IgG avidity in the serodiagnosis of acute Toxoplasma gondii infection: a multicenter study

Sensini, Alessandra; Pascoli, Susanna; Marchetti, D.; Castronari, Roberto; Marangi, M; Sbaraglia, Giovanni; Cimmino, Carmen; Favero, A.; Castelletto, Mariarosa; Mottola, Attilio

doi:10.1111/j.1469-0691.1996.tb00196.x

Cited by 59 publications

(56 citation statements)

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“…The observation that T. gondii-specific IgG maturation is delayed in treated pregnant women compared to nontreated individuals was reported in one previous study, which found significantly delayed IgG maturation in treated individuals (25). Our finding that treatment may influence IgG maturation emphasizes the need for further studies to better clarify the avidity maturation process in pregnant women receiving therapy in comparison with nontreated individuals.…”

Section: Discussionmentioning

confidence: 47%

European Multicenter Study of the LIAISON Automated Diagnostic System for Determination of Toxoplasma gondii -Specific Immunoglobulin G (IgG) and IgM and the IgG Avidity Index

et al. 2005

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The LIAISON system is a fully automated system based on chemiluminescence and antigen bound to magnetic microparticles. The system allows fast and precise measurement of Toxoplasma-specific immunoglobulin G (IgG) and IgM antibody levels and measurement of the IgG avidity index even at low levels of Toxoplasma-specific IgG antibodies in a single step without manual interference. Seven European centers participated in a multicenter evaluation of the LIAISON system. The sensitivity and specificity of the LIAISON system compared to the Sabin-Feldman dye test were 99.3 and 96.8%, respectively. In a comparison of the LIAISON Toxoplasma-specific IgM assay with an immunosorbent agglutination assay, the LIAISON assay had a sensitivity of 96.7% and a specificity of 95.4%. The LIAISON IgG assay showed agreements of 91, 100, and 100% with the AXSYM IgG (Abbott), VIDAS IgG (bioMérieux), and Platelia IgG (Bio-Rad) assays, respectively. The LIAISON IgM assay showed agreements of 95% with the AXSYM IgM and Platelia IgM assays, 96% with the ISAGA IgM assay (bioMérieux), and 97% with the VIDAS IgM assay. The coefficient of correlation between the LIAISON system and the VIDAS Toxoplasma-specific IgG avidity index was 0.81. By use of the Toxoplasma-specific IgG avidity index assay with specific IgM-positive samples, the diagnosis of infection with Toxoplasma gondii in early pregnancy has been improved significantly. The LIAISON avidity assay is a valuable assay for the exclusion of recently acquired infection with T. gondii (less than 4 months) in pregnant women, and it decreases significantly the necessity for follow-up testing.Primary maternal infection with Toxoplasma gondii carries the risk of transmitting the infection to the fetus, resulting in congenital infection. Congenital infection of the fetus in women infected just before conception is extremely rare, and even during the first few weeks of pregnancy, the maternalfetal transmission rate is low (6). It is therefore essential to estimate the time of infection as precisely as possible to properly manage the risk to the fetus of a maternal infection. Low levels of Toxoplasma-specific immunoglobulin M (IgM) antibodies may be found for up to several years, and the mere demonstration of low levels of Toxoplasma-specific IgM antibodies is therefore not a sign by itself of acute infection with T. gondii (16,17). The measurement of the avidity of IgG antibodies for T. gondii infections was first demonstrated in 1989 (8, 9, 15) and since then has been further developed (4,18).A study of the diagnostic value of various tests for acute infections with T. gondii, including Toxoplasma-specific IgG, IgM, and IgA antibodies and the IgG avidity index, showed that the combination of a sensitive test for Toxoplasma-specific IgM antibodies and a Toxoplasma-specific IgG avidity assay had the highest predictive value with regard to the time of infection (23).Since previous studies showed that some individuals have low-avidity IgG antibodies many months after infection, we also tested the hypo...

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Section: Discussionmentioning

confidence: 47%

European Multicenter Study of the LIAISON Automated Diagnostic System for Determination of Toxoplasma gondii -Specific Immunoglobulin G (IgG) and IgM and the IgG Avidity Index

et al. 2005

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“…Among these parameters, the sex of the person, pregnancy, immunodepression, and the type of treatment given have been cited (6,19,22). Starting treatment early in pregnant women could affect the increase in avidity (22). This hypothesis supported by some authors (6,19) has not, however, been confirmed by large-scale studies.…”

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confidence: 49%

“…Different parameters can modify the increase in the AI during the course of seroconversion. Among these parameters, the sex of the person, pregnancy, immunodepression, and the type of treatment given have been cited (6,19,22). Starting treatment early in pregnant women could affect the increase in avidity (22).…”

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confidence: 99%

Reliability of Immunoglobulin G Antitoxoplasma Avidity Test and Effects of Treatment on Avidity Indexes of Infants and Pregnant Women

Flori

Tardy

Patural

et al. 2004

Clin Vaccine Immunol

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The immunoglobulin G antitoxoplasma avidity test (Vidas; BioMérieux) is an immunoenzymatic test useful for excluding acute infection after the onset of pregnancy. The avidity index (AI) is the ratio of the signal in a test sample washed with urea, which disrupts low-avidity complexes, to that washed without urea. An AI of >0.3 is taken to mean that infection had occurred more than 4 months ago. The increase of the AI with time and the influence of the different treatments given to pregnant women and their newborns were evaluated. A total of 59 pregnant women (271 sera) and their 60 neonates (199 sera) were tested from 1998 to 2002. There were five groups of women based on the type and duration of treatment given. Thirteen pregnant women (group 1) did not receive any treatment, 15 (group 2), 11 (group 3), and 17 (group 4) women received treatment with spiramycin (9 MIU/day) for 0.5 to 2, 2.5 to 5, and 5.5 to 8 months, respectively, and the last 3 women (group 5) received tritherapy (pyrimethamine-sulfonamide and spiramycin alternatively) for 1.5 to 2.5 months. All of the maternal sera collected in the first 6 months had an AI of <0.30, with a mean of 0.07 (range, 0.01 to 0.21). The increase was slow (0.02/month), and there was no significant difference when comparisons were made between the treatment groups. Neonates with proven maternofetal transmission had an increasing AI, unlike those without transmission. However, long-term therapy with pyrimethamine-sulfonamide, as opposed to treatment with spiramycin alone, was found to slow down the progression of the AI. An AI of >0.2 is sufficient to exclude acute infection in pregnant women. In neonates, it is not of major use to diagnose congenital infection; however, it could be a good indicator of compliance and efficacy of treatment of infected infants.Toxoplasmosis, caused by Toxoplasma gondii, is widespread in humans and warm-blooded animals. Although usually asymptomatic in immunocompetent humans, toxoplasmosis may cause severe disorders in immunocompromised individuals and in pregnant women because of the high risk of transplacental transmission and the occurrence of abortion or multiple congenital lesions in the fetus (7, 9). In France, specific immunoglobulin G (IgG) and IgM antibody evaluation is mandatory in the first trimester of pregnancy. The presence of toxoplasma-specific IgM at the time of the first blood test is a cause for concern. In certain cases it could either be nonspecific IgM (8,10,[16][17]26) or residual IgM from a previous infection (8,12,16,20). In the remaining cases, it could of course be due to an acute infection. To confirm the latter, the presence of an associated elevated IgG level allows a complementary test to be done: the avidity test.The avidity test (Vidas; BioMérieux, Marcy l'Etoile, France) is of major interest when it is done during the first trimester of pregnancy. It permits dating (an avidity index [AI] of Ͼ0.3 means that infection occurred more than 4 months ago) and excludes infection that has occurred after the onset of...

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“…In addition, the presence of IgM negativity resulting from inappropriate timing of blood sampling or the loss of EBNA antibodies owing to a suppressed immune system can obscure the identifi cation of primary infections or can lead to misdiagnosis. In such cases, it is suggested that the study of IgG avidity is critical to interpreting serological results correctly (9)(10)(11)(12). In general, the kinetics of affi nity maturation occurs in a couple of weeks; however, in some cases this maturation process may arise within three months after the onset of symptoms.…”

Section: Discussionmentioning

confidence: 99%

Determination of serological profiles and avidity of specific antibodies in the sera of patients with potential Epstein-Barr virus (EBV) infection

Akpolat¹,

Gedik²,

Nergiz³

et al. 2013

BLL

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Abstract:Background: Epstein-Barr Virus, frequently referred to as EBV, is a member of the herpesvirus family and one of the most common human viruses. The virus occurs worldwide, and most people become infected with EBV sometime during their lives. Objectives: The purpose of this study was to investigate the serological profi les of specifi c antibodies among the sera of suspected EBV infection patients along with VCA-IgG avidity. Methods: A total of 522 patient's sera were sent to The Clinical Microbiology Laboratory for EBV specifi c antibody detection and were studied by IFA method during a two year period. The serum samples were tested for EBV specifi c VCA IgG, VCA IgM, EA, EBNA antibodies and VCA IgG aviditity. Results: Among 33 patients those who had low avidity for VCA IgG, 27 (81.8 %) of them had a serologic profi le as follows; positive VCA IgG, negative VCA IgM, negative EA and negative EBNA. Conclusion: While this profi le is considered as a primary infection, the frequency of the coexistence of VCA IgG low avidity with this profi le is interepreted that avidity may lead to detect primary infection (Tab. 2, Ref. 25 Abbreviations: IFA -indirect fl uorescent antibody, EBV -Epstein-Barr virus, EA -early antigen,VCA -viral capsid antigen, EBNA -epstein-barr nuclear antigen.Epstein-Barr virus, commonly referred to as EBV, is a human specifi c member of the herpesvirus family and is a B-cell lymphotropic virus. An EBV infection occurs by close contact with EBV presented in oral secretions. The virus initially wells in the oropharyngeal epithelial cells and causes persistent infections. Seroepidemiologic studies indicate that EBV infections are common in all communities and occur worldwide, and most people become infected with EBV sometime during their lives. In Europe including Turkey, as many as 70-80 % of adolescents and 80-90 % of adults are reported to be seropositive for EBV (1).The course of EBV infection can vary with regard to the age and health status of the person. In young children host-virus infection can take place with no apparent symptoms. By contrast, in 30-50 % of the adult patients EBV infection can cause diffuse lymphadenopathy, hepatomegaly, splenomegaly, and tonsillitis. In some cases exanthematous reactions triggered by EBV can be mistaken with an eruption of rubella (2). Moreover, EBV infection is shown to be associated with lymphoproliferative disorders in patients who are suffering from immunodefi ciency, Burkitt lymphoma, and nasopharyngeal carcinoma (3,4). Infectious mononucleosis is also caused by infection of B cells by EBV and is generally diagnosed by serological methods. EBV serology is utilized to help distinguish EBV reactivation infections from primary EBV infections and to demonstrate acute EBV infections. During this process, it is critically important to perform the tests at the same time for the presence of EBV-VCA IgM, EBV-VCAIgG, anti-EBV-EA, anti EBV-EBNA and VCA IgG avidity (2).The spectrum of antibody assays comprises unspecifi c tests, such as the long-known te...

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IgG avidity in the serodiagnosis of acute Toxoplasma gondii infection: a multicenter study

Cited by 59 publications

References 13 publications

European Multicenter Study of the LIAISON Automated Diagnostic System for Determination of Toxoplasma gondii -Specific Immunoglobulin G (IgG) and IgM and the IgG Avidity Index

European Multicenter Study of the LIAISON Automated Diagnostic System for Determination of Toxoplasma gondii -Specific Immunoglobulin G (IgG) and IgM and the IgG Avidity Index

Reliability of Immunoglobulin G Antitoxoplasma Avidity Test and Effects of Treatment on Avidity Indexes of Infants and Pregnant Women

Determination of serological profiles and avidity of specific antibodies in the sera of patients with potential Epstein-Barr virus (EBV) infection

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