Comparative evaluation of three commercial Toxoplasma-specific IgG antibody avidity tests and significance in different clinical settings

Bobić, Branko; Klun, Ivana; Vujanić, Marija; Nikolić, Aleksandra; Ivović, Vladimir; Živković, Tamara; Djurković–Djaković, Olgica

doi:10.1099/jmm.0.006668-0

Cited by 29 publications

(16 citation statements)

References 21 publications

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“…The evaluation of IgG avidity has been widely used in the routine diagnosis of various infectious diseases, not only toxoplasmosis (LAPPALAINEN; RAHBARI et al, 2012), but also rubella (REIS et al, 2004), varicella (ONO et al, 2004KNEITZ et al, 2004) and cytomegalovirus (BONALUMI et al, 2011), been very useful for assessing seroconversion during gestation (BOBIC et al, 2009). The avidity of IgG antibody against TES is potentially useful for immunodiagnostics of toxocariasis and should be included in the complementary diagnosis when IgM levels remain high throughout the infection.…”

Section: Resultsmentioning

confidence: 99%

Determination of IgG avidity in BALB/c mice experimentally infected with Toxocara canis

Schoenardie

Scaini

Ávila

et al. 2014

Rev. Bras. Parasitol. Vet.

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Toxocariasis is a zoonotic disease in that IgM titers can remain high for long periods making difficult to determine the stage of the disease. The aim of this study is to investigate the applicability of indirect ELISA, associated with urea, to discriminate between the acute and chronic toxocariasis. IgG avidity was evaluated in 25 BALB/c mice experimentally infected with 1000 Toxocara canis eggs. Blood samples were collected, and sera treated with 6 M urea and assayed by ELISA every two weeks. The percent IgG avidity was determined using the mean absorbance of sera treated with urea, divided by the mean absorbance of untreated sera. In the first 15 days post-inoculation, was observed a low percentage, between 7.25 and 27.5%, IgG avidity, characteristic of an acute infection. After 60 days of infection, all the mice showed between 31.4 and 58% IgG avidity, indicating a chronic infection.Keywords: Visceral larva migrans, toxocariasis, acute and chronic infections, ELISA. ResumoA toxocaríase é uma zoonose na qual os títulos de IgM podem permanecer elevados por longos períodos, tornando difícil a determinação do estágio em que a doença se encontra. O objetivo deste estudo foi investigar a aplicabilidade de um teste indireto de ELISA, associado com ureia, para fazer a discriminação entre as fases aguda e crônica da toxocaríase. A avidez de IgG foi avaliada em 25 camundongos BALB/c experimentalmente infectados com 1000 ovos embrionados de Toxocara canis. A cada duas semanas, amostras de sangue foram coletadas, o soro tratado com ureia 6M e realizado o ensaio pela técnica de ELISA. O percentual de avidez de IgG foi determinado, usando-se a média das absorbâncias dos soros tratados com ureia dividida pela média das absorbâncias dos soros não tratados. Nos primeiros 15 dias pós-inoculação, foi observado um baixo percentual de avidez de IgG, entre 7,25 e 27,5%, característico da fase aguda da infecção. Após 60 dias de infecção, todos apresentaram avidez de IgG entre 31,4 e 58%, indicando a fase crônica da infecção.Palavras-chave: Larva migrans visceral, toxocaríase, infecção aguda e crônica, ELISA.

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Section: Resultsmentioning

confidence: 99%

Determination of IgG avidity in BALB/c mice experimentally infected with Toxocara canis

Schoenardie

Scaini

Ávila

et al. 2014

Rev. Bras. Parasitol. Vet.

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“…incorporated in decision algorithms used in national recommendations (4). Today, several commercial IgG avidity assays are available, although few cross-evaluations of their diagnostic performance have been published (11,(16)(17)(18). One of the primary goals of the French National Center for Toxoplasmosis was to evaluate the performance of the commercialized assays used in the French national screening program for congenital toxoplasmosis (19).…”

Section: Discussionmentioning

confidence: 99%

Comparison of Four Commercially Available Avidity Tests for Toxoplasma gondii-Specific IgG Antibodies

Villard

Breit

Cimon

et al. 2013

Clin Vaccine Immunol

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Toxoplasma infection in pregnant women may cause congenital toxoplasmosis. Diagnosis of infection is based on serological tests aimed at detecting IgM and IgG antibodies against Toxoplasma gondii. However, IgM antibodies are not an accurate marker for discriminating between acute and latent infection. Detection of residual or persistent IgM may occur months or even years after primary infection, while the IgG avidity test is a rapid means of identifying latent infections in pregnant women who exhibit both IgG and IgM anti-Toxoplasma antibodies on initial testing during pregnancy. In this study, we assessed and compared the performances of four commercially available Toxoplasma IgG avidity tests in immunocompetent and immunocompromised patients with acute and latent toxoplasmosis. The positive predictive value of high avidity to confirm latent toxoplasmosis was 100% for all the assays, indicating that high avidity is a hallmark of latent infection. However, the negative predictive value of high avidity ranged from 99.2% (bioMérieux) to 95.3% (Abbott), indicating that acute toxoplasmosis could not be reliably diagnosed based on low IgG avidity alone. Thus, the avidity test provides a rapid means for identifying latent Toxoplasma infection in immunocompetent pregnant women presenting both IgG and IgM anti-Toxoplasma antibodies on initial testing. In terms of cost-effectiveness, avidity testing is a powerful tool that optimizes screening and follow-up of pregnant women while minimizing the costs of screening by avoiding subsequent costly maternal and fetal investigation and unnecessary treatment. The cheapest assay, Vidas Toxo IgG Avidity, also had the best performance for the diagnosis of latent toxoplasmosis.

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“…These results may reflect a recently acquired infection-and, thus, a risk of transmission of the parasite to the fetus-or an infection acquired before the pregnancy, as T. gondii IgM antibodies may be detected for an extended period after seroconversion (4,12,18). In this situation, measurement of IgG antibody avidity has been shown to be useful; notably, a high IgG avidity excludes the possibility that the T. gondii infection occurred within the last 4 months (3 months for some assays) (1,3,6,8,14,19,22). A high avidity value can, therefore, allow the physician to avoid (or stop) unnecessary treatment, reassure the patient, and in some cases provide evidence that excludes the need to consider termination of pregnancy.…”

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confidence: 99%

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

Murat

L’Ollivier

Hidalgo

et al. 2012

Clin. Vaccine Immunol.

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Detection and treatment of acute toxoplasmosis during pregnancy can avoid severe disease of the fetus. In this context, assessment of anti-Toxoplasma IgG 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 and n ‫؍‬ 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.

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Comparative evaluation of three commercial Toxoplasma-specific IgG antibody avidity tests and significance in different clinical settings

Cited by 29 publications

References 21 publications

Determination of IgG avidity in BALB/c mice experimentally infected with Toxocara canis

Determination of IgG avidity in BALB/c mice experimentally infected with Toxocara canis

Comparison of Four Commercially Available Avidity Tests for Toxoplasma gondii-Specific IgG Antibodies

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

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