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Backgrounds: Toxoplasmosis, a prevalent parasitic infection, is primarily caused by Toxoplasma gondii (T. gondii). This infection poses a significant threat to neonates during pregnancy and individuals with compromised immune systems. Consequently, it is imperative to develop a novel diagnostic approach that combines high sensitivity with low-risk sampling to effectively manage patients. The aim of this study is to utilize serological and molecular techniques for the diagnosis of T. gondii infection in 100 pregnant women who were under the care of a gynecologist and were candidates for amniocentesis., Methods: During the 15-19th weeks of pregnancy, a total of 100 samples each of amniotic fluid, buffy coat, plasma, and urine simultaneously were collected from pregnant women candidates for amniocentesis in Mazandaran province, northern Iran. This study involved various assessments: (1) detecting anti-T. gondii IgM and IgG in plasma through chemiluminescence assay (2) determining IgG avidity in plasma using the Enzyme-linked immunosorbent assay technique (3) identifying of T. gondii DNA in amniotic fluid, buffy coat and urine by nested PCR (nPCR) and quantitative real-time PCR (qPCR) methods targeting the REP-529 gene, as well as genotyping using GRA6 target genes, and (4) assessing the sensitivity and specificity of the nPCR and qPCR tests., Results: Out of 100 pregnant women screened, 70 were between the ages of 31 to 40 years old. Among them, 23 and 44 had one and two previous pregnancies. Additionally, 13 and 8 women had one and two history of abortions, respectively. Following serologic testing, 52% of the individuals were positive for T. gondii antibodies. Of these, 52 samples were positive for IgG antibodies, and one sample was positive for both IgG and IgM antibodies. Notably, all 52 cases with IgG positivity exhibited a high level of IgG avidity. Regarding the molecular testing of amniotic fluid samples, two pregnant women tested positive in the nPCR assay, while three tested positive in the qPCR assay. Furthermore, genotyping revealed that all positive samples belonged to type I of the T. gondii genotype. Moreover, none of the 100 buffy coat and urine samples tested positive for T. gondii using the nPCR and qPCR techniques., Conclusion: The findings of the current study suggest that serological methods alone may not be reliable in diagnosing congenital toxoplasmosis and cannot rule out the diagnosis of toxoplasmosis and must be approved by molecular tests., Competing Interests: Declarations. Ethics approval and consent to participate: This study was ethically approved by the Ethics Committee of Mazandaran University of Medical Sciences (IR.MAZUMS.REC.1400.11546), and all procedures adhered to ethical rules and principles set forth in the Declaration of Helsinki. Also, Informed consent was obtained from all the participants. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Aim: In spite of the importance of toxoplasmosis and toxocariasis among the high‐risk groups, such as pregnant women, the infections are categorized as a neglected tropical disease by the World Health Organization. Toxoplasma gondii and Toxocara spp. infections can cause systemic and ocular diseases in infants during pregnancy. In this study, we investigated seroprevalence and risk factors of toxoplasmosis, toxocariasis and their co‐infection in pregnant women and non‐pregnant women referred to the healthcare facilities of Ilam province, west of Iran. Methods: A total of 378 sera samples (189 pregnant women and 189 non‐pregnant women) was investigated for the presence of IgG antibodies against T. gondii and Toxocara spp. by Enzyme‐linked immunosorbent assay (ELISA). The samples of all pregnant women with abortion (56 cases) were also evaluated for IgM anti‐toxoplasmosis antibody by ELISA method. Moreover, associated factors were obtained from the participant's questionnaires. Data analysis for this study was performed using the spss software version 20. Results: Seroprevalence of T. gondii, Toxocara spp., and their co‐infection in pregnant women was 39.7%, 21.2% and 9.5%, respectively. Regarding the risk factors, the contact with a cat (P = 0.04) and dog (P = 0.00) were significantly associated with T. gondii and Toxocara spp., respectively. Conclusion: This study highlighted the importance of serological diagnosis before pregnancy. Moreover, we believe that more epidemiological studies are needed for a better understanding of overlaps between T. gondii and Toxocara spp. in pregnant women. [ABSTRACT FROM AUTHOR]

Background: Toxoplasmosis is a serious or life-threatening disease in immunosuppressed patients and pregnant women. This study examined the likely association between Toxoplasma gondii infection and COVID-19 patients with moderate illness., Methods: Seventy blood samples were collected from patients at the Health Reference Laboratory of Tabriz, Northwest Iran from April 2021 to September 2021. In addition, 70 healthy subjects of the same age (37 ± 15 years) and sex distribution were ethnically matched. Sera samples were examined for the detection of anti-Toxoplasma antibodies using ELISA. Nested-PCR targets were amplified based on the B1 and GRA6 genes. GRA6 amplicons were subjected to sequencing and phylogenetic analysis., Results: The seroprevalence of toxoplasmosis based on IgG titer was 35.7% in the COVID‑19 patients and 27.1% in the control group, representing not to be associated with the Toxoplasma seropositivity in COVID‑19 patients (P = 0.18) compared to healthy subjects. Anti-T. gondii IgM was not found in any of the patients and healthy individuals. According to PCR amplification of the B1 and GRA6 genes, the frequency of T. gondii in COVID-19 patients was 14.2% (10/70). However, no T. gondii infection was detected in the healthy group. The CD4 + T cell count was relatively lower in toxoplasmosis-infected patients (430-450 cells/mm3) than in control group (500-1500 cells/mm3). High genetic diversity (Hd: 0.710) of the type I strain of T. gondii was characterized in the patients. Present results showed that consumption of raw vegetables and close contact with stray cats can increase the transmission of T. gondii to COVID-19 patients (P < 0.01)., Conclusions: The current study revealed that T. gondii type I infection is unequivocally circulating among the COVID-19 patients in Tabriz; However, no significant association was observed between the occurrence of Toxoplasma and the severity of COVID-19. To make more accurate health decisions, multicenter investigations with a larger sample size of different ethnic groups of the Iranian population are needed., (© 2024. The Author(s).)

Objective: Since pre-transfusion screening for Toxoplasma gondii is not performed on blood packs, thalassemia patients are susceptible to acquiring toxoplasmosis; thus, the aim of this study was to evaluate the seroprevalence status of T. gondii in individuals who suffer from thalassemia in comparison to healthy persons in the southwest of Iran. Methods: In this case-control study, 117 thalassemia patients and 205 healthy persons participated. All samples were tested for the presence of specific IgG and IgM antibodies against T. gondii using ELISA technique. Data were analyzed using Chi-square test. Results: Seroprevalence of anti-T. gondii IgG was detected in 30.76% (36/117) of patients and 20% (41/205) of healthy individuals (P=0.04), also anti-T. gondii IgM in these groups was detected 1.70% (2/117) and 0.48% (1/205), respectively (P=0.3). In present study, nine related risk factors with toxoplasmosis were evaluated and data analysis showed that only contact with cat was significantly correlated with IgG seroprevalence (P=0.02). Conclusions: Current research suggests thalassemia patients are more prone than normal persons to acquiring T. gondii infection (P=0.04, OR:1.77). Due to limited studies in this high risk group, further studies are recommended. [ABSTRACT FROM AUTHOR]

Introduction: Toxoplasmosis and narcotic drug addiction are endemic in various regions of Iran. These drugs can provide situations for infections by disrupting the immune system. The current case-control study was designed to determine the prevalence of toxoplasmosis in narcotic drugaddicted persons in comparison with healthy subjects using serology and molecular techniques in the southwest of Iran., Methods: A total of 201 subjects (including 101 individuals with drug addiction and 100 control participants) were randomly selected. Chronic and acute toxoplasmosis was detected using the enzymelinked immunosorbent assay (ELISA) IgG avidity. T. gondii immunoglobulin G (IgG) and immunoglobulin M (IgM) were also determined by the ELISA. Moreover, the presence of T. gondii in blood samples was diagnosed using the nested-polymerase chain reaction (Nested-PCR)., Results: For T. gondii IgG, 17 (17.0%) of 100 and 39 (38.6%) of 101 cases were diagnosed in the control participants and drug-addicted people, respectively [P=0.001, OR=3.071, CI= (1.591-5.929)]. Moreover, 16 (15.8) and 5 (5.0%) cases were positive for the B1 gene in the drug-addicted patients and controls by the nested-PCR technique, respectively [P=0.019, OR=3.576, CI= (1.257-10.179)]. However, no significant differences were found between the opium (n=64) and crystal methamphetamine (n=37) groups in terms of T. gondii IgG and IgM antibodies and the presence of the parasite in the blood ( P >0.05)., Conclusion: The present results demonstrated that the outbreak of the infection was more frequent in narcotic drug-addicted persons than the controls using serology and molecular techniques., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The article discusses a study which aims to establish the frequency of serum anti-Toxocara specific antibody (IgG) and anti-Toxoplasma specific antibodies (IgG, IgM) in patients diagnosed with epilepsy including the use of serology and Western blotting as diagnostic tests.

Background: The differentiation between acute and latent forms of the Toxoplasma gondii (T. gondii) infection is still considered as a complicated issue. This study was aimed to elucidate the status of infection in the blood donors and the probable importance of blood transfusion in the transmission of the infection through detecting both immunological and genetic markers of acute and latent infection. Methods: Totally 235 blood samples from blood donors were collected. The levels of anti-T. gondii IgG and IgM antibodies were examined by specific ELISA kits. cDNA were synthesized from total extracted mRNA molecules from the serum samples and SAG1 gene, specific for tachyzoite form, were amplified using Real-Time PCR technique. Demographic information of study subjects including their gender, age, job, and habitat were recorded. Results: Out of 235 serum samples, 80 (34.04%) and 4 (1.71%) were positive regarding anti-T. gondii IgG and IgM antibodies, respectively. Real-Time PCR results showed that 14 out of 200 (6.97%) of blood donor had mRNA molecules of SAG1 gene. The positive results of Real-Time PCR of SAG1 in female gender and housekeepers were significantly higher than those of male gender and other job categories. Conclusion: The prevalence of chronic and acute infection is high in Iranian blood donors. Additionally, evaluation of antibodies could not be reliable, because several donors negative for anti-T. gondii IgM antibodies had detectable SAG1 mRNA molecules. Hence, it seems that molecular diagnostic tests are essential to detect acute infections. [ABSTRACT FROM AUTHOR]

Introduction: Toxoplasmosis, one of the most common infectious diseases among humans and livestock, with its operating Toxoplasma gondii, a protozoa intracellular parasites, may cause serious infections in humans and animals to be domesticated. Epidemiologic studies show Toxoplasma antibodies in the serum for at least 1/3 adult population in most countries, however, previous infection and spread of organisms represents a broad and powerful contact and ability of Toxoplasma to infect humans. Serologic tests for the diagnosis of toxoplasmosis are often the size of the antibodies used. Objective: Prevalence of Serum Antibodies (IgM and IgG) Toxoplasma gondii in Guilan by ELISA Method Materials and Methods: In this descriptive and analytical study, 800 sera of individuals referred to the medical diagnostic laboratories in Guilan in 1391 were randomly selected, and using ELISA, IgG and IgM antibodies against Toxoplasmosis were measured. Results: Based on the results of total 800, of the 301 men and 499 women, 261 (62/32 percent) had IgG antibody against a Toxoplasmosis of IgM antibody and all were negative. Population of men (9/87 percent) and women (22/75%) of IgG antibody were detected. Using chi square test, no significant relationship was found between antibody prevalence and age, sex, job location and no history of contact with pets. Conclusion: The results confirm the necessary test to diagnose toxoplasmosis. Promotion of health awareness among people can also reduce the risk of toxoplasmosis. Conflict of interest: non declared [ABSTRACT FROM AUTHOR]

Serum samples, 100 in the total number, were collected from different laboratories in Tehran, Iran and tested for anti-Toxoplasma specific IgG and IgM antibodies using indirect immunofluorescent antibody test (IFAT). Using the IgG (chronic) and IgM (acute) positive samples, the IgG avidity test was performed by ELISA in duplicate rows of 96-well microtiter plates. One row was washed with 6 M urea and the other with PBS (pH 7.2), then the avidity index (AI) was calculated. Sixteen out of 18 (88.9%) sera with acute toxoplasmosis showed low avidity levels (AI > 50), and 76 out of 82 (92.7%) sera in chronic phase of infection showed high avidity index (AI > 60). Six sera 0had borderline ranges of AI. The results showed that the IgG avidity test by ELISA could distinguish the acute and chronic stages of toxoplasmosis in humans. [ABSTRACT FROM AUTHOR]

Objectives: The organisms of Toxoplasma gondii , Rubella virus , Cytomegalovirus , and Herpes simplex virus as an acronym of TORCH are major pathogens in prepregnancy and reproductive-age women. These microorganisms are considered a serious problem and cause 2-3% of all birth defects in the fetus. Our study was aimed at screening the seroprevalence of TORCH antibodies among prepregnancy and reproductive-age women in Tabriz, Iran. Design and Setting . This study was carried out in 2726 prepregnancy and reproductive-age women, who were referred to the laboratory for prenatal TORCH screening. To detect the presence of IgG, IgM antibodies and Hepatitis B surface antigen against these microorganisms were carried out using a chemiluminescence immunoassay analyzer (CLIA)., Results: In the current study, the rates of anti- Toxoplasma gondii IgG, anti- Rubella virus IgG, and anti- Cytomegalovirus IgG were found in 722 cases (26.5%), 2579 cases (94.6%0), and 2718 cases (99.7%), respectively. Moreover, the rates of anti- Toxoplasma gondii IgM, anti- Rubella virus IgM, and anti- Cytomegalovirus IgM were discovered in 10 cases (0.4%), 13 cases (0.5%), and 16 cases (0.6%), respectively. The Hepatitis B surface antigen was found in 32 cases (1.2%). The dissemination of positive TORCH in various ages was different ( P < 0.05)., Conclusions: In our study, the seroprevalence of acute TORCH infections was relatively low. Due to the probability of vertical transmission to the fetus during pregnancy and the unpleasant complication of these pathogens, it is essential to be screened for detection of specific IgG and IgM antibodies in reproductive ages., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2022 Edris Nabizadeh et al.)

Background: Toxoplasmosis is one of the most common comorbidities in HIV-positive patients with CD4+ T lymphocytes below 200 cells/μl. Early diagnosis and treatment of toxoplasmosis reduces the mortality rate in HIV-positive people. The aim of this study was to estimate the seroprevalence of Toxoplasma gondii infection in HIV-positive patients in northwest Iran using serological and molecular methods., Methods: This prospective cross-sectional study included 124 HIV-positive outpatients and was conducted from January to May 2016. Anti-T. gondii IgM and IgG antibodies were detected from sera samples by chemiluminescence, while buffy coat samples were analyzed by RT-PCR for DNA detection. Patients' socioepidemiological data were collected., Results: Using chemiluminescence, 47/124 samples (37.9%) were positive for anti-Toxoplasma IgG antibodies, 2/124 samples (1.62%) were positive for IgM antibodies while 2/124 samples (1.62%) contained both IgM and IgG. There were no IgM-positive or IgG-negative patients. RT-PCR revealed four (3.22%) positive samples. On the basis of the results, a statistically significant relationship was found between anti-Toxoplasma IgG antibody seropositivity and residence (p=0.012)., Conclusions: The study showed a relatively low seroprevalence of anti-T. gondii IgG and IgM antibodies in HIV-positive patients in northwest Iran, while the prevalence was much higher in other regions of Iran. However, regular screening for T. gondii antibodies and early initiation of therapy are very important to decrease the mortality rate in HIV-positive patients., (© The Author(s) 2019. Published by Oxford University Press on behalf of Royal Society of Tropical Medicine and Hygiene. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

A valid estimate of test efficiency is needed to choose adequate screening and detecting strategies in diagnosis of acute toxoplasmosis. Therefore, in the present study we evaluated the efficiency of diagnostic laboratory methods to detect anti-toxoplasma antibodies in single serum samples of pregnant women by indirect immunofluorescence test (IIF), enzyme-linked immunosorbent assay (ELISA) and IgG avidity tests in north-western Iran. In an analytical-descriptive study, during March 2010 to April 2013, 391 pregnant women aged 21 to 35 years who were referred by gynaecologists or infectious disease specialists for anti-toxoplasma antibody evaluation were studied. A peripheral blood sample was collected from individuals and serum was prepared immediately for anti-toxoplasma antibody evaluation by IIF, ELISA and IgG avidity tests. ELISA and IgG avidity tests were used as gold standard. Evaluation of anti-toxoplasma antibodies by IIF revealed that 280 cases (71.61%) were seropositive and 111 (28.38%) seronegative, while evaluation by ELISA revealed that 267 cases (68.28%) were seropositive and 124 (31.70%) seronegative; 65 (16.62%) were IgM positive by both IIF and ELISA tests. There were 45 (69.23%) and 7 (10.76%) IgM positive suspected cases respectively in IIF and ELISA confirmed by the IgG avidity test for recent toxoplasmosis. This study highlights how to manage and evaluate pregnant women who are suspected to be infected with toxoplasmosis by using diagnostic tests, especially in a single serum sample indication.

Background: Congenital toxoplasmosis is that pregnant women acquire the infection during gestation; diagnosis of the acute infection during pregnancy is a complex subject of maternal toxoplasmosis. Thus, the presence of immunoglobulin G (IgG) and/or IgM Toxoplasma antibodies in a single serum sample drawn during gestation cannot be used to define whether the infection was recently acquired or chronic., Materials and Methods: At this cross-sectional descriptive study, sera of 391 pregnant women examined and compared. They were in an age range of 21-35 years, referred by gynecologists and infectious disease specialists, during March 2012-April 2013. They have referred, 215 (54.98%), 102 (26%), 74 (18.92%) in the first, second and third trimesters of gestation, respectively. For each of them, a questionnaire was completed and serum samples were prepared in an equal condition, examined according to the procedures of indirect immunofluorescence (IIF), enzyme-linked immunosorbent assay (ELISA) and IgG Avidity techniques., Results: We have found 111 (28.38%) seronegative and 280 (71.61%) seropositive cases by IIF and 124 (31.70%) seronegative, 267 (68.28%) seropositive cases by ELISA. The IgG avidity test confirmed 45 (69.23%) and 7 (10.76%) doubtful cases of IgM test in IIF and ELISA techniques., Conclusions: This study highlights how to manage pregnant women with toxoplasmosis, especially in a single serum sample condition.

Introduction: Toxoplasma gondii is a protozoan parasite which can be transmitted to human through a variety of routes including blood transfusion. This cross sectional study aimed to evaluate the seroprevalence of Toxoplasma infection and related epidemiological features among healthy blood donors., Methodology: A total of 1,480 healthy blood donors from five blood service centers in Fars province were analyzed for anti-Toxoplasma antibodies. Blood samples were tested for anti-T. gondii IgG and IgM antibodies by enzyme immunoassay. IgM-positive samples were also tested for the presence of Toxoplasma DNA by Polymerase Chain Reaction (PCR). Demographic characteristics of participants were also recorded during samples collection., Results: Anti T. gondii antibodies were detected in sera of 286 out of 1,480 blood donors corresponding to an overall seroprevalence of 19.3% in this population.  From these, 182 (12.3%) were seropositive only for IgG, 81 (5.47%) were seropositive only for IgM and 23 (1.6%) were positive for both IgG and IgM. PCR detected active parasitemia in two (1.9%) of the IgM-positive subjects. Age, place of residence and level of education were statistically significant (p < 0.05) with seropositivity to Toxoplasma., Conclusions: Our results highlighted that asymptomatic blood donors, especially those with active parasitemia, may constitute a significant risk of transmitting toxoplasmosis to susceptible recipients.

Early, accurate and effective diagnosis of toxoplasmosis can make an important contribution to the prevention and control of disease, especially in people who are at risk. In this study, two commonly used genomic repeats of Toxoplasma gondii, RE (GenBank accession number AF146527) and B1, were compared to each other in nested-PCR assay. Five hundred and thirty-five blood samples from children with leukemia were tested for the presence of T. gondii antibodies using enzyme immunoassays. One hundred and ten DNA samples of these patients (50 IgM+, IgG+, 10 IgM-, IgG+, and 50 IgM-, IgG-) were analyzed by nested-PCR. The specificity of two nested PCR assays was determined using the DNA samples of other parasites and human chromosomal DNA. As a result, 82% (41/50) and 68% (34/50) of the IgM+, IgG+ samples were positive on duplicate RE and B1-nested PCR analyses, respectively. None of the 10 IgM-, IgG+ seropositive samples was detected positive after testing RE and B1-nested PCR assays in duplicate. One (2%) of the 50 seronegative samples was positive by duplicate RE-nested PCR but none of them were positive by duplicate B1-nested PCR. The detection limit of the RE-nested PCR assay was 640 fg of T. gondii DNA whereas this rate for B1-nested PCR was 5.12 pg of the DNA template. No cross-reactivity with the DNA of other parasites and human chromosomal DNA was found. The results indicate that an RE-based nested PCR assay is more sensitive than B1 genomic target, of those tested, for detection of T. gondii. It is noteworthy that in comparison with B1-nested PCR, RE-nested PCR could detect the T. gondii DNA in seronegative samples too., (© 2013.)

Toxoplasma gondii causes the most common parasitic infection in the world. Congenital transmission, prenatal mortality and abortion are major problems of T. gondii. Prevalence of toxoplasmosis is high in Iran, especially in Azerbaijan. The current literature reviewed in this paper reveal results pertaining to various regions of Iran. The present cross-sectional e-study was designed to evaluate the seroprevalence of toxoplasmosis in childbearing women in Northwest Iran. We evaluated 1659 women in childbearing age from several cities in Northwestern Iran (Tabriz, Maragheh, Ahar, Marand, Sarab, Miane) from July 2009 to August 2010. Women aged between 20 and 40 years and seeking prenatal care were enrolled in the study. The subjects' sera were probed with indirect fluorescent antibody (IFA). A total of 1659 subjects were examined. Titres ranged from 1:100 to 1:800. In all, 899 subjects (54.13%) were seropositive. The highest frequency of seropositivity was shown in 1:200 dilution (36.08%) and in subjects from Maragheh (84% of 211 subjects). There was a direct linear relationship between seropositivity and age (p 0.001). Also, seroprevalence of toxoplasmosis was higher in subjects with primary school/lower educational level (p 0.001) and subjects living in rural regions (p 0.001). Overall, more than 50% of women in childbearing age were seropositive for toxoplasmosis in northwestern Iran. Increasing seroprevalence of toxoplasmosis with age was a predictable result due to longer exposure to the parasite. The relationship between increasing seroprevalence and lower educational level as well as living in rural areas is in line with the latest epidemiological findings, which also show such relationships due to lower socioeconomic status.

Toxoplasmosis caused by Toxoplasma gondii is an opportunistic infection. In healthy individuals, the infection is largely asymptomatic, but in immunocompromised people the parasite can become widely disseminated, causing severe toxoplasmosis. In patients undergoing haemodialysis, the phagocytic process shows a highly significant impairment. Therefore, this study aimed to investigate toxoplasmosis in patients with end-stage renal disease (ESRD) undergoing haemodialysis in Ahvaz hospitals, southwest of Iran. A total of 280 patients and 100 healthy subjects participated in this study. The presence of serum IgM and IgG antibodies against T. gondii was detected by ELISA and the presence of Toxoplasma parasites in whole blood was evaluated by GRA6 PCR. Anti-T. gondii IgG antibodies were detected in 82 (29.3 %) haemodialysis patients and 26 (26 %) controls. In addition, anti-T. gondii IgM antibodies were detected in 7.9 % of patients and in 4 % of controls. For both the antibodies, the differences were statistically significant (P < 0.05). PCR was performed with DNA extracted from blood samples of all patients and controls. PCR gave positive results with four of the 280 blood samples from patients but none for the control blood samples. The results revealed a high percentage of positivity for Toxoplasma antibodies in patients with ESRD undergoing haemodialysis and also confirmed the parasite in whole blood, indicating disseminated infection in these patients. Patients undergoing dialysis have a higher rate of active infection with Toxoplasma likely due to reactivation of a chronic infection. Thus, parasitological examinations of ESRD patients should be periodically carried out for monitoring and evaluating the possible dissemination of toxoplasmosis during haemodialysis.

The usefulness of a specific immunoglobulin G (IgG) avidity enzyme-linked immunosorbent assay (ELISA) based on recombinant GRA6 antigen for distinguishing between acute and chronic Toxoplasma infection was investigated. Two sets of serum samples obtained from pregnant women with acute, chronic, or no Toxoplasma infection collected in France and Iran were used. Among the French subjects, 19 of 20 (95%) women who experienced seroconversion during the past 4 months before sampling displayed low-avidity IgG antibodies against GRA6, while all 17 (100%) women with chronic infection had high-avidity antibodies. When the Euroimmun IgG avidity ELISA was used, 15 of 19 (78.9%) recently infected women had low-avidity antibodies, and 20 of 22 (90.9%) women with chronic infection displayed high-avidity antibodies. The results suggested better performance of the GRA6 avidity ELISA than the Euroimmun avidity ELISA for exclusion of a recent infection occurring less than 4 months previously. Similarly, all 35 Iranian women with acute Toxoplasma infection had low-avidity antibodies against GRA6, whereas all 34 women with chronic infection displayed IgG antibodies of high avidity, indicating the value of GRA6 avidity testing for ruling out a recent infection. Avidity tests based on lysed whole-cell Toxoplasma gondii antigen are currently used to exclude recently acquired infections; however, the use of recombinant antigen(s) might improve the diagnostic performance of avidity tests and facilitate the development of more standardized assays.

GRA2 is a highly immunogenic protein secreted from the dense granules of Toxoplasma gondii. Recent success in purifying full-length, soluble GRA2 from bacteria as a thioredoxin (TRX)-(Hisx6) fusion protein led to investigate the antigenicity of the recombinant protein against human sera. On immunoblots, TRX-(Hisx6)-GRA2 was recognized by sera collected in Iran from T. gondii-infected pregnant women. An IgG enzyme-linked immunosorbent assay was developed to evaluate the reactivity of sera, collected from pregnant women both in France and Iran, to the TRX-(Hisx6)-GRA2 fusion protein. Specificity of the test was 96.4%. Sensitivity of the GRA2 enzyme-linked immunosorbent assay ranged from 95.8% (sera collected in France) to 100% (sera collected in Iran) for sera of acute infection and from 65.7% (sera collected in France) to 71.4% (sera collected in Iran) for sera of chronic infection. The recombinant GRA2 could thus advantageously complement previously described T. gondii antigens for the serodiagnosis of acute Toxoplasma infection.