scholarly journals Toxoplasma gondii: Usefulness of ROP 1 Recombinant Antigen in an Immunoglobulin G Avidity Assay for Diagnosis of Acute Toxoplasmosis in Humans

2010 ◽  
Vol 59 (4) ◽  
pp. 307-310 ◽  
Author(s):  
LUCYNA HOLEC-GĄSIOR ◽  
DOROTA DRAPAŁA ◽  
DARIUSZ LAUTENBACH ◽  
JÓZEF KUR
Keyword(s):  
Toxoplasma Gondii ◽  
Immunoglobulin G ◽  
Chronic Infection ◽  
Recombinant Antigen ◽  
Acute Stage ◽  
High Avidity ◽  
Specific Antibodies ◽  
Avidity Assay ◽  
Avidity Test ◽  
Acute Toxoplasmosis

The results present in this study suggest that the Toxoplasma gondii recombinant ROP1 antigen in an IgG avidity test can be useful for detection of acute stage of infection. Specific antibodies of low avidity were detected in most of the sera from individuals with acute toxoplasmosis, while the absence or specific antibodies of high avidity were detected in sera from patients with chronic infection.

scholarly journals Toxoplasmosis and pregnancy: Perinatal results and association of the IgG avidity test with congenital infection in pregnant women with positive anti-Toxoplasma gondii IgM [Abstract in English]

2010 ◽  
Vol 20 (1) ◽  
pp. 45
Author(s):  
Virgílio Gonçalves de Souza-Júnior ◽  
Ernesto Antonio Figueiró-Filho ◽  
Danilo De Cerqueira Borges ◽  
Vanessa Marcon Oliveira ◽  
Lílian Rezende Coelho
Keyword(s):  
Toxoplasma Gondii ◽  
Pregnant Women ◽  
Predictive Value ◽  
Congenital Infection ◽  
Neonatal Infection ◽  
High Avidity ◽  
Igg Avidity ◽  
Risk Pregnancy ◽  
Avidity Test ◽  
Acute Toxoplasmosis

AIMS: To verify the perinatal outcomes in pregnant women with acute toxoplasmosis, and to determine if there was association between the results of Toxoplasma gondii-specific IgG avidity test and the presence or absence of fetal/neonatal infection. METHODS: A cross-sectional study included pregnant women with serological diagnosis of acute toxoplasmosis (presenting a positive Toxoplasma gondii-specific IgM test) attended at the outpatient unit for high-risk pregnancy of the Faculty of Medicine, Federal University of Mato Grosso do Sul, Brazil, in the period from November 2002 to November 2007. Test results demonstrating IgG avidity index above 30% were considered high avidity, while values below 30% were considered low avidity. Fetal and/or neonatal infection was defined by positive result for the polymerase chain reaction in amniotic fluid, or by a positive Toxoplasma gondii-specific IgM test in the newborn's serum. RESULTS: Considering all pregnant women referred to the outpatient unit for high-risk pregnancy in the period of study, frequency of pregnant women with positive Toxoplasma gondii-specific IgM was 10.8% (176/1.634). The rate of congenital infection in these patients was 4% (7/176). The IgG avidity test was performed in 162 patients (92% of the 176 pregnant women with positive IgM), and the avidity was high in 144 (88.9%). There was an association (p=0.003) between high avidity and no fetal/neonatal toxoplasmosis in our sample, with a prevalence ratio of 13.4 (confidence interval [CI] 95% 2.2-86.6). The positive predictive value of the avidity test (probability of congenital infection with a low avidity) was 22% (95% 6%-47%), while the negative predictive value (probability of absence of congenital infection with a high avidity) was 98% (95% CI 94% -99%). CONCLUSIONS: In this study the rate of congenital infection in pregnant women diagnosed with acute toxoplasmosis was 4%. In pregnant women with positive Toxoplasma gondii-specific IgM, results of Toxoplasma gondii-specific IgG avidity test were associated with the presence or absence of congenital infection, with a high negative predictive value (no fetal/neonatal infection when avidity was high).

scholarly journals Use of MAG1 Recombinant Antigen for Diagnosis of Toxoplasma gondii Infection in Humans

2007 ◽  
Vol 14 (3) ◽  
pp. 220-225 ◽  
Author(s):  
Lucyna Holec ◽  
Elżbieta Hiszczyńska-Sawicka ◽  
Artur Gąsior ◽  
Anna Brillowska-Dąbrowska ◽  
Józef Kur
Keyword(s):  
Toxoplasma Gondii ◽  
Diagnostic Tests ◽  
Expression System ◽  
Recombinant Antigen ◽  
Acute Stage ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Acute Toxoplasmosis ◽  
Toxoplasma Gondii Infection ◽  
Potential Use

ABSTRACT This paper describes the cloning, purification, and serological applications of matrix antigen MAG1 of Toxoplasma gondii. The expression system used allows the production of a large amount of T. gondii recombinant protein, which was assessed for its potential use in an enzyme-linked immunosorbent assay (ELISA) for detection of T. gondii infection in humans. Serum samples from 117 patients with different stages of infection, along with 10 serum samples from seronegative patients obtained for routine diagnostic tests, were used. The results were compared with those of an ELISA that uses a native T. gondii antigen extract. The MAG1 antigen detected antibodies more frequently from the acute stage (97.3%) than from the chronic stage (7.5%) of toxoplasmosis. Hence, this antigen may be used as a tool for detection of T. gondii immunoglobulin G antibodies in persons with acute toxoplasmosis.

scholarly journals IgG AVIDITY WESTERN BLOT USING Toxoplasma gondii rGRA-7 CLONED FROM NUCLEOTIDES 39-711 FOR SERODIAGNOSIS OF ACUTE TOXOPLASMOSIS

2013 ◽  
Vol 55 (2) ◽  
pp. 79-83 ◽  
Author(s):  
Poonam S. Deshpande ◽  
Dupadahalli Kotresha ◽  
Rahmah Noordin ◽  
Muhammad Hafiznur Yunus ◽  
Geita Saadatnia ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Western Blot ◽  
Chronic Infection ◽  
Acute Infection ◽  
Congenital Infection ◽  
Recombinant Antigen ◽  
Serum Samples ◽  
Serological Profile ◽  
Igg Avidity ◽  
Acute Toxoplasmosis

Toxoplasmosis is an important cause of congenital infection. The present study was performed to evaluate the usefulness of recombinant (r) GRA-7 cloned from nucleotides (n) 39-711 in discriminating between acute and chronic toxoplasmosis. First, commercial IgM, IgG and IgG avidity ELISAs were used to determine the serological profile of the sera. Serum samples were from 20 symptomatic patients with acute infection (low IgG avidity, IgM positive), 10 with chronic infection (high IgG avidity, IgM negative) and 10 with indeterminate IgG avidity (IgM positive) which were tested for IgG avidity status with an in-house developed IgG avidity Western blot using the rGRA-7 recombinant antigen. All 20 sera from cases of probable acute infection showed bands which either faded out completely or reduced significantly in intensity after treatment with 8 M urea, whereas the band intensities of the 10 serum samples from chronic cases remained the same. Of the 10 sera with indeterminate IgG avidity status, after treatment with 8 M urea the band intensities with six sera remained the same, two sera had completely faded bands and another two sera had significantly reduced band intensities. Discrimination between acute and chronic toxoplasmosis was successfully performed by the in-house IgG avidity Western blot.

scholarly journals Toxoplasma gondii specific IgG avidity assay: Role and implication in the confirmatory diagnosis of acute toxoplasmosis in seropositive pregnant women

2016 ◽  
Vol 9 (2) ◽  
pp. 96
Author(s):  
Chowdhury Rafia Naheen ◽  
Shirin Tarafder ◽  
Humayun Sattar ◽  
Shafinaz Khan
Keyword(s):  
Toxoplasma Gondii ◽  
Pregnant Women ◽  
Acute Infection ◽  
High Avidity ◽  
Past Infection ◽  
Congenital Transmission ◽  
Avidity Assay ◽  
Igg Avidity ◽  
Avidity Test ◽  
Specific Igg

<p>This study was undertaken to apply<em> Toxoplasma gondii</em> specific IgG avidity test in seropositive pregnant women to differentiate acute and past infection. <em>T. gondii</em> specific IgG avidity test was conducted in 39 seropositive pregnant women and their pregnancy outcomes were observed later on. Out of 39 <em>T. gondii</em> seropositive pregnant women 33 (84%) were only IgG positive and 6 (15.4%) were both IgG-IgM positive. All the IgG positive cases (100%) and 2(33.3%) IgG-IgM positive cases had high avidity antibodies and they gave birth to healthy babies. Rest of the 4 (66.7%) IgG-IgM positive women had low avidity and 50% of them had abortion and 50% gave birth to unhealthy babies. This reveals that the seropositive mothers having high IgG avidity had past infection and no risk of congenital transmission. Seropositive mothers having low IgG avidity had acute infection and so congenital transmission occurred. Presence of<em> T. gondii</em> specific IgG and IgM antibody does not indicate acute infection always. IgG-IgM positive pregnant women should be further evaluated by IgG avidity assay to confirm acute infection.</p><p> </p>

scholarly journals Use of Dense Granule Antigen GRA6 in an Immunoglobulin G Avidity Test To Exclude Acute Toxoplasma gondii Infection during Pregnancy

2010 ◽  
Vol 17 (9) ◽  
pp. 1349-1355 ◽  
Author(s):  
Hossein Elyasi ◽  
Jalal Babaie ◽  
Hélène Fricker-Hidalgo ◽  
Marie-Pierre Brenier-Pinchart ◽  
Mehrak Zare ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Immunoglobulin G ◽  
Chronic Infection ◽  
Dense Granule ◽  
Enzyme Linked Immunosorbent Assay ◽  
High Avidity ◽  
Igg Antibodies ◽  
Serum Samples ◽  
Recent Infection ◽  
Igg Avidity

ABSTRACT The usefulness of a specific immunoglobulin G (IgG) avidity enzyme-linked immunosorbent assay (ELISA) based on recombinant GRA6 antigen for distinguishing between acute and chronic Toxoplasma infection was investigated. Two sets of serum samples obtained from pregnant women with acute, chronic, or no Toxoplasma infection collected in France and Iran were used. Among the French subjects, 19 of 20 (95%) women who experienced seroconversion during the past 4 months before sampling displayed low-avidity IgG antibodies against GRA6, while all 17 (100%) women with chronic infection had high-avidity antibodies. When the Euroimmun IgG avidity ELISA was used, 15 of 19 (78.9%) recently infected women had low-avidity antibodies, and 20 of 22 (90.9%) women with chronic infection displayed high-avidity antibodies. The results suggested better performance of the GRA6 avidity ELISA than the Euroimmun avidity ELISA for exclusion of a recent infection occurring less than 4 months previously. Similarly, all 35 Iranian women with acute Toxoplasma infection had low-avidity antibodies against GRA6, whereas all 34 women with chronic infection displayed IgG antibodies of high avidity, indicating the value of GRA6 avidity testing for ruling out a recent infection. Avidity tests based on lysed whole-cell Toxoplasma gondii antigen are currently used to exclude recently acquired infections; however, the use of recombinant antigen(s) might improve the diagnostic performance of avidity tests and facilitate the development of more standardized assays.

Usefulness of Toxoplasma gondii recombinant antigens (GRA1, GRA7 and SAG1) in an immunoglobulin G avidity test for the serodiagnosis of toxoplasmosis

2006 ◽  
Vol 100 (2) ◽  
pp. 333-337 ◽  
Author(s):  
H. Pietkiewicz ◽  
E. Hiszczyńska-Sawicka ◽  
J. Kur ◽  
E. Petersen ◽  
H. V. Nielsen ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Immunoglobulin G ◽  
Recombinant Antigens ◽  
Avidity Test

scholarly journals Evaluation of the New Elecsys Toxo IgG Avidity Assay for Toxoplasmosis and New Insights into the Interpretation of Avidity Results

2012 ◽  
Vol 19 (11) ◽  
pp. 1838-1843 ◽  
Author(s):  
Jean-Benjamin Murat ◽  
Coralie L'Ollivier ◽  
Hélène Fricker Hidalgo ◽  
Jacqueline Franck ◽  
Hervé Pelloux ◽  
...  
Keyword(s):  
Severe Disease ◽  
High Avidity ◽  
Serum Samples ◽  
Recent Infection ◽  
Content Type ◽  
Additional Information ◽  
Avidity Assay ◽  
Igg Avidity ◽  
Acute Toxoplasmosis ◽  
Almost All

ABSTRACTDetection and treatment of acute toxoplasmosis during pregnancy can avoid severe disease of the fetus. In this context, assessment of anti-ToxoplasmaIgG avidity has been shown to exclude recent infection. The Elecsys Toxo IgG and IgM assays (Roche Diagnostics) have been validated for screening pregnant women and a new assay, Elecsys Toxo IgG Avidity, was recently developed. Our aims were to investigate the performance characteristics of this new avidity assay and explore whether additional information can be provided by avidity assays. The Elecsys assay was compared with the Vidas (bioMérieux) and Architect (Abbott) Avidity assays using two sets of serum samples (n= 291 andn= 255). The rate of general agreement between the Elecsys and Vidas assays was 74%, and that between the Elecsys and Architect assays was 83%. For 11% of the serum samples, avidity was high with the Vidas assay and within the gray zone with the Elecsys assay. None of the assays detected high-avidity antibodies in serum taken <4 months after infection. Avidity values of >90% were exclusively reported in sera taken >9 months after infection by the Elecsys and Architect assays. Almost all avidities of <19% with the Elecsys assay and <17% with the Architect assay corresponded to sera taken <3 and <2 months after infection, respectively. The Elecsys IgG Avidity assay can be used to exclude recent infection. New ways of interpreting the avidity result are also suggested: very high or low values could exclude infections within the last 9 months or help to confirm a recent infection, respectively. However, these potential interpretations require further investigation.

scholarly journals GRA2 and ROP1 Recombinant Antigens as Potential Markers for Detection of Toxoplasma gondii-Specific Immunoglobulin G in Humans with Acute Toxoplasmosis

2009 ◽  
Vol 16 (4) ◽  
pp. 510-514 ◽  
Author(s):  
Lucyna Holec-Gąsior ◽  
Józef Kur ◽  
Elżbieta Hiszczyńska-Sawicka
Keyword(s):  
Toxoplasma Gondii ◽  
Recombinant Proteins ◽  
Immunoglobulin G ◽  
Expression System ◽  
Chronic Phase ◽  
Chronic Infections ◽  
Serum Samples ◽  
Past Infection ◽  
Recombinant Antigens ◽  
Acute Toxoplasmosis

ABSTRACT A goal of the current study was to evaluate serological applications of Toxoplasma gondii GRA2 and rhoptry protein 1 (ROP1) antigens. Soluble recombinant GRA2 and ROP1 antigens as fusion proteins containing six histidyl residues at the N and C terminals were obtained using an Escherichia coli expression system. Purification by one-step metal affinity chromatography allowed recovery of milligram amounts of pure recombinant proteins per liter of culture. The usefulness of these antigens for diagnosis of human infections was tested on 167 serum samples obtained during routine diagnostic tests. A panel of 37 serum samples from patients with acute toxoplasmosis was compared to a panel of 90 serum samples from individuals with past infection. The results indicated that both GRA2 and ROP1 recombinant antigens detected antibodies more frequently in samples from individuals with acute infections (100% and 94.6%, respectively) than in samples from individuals with chronic infections (22.5% and 15.5%, respectively). These results suggest that immunoglobulin G antibodies against GRA2 and ROP1 antigens are produced during the acute stage of toxoplasmosis but are uncommon in the chronic phase of the infection. Hence, these recombinant proteins can be used as specific molecular markers to differentiate between acute and chronic infections.

scholarly journals Enzyme-Linked Immunosorbent Assays Using the Recombinant Dense Granule Antigens GRA6 and GRA1 of Toxoplasma gondii for Detection of Immunoglobulin G Antibodies

2000 ◽  
Vol 7 (4) ◽  
pp. 607-611 ◽  
Author(s):  
Laurence Lecordier ◽  
Marie-Pierre Fourmaux ◽  
Corinne Mercier ◽  
Eric Dehecq ◽  
E. Masy ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Toxoplasma Gondii ◽  
Recombinant Protein ◽  
Optical Density ◽  
Immunoglobulin G ◽  
Recombinant Antigen ◽  
Dense Granule ◽  
Human Sera ◽  
Density Values ◽  
Immunosorbent Assays

ABSTRACT The potential of the dense granule antigens GRA1 and GRA6 ofToxoplasma gondii to be used as diagnosis reagents in a recombinant form was evaluated. Both proteins were expressed inEscherichia coli as glutathione-S-transferase (GST) fusions. The GST-GRA1 fusion comprises the entire GRA1 sequence devoid of its N-terminal signal peptide. Separate expression of the two N- and C-terminal hydrophilic regions of GRA6 showed that only the N-terminal hydrophilic part of the protein was recognized by a pool of positive human sera in an immunoblot. One hundred T. gondii-positive and 98 negative human sera were tested in two separate immunoglobulin G (IgG)-direct enzyme-linked immunosorbent assays (ELISAs) using either GST-GRA1 or GST-GRA6-Nt recombinant protein. Whereas the sensitivity of the GST-GRA1 IgG ELISA was low (68%), the GST-GRA6-Nt IgG ELISA reached a sensitivity of 96%. The reactivity to GRA6-Nt was shown to be high even with human sera of low IgG titers. In addition, comparison of the optical density values for each serum revealed that GRA1 may complement GRA6-Nt to reach an overall sensitivity of 98%. Therefore, the GST-GRA6-Nt ELISA could be used together with another antigen like GRA1 for the development of a recombinant antigen-based test for serodiagnosis of toxoplasmosis.

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