Toxoplasma gondii: An evaluation of diagnostic value of recombinant antigens in a murine model

Gatkowska, Justyna; Hiszczyńska-Sawicka, Elżbieta; Kur, Józef; Holec, Lucyna; Długońska, Henryka

doi:10.1016/j.exppara.2006.03.011

Cited by 43 publications

(39 citation statements)

References 28 publications

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“…The immune response against GRA6 and GRA7 is very heterogeneous since different patients infected with the same strain may present with different profiles of reactivity against the same peptides. GRA6 and GRA7 are antigens characteristic of recent infections (27,28,49,51,52). The use of single peptides derived from these two antigens may not allow serotyping of serum samples from patients with chronic infections.…”

Section: Discussionmentioning

confidence: 99%

“…GRA6 is a glycine-rich protein and behaves like an integral membrane protein within the parasitophorous vacuole (36,41). GRA6 is considered a good marker of acute infection (27,28,52). However, the immune response to GRA6 is very heterogeneous (25).…”

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confidence: 99%

“…It migrates from the GRA to the parasitophorous vacuolar membrane through the intravacuolar network during host cell invasion (9). GRA7 is an antigen characteristic of the acute phase of the infection (27,49,51) and a target antigen in the intracerebral immune response during the chronic phase of infection (23,45). These immunogenic properties make this antigen a good marker for serodiagnostic studies (5,6,7,50).…”

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confidence: 99%

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Selection of Polymorphic Peptides from GRA6 and GRA7 Sequences of Toxoplasma gondii Strains To Be Used in Serotyping

Sousa

Ajzenberg

Marle

et al. 2009

Clin Vaccine Immunol

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The evaluation of Toxoplasma gondii isolates obtained from geographical environments other than Europe and North America revealed the existence of atypical strains that are not included in the three archetypal clonal lineages (lineages I, II, and III). GRA6 and GRA7 are polymorphic genes that have been used for the genotyping of Toxoplasma. The coding regions of GRA6 and GRA7 from 49 nonarchetypal strains were sequenced and compared with the sequences of type I, II, and III reference strains. Eighteen and 10 different amino acid sequences were found for GRA6 and GRA7, respectively. The polymorphisms found between the different sequences were analyzed, with the objective of defining peptides to be used for the serotyping of Toxoplasma infections. Two peptides specific for clonal lineages I and III (peptides GRA7I and GRA7III, respectively) were selected from the GRA7 locus. Three peptides specific for some atypical strains (peptides Am6, Af6, and Am7) were selected from both the GRA6 and the GRA7 loci. Serum samples from humans infected with Toxoplasma strains of known genotypes were serotyped with the selected peptides. Peptide GRA7III seems to be a good candidate for the serotyping of infections caused by type III strains. Peptide GRA7I had a very low sensitivity. Peptides Am6 and Af6 had low specificities, since they reacted with serum samples from patients infected with strains belonging to the three archetypal lineages. Although peptide Am7 was specific, it had low sensitivity.The vast majority of Toxoplasma gondii isolates from human patients and domestic animals in Europe and North America belong to three archetypal clonal lineages, namely, types I, II, and III (1,11,30). However, nonarchetypal strains with atypical genotypes have recently been described in unusual hosts such as sea otters (10,42,43) and in tropical areas such as South America and Africa (2,32,39,46,54). Genotyping studies that distinguish different types of strains are important to gain knowledge of the biodiversity of the parasite in order to understand the molecular epidemiology of Toxoplasma and to highlight the correlation between the genotype of the parasite and the pathogenesis of human toxoplasmosis.The dense granules (GRA) are parasitic organelles involved in cell invasion and in the intracellular survival of the parasite. GRA proteins are expressed by the three stages of T. gondii: the tachyzoite, bradyzoite (38), and sporozoite (55) stages. GRA6 is a GRA antigen of 32 kDa described for the first time by Lecordier et al. (38). In extracellular parasites, GRA6 exists in dense secretor granules mostly as soluble proteins. Like the other GRA proteins, GRA6 is involved in host cell invasion. GRA6 is a glycine-rich protein and behaves like an integral membrane protein within the parasitophorous vacuole (36,41). GRA6 is considered a good marker of acute infection (27,28,52). However, the immune response to GRA6 is very heterogeneous (25).GRA7 is a GRA antigen of 29 kDa (26, 31). Like GRA6, it is involved in host cell invasion. This pro...

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Section: Discussionmentioning

confidence: 99%

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Selection of Polymorphic Peptides from GRA6 and GRA7 Sequences of Toxoplasma gondii Strains To Be Used in Serotyping

Sousa

Ajzenberg

Marle

et al. 2009

Clin Vaccine Immunol

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“…In most studies, rSAG1 also showed high reactivity with IgG antibodies in serum samples from acutely infected patients (5,22,24). In other studies, rSAG1 was more immunogenic in the chronic phase of infection (1,11,12). It is believed that the diverse outcome of immunogenicity depends on the preparation of the recombinant antigen (17).…”

Section: Discussionmentioning

confidence: 99%

Identification of Toxoplasma gondii SUB1 Antigen as a Marker for Acute Infection by Use of an Innovative Evaluation Method

Hruzik¹,

Asif²,

Groß³

2011

J Clin Microbiol

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By the separation of Toxoplasma lysate using two-dimensional gel electrophoresis and its analysis with human serum samples and mass spectrometry, the subtilisin-like protein (SUB1) was identified to be a potential marker for acute toxoplasmosis. Following expression of the C-terminal domain of SUB1 in Escherichia coli, it was tested in a line blot assay using a total of 80 human serum samples. Two computer programs based on different evaluation strategies were used for judgment of the line blot results: (i) a time-dependent method with a predefined cutoff value and (ii) a fixed-time-point method with a calculated cutoff. Thereby, SUB1 was proven to be rather reactive with specific immunoglobulin A (IgA), IgM, and IgG of patients with an acute infection. This finding makes this antigen an attractive candidate for improving diagnosis of toxoplasmosis and demonstrates that not only the selection of respective antigens but also the evaluation method chosen are important for the evaluation of new diagnostic markers.One of the most successful protozoan parasites is Toxoplasma gondii. In humans and other intermediate hosts, the tachyzoite stage of the parasite represents the active phase of infection, whereas the bradyzoite stage represents the chronic or latent phase of infection. In immunocompetent human hosts, the infection is asymptomatic in most cases. A special threat exists when primary infection takes place in the developing fetus or in immunocompromised hosts, particularly patients suffering from AIDS (21, 27) and transplant recipients (6, 27).Many commercial tests are available for the serological diagnosis of T. gondii infection. Here, the enzyme-linked immunosorbent assay (ELISA) and immunoblotting are widespread techniques that are performed automatically or manually for the detection of T. gondii-specific immunoglobulin G (IgG), IgM, and IgA.We tried to identify Toxoplasma antigens that might be suitable for the serological identification of early infection by twodimensional (2D) gel electrophoresis and mass spectrometry (MS) analysis. After recombinant production of the IgA-reactive T. gondii protein subtilisin-like protein 1 (SUB1), we evaluated it on human serum samples which were previously tested with commercial tests and classified as having either no T. gondii infection, acute infection (high IgM or IgA titer), or chronic infection (no IgM or IgA, high IgG titer). MATERIALS AND METHODSParasites and host cells. Tachyzoites of the type II strain NTE were isolated from an L929 fibroblast-T. gondii coculture. These parasites were used to infect human foreskin fibroblasts (HFFs) and cultured in Dulbecco modified Eagle medium containing 10% fetal calf serum, 1% penicillin-streptomycin, 1% sodium pyruvate, and 1% nonessential amino acids (NEAA) for 3 to 4 days. Infected cells were cultured at 37°C in 5% CO 2 atmosphere.T. gondii antigen preparation. Extracellular parasites were isolated from the supernatant of infected HFFs by filtration (pore size, 0.02 m; Millipore, Billerica, MA). The cell pellet of 4 ...

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“…Although the prevalence rate of toxoplasmosis is approximately one-third of the world's human population, T. gondii infection in immunocompetent individuals is usually asymptomatic, even though some patients may experience fever and other non-specific clinical signs [1]. In immunocompromised patients, this disease may be serious or even fatal; furthermore, primary invasion during pregnancy may endanger the life of the fetus as well as the infected mothers [1,2]. Accurate diagnosis of the acquired infection by highly sensitive and specific methods is crucial for proper management of animal and human toxoplasmosis and represents the key step in the prevention and treatment of the disease [3].…”

Section: Introductionmentioning

confidence: 99%

Effective Diagnostic Marker for Serodiagnosis of Toxoplasma gondii Infection: New Developments and Perspectives

Mohamed¹,

Hajissa²

2017

Toxoplasmosis

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Toxoplasmosis is a prevalent parasitic infection caused by an obligate intracellular parasite Toxoplasma gondii. Various methods have been established in the laboratory diagnosis of toxoplasmosis. Among these methods, serological tests are common and provide satisfactory results. However, producing reliable reagents and standard antigen remains difficult and expensive. Replacing native antigens in all current diagnostic kits with standard and reliable reagents are speculated to achieve more sensitive and specific detection that can significantly improve the assay performance. This review provides updated data on toxoplasmosis serodiagnosis. It focuses on the recent trends of producing reliable and standard antigens that have been used in the serological tests of toxoplasmosis, as well as the future direction in this field.

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Toxoplasma gondii: An evaluation of diagnostic value of recombinant antigens in a murine model

Cited by 43 publications

References 28 publications

Selection of Polymorphic Peptides from GRA6 and GRA7 Sequences of Toxoplasma gondii Strains To Be Used in Serotyping

Selection of Polymorphic Peptides from GRA6 and GRA7 Sequences of Toxoplasma gondii Strains To Be Used in Serotyping

Identification of Toxoplasma gondii SUB1 Antigen as a Marker for Acute Infection by Use of an Innovative Evaluation Method

Effective Diagnostic Marker for Serodiagnosis of Toxoplasma gondii Infection: New Developments and Perspectives

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