Toxoplasma gondii specific IgG avidity assay: Role and implication in the confirmatory diagnosis of acute toxoplasmosis in seropositive pregnant women (original) (raw)
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Journal of Clinical Microbiology, 2020
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.
Parasite (Paris, France), 2016
A maternal Toxoplasma gondii infection during pregnancy is a risk for congenital infection through maternal-fetal transplacental transmission. Estimation of the date of infection is of the utmost importance for management and treatment recommendations. In this setting, IgG avidity has been shown to be useful as high avidity rules out an infection dating less than 4 months. The estimated date of infection can also be obtained by the ratio of T. gondii IgG titers measured by the Vidas (bioMérieux) assay versus T. gondii IgG titers measured by the Architect (Abbott Laboratories) test, together with T. gondii IgM and IgA antibody responses. In this study, using 117 serum samples from pregnant women, we compared the IgG avidity values obtained by Architect and Vidas with the presumed date of T. gondii infection established by the T. gondii IgG ratio of IgG Vidas and IgG Architect plus the IgM and IgA results. To date, IgG avidity Vidas seems to exhibit better performance than Architect. ...
Kirkuk University Journal-Scientific Studies
Toxoplasmosis is caused by Toxoplasma gondii, which is an intracellular protozoan parasite. Its main host is the cat. It is one of the most common human parasites. The main objective of this study is to determine the time of T. gondii infection among pregnant women by using avidity test of Toxoplasma IgG to various Toxoplasma antigens. The study period was from August 2017 to February 2018 to study the time of toxoplasmosis among 180 pregnant women and 100 non pregnant married women as control attending to hospitals, primary health care centers and some private medical laboratories. The pregnant women were examined for Toxo-IgG seroprevalence by using ELISA technique, and then examined their avidity of antibodies for specific Toxoplasma antigens by using line immune assay. The rates of Toxo-IgG seropositive were64 (35.56 %) among pregnant women. Regarding the reactivity of determined Toxo-IgG against various Toxoplasma antigens, the rates were 40(62.50%), 39 (60.93%), 63(98.43%) ,55(85.93%) ,63(98.43%), 62(96.87%) ,41(64.04%) and 42(65.62) positive for Toxoplasma ROP1C, MIC3, GRA7, GRA8, p30, MAG1,GRA1,rSAG1 antigens, respectively. Considering the avidity of Toxo-IgG for these antigens, the rates of high avidity were higher than low and intermediate avidity. So, the highest rate of high avidity was 85.0% for ROP1c antigen. It is concluded that the highest rate of predicting Toxoplasma infection among pregnant women was for a period of more than 6 months, which makes it less dangerous for maternal and fetal health.
Journal of Clinical Microbiology, 2003
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.
***, 2014
Background Toxoplasma gondii (T. gondii) is intracellular protozoa. Infection with T. gondii can result in a serious sequel to the fetus if infection occurs in the first trimester of pregnancy. Laboratory diagnosis is the main method of diagnosis. Aim The aim of the present study was to detect recent infection with Toxoplasma gondii in cohort pregnant Egyptian women in the first trimester by serological detection of concrete IgM, IgG and IgG avidity test. The results of serological tests were compared by nested PCR method. Materials and Methods One hundred and twenty pregnant women in the first trimester of pregnancy were included in the study. Blood samples were obtained and subjected to serological studies for specific immunoglobulins M (IgM), G (IgG) and avidity IgG for T. gondii. Suspected results were confirmed by nested polymerase chain reaction for detection of T. gondii DNA. Results Positive IgG for Toxoplasma gondii was (31.7%) and positive IgM was (18.3%). IgG avidity results showed that low avidity IgG and high avidity IgG represented 31.7% for each of positive IgG for Toxoplasma while intermediate avidity represented 36.8%, Table 1. Twenty two pregnant women were positive for IgM, however, only 7 of them
Toxoplasma gondii infection in pregnancy
Brazilian Journal of Infectious Diseases, 2007
Toxoplasmosis is caused by an intracellular protozoan, Toxoplasma gondii, which has a wide geographical distribution. The main infection routes are ingestion of cysts from raw or badly-cooked meat, ingestion of oocysts from substrates contaminated with the feces of infected felines and congenital transmission by tachyzoites. The congenital form results in a severe systemic disease, because if the mother is infected for the first time during gestation, she can present a temporary parasitemia that will infect the fetus. Many of the clinical symptoms are seen in congenitallyinfected children, from a mild disease to serious signs, such as mental retardation. Early diagnosis during the pregnancy is highly desirable, allowing prompt intervention in cases of infection, through treatment of pregnant women, reducing the probability of fetal infection and consequent substantial damage to the fetus. Conventional tests for establishment of a fetal diagnosis of toxoplasmosis include options from serology to PCR. Prevention of human toxoplasmosis is based on care to avoid infection, understanding the disease and serological exams during gestation. Pregnant women should be tested serologically from three months gestation, until one month after childbirth. Inclusion of serology for congenital toxoplasmosis along with the basic Guthrie test for PKU is of fundamental importance for early diagnosis of infection and so that treatment is initiated, in order to avoid possible sequels in the infant.