyrimethamine-sulfonamide therapy should be undertaken and modulated according to laboratory results in order to prevent or treat any possible fetopathy. Congenital toxoplasmosis can be prevented in utero through biological diagnosis and specific therapy.
Adult↗
Spontaneous abortion and reinfection by Toxoplasma gondii.
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Abortion, Spontaneous↗
Detection of specific antibodies to Toxoplasma gondii by a competitive enzyme immunoassay using a monoclonal antibody against the P30 antigen.
An inhibition EIA using a monoclonal antibody against the major P30 Toxoplasma gondii surface protein was designed for detection of specific antibodies in human sera. The assay was based on the inhibition of binding of peroxidase labelled monoclonal antibody to Toxoplasma gondii crude antigen coated plates by the corresponding antibodies present in human sera. This rapid and simple assay was compared to indirect immunofluorescence, direct agglutination and an immunosorbent agglutination assay using 435 human sera. The specificity and sensitivity were 100% and 97% respectively. This test was found to be as sensitive as the dye test.
Animals↗
Characterization of microneme proteins of Toxoplasma gondii.
Three microneme proteins of Toxoplasma gondii have been characterized using 3 monoclonal antibodies and a recombinant protein specific antiserum. In all cases, apical labeling of tachyzoites and bradyzoites was observed by indirect immunofluorescence assay. Immunogold localization on ultrathin sections of bradyzoites or tachyzoites showed a specific labeling of micronemes. The following proteins were characterized using 2-dimensional gel electrophoresis and Western immunoblotting: Mic 1 (60 kDa, Pi 6.5), Mic 2 (120 kDa, Pi 5) and Mic 3 (90 kDa, Pi 6.75). The 90-kDa protein (Mic 3) is a heterodimer of two 38-kDa polypeptides (Pi 6.7 and 6.75 respectively) linked by disulfide bridges. Metabolic labeling and immunoprecipitation assays showed that at least one of the 38-kDa polypeptides was processed from a 40-kDa precursor. No processing was observed during the biosynthesis of the 120- and 60-kDa polypeptides.
Animals↗
Differential targeting of dense granule proteins in the parasitophorous vacuole of Toxoplasma gondii.
The biosynthesis and fate of 4 different dense granule proteins of Toxoplasma gondii were studied with 3 monoclonal antibodies raised against tachyzoites and 1 polyclonal antibody raised against a recombinant protein. These proteins have the following molecular weights: 27 kDa (GRA 1), 28 kDa (GRA 2), 30 kDa (GRA 3) and 40 kDa (GRA 4). All four proteins were found in dense granules by immunoelectron microscopy; in T. gondii-infected cells, they were found in the vacuolar network but, in addition, GRA 3 was also detected on the parasitophorous vacuole membrane. Therefore, dense granule contents undergo differential targeting when exocytosed in the parasitophorous vacuole. Metabolic labelling and immunoprecipitation showed that GRA 2 and GRA 3 were processed from lower molecular weight precursors, and that GRA 2 and GRA 4 incorporated [3H] glucosamine and are thus likely to be glycosylated.
Animals↗
Characterization of bradyzoite-specific antigens of Toxoplasma gondii.
Monoclonal antibodies that react specifically with bradyzoite antigens of Toxoplasma gondii were selected by differential immunofluorescence among hybridomas produced against these organisms. These antigens were further characterized by immunofluorescence on living bradyzoites and Western immunoblotting. Four pellicular antigens (36, 34, 21, and 18 kDa) were identified; three of these are exposed on the surface of the organism and accessible to either antibodies, trypsin cleavage, or both of these surface-probing procedures. These antigens were found on recent human isolates of T. gondii, as well as on laboratory strain bradyzoites obtained from either brain cysts or in vitro-grown parasites.
Animals↗
[Detection of early humoral response in experimental toxoplasmosis in mice].
Experimental infection of mice by Toxoplasma gondii is the best way for antigen production or direct diagnosis. Early serological response from sera and peritoneal exudate of mice infected by T. gondii has been studied. In this report the authors show that specific antibodies (IgM) are found in the serum at 24 hours after intraperitoneal inoculation. Serological methods were unable to detect free antibodies in the peritoneal exudate. Specific antibodies coating the parasite surface were detected by direct immunofluorescence as soon as 48 hours post infection. Biochemical treatment usually used for antigen production (trypsin, pepsin) were unable to destroy this antibodies which where no longer detected after 2 mercapto-ethanol treatment. Control experiments showed that, in these conditions, 2 mercapto-ethanol treatment had no effect on the reactivity of surface antigens with antibodies. Therefore, this results show that checking for specific antibodies absorbed at the surface of T. gondii is a prerequisite of the use of antigen produced in vivo.
Agglutination Tests↗
Characterization of a 225 kilodalton rhoptry protein of Plasmodium falciparum.
A monoclonal antibody (24C6 4F12) raised against Plasmodium falciparum culture supernatant antigens gave a multiple dot picture on schizonts when assayed by immunofluorescence on P. falciparum erythrocytic stages. The corresponding antigen was localized in the peduncle of rhoptries by immunoelectronmicroscopy. On Western blots of P. falciparum schizonts, a major antigen of 225 kDa and a minor one of 240 kDa were recognized by this McAb. Pulse chase analysis of [35S]methionine biosynthetic labeling of P. falciparum culture demonstrated that the 240 kDa molecule was the precursor of the 225 kDa and that its processing occurred between 0 and 4 h after synthesis. Biosynthesis of the 240-225 kDa antigen occurred only during schizogony.
Animals↗
Characterization of a family of rhoptry proteins of Toxoplasma gondii.
A monoclonal antibody (McAb 4A7) raised against a rhoptry enriched subcellular fraction of Toxoplasma gondii tachyzoites reacted in immunofluorescence studies with rod-like organelles located in the anterior part of the organisms and gave specific labeling of rhoptries in immunoelectron microscopy. On immunoblots, two major proteins of 55 and 60 kDa were identified by McAb 4A7. Similar results were obtained both by immunodetection and immunoblotting with tachyzoites, bradyzoites and sporozoites. Pulse chase analysis of [35S]methionine labeled tachyzoites demonstrated that the 55 and 60 kDa rhoptry proteins derived from a 66-68 kDa doublet which was processed approximately 30 min after biosynthesis. Two other monoclonal antibodies (McAb 2F8, McAb 2H3) respectively specific for rhoptry proteins of 55 kDa having a 66 kDa precursor and 60 kDa having a 68 kDa precursor were also obtained; we suggest that they recognize separately the two components of the 55-60 kDa rhoptry protein family of Toxoplasma.
Animals↗
Protein p126: a parasitophorous vacuole antigen associated with the release of Plasmodium falciparum merozoites.
The p126 protein is synthesized by P. falciparum between the 32nd and the 36th hour of the erythrocytic cycle, and is localized in the parasitophorous vacuole. It is processed when schizonts rupture and the major fragments (50, 47 and 18 kDa), which are released into culture supernatant, have been characterized using monoclonal antibodies. The 47 kDa fragment has been mapped at the N-terminus of the molecule. The portion of the protein p126 gene coding for this fragment contains 3 introns and is characterized by a sequence coding for 6 repeats of 8 aminoacids and by repeats of TCA/T-AGT coding for a polyserine sequence of 37 serines in a row for the FCR-3 strain. The 50 kDa fragment is also found in culture supernatant when merozoites are released from mature schizonts. The incubation of mature schizonts with leupeptin inhibits the release of merozoites and, in this case, a 56 kDa intermediate product is found. In those conditions, merozoites were observed free in the erythrocyte cytoplasm, the membrane of the parasitophorous vacuole being destroyed. The 50 kDa fragment can be obtained from the 56 kDa fragment by treatment with trypsin (a protease inhibited by leupeptin). Our results suggest that the processing of the 56 kDa fragment: 1) is protease-dependent, and could depend on a trypsin-like activity; 2) cannot occur after the release of merozoites because of the protease inhibitors contained in the serum; 3) does not occur before the release of merozoites, since no processed products of the protein p126 are observed in unruptured schizonts.(ABSTRACT TRUNCATED AT 250 WORDS)
Amino Acid Sequence↗
Surface antigens of Toxoplasma gondii.
Monoclonal antibodies reacting with pellicular antigens of Toxoplasma gondii tachyzoites have been selected among hybridomas produced against this organism by immunofluorescence assay. These antigens have been further characterized by immunofluorescence on living zoites, Western immunoblotting and immunoprecipitation of lactoperoxidase surface radio-iodinated tachyzoite lysates. The simultaneous characterization of 5 different surface antigens (P43, P35, P30, P23, P22) some of which have already been studied individually allowed a better definition of these antigens and the characterization of a yet undescribed surface molecule (P23).
Animals↗
Electric and chemical fusions for the production of monoclonal antibodies reacting with the in-vivo growth phase of Candida albicans.
To obtain monoclonal antibodies (MAbs) directed preferentially against the pathogenic phase of Candida albicans, mice were immunised with germ tubes of C. albicans serotype A, strain VW.32, killed by exposure to ultraviolet (UV) irradiation. Fusions were performed either by the standard chemical procedure with polyethylene glycol, or by electric discharge following linkage of the myeloma and lymphocyte cells with a Concanavalin A-mannoprotein bridge. The preliminary characteristics of one MAb obtained from each of these fusions are described. An IgM antibody (3B7) obtained from the chemical fusion reacted with a polysaccharide antigen that was heterogeneously distributed on both in-vitro and in-vivo forms of C. albicans. This MAb agglutinated different strains of C. albicans irrespective of their serotype. An IgG1 antibody (3G6) that had been obtained from the electric fusion was found to react in vitro with a proteinaceous antigen located only on the germ tubes of strain VW.32. However, MAb 3G6 displayed strong reactivity against all growth forms of C. albicans in vivo and reactivity extended to other strains.
Agglutination Tests↗
[Guillain-Barré syndrome with favorable outcome in a case of recent human immunodeficiency virus infection].
An acute polyradiculoneuropathy occurred in a 30 years homosexual male. E.L.I.S.A. test and Western Blot showed recent infection by H.I.V. Besides, endogenous reinfestation by cytomegalovirus was found: high concentrations of specific IgG antibodies and presence of the virus in the blood. T4 helper cells were severely reduced, without any other sign of cellular immunity failure. None of the two viruses was found in the nervous biopsy. This Guillain-Barre syndrome with a subsequent cellular reaction in the CSF, is probably to be related to an immunoallergic mechanism. Brief increase of antibodies specific for HBsAg and Borrelia Burgdorferri and the beneficial effect of plasmapheresis, supported this view. Two months later, the patient showed superficial lymph nodes hyperplasia, without any other symptom of pre-Acquired Immuno-Depression Syndrome.
Adult↗
Enzyme immunoassay for detection of antigen in acute Plasmodium falciparum malaria.
A monoclonal antibody specific for an epitope of a 50 kDa Plasmodium falciparum antigen was used in an enzyme immunoassay for detection of the corresponding exo-antigen in culture supernatant and in the sera of 31 patients suffering from acute malaria. The assay was specific for Plasmodium falciparum and did not appear to be strain restricted. A parasitaemia level below 0.001% could be detected.
Acute Disease↗
Localization, biosynthesis, processing and isolation of a major 126 kDa antigen of the parasitophorous vacuole of Plasmodium falciparum.
Monoclonal antibodies prepared against a 50 kDa antigen found in Plasmodium falciparum culture supernatants identify a 126 kDa polypeptide which can be localized by immunofluorescence and immunoelectronmicroscopy at the periphery of the schizonts. This polypeptide is released from the infected erythrocytes by mild saponin lysis and is probably a component of the parasitophorous vacuole. Pulse chase kinetic analysis demonstrated its disappearance from the parasitized red blood cell from 6 to 10 h after being synthesized and the concomitant appearance of the 50 kDa molecule in the culture supernatant. Purification of metabolically labeled, schizont infected cells demonstrated that spontaneous release of merozoites is needed for the processing of the 126 to the 50 kDa whereas reinvasion is not. Polyclonal antibodies were raised in rabbit against affinity purified 126 kDa protein. These antibodies, together with another 126 kDa specific monoclonal antibody have enabled us to characterize two other cleavage products of the 126 kDa antigen in culture supernatants, namely 47 and 18 kDa polypeptides. We believe that the processing of the 126 kDa protein into low molecular weight fragments reflects a proteolytic event which may participate in merozoite release.
Animals↗
Immunochemical analysis of a major antigen of Plasmodium falciparum (P126) among ten geographic isolates.
Protein P126, a parasitophorous vacuole major antigen of Plasmodium falciparum and precursor of 3 major exoantigens (50, 47, and 18 Kd in strain FCR-3) has been studied in 10 culture-adapted isolates originating from various endemic areas. Two monoclonal antibodies (specific for 50 and 47 Kd exoantigens, respectively) were used to immunoprecipitate culture supernatants and parasitized erythrocytes in each case. It was observed that all the parasite isolates reacted with both monoclonal antibodies, indicating the ubiquity of the epitopes analyzed. Further, two of the exoantigens (the 50 and 18 Kd of FCR-3) were found to have a stable molecular mass in all the isolates tested, whereas, the other one (47 Kd in FCR-3) was found to have a variable molecular mass, from 47 to 50 Kd. The molecular mass of the precursor varied from 126 Kd to 128 Kd. No correlation was found between geographic origin and antigenic size.
Antibodies, Monoclonal↗
A monoclonal antibody to a cell wall component of Candida albicans.
A heterologous fusion between mouse myeloma cells and rat lymphocytes resulted in the isolation of a rat immunoglobulin M monoclonal antibody with both agglutinating and precipitating activity. Indirect immunofluorescence and direct agglutination tests showed that the corresponding antigen was present in the cell wall of the three Candida species considered to be the most pathogenic, C. albicans, C. tropicalis, and C. glabrata, and also in the cell wall of C. guilliermondii. The antigen appeared to be predominantly polysaccharide in nature. Precipitation by counterimmunoelectrophoresis suggested that the epitope is shared by at least two separate molecules with different electrophoretic mobilities. Presence of this epitope varied from strain to strain within a given species and may be related to the morphological stage in the cell cycle. Antigen was shown to be present in the cytoplasm, in the periplasmic space, and at the cell surface of C. albicans. Indirect immunofluorescence also suggested that antigen is excreted from the cell.
Agglutination↗