Toxoplasma gondii infection in pregnancy: opportunities and pitfalls of serological diagnosis

MicroRNA mmu-miR-511-5p: A promising Diagnostic Biomarker in Experimental Toxoplasmosis Using Different Strains and Infective Doses in Mice with Different Immune States Before and After Treatment

PURPOSE

Searching for a novel early diagnostic biomarker for toxoplasmosis, real-time-PCR was currently used to measure the serum mmu-miR-511-5p level in male Swiss-albino mice infected with either; ME49 or RH Toxoplasma gondii (T. gondii) strains.

METHODS

Three mice groups were used; (GI) constituted the non-infected control group, while (GII) and (GIII) were experimentally infected with ME49 or RH strains, respectively. GII mice were orally infected using 10 or 20 ME49 cysts (ME-10 and ME-20), both were subdivided into; non-treated (ME-10-NT and ME-20-NT) and were further subdivided into; immunocompetent (ME-10-IC and ME-20-IC) [euthanized 3-days, 1, 2, 6 or 8-weeks post-infection (PI)], and immunosuppressed using two Endoxan® injections (ME-10-IS and ME-20-IS) [euthanized 6- or 8-weeks PI], and spiramycin-treated (ME-10-SP and ME-20-SP) that received daily spiramycin, for one-week before euthanasia. GIII mice individually received 2500 intraperitoneal RH strain tachyzoites, then, were subdivided into; non-treated (RH-NT) [euthanized 3 or 5-days PI], and spiramycin-treated (RH-SP) that were euthanized 5 or 10-days PI (refer to the graphical abstract).

RESULTS

Revealed significant upregulation of mmu-miR-511-5p in GII, one-week PI, with gradually increased expression, reaching its maximum 8-weeks PI, especially in ME-20-NT group that received the higher infective dose. Immunosuppression increased the upregulation. Contrarily, treatment caused significant downregulation. GIII recorded significant upregulation 3-days PI, yet, treatment significantly decreased this expression.

CONCLUSION

Serum mmu-miR-511-5p is a sensitive biomarker for early diagnosis of ME49 and RH infection (as early as one-week and 3-days, respectively), and its expression varies according to T. gondii infective dose, duration of infection, spiramycin-treatment and host immune status.

Neuroserpin, IL-33 and IL-17A as potential markers of mild symptoms of depressive syndrome in Toxoplasma gondii-infected pregnant women

Introduction

Depressive syndrome (DS) is a common complication during pregnancy and the postpartum period, and is triggered by multiple organic/genetic and environmental factors. Clinical and biochemical follow-up is essential for the early diagnosis and prognosis of DS. The protozoan Toxoplasma gondii causes infectious damage to the fetus during parasite primary-infection. However, in long-term infections, pregnant women develop immune protection to protect the fetus, although they remain susceptible to pathological or inflammatory effects induced by T. gondii. This study aimed to investigate plasma inflammatory biomarkers in pregnant women seropositive and seronegative for T. gondii, with diagnoses of minor and moderate/severe DS.

Methods

Pregnant women (n=45; age=18-39 years) were recruited during prenatal care at health centers in Ouro Preto, Minas Gerais, Brazil. Participants were asked to complete a socio-demographic questionnaire to be submitted to well-standardized DS scale calculators (Beck Depression Inventory Questionnaire, Edinburgh Postnatal Depression Scale, and Major Depressive Episode Module). Additionally, 4 mL of blood was collected for plasma neuroserpin, CCL2, IL-17A, and IL-33 analysis.

Results

Pregnant volunteers with chronic T. gondii contact were all IgG+ (44%; n=21) and exhibited increased plasma IL-33, IL-17A, and neuroserpin levels, but not CCL2, compared to uninfected pregnant women. Using Beck's depression inventory, we observed an increase in plasma IL-17A and IL-33 in women with T. gondii infeCction diagnosed with mild DS, whereas neuroserpin was associated with minor and moderate/severe DS.

Discussion

Our data suggest a close relationship between DS in pregnant women with chronic T. gondii infection and neurological conditions, which may be partially mediated by plasma neuroserpin, IL-33, and IL-17A levels.

Seroprevalence of high incidence congenital infections among pregnant women in Coatepeque, Guatemala and surrounding areas, 2017-2018

Maternal infections during pregnancy can potentially cause birth defects and severe adverse effects in infants. From 2017 to 2018, we investigated the seroprevalence of five antibodies among 436 mother-infant pairs enrolled in a pregnancy cohort study in Coatepeque, Guatemala. Upon enrollment (< 20 weeks gestational age) and shortly after delivery, we measured the prevalence of IgG and IgM antibodies against Toxoplasma gondii (T. gondii), rubella, and cytomegalovirus (CMV) in mothers and newborns and used rapid tests to detect HIV and syphilis (Treponema pallidum) in mothers. The mean cohort age was 24.5 years. Maternal T. gondii IgM and IgG seropositivity was 1.9% and 69.7%, respectively. No women were positive for HIV, syphilis, or rubella IgM. Maternal rubella IgG seropositivity was 80.8% and significantly increased with age. Maternal CMV IgM and IgG seropositivity were 2.3% and 99.5%, respectively. Of the 323 women tested at both timepoints, IgM reactivation occurred in one woman for T. gondii infection and in eight for CMV. No newborn was seropositive for CMV IgM or rubella IgM. One newborn was seropositive for T. gondii IgM. Congenital T. gondii and CMV infections are important public health issues for pregnant women, newborns, and healthcare providers in Coatepeque and Guatemala.

First description of congenital toxoplasmosis after maternal coinfection with Toxoplasma gondii and severe acute respiratory syndrome coronavirus 2: a case report

BACKGROUND

Congenital toxoplasmosis can be associated with serious clinical consequences from fetus to adulthood. Hence, early detection is required to minimize severe sequelae through appropriate therapy. We describe the first case of a congenital toxoplasmosis after maternal coinfection with Toxoplasma gondii and severe acute respiratory syndrome coronavirus 2 and the challenging serological diagnosis of the disease in this context.

CASE PRESENTATION

A Caucasian boy was born at 27 weeks 2 days of gestation by cesarean section due to maternal COVID-19-related respiratory failure. Postpartum serological screening of the mother revealed a previously unrecognized active Toxoplasma gondii infection. The premature child initially tested negative for anti- Toxoplasma gondii immunoglobulin A and M antibodies 1, 2 and 4 weeks after birth, whereas immunoglobulin G antibodies were only weakly positive with no evidence of child-specific production. Neither neurological nor ophthalmological abnormalities were detected. Approximately 3 months after birth, serological testing indicated a congenital toxoplasmosis by presence of immunoglobulin A and M, in combination with a child-specific immunoglobulin G synthesis. Additionally, cerebrospinal fluid was tested positive for Toxoplasma gondii DNA. Although no clinical manifestations of congenital toxoplasmosis were detected, an antiparasitic therapy was initiated to minimize the risk of late sequelae. There were no hints for a transplacental transmission of severe acute respiratory syndrome coronavirus 2.

CONCLUSION

This case raises the awareness of possible coinfections with the risk of transplacental transmission in cases of maternal coronavirus disease 2019. The report emphasizes the need for screening vulnerable patients for toxoplasmosis in general and especially in the context of pregnancy. It becomes evident that prematurity can complicate the serological diagnosis of congenital toxoplasmosis due to a delayed antibody response. Repeated testing is recommended to carefully monitor children at risk and especially those with a history of preterm birth.

Advances and Challenges in Diagnostics of Toxoplasmosis in HIV-Infected Patients

Toxoplasma gondii is a worldwide distributed protozoan parasite. This apicomplexan parasite infects one-third of the population worldwide, causing toxoplasmosis, considered one of the neglected parasitic infections. In healthy humans, most infections are asymptomatic. However, in immunocompromised patients, the course of the disease can be life-threatening. Human immunodeficiency virus (HIV)-infected patients have a very high burden of Toxoplasma gondii co-infection. Thus, it is essential to use modern, sensitive, and specific methods to properly monitor the course of toxoplasmosis in immunodeficient patients.

Anti-Toxoplasma gondii IgM Long Persistence: What Are the Underlying Mechanisms?

Diagnosis of Toxoplasma gondii acute infection was first attempted by detection of specific IgM antibodies, as for other infectious diseases. However, it was noted that this immunoglobulin declines slowly and may last for months or even years. Apart from the diagnostic problem imposed on clinical management, this phenomenon called our attention due to the underlying phenomena that may be causing it. We performed a systematic comparison of reports studying IgM antibody kinetics, and the data from the papers were used to construct comparative plots and other graph types. It became clear that this phenomenon is quite generalized, and it may also occur in animals. Moreover, this is not a technical issue, although some tests make more evident the prolonged IgM decay than others. We further investigated biological reasons for its occurrence, i.e., infection dynamics (micro-reactivation–encystment, reinfection and reactivation), parasite strain relevance, as well as host innate, natural B cell responses and Ig class-switch problems inflicted by the parasite. The outcomes of these inquiries are presented and discussed herein.

Seroprevalence of Gestational and Neonatal Toxoplasmosis as well as Risk Factors in Yaoundé, Cameroon

Background. Toxoplasmosis, caused by Toxoplasma gondii in pregnant women, is a significant public health problem due to risk of mother to child transmission. The aim of the study was to determine the seroprevalence of toxoplasmosis in pregnant women and corresponding cord blood among women attending Biyem-Assi and CASS Nkoldongo hospitals in Yaoundé, Cameroon. Methods. An institutional based cross-sectional study was conducted between June 2019 and May 2020 on 300 pregnant women from late second trimester to third trimester. A total of 259 cord blood samples were collected at birth from these women. Toxoplasma gondii-specific IgG and IgM antibodies in maternal and cord blood were detected using the Toxoplasma Enzyme Immunosorbent Assay kit, and potential risk factors captured through questionnaire were identified using binary logistic regression model. Statistical significance was measured at $P<0.05$ . Results. The overall seroprevalence of gestational and neonatal toxoplasmosis was 80% and 88%, respectively. IgG seropositivity was 72.7%, IgM only was 1.3% and cooccurrence of IgG/IgM was 6% amongst pregnant women. Out of 259 newborn cord bloods, 72.2% were positive for IgG only, 8.9% for IgM only, and 23.9% for both IgG/IgM. Pregnant women 15-24 years ( $\text{AOR}=4.6$ , $P=0.011$ ) and women with primary level of education ( $\text{AOR}=3.9$ , $P=0.042$ ) were significantly at risk of infection with Toxoplasma gondii. Conclusion. Gestational and neonatal toxoplasmosis appears to be more common with higher risk of infection in younger women and less educated women. Hence, these findings will serve as baseline data for further investigations on mother to child transmission of toxoplasmosis in Yaoundé and the need for reinforcement of pregnant women toxoplasmosis-related health measures.

Serological diagnosis of toxoplasmosis: evaluation of the commercial test recomLine Toxoplasma IgG immunoblot (Mikrogen) based on recombinant antigens

Background: IgG detection to determine immune status to Toxoplasma gondii infection and seroconversion mainly relies on ELISA techniques and, if necessary, on a confirmatory test, Western blot. This study evaluated the performance of the recomLine Toxoplasma IgG immunoblot (IB-recomLine) (Mikrogen) as a confirmatory test on a large number of sera. A total of 171 sera were selected (113 patients) and had previously been analyzed by two ELISA tests, ARCHITECT (Abbott) and VIDAS (bioMérieux) ± LDBIO-Toxo II IgG Western blot (WB-LDBIO) (LDBio). The sera were classified into three groups: group 1 included 50 sera without difficulty in interpreting the IgG results (patients with documented past infection or uninfected); group 2 included 47 sera with difficulty in interpreting the ELISA results; and group 3 included 74 sequential sera from 25 pregnant women with seroconversion. Results: In group 1, overall IgG agreements were 94% and 90% with ARCHITECT and VIDAS, respectively. In group 2, low agreement was observed between IB-recomLine and WB-LDBIO, with eight false-positive and 13 false-negative results. In group 3, 4/13 seroconversions were detected earlier with IB-recomLine compared to other tests. Conclusions: IB-recomLine allowed for earlier diagnosis of toxoplasmic seroconversion compared to both ELISA tests and WB-LDBIO but led to insufficient performance to confirm the immune status when ELISA results were discordant or equivocal.

Tubulointerstitial nephritis and uveitis syndrome following meningitis and systemic lymphadenopathy with persistent Toxoplasma immunoglobulin M: a case report

Background

Tubulointerstitial nephritis and uveitis syndrome is a rare lymphocyte-related oculorenal inflammatory disease presumed to be associated with drug use and infectious agents. Toxoplasma gondii is one of such pathogens that could exhibit encephalitis, meningitis, and uveitis in immunocompromised or in some immunocompetent individuals. If the immunoglobulin M of Toxoplasma is positive on screening, the interpretation of the result is not simple, especially when immunoglobulin M stays positive persistently.

Case presentation

A 34-year-old Asian male developed fever, headache, and lymphadenopathy with tenderness, which was initially diagnosed as meningitis. Antibiotics were started, and diclofenac sodium was used for the fever. Although his symptoms were alleviated in a week by the treatment, gradual decline in renal function was noted, prompting a renal biopsy that indicated acute granulomatous interstitial nephritis. A week later, tenderness in both eyes with blurred vision appeared and revealed iritis and keratic precipitations in both eyes; hence, the diagnosis of acute tubulointerstitial nephritis and bilateral uveitis syndrome was made. Toxoplasma gondii-specific immunoglobulin G and immunoglobulin M titers were both positive. Although we could not rule out recent infection of Toxoplasma gondii, which may cause uveitis initially, Toxoplasma immunoglobulin G avidity test indicated a distant infection, which allowed us to rule out meningitis and uveitis as responsible for the complication of recent Toxoplasma gondii infection. Drug-induced lymphocyte stimulation test, or lymphocyte transformation test of diclofenac sodium, was solely positive among the tested drugs. Uveitis was alleviated only with ophthalmic steroid, and renal function returned to normal without administration of systemic steroid.

Conclusions

We experienced a case of diclofenac-induced tubulointerstitial nephritis and uveitis syndrome. In ruling out infections, Toxoplasma immunoglobulin M was persistently positive, and Toxoplasma immunoglobulin G avidity test indicated a “distant” infection. From these two results, we ruled out recent infection. However, it should be noted that “distant” infection indicated by commercial immunoglobulin G avidity is still a multiplex profile consisting of reinfection, reactivation, and latent infection. Narrowing down the infection profile of Toxoplasma is challenging in some cases. Therefore, careful diagnosis and extended follow-up of such patients are needed.

Congenital Toxoplasmosis: Findings in Fetal MRI

Toxoplasma gondii infection, when acquired as an acute infection during pregnancy, can have substantial adverse effects on fetuses. We present the case of a 19-year-old pregnant woman with no previous relevant medical history. The ultrasound in the third trimester showed brain and abdominal abnormalities such as congenital hydrocephalus, volume loss of the brain parenchyma, and hepatosplenomegaly. The laboratory test showed positive IgM for Toxoplasma gondii. MRI was performed for better assessment and it shows the lesions in the central nervous system and other organs with more details.

Toxoplasma gondii infection: seroprevalence and associated risk factors for women of childbearing age in Osun State, Nigeria

Toxoplasmosis is a common parasitic infection caused by an obligate intracellular protozoan, Toxoplasma gondii. Prevalence and risk factors of T. gondii infection in women of childbearing age in Osun State, Nigeria are unknown. This study was aimed to determine the seroprevalence and potential risk factors in acquiring T. gondii infection by women of childbearing age in Osun State, Nigeria. A community-based cross-sectional study was conducted from May 2019 to December 2019 in childbearing age women. Sera of 415 women aged 18-49 years randomly selected were collected and analyzed by enzyme-linked immunosorbent assay (ELISA) test. A questionnaire survey was administered for all study participants to collect socio-demographic and risk factors data. The study revealed that the overall seroprevalence of T. gondii infection was 76.63%, which comprised 6.02% positivity for anti-T. gondii IgM (25/415), 44.10% for IgG (183/415) and 26.51% for IgG plus IgM (110/415). Seroprevalence of IgM antibodies to T. gondii (6.02%) suggested recent infections. Women residing in rural communities and women of Islam religion showed significant association with anti-T. gondii seropositivity (p < 0.05). Residence location and women who are of Islam religion are risk factors to acquire T. gondii infection. Hence, health education and awareness on the disease and its transmission to women of childbearing age group in general and pregnant women in particular should be created during antenatal follow up to reduce the risk of T. gondii infection in pregnant women.

Identification of Biomarkers for Diagnosis and Prognosis of Congenital and Acute Toxoplasmosis

BACKGROUND

The diagnosis of congenital toxoplasmosis can be inconclusive in many cases. Despite the several serological tests developed, the literature on biomarkers that can assist in the diagnosis of congenital an acute toxoplasmosis is limited. The objective of this study was to analyze the immunoreactive profile of Toxoplasma gondii protein bands with the potential to be biomarkers for diagnosis and prognosis of congenital and acute toxoplasmosis.

METHODS

Peripheral blood samples from women of childbearing age and/or pregnant women diagnosed with acquired toxoplasmosis as well as from congenitally infected children were selected and submitted to immunoblotting for analysis of the immunoreactive bands profile by immunoglobulin G (IgG) antibodies.

RESULTS

When comparing the immunoreactive bands profile for antibodies present in samples from different groups and subgroups, the 150, 18.5, and 16.96-kDa bands were more immunoreactive with the antibodies present in serum samples from the acquired infection group. The 343, 189, 150, 75, and 42-kDa bands showed more chance to be detected by the symptomatic congenital infection subgroup samples, while the 61, 50, and 16.96-kDa bands were significantly immunoreactive with the acute infection subgroup samples.

CONCLUSIONS

The identification of these potential biomarkers can assist in early diagnosis and treatment of congenital toxoplasmosis.

Infective myositis

Myositis is inflammation especially of the voluntary muscles, characterized by localized or diffuse pain, tenderness on movement or palpation, swelling, and/or weakness. The two main categories of myositis include non-infectious and infectious. Infective myositis may be due to a wide variety of pathogens, including bacteria, fungi, viruses, and parasites. A brief account of the various pathogens causing infective myositis is discussed.

Seroprevalence and risk factors of Toxoplasma gondii infection in women with recurrent fetal loss from the province of Khyber Pakhtunkhwa, Pakistan

BACKGROUND

In women with a bad obstetric history (BOH), infection is an established cause of recurrent fetal loss. A common infecting agent is the protozoan parasite Toxoplasma gondii (T. gondii). The aim of this study was to measure the prevalence of toxoplasmosis in women with recurrent fetal loss from the Khyber Pakhtunkhwa province of Pakistan.

METHODS

The study included 360 females aged 16-40 years, of which 180 had a bad obstetric history (study group) and the other 180 had no such history (control group). Blood serum samples were tested for toxoplasma IgM antibodies by Enzyme Linked Immunosorbent Assay and for toxoplasma IgG antibodies using an Immunochromatographic technique.

RESULTS

The overall seroprevalence of toxoplasma infection in study group females was 40.6% and in control group females it was 7.2%. Specifically, IgM prevalence was 12.8% in the study group and 1.1% in the control group. IgG prevalence was 23.9% in the study group and 6.1% in the control group. IgM and IgG combined prevalence was 3.9% in the study group cases. There is a statistically significant association between BOH and seropositivity for T. gondii (p < 0.0001, Chi square test). Various risk factors associated with T. gondii seroprevalence in study and control groups were analyzed.

CONCLUSION

The seroprevalence of toxoplasmosis was significantly higher in women with a bad obstetric history compared to those with no such history. Associated risk factors had no significant effects on the results.

Toxoplasmosis in pregnancy: a clinical, diagnostic, and epidemiological study in a referral hospital in Rio de Janeiro, Brazil

Toxoplasmosis in pregnant women can cause significant morbidity and mortality in the fetus, which may be mitigated by early diagnosis and treatment. Social factors have also been related to the risk of developing the congenital form of toxoplasmosis, since some of these factors interfere directly in the quality of prenatal care. This study aimed to describe the clinical, laboratory, and epidemiological data of pregnant women diagnosed with toxoplasmosis and their newborns followed up at a referral hospital in Rio de Janeiro, Brazil. This was descriptive cohort study of 334 pregnant women with toxoplasmosis followed from May 2014 to December 2017. We conducted interviews to assess knowledge about the disease and its preventive measures, analyzed clinical and laboratory data during antenatal visits, and collected data from the newborns’ medical charts.

Results

This was a predominantly low-income women cohort study, with little schooling, mainly referred from public health services late in pregnancy (178; 53.3%), in the second and third trimesters (286; 85.6%). Diagnosis of acute toxoplasmosis had not been confirmed in 171 cases (51.2%). Out of 183 (54.9%) women who had initiated treatment at the original health services, 45 (24.6%) received an incorrect prescription. Seventy-two amniocenteses were performed, with positive real-time polymerase chain reaction (qPCR) in the amniotic fluid in two cases (2.8%). Congenital toxoplasmosis at birth was identified in eight newborns (5.4%).

Conclusion

Late referral to specialized medical services, inadequate toxoplasmosis management at the original prenatal care services, and social vulnerabilities are contributing factors to the persistent occurrence of congenital toxoplasmosis cases.

Construction of A Synthetic Gene Encoding the Multi-Epitope of Toxoplasma gondii and Demonstration of the Relevant Recombinant Protein Production: A Vaccine Candidate

BACKGROUND

Toxoplasma gondii is a widely-distributed parasite all over the world whose attributed severe afflicting complications in human necessitate the development of serodiagnostic tests and vaccines for it. Immunological responses to monovalent vaccines and the application of diagnostic reagents including single antigens are not optimally effective. Bioinformatics approaches were used to introduce these epitopes, predict their immunogenicity and preliminarily evaluate their potential as an effective DNA vaccine and for serodiagnostic goals.

MATERIALS AND METHODS

A 3D structure of proteins was predicted by I-TASSER server, and linear and conformational B cell and T cell epitopes were predicted using the online servers. Then, the predicted epitopes were constructed and called Toxoeb, and their expression in the prokaryotic and eukaryotic cells was demonstrated using SDS-PAGE. In the next step, Western blotting with pooled sera of mice infected with T. gondii was done.

RESULTS

The current in silico analysis revealed that the B cell epitopes with high immunogenicity for GRA4 protein were located in the residues 34-71, and 230-266, for GRA14 in 308-387, for SAG1 in 182-195, 261-278, and for GRA7 in residues 101-120, 160-176. The T cell epitopes were selected in overlapping regions with the B cell epitopes. The immunogenic region for GRA4 are in the residues 245-253, 50-58, and 40-54, for GRA14 in 307-315, 351-359, and 308- 322, for SAG1 261-269, and 259-267, and for GRA7 in the residues 103-112, and 167-175. The results of the western blotting showed that the expressed protein had immunogenicity.

CONCLUSION

Our constructed multi-epitope of T. gondii could be considered as a candidate for diagnostic and vaccination purposes.

Serological and molecular detection of Neospora caninum and Toxoplasma gondii in human umbilical cord blood and placental tissue samples

Neosporosis primarily affects cattle and dogs and is not currently considered a zoonotic disease. Toxoplasmosis is a zoonosis with a worldwide distribution that is asymptomatic in most cases, but when acquired during pregnancy, it can have serious consequences. The seropositivity rates determined by the indirect fluorescent antibody test for Neospora caninum (N. caninum) and Toxoplasma gondii (T. gondii) were 24.3% (49 samples) and 26.8% (54 samples), respectively. PCR positivity for N. caninum was observed in two samples of cord blood (1%) using the Nc5 and ITS1 gene, positivity for T. gondii was observed in 16 samples using the primer for the B1 gene (5.5% positivity in cord blood and 2.5% positivity in placental tissue). None of the samples showed structures characteristic of tissue cysts or inflammatory infiltrate on histopathology. Significant associations were observed only between N. caninum seropositivity and the presence of domestic animals (p = 0.039) and presence of dogs (p = 0.038) and between T. gondii seropositivity and basic sanitation (p = 0.04). This study obtained important findings regarding the seroprevalence and molecular detection of N. caninum and T. gondii in pregnant women; however, more studies are necessary to establish a correlation between risk factors and infection.

RHΔgra17Δnpt1 Strain of Toxoplasma gondii Elicits Protective Immunity Against Acute, Chronic and Congenital Toxoplasmosis in Mice

: In the present study, a dense granule protein 17 (gra17) and novel putative transporter (npt1) double deletion mutant of Toxoplasma gondii RH strain was engineered. The protective efficacy of vaccination using RHΔgra17Δnpt1 tachyzoites against acute, chronic, and congenital toxoplasmosis was studied in a mouse model. Immunization using RHΔgra17Δnpt1 induced a strong humoral and cellular response, as indicated by the increased levels of anti-T. gondii specific IgG, interleukin 2 (IL-2), IL-10, IL-12, and interferon-gamma (IFN-γ). Vaccinated mice were protected against a lethal challenge dose (10³ tachyzoites) of wild-type homologous (RH) strain and heterologous (PYS and TgC7) strains, as well as against 100 tissue cysts or oocysts of Pru strain. Vaccination also conferred protection against chronic infection with 10 tissue cysts or oocysts of Pru strain, where the numbers of brain cysts in the vaccinated mice were significantly reduced compared to those detected in the control (unvaccinated + infected) mice. In addition, vaccination protected against congenital infection with 10 T. gondii Pru oocysts (administered orally on day 5 of gestation) as shown by the increased litter size, survival rate and the bodyweight of pups born to vaccinated dams compared to those born to unvaccinated + infected dams. The brain cyst burden of vaccinated dams was significantly lower than that of unvaccinated dams infected with oocysts. Our data show that T. gondii RHΔgra17Δnpt1 mutant strain can protect mice against acute, chronic, and congenital toxoplasmosis by balancing inflammatory response with immunogenicity.

Evaluation and optimisation of commercial Zika IgG avidity assay

BACKGROUND

ZIKV infection has potentially severe consequences particularly in fetuses/newborns born to mothers that were infected early in pregnancy. Diagnosis relies on the detection of ZIKV IgM that can also be detected due to cross reactivity or to nonspecific polyclonal activation of the immune system. Therefore, in case of ZIKV IgM detection, identification of a recent infection can be of major importance for the optimal management of pregnant women.

OBJECTIVE

This study evaluates the performances of a commercially available assay to measure ZIKV-IgG avidity.

STUDY DESIGN

A total of 110 serum or plasma samples collected from symptomatic or asymptomatic patients living or returning from a ZIKV endemic area were classified according to epidemiological and clinical information, and to serology and molecular assays' results. Samples were tested with the IgG ZIKV Avidity Test (DIA.PRO®) according to manufacturer's instruction and with a modified protocol.

RESULTS

By using the manufacturer's Avidity Index cut-off, distinction between recent and past infection was unclear with similar AIs in the two situations (p = 0.8872). Sensitivity and specificity in identifying recent infection were poor, 67.3 % and 4.5 % respectively. By using a modified protocol, a better discrimination was observed with significant differences between mean AIs (p = 0.0318), and with higher sensitivity and specificity, respectively 87.8 % and 100 %.

CONCLUSION

Our results highlight that IgG ZIKV Avidity Test DIA.PRO® assay is not reliable enough to be used in clinical practice without modifications.

Toxoplasma gondii tkl1 Deletion Mutant Is a Promising Vaccine against Acute, Chronic, and Congenital Toxoplasmosis in Mice

In this study, we generated a tkl1 deletion mutant in the Toxoplasma gondii type 1 RH (RHΔtkl1) strain and tested the protective efficacies of vaccination using RHΔtkl1 tachyzoites against acute, chronic, and congenital T. gondii infections in Kunming mice. Mice vaccinated with RHΔtkl1 mounted a strong humoral and cellular response as shown by elevated levels of anti-T. gondii-specific IgG, IL-2, IL-12, IFN-γ, and IL-10. All RHΔtkl1-vaccinated mice survived a lethal challenge with 1 × 10³ tachyzoites of type 1 RH or ToxoDB#9 (PYS or TgC7) strain as well as 100 cysts or oocysts of Prugniuad strain. All mock-vaccinated plus infected mice have died. Vaccination also protected against cyst- or oocyst-caused chronic infection, reduced vertical transmission caused by oocysts, increased litter size, and maintained body weight of pups born to dams challenged with 10 oocysts on day 5 of gestation. In contrast, all mock-vaccinated plus oocysts-infected dams had aborted, and no fetus has survived. Vaccinated dams remained healthy postinfection, and their brain cyst burden was significantly reduced compared with mock-vaccinated dams infected with oocysts. In vivo depletion of CD4⁺ T cells, CD8⁺ T cells, and B cells revealed that CD8⁺ T cells are involved in the protection of mice against T. gondii infection. Additionally, adoptive transfer of CD8⁺ T cells from RHΔtkl1-vaccinated mice significantly enhanced the survival of naive mice infected with the pathogenic strain. Together, these data reaffirm the importance of CD8⁺ T cell responses in future vaccine design for toxoplasmosis and present T. gondii tkl1 gene as a promising vaccine candidate.

Anti-toxoplasma Antibody Prevalence and Cost-effectiveness in Pregnant Women at the King Abdulaziz University Hospital, Jeddah, Saudi Arabia

Background: Toxoplasma gondii (T. gondii) is one of the most prevalent infectious parasites in humans worldwide. The diagnosis of toxoplasmosis is based on serological screening through the detection of anti-toxoplasmosis antibodies: IgG, which indicates previous exposure and the presence of active immunity, and IgM, which indicates a recent infection. We aimed to determine the prevalence of anti-toxoplasma antibodies in pregnant women at King Abdulaziz University Hospital (KAUH), Jeddah, Saudi Arabia, and explore the cost-effectiveness of anti-toxoplasma screening.

Method: This was an analytic retrospective study of women who underwent serology testing for anti-toxoplasmosis antibodies at KAUH in 2013-2018. Data were collected from hospital documentation and IBM Statistical Package for Social Sciences (SPSS Inc., Chicago, IL) version 22 was used for analysis.

Result: Of the 9,098 pregnant women seen at KAUH, 2,754 had undergone the test, and 38 had a positive result, i.e., a seroprevalence rate of 1.4%. Most women were Saudis (57.9%), and almost all were multiparous. Of those with a positive result, 36.8% were in the third trimester. Most births were by spontaneous vaginal delivery (65.8%). Twelve (31.6%) of the women with toxoplasmosis experienced obstetric complications. The estimated total cost of screening the pregnancies was US $919,646.00

Conclusion: The prevalence of pregnant women with a positive anti-toxoplasmosis test result was low, and we believe there is no net benefit from screening all pregnant women for toxoplasmosis. Primary prevention should be through health education, and we recommend screening only women with high-risk pregnancies.

Prevalence and predictors of Toxoplasma gondii infection in pregnant women from Dhamar, Yemen

BACKGROUND

Toxoplasmosis is a common and serious parasitic infection caused by the ubiquitous obligatory intracellular protozoan organism, Toxoplasma gondii. Although infection with T. gondii is usually asymptomatic in healthy individuals, it can lead to severe pathological effects in congenital cases and immunocompromised patients. This study aimed to determine the seroprevalence of T. gondii and its predictors among pregnant women seeking prenatal and medical care at the general maternal and child health facility in Dhamar district of Dhamar governorate, Yemen.

METHODS

A total of 420 pregnant women were randomly selected for this cross-sectional study. Participants were screened for anti-T. gondii antibodies (i.e. immunoglobulin M; IgM and immunoglobulin G; IgG) using electrochemiluminescence immunoassay. Demographic, socioeconomic, obstetric and behavioural data were collected using a pretested questionnaire via face-to-face interview. Univariate and multivariate analyses were used to identify the independent predictors of T. gondii seroprevalence.

RESULTS

The overall seroprevalence of anti-T. gondii antibodies (IgG and/or IgM) among the participants was 21.2% (89/420; 95% CI = 17.3-25.1). Anti-T. gondii IgG antibodies were detected in 20.0% (84/420) of the women of which 12.9% (54/420) were positive for only IgG and 7.1% (30/420) were positive for both IgG and IgM antibodies. Moreover, 5 women (1.2%) were reactive only for IgM antibodies. Significant associations between T. gondii seroprevalence and history of spontaneous abortion (P <  0.001), raw vegetables consumption (P = 0.036), and presence of cats in household (P = 0.049) were reported. Multivariate analysis confirmed that history of spontaneous abortion (AOR = 4.04; 95% CI = [2.46, 6.63]) and presence of cats in household (AOR = 1.77; 95% CI = [1.02, 3.07]) are significant predictors of T. gondii seroprevalence among the studied participants.

CONCLUSION

The study found a high seroprevalence (21.2%) of T. gondii infection during pregnancy in Dhamar district, which is significantly associated with adverse pregnancy outcomes. The provision of adequate maternal healthcare and health education pertaining to the prevention of T. gondii infection is therefore imperative to curtail the prevalence of infection among the studied population.

Performance of Zika Assays in the Context of Toxoplasma gondii, Parvovirus B19, Rubella Virus, and Cytomegalovirus (TORCH) Diagnostic Assays

Infections during pregnancy that may cause congenital abnormalities have been recognized for decades, but their diagnosis is challenging. This was again illustrated with the emergence of Zika virus (ZIKV), highlighting the inherent difficulties in estimating the extent of pre- and postnatal ZIKV complications because of the difficulties in establishing definitive diagnoses. We reviewed the epidemiology, infection kinetics, and diagnostic methods used for Toxoplasma gondii, parvovirus B19, rubella virus, and cytomegalovirus (TORCH) infections and compared the results with current knowledge of ZIKV diagnostic assays to provide a basis for the inclusion of ZIKV in the TORCH complex evaluations. Similarities between TORCH pathogens and ZIKV support inclusion of ZIKV as an emerging TORCH infection. Our review evaluates the diagnostic performance of various TORCH diagnostic assays for maternal screening, fetal screening, and neonatal screening. We show that the sensitivity, specificity, and positive and negative predictive value of TORCH complex pathogens are widely variable, stressing the importance of confirmatory testing and the need for novel techniques for earlier and accurate diagnosis of maternal and congenital infections. In this context it is also important to acknowledge different needs and access to care for different geographic and resource settings.

Evaluation of a PCR assay for diagnosis of toxoplasmosis in serum and peripheral blood mononuclear cell among HIV/AIDS patients

Cerebral toxoplasmosis is one of the neurological infections with high morbidity and mortality in patients with AIDS, so the accurate method for diagnosis of cerebral toxoplasmosis seems necessary. In this study, nested PCR assay using B1 gene was evaluated in diagnosis of toxoplasmosis in serum and peripheral blood mononuclear cell (PBMC) among HIV/AIDS patients. One hundred eight blood samples from HIV/AIDS patients, including four patients with cerebral toxoplasmosis and 104 HIV/AIDS patients without cerebral toxoplasmosis were evaluated for the Toxoplasma gondii antibodies using Enzyme Linked immunosorbent Assay. DNA of serum and PBMC of these patients were extracted and nested-PCR was carried out. Of 108 participants, 95 cases (88%) were positive for Toxoplasma IgG antibodies and one patient was found positive for Toxoplasma IgM antibody. In general, four patients, including three patients with cerebral toxoplasmosis, who were positive for Toxoplasma IgG antibodies and one patient without cerebral toxoplasmosis who was positive for Toxoplasma IgM antibody were found to be PCR positive. DNA of T. gondii was detected in both serum and PBMC in two cerebral toxoplasmosis patients; however DNA was detected in only PBMC in other cerebral toxoplasmosis patient. All cases with cerebral toxoplasmosis were also diagnosed by clinical and radiological manifestations. The results of this study showed that the numbers of positive samples by PCR in PBMC were higher than serum specimens for diagnosis of toxoplasmosis. If molecular method and immunological assay are complemented with magnetic resonance imaging, the results can be useful for diagnosis of cerebral toxoplasmosis.

The first study on the usefulness of recombinant tetravalent chimeric proteins containing fragments of SAG2, GRA1, ROP1 and AMA1 antigens in the detection of specific anti-Toxoplasma gondii antibodies in mouse and human sera

This study presents an evaluation of four tetravalent recombinant chimeric proteins containing fragments of the Toxoplasma gondii antigens, SAG2, GRA1, ROP1 and AMA1, as potential replacements of a the soluble, whole-cell tachyzoite lysate (TLA) used in serological assays. Recombinant chimeric proteins (SAG2-GRA1-ROP1-AMA1N, AMA1N-SAG2-GRA1-ROP1, AMA1C-SAG2-GRA1-ROP1, and AMA1-SAG2-GRA1-ROP1) obtained by genetic engineering were tested for their reactivity with specific IgM and IgG antibodies from sera of experimentally infected mice and humans with T. gondii infection using an enzyme-linked immunosorbent assay (ELISA). In total 192 serum samples from patients with acquired T. gondii infection and 137 sera from seronegative individuals were examined. The reactivity of chimeric antigens with antibodies generated during T. gondii invasion was measured and compared to the results obtained in assays based on whole-cell Toxoplasma antigen. Chimeric proteins proved effective in differentiation between T. gondii-infected and uninfected individuals (100% sensitivity and specificity in the IgG ELISAs) which shows their potential usefulness as a replacements for TLA in standardized commercial tests for the serodiagnosis of toxoplasmosis. In addition, the chimeric proteins were tested for use in avidity determination. Obtained results were comparable to those of the corresponding commercial assays, suggesting the utility of these proteins for avidity assessment. Furthermore, this study demonstrated that the AMA1-SAG2-GRA1-ROP1 chimeric protein has the potential to distinguish specific antibodies from serum samples of individuals with the early and chronic phase of T. gondii infection.

Seroprevalence and risk factors of Toxoplasma gondii among pregnant women in Adwa district, northern Ethiopia

Background

Toxoplasma gondii infection is a great health concern to pregnant women and the developing fetus. The aim of this study was to determine the seroprevalence of T. gondii and its associated factors in Adwa district.

Methods

A facility based cross-sectional study was conducted from January to June 2018 in Adwa district. Structured, a pre-tested questionnaire was used to collect the demographic and risk factor related data. Serum sample, collected from each of the study subjects was tested for IgG and IgM anti T.godii specific antibodies using Enzyme-Linked Immunosorbent Assay. A bivariable and multivariable logistic regression model was applied to show association between the dependent and independent variables considering P < 0.05 and the 95% confidence interval.

Result

Out of the 360, 128 (35.6%) pregnant women were found to be positive for antibodies specific to T. gondii. Furthermore, 117 (32.5%) women were positive only for IgG, and 11 (3.1%) were positive both for IgM and IgG antibodies. Age, educational level, habit of hand washing after contact with garden soil or domestic animals, presence of domestic cat, history of contact with domestic dog and consumption of raw vegetables were significantly associated with T. gondii.

Conclusion

The seroprevalence of T. gondii among pregnant women in the study area is low compared to the other regions of Ethiopia, and within the range of the seroprevalences in the central and East Africa region. However, efforts should be done to create awareness on the potential risk factors of the parasite in the community.

Biological tests carried out on serum/plasma samples from donors of human body material for transplantation: Belgian experience and practical recommendations

This paper on the biological tests carried out on serum/plasma samples from donors of human body material (HBM) is the result of a project of the working Group of Superior Health Council of Belgium formed with experts in the field of HBM and infectious serology. Indeed, uncertainty about the interpretation of biological test results currently leads to the sometimes unjustified cancelling of planned donations or the rejection of harvested HBM, whilst more sophisticated diagnostic algorithms would still allow the use of organs or HBM that would otherwise have been rejected. NAT tests will not be discussed in this publication. In the first part some general aspects as the need for a formal agreement between the Tissue Establishment l and the laboratory responsible for the biological testing, but also some specifications regarding testing material, the choice of additional biological tests, and some general aspects concerning interpretation and reporting are discussed. In a second part, detailed information and recommendations concerning the interpretation are presented for each of the mandatory tests (human immunodeficiency virus, hepatitis B virus, hepatitis C virus and syphilis) is presented. A number of not mandatory, but regularly used optional serological tests (e.g. for the detection of antibodies to Toxoplasma gondii, Epstein-Barr virus, human T cell leukemia virus and cytomegalovirus) are also extensively discussed. Although the project was meant to provide clarification and recommendations concerning the Belgian legislation, the majority of recommendations are also applicable to testing of donors of tissues and cells in other (European) countries.

Evaluation of a New Immunochromatography Technology Test (LDBio Diagnostics) To Detect Toxoplasma IgG and IgM: Comparison with the Routine Architect Technique

A study comparing the ICT (immunochromatography technology) Toxoplasma IgG and IgM rapid diagnostic test (LDBio Diagnostics, France) with a fully automated system, Architect, was performed on samples from university hospitals of Marseille and Saint-Etienne. A total of 767 prospective sera and 235 selected sera were collected. The panels were selected to test various IgG and IgM parameters. The reference technique, Toxoplasma IgGII Western blot analysis (LDBio Diagnostics), was used to confirm the IgG results, and commercial kits Platelia Toxo IgM (Bio-Rad) and Toxo-ISAgA (bioMérieux) were used in Saint-Etienne and Marseille, respectively, as the IgM reference techniques. Sensitivity and specificity of the ICT and the Architect IgG assays were compared using a prospective panel. Sensitivity was 100% for the ICT test and 92.1% for Architect (cutoff at 1.6 IU/ml). The low-IgG-titer serum results confirmed that ICT sensitivity was superior to that of Architect. Specificity was 98.7% (ICT) and 99.8% (Architect IgG). The ICT test is also useful for detecting IgM without IgG and is both sensitive (100%) and specific (100%), as it can distinguish nonspecific IgM from specific Toxoplasma IgM. In comparison, IgM sensitivity and specificity on Architect are 96.1% and 99.6%, respectively (cutoff at 0.5 arbitrary units [AU]/ml). To conclude, this new test overcomes the limitations of automated screening techniques, which are not sensitive enough for IgG and lack specificity for IgM (rare IgM false-positive cases).

Establishing tools for early diagnosis of congenital toxoplasmosis: Flow cytometric IgG avidity assay as a confirmatory test for neonatal screening

The aim of this study was to evaluate the performance of conventional serology (Q-Preven™ and ELFAVIDAS™) and flow cytometry-based serologic tools for early serologic diagnosis of congenital toxoplasmosis. The study groups included prospectively confirmed cases of congenital toxoplasmosis (TOXO=88) and age-matching non-infected controls (NI=15).The results demonstrated that all samples tested positive/indeterminate for anti-T. gondii IgM screening at birth using air-dried whole blood samples. Serum samples collected at 30-45days after birth tested positive for ELFAVIDAS™ IgG in both groups. While all NI tested negative for ELFAVIDAS™ IgM and IgA, only 78% and 36% of TOXO tested positive for IgM and IgA, respectively. Flow cytometry-based anti-T. gondii IgM, IgA and IgG reactivity displayed moderate performance with low sensitivity (47.6%, 72.6% and 75.0%, respectively). Regardless the remarkable specificity of IgG1, IgG2 and IgG3 subclasses for early diagnosis, weak or moderate specificity was observed (Se=73.9%, 60.2% and 83.0%, respectively). The analysis of IgG avidity indices (AI) demonstrated the highest performance among the flow cytometry-based methods (Se=96.6%; Sp=93.3%), underscoring the low avidity index (AI<60%) within TOXO (97.0%) in contrast with the high avidity index (AI>60%) in NI (93%). Analysis of anti-T. gondii IgG and IgG3 reactivity for mother:infant paired samples may represent a relevant complementary tests for early diagnosis. In conclusion, a feasible high-standard algorithm (Accuracy=97.1%) was proposed consisting of Q-Preven™ IgM screening at birth, followed by ELFAVIDAS™ IgM and flow cytometric IgG avidity analysis at 30-45days after birth as a high performance tool for early serological diagnosis of congenital toxoplasmosis.

P35 and P22 Toxoplasma gondii antigens abbreviate regions to diagnose acquired toxoplasmosis during pregnancy: toward single-sample assays

BACKGROUND

P35 and P22 Toxoplasma gondii proteins are recognized by specific IgG at the early infection stage, making them ideal for acute toxoplasmosis pregnancy control. Both proteins have been studied to discriminate between acute and chronic toxoplasmosis. However, results were hardly comparable because different protein obtainment procedures led to different antigens, the reference panels used were not optimally typified, and avidity tests were either not performed or narrowly examined.

METHODS

We bioinformatically predicted P35 and P22 regions with the highest density of epitopes, and expressed them in pET32/BL21DE3 alternative expression system, obtaining the soluble proteins rP35a and rP22a. We assessed their diagnostic performance using pregnant woman serum samples typified as: not infected, NI (IgG-, IgM-), typical-chronic, TC (IgM-, IgG+), presumably acute, A (IgG+, IgM+, low-avidity IgG), and recently chronic, RC (IgG+, IgM+, high-avidity IgG).

RESULTS

rP35a performed better than rP22a to differentiate A from RC, the areas under the curve (AUC) being 0.911 and 0.818, respectively. They, however, performed similarly to differentiate A from TC+RC (AUC: 0.915 and 0.907, respectively). rP35a and rP22a evaluation by avidity ELISA to discriminate A from RC rendered AUC values of 0.974 and 0.921, respectively. The indirect ELISA and avidity ELISA results analyzed in tandem were consistent with those obtained using commercial kits.

CONCLUSIONS

rP35a and rP22a features suggest that, with complementary use, they could replace parasite lysate for toxoplasmosis infection screening and for acute toxoplasmosis diagnosis. Our proposal should be validated by a longitudinal study and may lead to a reliable toxoplasmosis pregnancy control, performing tests in only one serum sample.

DETECTION OF HUMAN ANTI-ZIKA VIRUS IgG BY ELISA USING AN ANTIGEN FROM in vitro INFECTED VERO CELLS: PRELIMINARY RESULTS

Zika virus (ZKV) infection is a huge public health problem in Brazil because of the increased incidence of microcephaly in neonates from infected mothers. Detection of specific IgG antibodies in maternal serum samples constitutes an important approach for diagnosing ZKV infection and evaluating its relationship with neonatal microcephaly. However, as there is no serological test produced in Brazil to detect IgM and IgG antibodies against ZKV, we sought to examine specific IgG in serum samples from patients or suspected mothers to detect previous infection and to test for specificity with regard to flaviviral infections occurring in the same area. Brazilian Zika virus native antigens were obtained from infected Vero cell layers or free virions in the culture medium and then used in ELISA. We tested sera from eight ZKV RNA-diagnosed infected patients (ZKVR), seven neonates with microcephaly and their mothers after delivery (MM), 140 dengue virus IgM-positive (DM) and IgG (DG)-positive patients, and 100 yellow fever (YF)-vaccinated patients. According to the ELISA, ZKVR samples were mostly positive (7/8), and all the MM serum samples were positive for ZKV IgG (7/7). In contrast, cross-reactions for dengue or yellow fever-vaccinated patients were observed, including DM (48/95), DG (10/45) or YF (3/100) serum samples; however, these cross-reactions exhibited low antigen avidity so that 6 M urea largely removed this cross-reactivity, with only a few cross-reacting samples remaining (8/140). ELISA based on extracted virions was much more specific, with all ZKVR (8/8) and MM sera being positive for ZKV IgG (7/7) and only borderline cross-reactivity found for DM (6/95), DG (3/45) or YF (4/100)-vaccinated serum samples. This technique (ELISA) can identify specific IgG in ZKV-infected patients and may be helpful in diagnosing congenital infetions after maternal RNA virus clearance or in epidemiological studies.

Detection of Natural Toxoplasma gondii Infection in Chicken in Thika Region of Kenya Using Nested Polymerase Chain Reaction

The detection of Toxoplasma gondii in free-range chickens is a good indicator of possible risk to human beings. The aim of this study was to investigate the occurrence of T. gondii in free-range chicken using polymerase chain reaction (PCR). Brain samples from 105 free-range chickens from three administrative areas in Thika region, Kenya, were collected, DNA-extracted, and analyzed using PCR to detect presence of T. gondii. The overall prevalence of T. gondii in all the three areas was 79.0% (95% CI: 70.0–86.4%) and the prevalence across the three areas was not significantly different (P = 0.5088; χ² = 1.354). Female chickens had higher (79.4%) prevalence than males (78.6%), although the difference was not significant (P = 0.922, χ² = 0.01). However, chickens that were more than 2 years old had significantly (P = 0.003; χ² = 11.87) higher prevalence compared to younger ones. The study indicates that there was a high occurrence of T. gondii infection in free-range chickens from Thika region and that the infection rate is age dependent. Further studies should be carried out to determine the possible role of roaming chickens in the epidemiology of the disease among humans in the area.

Evaluation of the Western blotting method for the diagnosis of congenital toxoplasmosis

OBJECTIVE

To evaluate the Western blotting method for the detection of IgG anti-Toxoplasma gondii (T. gondii) (IgG-WB) in the serum of children with suspected congenital toxoplasmosis.

METHODS

We accompanied 47 mothers with acquired toxoplasmosis in pregnancy and their children, between June of 2011 and June of 2014. The IgG-WB was done in house and the test was considered positive if the child had antibodies that recognized at least one band on IgG blots different from the mother's or with greater intensity than the corresponding maternal band, during the first three months of life.

RESULTS

15 children (15.1%) met the criteria for congenital toxoplasmosis and 32 (32.3%) had the diagnosis excluded. The symptoms were observed in 12 (80.0%) children and the most frequent were cerebral calcification in 9 (60.0%), chorioretinitis in 8 (53.3%), and hydrocephalus in 4 (26.6%). IgM antibodies anti-T. gondii detected by chemiluminescence (CL) were found in 6 (40.0%) children and the polymerase chain reaction (PCR) for detection of T. gondii DNA was positive in 5 of 7 performed (71.4%). The sensitivity of IgG-WB was of 60.0% [95% confidence interval (CI) 32.3-83.7%] and specificity 43.7% (95% CI 26.7-62.3%). The sensitivity of IgG-WB increased to 76.0 and 89.1% when associated to the research of IgM anti-T. gondii or PCR, respectively.

CONCLUSIONS

The IgG-WB showed greater sensitivity than the detection of IgM anti-T. gondii; therefore, it can be used for the diagnosis of congenital toxoplasmosis in association with other congenital infection markers.

Help in the Choice of Automated or Semiautomated Immunoassays for Serological Diagnosis of Toxoplasmosis: Evaluation of Nine Immunoassays by the French National Reference Center for Toxoplasmosis

Toxoplasmosis, a benign infection, is asymptomatic or paucisymptomatic in over 80% of cases, except in immunocompetent patients suffering from ocular toxoplasmosis or in immunocompromised patients with opportunistic or congenital toxoplasmosis. Diagnosis is based mainly on serology testing. Thus, we compared the performance of the nine most commonly used commercial automated or semiautomated immunoassays for IgG and IgM Toxoplasma gondii antibody detection, that is, the Advia Centaur, Architect, AxSYM, Elecsys, Enzygnost, Liaison, Platelia, VIDAS, and VIDIA assays. The assays were conducted on four panels of serum samples derived during routine testing from patients with an interfering disease and who exhibited a low IgG antibody level in one of two clinical settings, namely, acute or chronic toxoplasmosis. As a result, IgG sensitivities ranged from 97.1% to 100%, and IgG specificities ranged from 99.5% to 100%. For IgG quantification, strong differences in IgG titers (expressed in IU/ml) were noted depending on the assay used. IgM sensitivities ranged from 65% to 97.9%, and IgM specificities ranged from 92.6% to 100%. For defining the best serological strategies to be implemented, it appears crucial to compare the diagnostic performance of the different tests with respect to their specificity and sensitivity in detecting the presence of IgG and IgM antibodies.

Evaluation of Anti-Toxoplasma gondii Antibodies in Hemodialysis Patients with Chronic Kidney Disease in Sari, Iran

Background

Toxoplasma gondii has worldwide distribution and is one of the most prevalent infectious agents in humans.

Objectives

The aim of this study was to determine the prevalence of anti-Toxoplasma gondii antibodies in hemodialysis patients with chronic kidney disease (CKD) in the hemodialysis unit of Fatemeh Zahra hospital at the Mazandaran University of Medical Sciences in Sari, Iran.

Methods

Seventy-three patients with CKD and 145 healthy volunteers were assessed for anti-Toxoplasma gondii (IgG, IgM, and IgA) antibodies using a conventional ELISA technique.

Results

The anti-Toxoplasma gondii IgG antibody was detected in 80.8% of the cases in the patient group, while 31.5% of the cases in the CKD patient group and 31.8% in the control group were found to be positive for the anti-Toxoplasma gondii IgA antibody. All the patients in the CKD group were negative for the anti-Toxoplasma gondii IgM antibody, although 2.76% of the healthy volunteers were found to be positive. The present study suggests that there was no significant difference between the hemodialysis patient group and the healthy volunteers.

Conclusions

The epidemiological data collected in this study could serve as a reference for future studies and may be useful in developing preventive and educational strategies, and consequently reducing healthcare expenditure.

Label-free proteomic analysis of placental proteins during Toxoplasma gondii infection

Toxoplasma gondii is a ubiquitous, obligate intracellular parasite capable of crossing the placental barrier and causing spontaneous abortion, preterm labor, or significant disease in the surviving neonate. To better understand molecular mechanisms underlying abnormal pregnancy outcomes caused by T. gondii, placental proteins extracted from T. gondii-infected and -uninfected mice were comparatively analyzed using label-free liquid chromatography-tandem mass spectrometry. Significant difference was observed in the expression of 58 out of 792 proteins in infected placentas (p<0.05) compared with that in uninfected placentas. Quantitative real-time polymerase chain reaction, western blotting, and immunohistochemical staining were used to validate the results of the proteomic analysis. Some placental proteins differentially expressed in infected and uninfected mice were found to be associated with several different biological processes of pregnancy, particularly with trophoblast invasion and placental development. The results provide possible novel insights into the molecular mechanisms for abnormal pregnancy outcomes associated with T. gondii infection.

SIGNIFICANCE

In order to further explore the mechanisms of abnormal pregnant outcomes caused by T. gondii infection, we first applied label-free proteomic technology to analyze the differentially expressed host placental proteins with T. gondii infection. The results showed that some differential proteins are associated with trophoblast invasion and placenta development. The findings provide a systemic view of the altered placental proteins and help to declare the molecular mechanisms of abnormal pregnancy outcomes caused by T. gondii infection.

Congenital toxoplasmosis: Clinical features, outcomes, treatment, and prevention

Toxoplasmosis is caused by a coccidian parasite, Toxoplasma gondii. The parasite is highly prevalent both in humans and in warm-blooded animals. Cat family animals are definitive host, and these animals excrete the infective oocysts in their feces. Humans, though not definitive host, get infection by consuming water or food contaminated with cat feces. Rarely, infection can also take place through transfusing the infected blood, through transplantation of infected organs, or transplacentally from infected mother to fetus. Transplacental infection can cause congenital infection with varied degree of clinical manifestations, which depend on the age of fetus when infection took place. Diagnosis of congenital toxoplasmosis is difficult to establish until it is suspected and laboratory investigations are carried out. In more than 75% of cases, acute infection is missed due to very mild or unnoticeable clinical symptoms and signs. In India, a prevalence rate of 22.4% (8.8-37.3%) has been reported with an overall IgM positivity of 1.43%. It is estimated that approximately between 56,737 and 176,882 children per year are born in India with a possible risk of congenital toxoplasmosis. The diagnosis of congenital toxoplasmosis can be made by serological methods which are most commonly used. The other methods are parasite isolation by culture and molecular methods. Toxoplasmosis is treatable and transplacental transmission can be prevented by spiramycin, which concentrates in the placenta. However, if infection has done any damage to the fetus or the parasite has passed the placenta, spiramycin cannot reverse the damage. Prevention remains the best remedy.

Relevance of and New Developments in Serology for Toxoplasmosis

Toxoplasmosis is a widespread parasitic disease caused by the intracellular parasite Toxoplasma gondii with a wide spectrum of clinical outcomes. The biological diagnosis of toxoplasmosis is often difficult and of paramount importance because clinical features are not sufficient to discriminate between toxoplasmosis and other illnesses. Serological tests are the most widely used biological tools for the diagnosis of toxoplasmosis worldwide. This review focuses on the crucial role of serology in providing answers to the most important questions related to the epidemiology and diagnosis of toxoplasmosis in human pathology. Notwithstanding their undeniable importance, serological tools need to be continuously improved and the interpretation of the ensuing results remains complex in many circumstances.

HLA-DQA1/B1 alleles as putative susceptibility markers in congenital toxoplasmosis

Host and parasite genotypes are among the factors associated with congenital toxoplasmosis pathogenesis. As HLA class II molecules play a key role in the immune system regulation, the aim of this study was to investigate whether HLA-DQA1/B1 alleles are associated with susceptibility or protection to congenital toxoplasmosis. One hundred and twenty-two fetuses with and 103 without toxoplasmosis were studied. The two study groups were comparable according to a number of socio-demographic and genetic variables. HLA alleles were typed by PCR-SSP. In the HLA-DQA1 region, the allele frequencies showed that *01:03 and *03:02 alleles could confer susceptibility (OR= 3.06, p = 0.0002 and OR= 9.60, p= 0.0001, respectively) as they were more frequent among infected fetuses. Regarding the HLA-DQB1 region, the *05:04 allele could confer susceptibility (OR = 6.95, p < 0.0001). Of the 122 infected fetuses, 10 presented susceptibility haplotypes contrasting with only one in the non-infected group. This difference was not statistically significant after correction for multiple comparison (OR = 9.37, p=0.011). In the casuistic, there were two severely damaged fetuses with high parasite loads determined in amniotic fluid samples and HLA-DQA1 susceptibility alleles. In the present study, a discriminatory potential of HLA-DQA1/B1 alleles to identify susceptibility to congenital toxoplasmosis and the most severe cases has been shown.

Assessment of the IgA immunosorbent agglutination assay for the diagnosis of congenital toxoplasmosis on a series of 145 toxoplasmic seroconversions

A retrospective analysis of 145 medical records from our teaching hospital laboratory showed an overall specificity of greater than 97% for the IgA immunosorbent agglutination assay (ISAGA A) performed on the sera of babies to diagnose congenital toxoplasmosis (CT). These actualized data emphasize the ability of this test to confirm a diagnosis of congenital toxoplasmosis.