scholarly journals Role of Toxoplasma gondii IgG Avidity Testing in Discriminating between Acute and Chronic Toxoplasmosis in Pregnancy

2020 ◽  
Vol 58 (9) ◽  
Author(s):  
Aref Teimouri ◽  
Sina Mohtasebi ◽  
Elham Kazemirad ◽  
Hossein Keshavarz
Keyword(s):  
Toxoplasma Gondii ◽  
Primary Infection ◽  
Diagnostic Technique ◽  
Acquisition Time ◽  
Avidity Index ◽  
Recent Infection ◽  
Content Type ◽  
Avidity Assay ◽  
Igg Avidity ◽  
In Pregnancy

ABSTRACT Risk of mother-to-child transmission of Toxoplasma gondii during pregnancy is much greater in women who are exposed to primary T. gondii infection (toxoplasmosis) after conception compared to those who were exposed to the infection before conception. Therefore, laboratory tests that help classify recent primary toxoplasmosis are important tools for the management of pregnant women suspected to have T. gondii exposure. Detection of Toxoplasma IgM (Toxo IgM) is a sensitive indicator of primary toxoplasmosis, but the indicator specificity is low because sometimes natural IgM antibodies react with Toxoplasma antigens in the absence of the infection. Furthermore, Toxo IgM sometimes persists in blood serum for several months or years following the primary infection. In recent decades, Toxo IgG avidity assay has been used as a standard diagnostic technique for a better estimation of the infection acquisition time and identification of the primary T. gondii infection during pregnancy. Avidity is described as the aggregate strength; by which, a mixture of polyclonal IgG molecules reacts with multiple epitopes of the proteins. This parameter matures gradually within 6 months of the primary infection. A high Toxo IgG avidity index allows a recent infection (less than 4 months) to be excluded, whereas a low Toxo IgG avidity index indicates a probable recent infection with no exclusions of the older infections. This minireview is based on various aspects of T. gondii IgG avidity testing, including (i) description of avidity and basic methods used in primary studies on T. gondii IgG avidity and primary infections; (ii) importance of IgG avidity testing in pregnancy; (iii) result summary of the major studies on the use of T. gondii IgG avidity assay in pregnancy; (iv) brief explanation of the T. gondii IgG avidity values in newborns; (v) result summary of the major studies on T. gondii IgG avidity and PCR; (vi) discussion of commercially available T. gondii IgG avidity assays, including newer automated assays; and (vii) current issues and controversies in diagnosis of primary T. gondii infections in pregnancy.

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 Pitfalls in the Serological Diagnosis of Primary Human Cytomegalovirus Infection in Pregnancy Due to Different Kinetics of IgM Clearance and IgG Avidity Index Maturation

Diagnostics ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 396
Author(s):  
Antonella Sarasini ◽  
Alessia Arossa ◽  
Maurizio Zavattoni ◽  
Chiara Fornara ◽  
Daniele Lilleri ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Human Cytomegalovirus ◽  
Primary Infection ◽  
Hcmv Infection ◽  
Serological Diagnosis ◽  
Avidity Index ◽  
Igm Antibody ◽  
Igg Avidity ◽  
Kinetics Of ◽  
In Pregnancy

Primary infection occurs when seronegative women are infected by human cytomegalovirus (HCMV). Diagnosis of primary infection is based on the following: antibody seroconversion, presence of IgM and low IgG avidity index (AI), and presence of DNAemia. The kinetics of HCMV-specific IgM antibody and maturation of AI might be very rapid or long-lasting during primary infection, which makes serological diagnosis insidious. The aims of this study were as follows: (i) to report atypical kinetics of HCMV-specific IgM antibody and AI early after onset of primary HCMV infection in a population of pregnant women, and (ii) to assess the frequency of such results. Altogether, 1309 sequential serum samples collected from 465 pregnant women with primary HCMV infection were included in the study. As a general rule, using the LIAISON®CMVIgMII and LIAISON®CMVIgGAvidityII assays, virus-specific IgM antibody levels decreased, while IgG AI increased over time during the first three months after infection onset. However, early clearance of IgM antibody and/or early IgG AI maturation occurred in 46/426 (10.7%) women. In more details, 20/426 (4.7%) and 26/418 (6.2%) women had undetectable IgM antibody or high IgG AI, respectively, when tested within 1–3 months after well-defined infection onset. Twenty sera from as many women with high IgG AI by the LIAISON assay were further tested for IgG AI by VIDAS®CMVIgGAvidityII and Mikrogen recomLineCMVIgG Avidity assays. Comparable results were obtained with VIDAS, whereas 14/20 sera gave low AI with the Mikrogen assay. In conclusion, about 11% of pregnant women undergoing a primary HCMV infection showed misleading serological results. Additional and appropriate testing might help in reducing the risk of missing HCMV primary infection in pregnancy. Furthermore, preconceptional testing should be strongly recommended.

scholarly journals Toxoplasma gondii seroprevalence among pregnant women in Rabat, Morocco

2021 ◽  
Vol 49 (1) ◽  
Author(s):  
Majda Laboudi ◽  
Zoubida Taghy ◽  
Oussama Duieb ◽  
François Peyron ◽  
Abderrahim Sadak
Keyword(s):  
Toxoplasma Gondii ◽  
Pregnant Women ◽  
Congenital Toxoplasmosis ◽  
Immunoglobulin M ◽  
Bivariate Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Seroprevalence Rate ◽  
Recent Infection ◽  
Igg Avidity ◽  
Avidity Test

Abstract Background Toxoplasmosis is an infectious disease caused by a protozoan parasite named Toxoplasma gondii (T.gondii). Pregnant women are considered one of the risk groups. The objective of this retrospective study is to provide an updated estimate of the seroprevalence of anti-T. gondii antibodies among a group of Moroccan pregnant women monitored at the Parasitology Laboratory of the National Institute of Hygiene in Rabat in Morocco. Methods Serum samples were tested for the presence of specific anti-T. gondii immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies using indirect enzyme-linked immunosorbent assay (ELISA). Anti-Toxoplasma IgM- and IgG-positive cases were also evaluated with the anti-Toxoplasma IgG avidity test. All cases were evaluated according to the age, parity, and historical of abortion. Results Among 677 pregnant women, 94.1% (637/677) were serologically screened for the first time and therefore had no knowledge of their serological status, and only 5.9% (40/677) were screened for the second or third time. The overall anti-T. gondii IgG and IgM seropositivity among the 637 pregnant women included in the study analysis was 43% (274/637) and 3.9% (25/637), respectively. The use of the IgG avidity test allowed excluding recent infection among 83% of cases with IgG and IgM positive sera. The mean age was 29.4 ± 6.3 years. The result of the bivariate analysis revealed that the age influenced significantly the seroprevalence rate, while the parity and the existence of previous spontaneous abortion did not have any significant statistical correlation with seropositivity to T. gondii. Conclusion This study shows that 43% of pregnant women were positive and 57% of them had no antibody against the T. gondii infection. However, the pregnancy follow-up and the counseling of pregnant women remain essential for the prevention of congenital toxoplasmosis.

scholarly journals Identification, production and assessment of two Toxoplasma gondii recombinant proteins for use in a Toxoplasma IgG avidity assay

2016 ◽  
Vol 110 (7-8) ◽  
pp. 277-286 ◽  
Author(s):  
Ai Ying Teh ◽  
Atefeh Amerizadeh ◽  
Sabariah Osman ◽  
Muhammad Hafiznur Yunus ◽  
Rahmah Noordin
Keyword(s):  
Toxoplasma Gondii ◽  
Recombinant Proteins ◽  
Avidity Assay ◽  
Igg Avidity

Use of the immunoglobulin G avidity assay to differentiate between recent Zika and past dengue virus infections

2019 ◽  
Vol 133 (7) ◽  
pp. 859-867 ◽  
Author(s):  
Andrea K.M. Furuya ◽  
Danielle Hunt ◽  
Kirsten St. George ◽  
Alan P. Dupuis ◽  
Laura D. Kramer ◽  
...  
Keyword(s):  
New York ◽  
Immunoglobulin G ◽  
New York State ◽  
Viral Envelope ◽  
York State Department ◽  
Virus Infections ◽  
Avidity Index ◽  
York State ◽  
Avidity Assay ◽  
Igg Avidity

Abstract Zika (ZIKV) and dengue (DENV) virus infections elicit a robust but cross-reactive antibody response against the viral envelope protein, while antibody responses against non-structural proteins (NS) are more virus specific. Building on this premise, we have previously developed a flavivirus multiplex microsphere immunoassay (MIA) for the serologic diagnosis of ZIKV and DENV infections. This assay significantly improved diagnostic accuracy; however, MIA could not differentiate more recent from past infections, which still represents a major diagnostic challenge. Therefore, an immunoglobulin G (IgG) based avidity assay was developed and its diagnostic performance evaluated. Specimens from New York State residents were submitted to the Wadsworth Center New York State Department of Health (NYSDOH) for routine clinical testing by Zika IgM ELISA and plaque reduction neutralization test (PRNT). Using our previously developed flavivirus MIA as a platform, we developed an IgG avidity assay to discriminate recent ZIKV from past DENV infections. Zika IgM positive specimens had an average Zika IgG avidity index of 14.8% (95% CI: 11.0–18.4%), while Zika IgM negative but flavivirus MIA and PRNT positive samples had an average Zika IgG avidity index of 34.9% (95% CI: 31.1–38.7%). Specimens positive for dengue antibodies by flavivirus MIA and PRNT had an average dengue IgG avidity index of 68.7% (95% CI: 62.7–75.0%). The IgG avidity assay accurately distinguished recent ZIKV from past DENV infections in patients who traveled to dengue endemic regions. This assay could be very useful in patients with high risk of Zika complications such as pregnant women and monitoring immune responses in vaccine trials.

scholarly journals Microsphere-Based IgM and IgG Avidity Assays for Human Parvovirus B19, Human Cytomegalovirus, and Toxoplasma gondii

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Yilin Wang ◽  
Lea Hedman ◽  
Visa Nurmi ◽  
Inga Ziemele ◽  
Maria F. Perdomo ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Human Cytomegalovirus ◽  
Parvovirus B19 ◽  
Clinical Samples ◽  
Human Parvovirus B19 ◽  
Serum Samples ◽  
Content Type ◽  
Reference Methods ◽  
Igg Avidity ◽  
Highly Sensitive

ABSTRACT Human parvovirus B19 (here B19), human cytomegalovirus (HCMV), and Toxoplasma gondii infections during pregnancy can lead to severe complications. While traditional diagnosis of infections is mostly confined to one pathogen at a time, a multiplex array is a feasible alternative to improve diagnostic management and cost-efficiency. In the present study, for these three pathogens, we developed microsphere-based suspension immunoassays (SIAs) in multiplex and monoplex formats for the detection of antimicrobial IgM antibodies as well as corresponding chaotrope-based IgG avidity SIAs. We determined the diagnostic performances of the SIAs versus in-house and commercial reference assays using a panel of 318 serum samples from well-characterized clinical cohorts. All the newly developed assays exhibited excellent performance compared to the corresponding high-quality reference methods. The positive and negative percent agreements of the IgM SIAs in comparison with reference methods were 95 to 100% and 98 to 100%, and those of the IgG avidity SIAs were 92 to 100% and 95 to 100%, respectively. Kappa efficiency values between the SIAs and the corresponding reference assays were 0.91 to 1. Furthermore, with another panel comprising 391 clinical samples from individuals with primary infection by B19, HCMV, or T. gondii, the IgM SIAs were highly sensitive for the detection of acute infections, and the IgG avidity SIAs were highly specific for the separation of primary infections from past immunity. Altogether, the strategy of IgM multiplex screening followed by IgG avidity reflex testing can provide high-throughput and accurate means for the detection and stage determination of B19, HCMV, and T. gondii infections. IMPORTANCE Human parvovirus B19, human cytomegalovirus, and Toxoplasma gondii are ubiquitous pathogens. Their infections are often asymptomatic or mild in the general population yet may be transmitted from mother to fetus during pregnancy. Maternal infections by these pathogens can cause severe complications to the fetus or congenital abnormalities. As a rule, the risk of maternal transmission is critically related to the infection time; hence, it is important to determine when a pregnant woman has acquired the infection. In this study, we developed new diagnostic approaches for the timing of infections by three pathogens. All the new assays appeared to be highly sensitive and specific, providing powerful tools for medical diagnosis.

scholarly journals Anti-HEV IgG Avidity Testing: Utility for Diagnosing Acute and Resolved Genotype 3 Infections

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 236
Author(s):  
Claudia Minosse ◽  
Daniele Lapa ◽  
Antonio Coppola ◽  
Federica Rapagna ◽  
Gianpiero D’Offizi ◽  
...  
Keyword(s):  
False Negative ◽  
Molecular Testing ◽  
Test Results ◽  
Genotype 3 ◽  
Avidity Index ◽  
Serum Samples ◽  
Recent Infection ◽  
Assay Sensitivity ◽  
Igg Avidity ◽  
Automated Instrument

European Association of the Study of the Liver (EASL) guidelines specify HEV RNA, as well as anti-HEV IgG and IgM as positive markers for acute HEV infection. HEV RNA assay sensitivity limitations may lead to false negative test results in patients with low levels of viremia. Moreover, anti-HEV IgM positivity is not a reliable indicator for distinguishing between acute and resolved infections given the ability of this antibody to persist several months after a resolved infection. Our study aims were to assess HEV IgG avidity for diagnosing acute and resolved infections, regardless of the anti-HEV IgM serostatus, and examine assay reliability when evaluating different genotype 3 (GT3) HEV subtypes. Patient serum samples (n = 104) were tested for HEV IgG avidity by utilizing the DIA.PRO kit on a DSX automated instrument. Among patients identified with acute HEV infections, 32 were infected with GT3: GT3c (n = 5), GT3e (n = 8), 3f (n = 17) and GT3-unsubtyped (n = 2). Avidity sensitivity was 91.2% and specificity was 100%. For patients with long-lasting anti-HEV IgM persistence, an Avidity Index >70% was observed. Thus, the DIA.PRO avidity assay may be utilized to distinguish between recently acquired and resolved HEV GT3 infections. However, for equivocal results (Avidity Index > 40–70%), HEV RNA molecular testing will be required to confirm a recent infection.

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 Evaluating the sensitivity and predictive value of tests of recent infection: toxoplasmosis in pregnancy

1991 ◽  
Vol 107 (3) ◽  
pp. 527-535 ◽  
Author(s):  
A. E. Ades
Keyword(s):  
Early Pregnancy ◽  
Predictive Value ◽  
Predictive Value Of Tests ◽  
Maternal Infection ◽  
Mathematical Methods ◽  
Recent Infection ◽  
Igg Avidity ◽  
In Pregnancy

SUMMARYThe diagnosis of maternal infection in early pregnancy depends on tests which are sensitive to recent infection, such as specific IgM. Two types of test are considered: those where the response persists for a period following infection and then declines, such as IgM. and those whose response increases with time since infection, such as IgG-avidity. However, individuals vary in their response to infection, and it may not always be possible to determine whether an infection occurred during pregnancy or before it. Mathematical methods are developed to evaluate the performance of these tests, and are applied to the diagnosis of toxoplasmosis in pregnancy. It is shown that, based on existing information, tests of recent infection are unlikely to be both sensitive and predictive. More data on these tests are required, before they can be reliably used to determine whether infection has occurred during pregnancy or before it.

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