Determination of anti–Toxoplasma gondii immunoglobulin G avidity: adaptation to the vidas system (bioMérieux)

Pelloux, Hervé; Brun, Emmanuelle; Vernet, Guy; Marcillat, S.; Jolivet, Michel; Guergour, Dorra; Fricker‐Hidalgo, Hélène; Goullier-Fleuret, A.; Ambroise-Thomas, P

doi:10.1016/s0732-8893(98)00077-7

Cited by 100 publications

(79 citation statements)

References 12 publications

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“…There was a close correlation between the avidity indexes for lysed whole-cell Toxoplasma antigen and those for a recombinant antigen mixture. However, the assays performed with whole parasite extract and with a recombinant antigen mixture detected low-avidity antibodies in the sera of patients who seroconverted Ͼ2 months before sampling, which is in accordance with other studies which have found that low-avidity IgG antibodies may persist for many months beyond the acute infection (7,21,23). Therefore, the use of this mixture of recombinant antigens would have the same limitation as tests based on whole-cell lysate antigen.…”

Section: Discussionsupporting

confidence: 87%

“…The whole-cell lysate assay detected low-avidity antibodies in sera from patients who had seroconverted up to 9 months previously, in practice making a low-avidity index of almost no use for the clinician in the timing of infection. Previous studies have also found that low-avidity IgG antibodies may persist for many months beyond the acute infection (7,21,23).…”

Section: Discussionmentioning

confidence: 94%

“…Measurement of specific IgG avidity has been shown to be the best tool, in combination with IgM analysis, for determining when the infection took place (14,16,18,19,21,23,25). The functional affinity of specific IgG antibodies is initially low after primary antigenic challenge and increases during subsequent weeks and months by antigendriven B-cell selection.…”

mentioning

confidence: 99%

“…The functional affinity of specific IgG antibodies is initially low after primary antigenic challenge and increases during subsequent weeks and months by antigendriven B-cell selection. One problem with this method is that some patients have persistent, low-avidity IgG antibodies for many months against lysed whole-cell Toxoplasma antigen, emphasizing the need for improvement of the IgG avidity assay (7,21,23).…”

mentioning

confidence: 99%

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Use of an Immunoglobulin G Avidity Assay Based on Recombinant Antigens for Diagnosis of PrimaryToxoplasma gondiiInfection during Pregnancy

Beghetto¹,

Buffolano²,

Spadoni³

et al. 2003

J Clin Microbiol

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The objective of this work was to develop an antibody-specific immunoglobulin G (IgG) avidity assay to discriminate between acute and latent phases of Toxoplasma gondii infection by using recombinant antigens. One hundred twenty-one serum samples from women who developed IgG antibodies against Toxoplasma during pregnancy were used. The IgG avidities of antibodies directed against epitopes carried by fragments of GRA3, GRA7, MIC3, and SAG1 antigens were measured by performing parallel enzyme immunoassays. The avidity index for Toxoplasma-specific antibodies against a homogeneous mixture of recombinant GRA3, GRA7, MIC3, and SAG1 antigens correlated closely with the IgG avidity of antibodies against lysed whole-cell T. gondii antigen. The avidity assay performed with the recombinant MIC3 antigen highlighted the presence of avidity low-antibodies IgG exclusively in sera collected within 2 months after primary infection. The presence of T. gondii-specific, low-avidity IgG antibodies against recombinant MIC3 antigen can be used to determine the point of infection with T. gondii within a 2-month time frame after infection.

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 94%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Use of an Immunoglobulin G Avidity Assay Based on Recombinant Antigens for Diagnosis of PrimaryToxoplasma gondiiInfection during Pregnancy

Beghetto¹,

Buffolano²,

Spadoni³

et al. 2003

J Clin Microbiol

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“…Consequently, serological tests other than those for IgG and IgM detection have been developed to facilitate the diagnosis of seroconversion. The measurement of IgG avidity was developed almost 20 years ago to exclude any infection acquired in the preceding 3 or 4 months using most commercial tests (16,17,18,19,20,21,22,23,24). Immunoblot analysis (Toxo II IgG test; LDBio, Lyon, France) may promptly confirm the seroconversion when IgG concentrations detected with routine tests are negative or equivocal (25,26,27).…”

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confidence: 99%

Toxoplasma Seroconversion with Negative or Transient Immunoglobulin M in Pregnant Women: Myth or Reality? A French Multicenter Retrospective Study

et al. 2013

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Classically, Toxoplasma infection is associated with high levels of specific IgM antibody and a rise in specific IgG levels 1 to 3 weeks later. Atypical IgG seroconversion, without IgM detection or with transient IgM levels, has been described during serologic follow-up of seronegative pregnant women and raises difficulties in interpreting the results. To evaluate the frequency and the characteristics of these atypical cases of seroconversion, an investigation was conducted within the French National Reference Center for Toxoplasmosis, from which 26 cases collected from 12 laboratories belonging to the network were identified. The aim of this work was to retrospectively analyze the results of serologic testing, the treatments administered, and the results of prenatal and postnatal follow-up for these women. In each case, IgG antibodies were detected using both screening and confirmatory tests. IgM antibodies were not detected in 15 cases, and the levels were equivocal or low-positive in 11 cases. The IgG avidity results were low in 16 cases and high in one case. Most of the pregnant women (22/26) were treated with spiramycin from the time that IgG antibodies appeared until delivery. Amniotic fluid was analyzed for Toxoplasma gondii DNA by PCR in 11/26 cases, and the results were negative in all cases. Congenital toxoplasmosis was ruled out in 12/26 newborns. There was no abnormality observed at birth for 10 newborns and no information available for 4 newborns. In conclusion, when the interpretation of serological results is so difficult, it seems cautious to initiate treatment by spiramycin and to follow the pregnant women and their newborns.

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ISUOG Practice Guidelines: role of ultrasound in congenital infection

Khalil

Sotiriadis

Chaoui³

et al. 2020

Ultrasound in Obstet & Gyne

130

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ISUOG Practice Guidelines: role of ultrasound in congenital infection Clinical Standards Committee The International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) is a scientific organization that encourages sound clinical practice, and high-quality teaching and research related to diagnostic imaging in women's healthcare. The ISUOG Clinical Standards Committee (CSC) has a remit to develop Practice Guidelines and Consensus Statements as educational recommendations that provide healthcare practitioners with a consensus-based approach, from experts, for diagnostic imaging. They are intended to reflect what is considered by ISUOG to be the best practice at the time at which they are issued. Although ISUOG has made every effort to ensure that Guidelines are accurate when issued, neither the Society nor any of its employees or members accepts any liability for the consequences of any inaccurate or misleading data, opinions or statements issued by the CSC. The ISUOG CSC documents are not intended to establish a legal standard of care, because interpretation of the evidence that underpins the Guidelines may be influenced by individual circumstances, local protocol and available resources. Approved Guidelines can be distributed freely with the permission of ISUOG (

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Determination of anti–Toxoplasma gondii immunoglobulin G avidity: adaptation to the vidas system (bioMérieux)

Cited by 100 publications

References 12 publications

Use of an Immunoglobulin G Avidity Assay Based on Recombinant Antigens for Diagnosis of PrimaryToxoplasma gondiiInfection during Pregnancy

Use of an Immunoglobulin G Avidity Assay Based on Recombinant Antigens for Diagnosis of PrimaryToxoplasma gondiiInfection during Pregnancy

Toxoplasma Seroconversion with Negative or Transient Immunoglobulin M in Pregnant Women: Myth or Reality? A French Multicenter Retrospective Study

ISUOG Practice Guidelines: role of ultrasound in congenital infection

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