The diagnosis of toxoplasmosis using IgG avidity

Holliman, R E; Raymond, Reid; Renton, Nicola E.; Johnson, Julie

doi:10.1017/s0950268800057812

Cited by 59 publications

(50 citation statements)

References 19 publications

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“…One method was based on the titration of each serum sample and calculation of the titres, with and without urea treatment, in relation to a de®ned cut-off value [22,25]. In the other method, a single serum dilution was used and the absorbances of the reactions performed in the presence and absence of urea were compared [24,26]. The titration method was found to be more sensitive for diagnosing a recent primary T. gondii infection, as all 31 sera from patients with acute toxoplasmosis had avidity indices compatible with a recent infection.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of serological markers for the immunodiagnosis of acute acquired toxoplasmosis

Suzuki¹,

Rocha

Rossi³

2001

Journal of Medical Microbiology

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The detection of speci®c IgM antibodies has been the most frequently used serological marker for diagnosing recent toxoplasmosis. However, the persistence of speci®c IgM antibodies in some patients and the use of tests with a low speci®city have complicated the interpretation of serological results when toxoplasmosis is suspected. The purpose of the present study was to determine the value of newer serological techniques in the diagnosis of acute acquired toxoplasmosis. Sixty-four sera, 31 from patients with Toxoplasma gondii infection and 33 from patients with latent infection, were tested. Anti-T. gondii IgA was measured by two antibody capture ELISA tests (Platelia 1 Toxo IgA and ETI-TOXOK A) and an automated direct ELISA (IMx 1 Toxo IgA); all three assays detected antibody levels compatible with a recent infection in sera from all 31 patients with acute toxoplasmosis. However, signi®cant levels of IgA were also detected with high frequency by all three assays in sera from patients with latent infection. IgE antibodies detected by IgE immunosorbent agglutination assay (ISAGA) were present in 26 (84%) of 31 patients with acute toxoplasmosis and in sera from two subjects with latent infection taken >1 year after the beginning of the clinical symptoms of infection. Thirty (97%) of 31 patients with a recent T. gondii infection and 15 (45%) of 33 subjects with latent infection had an AC/HS pattern compatible with acute toxoplasmosis. The avidity of T. gondii IgG was evaluated by two methods. One method was based on the titration of each serum sample and calculation of the titres, in the absence and presence of urea, in relation to a de®ned cut-off value. In the other method, a single serum dilution was used and the absorbances of the reactions in the presence and absence of urea were compared. The titration method was more sensitive for diagnosing recent primary infection; all 31 sera from patients with acute toxoplasmosis had avidity indices compatible with acute toxoplasmosis by the titration method, whereas with the single dilution method, sera from four patients had equivocal results. In the 33 individuals with latent infection, similar results were obtained with the two avidity methods; only one serum sample had a non-compatible avidity value with the titration method. The results obtained in the present study show that the current serological markers used for diagnosing acute acquired toxoplasmosis have signi®cant limitations. The data suggest that determination of the avidity of T. gondii-speci®c IgG by the titration method in patients with detectable IgM antibodies de®nes most accurately the stage of infection by T. gondii.

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Section: Discussionmentioning

confidence: 99%

Evaluation of serological markers for the immunodiagnosis of acute acquired toxoplasmosis

Suzuki¹,

Rocha

Rossi³

2001

Journal of Medical Microbiology

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“…Other explaination is localization of the parasite in skeletal muscles of chickens or other organs that were not used in the bioassay. Besides the possibility of amplifying the DNA of a microorganism dead (Holliman 1994), another limitation of PCR is the possibility of false-negative results when the parasite is not present in the material used. For this reason DNA extraction was performed in triplicate to increase the sensitivity of the technique.…”

Section: Resultsmentioning

confidence: 99%

“…However, the limitation of the technique is to not distinguish whether the ampliϐied DNA is derived from viable parasites or fragments of the parasite (Holliman 1994). Because of this, the bioassay in susceptible animals reproduce the infection when there is viable parasites in animal tissues, reϐlecting the active presence of the same.…”

Section: Introductionmentioning

confidence: 99%

Serologic and molecular diagnostic and bioassay in mice for detection of Toxoplasma gondii in free ranges chickens from Pantanal of Mato Grosso do Sul

et al. 2012

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The aim of this study was to investigate the occurrence of Toxoplasma gondii and compare the results obtained in the Modiϐied Agglutination Test (MAT), Polimerase Chain Reaction (PCR) and bioassay in mice. In order to accomplish this, 40 free-range chickens from eight farms in neighboring areas to the Pantanal in Nhecolândia, Mato Grosso do Sul, were euthanized and blood samples, brain and heart were collected. The occurrence of anti-T. gondii antibodies found in chickens was 67.5% (27 samples), considering as a cutoff point the dilution 1:5. Among the samples analyzed, 7 (25.9%) were positive in the dilution 1:5, 3 (11.1%) in 1:10, 2 (7.4%) in 1:20, 3 (11.1%) in 1:320, 1 ( 3.7%) in 1:640, 3 (11.1%) in 1:1280, 2 (7.4%) in 1:2560, 4 (14.8%) in 1:5120 and 2 (7.4%) in 1:10.240. From the mixture of tissue samples (brain and heart) from the chickens analyzed, 16 (40%) presented electrophoretic bands compatible with T. gondii by PCR (gene B1). In the comparison of techniques, 59.26% positivity in PCR was revealed among animals that were seropositive in MAT (cutoff 1:5). From 141 inoculated mice, six (4.44%) died of acute toxoplasmosis between 15 and 23 days after inoculation. Surviving mice were sacriϐiced at 74 days after inoculation, and a total of 28 cysts were found in the brains of 10 distinct groups. From the seropositive hens, 27 bioassays were performed and 11 (40.7%) isolates were obtained. A greater number of isolations happened in mice that were inoculated with tissues from chickens that had high titers for anti-T. gondii antibodies. Chronic infection in mice was observed in nine groups (33.3%) from ϐive different properties. Among the surviving mice, 25.6% were positive for T. gondii in MAT (1:25). From mice positive in PCR, 87.5% were also positive in MAT. Among the PCR-negative mice, 5.2% were positive for T. gondii in MAT. It can be concluded through this study that the occurrence of infecton by T. gondii in the rural properties studied was high, that PCR directed to gene B1 does not conϐirm the viability of the parasite, but it can be used as a screening method for the selection of chickens infected by T. gondii, that the animals with titer greater than 10 must be prioritized for the selection of animals for bioassay, since for them, the chances of isolating the parasite are greater and that seroconversion in experimentally infected mice is not a good indicator for isolating the agent.

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“…Tachyzoites from Toxoplasma gondii (RH strain) were obtained by intraperitoneal inoculation of adult Swiss mice with a mixture of 14x10 6 RH T and 11x10 6 sarcoma cells (TG180, ATCC) 1 . Four days later, parasites were harvested by washing the peritoneal cavity with 5 mL of 20 mM phosphate buffered saline pH 7.2 (PBS).…”

Section: Parasitesmentioning

confidence: 99%

“…SDS-PAGE (12% resolving gels) of 5x10 6 T per lane was carried out under reducing conditions following standard protocols 8 as well as for immunoblotting 13 . After electrophoresis was completed the gel was blotted onto nitro-cellulose (NC) (Schleicher and Schuell, Germany) for 70 min at 12 V in a semidry transfer apparatus (LKB, Sweden).…”

Section: Immunoblottingmentioning

confidence: 99%

IgG recognizing 21-24 kDa and 30-33 kDa tachyzoite antigens show maximum avidity maturation during natural and accidental human toxoplasmosis

Villavedra

Battistoni

Nieto

1999

Rev. Inst. Med. trop. S. Paulo

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SUMMARYWe describe the avidity maturation of IgGs in human toxoplasmosis using sequential serum samples from accidental and natural infections. In accidental cases, avidity increased continuously throughout infection while naturally infected patients showed a different profile. Twenty-five percent of sera from chronic patients having specific IgM positive results could be appropriately classified using exclusively the avidity test data. To take advantage of the potentiality of this technique, antigens recognized by IgG showing steeper avidity maturation were identified using immunoblot with KSCN elution. Two clusters of antigens, in the ranges of 21-24 kDa and 30-33 kDa, were identified as the ones that fulfill the aforementioned avidity characteristics.

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The diagnosis of toxoplasmosis using IgG avidity

Cited by 59 publications

References 19 publications

Evaluation of serological markers for the immunodiagnosis of acute acquired toxoplasmosis

Evaluation of serological markers for the immunodiagnosis of acute acquired toxoplasmosis

Serologic and molecular diagnostic and bioassay in mice for detection of Toxoplasma gondii in free ranges chickens from Pantanal of Mato Grosso do Sul

IgG recognizing 21-24 kDa and 30-33 kDa tachyzoite antigens show maximum avidity maturation during natural and accidental human toxoplasmosis

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