Use of Toxoplasma gondi Specific IgG Avidity Assay for Diagnosis of Acquired Toxoplasmosis in Pregnant Women

This study was undertaken to apply Toxoplasma gondii specific IgG avidity test in seropositive pregnant women to differentiate acute and past infection. T. gondii specific IgG avidity test was conducted in 39 seropositive pregnant women and their pregnancy outcomes were observed later on. Out of 39 T. gondii 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 T. gondii 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.

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IgG avidity assay firms up the diagnosis of acute toxoplasmosis on the first serum sample in immunocompetent pregnant women

Diagnostic Microbiology and Infectious Disease ◽

10.1016/j.diagmicrobio.2006.12.010 ◽

2007 ◽

Vol 58 (1) ◽

pp. 83-88 ◽

Cited By ~ 51

Author(s):

Ermanno Candolfi ◽

Rebecca Pastor ◽

Rachel Huber ◽

Denis Filisetti ◽

Odile Villard

Keyword(s):

Pregnant Women ◽

Serum Sample ◽

Avidity Assay ◽

Igg Avidity ◽

Acute Toxoplasmosis

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Development and Use of an Endpoint Titration Assay To Characterize Mumps IgG Avidity following Measles, Mumps, and Rubella Vaccination and Wild-Type Mumps Infection

mSphere ◽

10.1128/msphere.00320-18 ◽

2018 ◽

Vol 3 (5) ◽

Cited By ~ 3

Author(s):

Sara Mercader ◽

Marcia McGrew ◽

Sun B. Sowers ◽

Nobia J. Williams ◽

William J. Bellini ◽

...

Keyword(s):

Virus Infection ◽

Characteristic Curve ◽

Vaccine Dose ◽

The United States ◽

Mumps Virus ◽

Igg Antibody ◽

Avidity Assay ◽

Igg Avidity ◽

Specific Igg ◽

Avidity Maturation

ABSTRACTWaning mumps IgG antibody and incomplete IgG avidity maturation may increase susceptibility to mumps virus infection in some vaccinees. To measure mumps IgG avidity, serum specimens serially diluted to the endpoint were incubated on a commercial mumps-specific IgG enzyme immunoassay and treated with the protein denaturant diethylamine (60 mM, pH 10). End titer avidity indices (etAIs [percent ratio of detected diethylamine-resistant IgG at endpoint]) were calculated. Unpaired serum specimens (n= 108) from 15-month-old children living in a low-incidence setting were collected 1 month and 2 years after the first measles, mumps, and rubella vaccine dose (MMR1) and tested for mumps avidity. Per the receiver operating characteristic curve, the avidity assay is accurate (area under the curve, 0.994; 95% confidence interval [CI], 0.956 to 1.000), 96.5% sensitive (95% CI, 87.9 to 99.6%), and 92.2% specific (95% CI, 81.1 to 97.8%) at an etAI of 30%. When 9 sets of paired serum specimens collected 1 to 60 months post-MMR1 were tested for mumps and measles IgG avidity using comparable methods, the mumps etAI increased from 11% to 40 to 60% in 6 months. From 6 to 60 months, avidity was sustained at a mean etAI of 50% (95% CI, 46 to 54%), significantly lower (P < 0.0001) than the mean measles etAI of 80% (95% CI, 74 to 86%). Mean etAIs in children 2 years post-MMR1 (n= 51), unvaccinated adults with distant mumps disease (n= 29), and confirmed mumps cases (n= 23) were 54, 62, and 57%, respectively. A mumps-specific endpoint avidity assay was developed and validated, and mumps avidity was determined to be generally sustained at etAIs of 40 to 60%, reaching etAIs of >80% in some individuals.IMPORTANCENumerous outbreaks of mumps have occurred in the United States among two-dose measles-mumps-rubella (MMR)-vaccinated populations since 2006. The avidity of mumps-specific IgG antibodies may affect susceptibility to mumps virus infection in some vaccinated individuals. To accurately measure mumps avidity, we developed and validated a mumps-specific IgG avidity assay that determines avidity at the endpoint titer of serially diluted serum specimens, providing results that are independent of IgG concentration. At low antibody titers, endpoint methods are considered more accurate than methods that determine avidity at a single dilution. We determined that 6 months after the first MMR dose, mumps IgG avidity is high and generally sustained at avidity indices of 40 to 60%, reaching values of >80% in some individuals. Additionally, 4% (4/103) of individuals had avidity indices of ≤30% (low avidity) 2 years after vaccination. Inadequate mumps avidity maturation may be one factor influencing susceptibility to mumps virus infection among previously vaccinated or naturally infected individuals.

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Seroprevalence of Toxoplasma gondii infection among pregnant women in Windhoek, Namibia, in 2016

Southern African Journal of Infectious Diseases ◽

10.4102/sajid.v35i1.25 ◽

2020 ◽

Vol 35 (1) ◽

Author(s):

Berta E. Van der Colf ◽

Gert U. Van Zyl ◽

Bruce H. Noden ◽

Dismas Ntirampeba

Keyword(s):

Developing Countries ◽

Toxoplasma Gondii ◽

Antenatal Care ◽

Pregnant Women ◽

Demographic Data ◽

Congenital Toxoplasmosis ◽

Immunoglobulin M ◽

Enzyme Linked Immunosorbent Assay ◽

Igg Avidity ◽

Specific Igg

Background: When a pregnant woman contracts Toxoplasma gondii (T. gondii) infection during pregnancy, it may be vertically transmitted to the foetus. Information on the incidence of congenital toxoplasmosis (CT) in developing countries is scarce. Most studies focus on the seroprevalence of T. gondii infection among pregnant women. This study aimed to determine the seroprevalence of T. gondii infection among pregnant women attending public antenatal care in Windhoek, Namibia, in 2016.Methods: In this descriptive study, 344 urban pregnant women attending public antenatal care were voluntarily enrolled in the study. Seroprevalence of anti-T. gondii Immunoglobulin G (IgG) was determined by automated immunoassay. Samples with a positive T. gondii IgG result were tested for T. gondii Immunoglobulin M (IgM) and specific IgG avidity by using an enzyme-linked immunosorbent assay (ELISA) test. A questionnaire captured demographic data and exposure to risk factors. Data were analysed using Statistical Package for the Social Sciences (SPSS) and R.Results: Anti-T. gondii IgG was found in nine (2.61%) pregnant women. There was no association of anti-T. gondii IgG with demographic characteristics or exposure to risk factors.Anti-T. gondii IgM was positive in one (0.3%) woman, while three (0.9%) women had borderline anti-T. gondii IgM results. Specific IgG avidity was low, equivocal and high in 0%, 33% and 67% of seropositive pregnant women, respectively.Conclusion: Seroprevalence of anti-T. gondii IgG is much lower in Namibia than is reported in other developing countries. Investigation into specific IgM seropositivity and IgG avidity showed that pregnant women in the central region of Namibia are at low risk of vertical transmission and development of CT.

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Evaluation of the Abbott AxSYM Cytomegalovirus (CMV) Immunoglobulin M (IgM) Assay in Conjunction with Other CMV IgM Tests and a CMV IgG Avidity Assay

Clinical and Diagnostic Laboratory Immunology ◽

10.1128/cdli.8.1.196-198.2001 ◽

2001 ◽

Vol 8 (1) ◽

pp. 196-198 ◽

Cited By ~ 23

Author(s):

T. Lazzarotto ◽

C. Galli ◽

R. Pulvirenti ◽

R. Rescaldani ◽

R. Vezzo ◽

...

Keyword(s):

Pregnant Women ◽

Accurate Diagnosis ◽

Immunoglobulin M ◽

Igg Antibodies ◽

Cmv Infection ◽

Avidity Assay ◽

Igg Avidity ◽

Avidity Test ◽

Reflex Testing ◽

Initial Reactivity

ABSTRACT The measurement of the avidity of cytomegalovirus (CMV) immunoglobulin G (IgG) antibodies has been shown by several investigators to be useful in identifying and excluding primary CMV infections in pregnant women. In this work, we examined the diagnostic utility of reflex testing of CMV IgM-positive specimens from pregnant women by using a CMV IgG avidity assay. The utility of this approach was directly dependent on the sensitivity of the CMV IgM assay employed during the initial screen. The higher initial reactivity rate of the AxSYM CMV IgM assay was necessary in order to detect CMV IgM in specimens containing low-avidity CMV IgG antibodies, indicative of a primary CMV infection, which other CMV IgM assays (Behring, Vidas, Captia, and Eurogenetics) fail to detect in some cases. The use of the AxSYM CMV IgM assay, followed by an avidity test, should result in more accurate diagnosis of CMV infection in pregnant women.

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Toxoplasma gondii-specific IgG avidity testing in pregnant women

Clinical Microbiology and Infection ◽

10.1016/j.cmi.2020.04.014 ◽

2020 ◽

Vol 26 (9) ◽

pp. 1155-1160 ◽

Cited By ~ 1

Author(s):

C. Garnaud ◽

H. Fricker-Hidalgo ◽

B. Evengård ◽

M.J. Álvarez-Martínez ◽

E. Petersen ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Pregnant Women ◽

Igg Avidity ◽

Specific Igg

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Distinguishing between primary infection and reinfection with rubella vaccine virus by IgG avidity assay in pregnant women

Eastern Mediterranean Health Journal ◽

10.26719/2009.15.1.94 ◽

2009 ◽

Vol 15 (1) ◽

pp. 94-103 ◽

Cited By ~ 3

Author(s):

R. Hamkar ◽

S. Jalilvand ◽

M.H. Abdol Baghi ◽

K.N. Jelyani ◽

A. Esteghamati ◽

...

Keyword(s):

Pregnant Women ◽

Primary Infection ◽

Vaccine Virus ◽

Rubella Vaccine ◽

Avidity Assay ◽

Igg Avidity

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Diagnosis of Toxoplasmosis in Pregnant Women by IgG Avidity Assay

Alborz University Medical Journal ◽

10.18869/acadpub.aums.4.1.11 ◽

2015 ◽

Vol 4 (1) ◽

pp. 11-16

Author(s):

M. Roozbehani ◽

M.J. Gharavi ◽

H. Keshavarz ◽

◽

...

Keyword(s):

Pregnant Women ◽

Avidity Assay ◽

Igg Avidity

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Measles Virus IgG Avidity Assay for Use in Classification of Measles Vaccine Failure in Measles Elimination Settings

Clinical and Vaccine Immunology ◽

10.1128/cvi.00406-12 ◽

2012 ◽

Vol 19 (11) ◽

pp. 1810-1817 ◽

Cited By ~ 38

Author(s):

Sara Mercader ◽

Philip Garcia ◽

William J. Bellini

Keyword(s):

Measles Virus ◽

Area Under The Curve ◽

Epidemiological Data ◽

Diagnostic Tools ◽

High Avidity ◽

Characteristic Analysis ◽

Vaccine Failure ◽

Avidity Assay ◽

Igg Avidity

ABSTRACTIn regions where endemic measles virus has been eliminated, diagnostic assays are needed to assist in correctly classifying measles cases irrespective of vaccination status. A measles IgG avidity assay was configured using a commercially available measles-specific IgG enzyme immunoassay by modifying the protocol to include three 5-min washes with diethylamine (60 mM; pH 10.25) following serum incubation; serum was serially diluted, and the results were expressed as the end titer avidity index. Receiver operating characteristic analysis was used for evaluation and validation and to establish low (≤30%) and high (≥70%) end titer avidity thresholds. Analysis of 319 serum specimens expected to contain either high- or low-avidity antibodies according to clinical and epidemiological data indicated that the assay is highly accurate, with an area under the curve of 0.998 (95% confidence interval [CI], 0.978 to 1.000), sensitivity of 91.9% (95% CI, 83.2% to 97.0%), and specificity of 98.4% (95% CI, 91.6% to 100%). The assay is rapid (<2 h) and precise (standard deviation [SD], 4% to 7%). In 18 samples from an elimination setting outbreak, the assay identified 2 acute measles cases with low-avidity results; both were IgM-positive samples. Additionally, 11 patients (15 samples) with modified measles who were found to have high-avidity IgG results were classified as secondary vaccine failures; one sample with an intermediate-avidity result was not interpretable. In elimination settings, measles IgG avidity assays can complement existing diagnostic tools in confirming unvaccinated acute cases and, in conjunction with adequate clinical and epidemiologic investigation, aid in the classification of vaccine failure cases.

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