Strain hypothesis of Toxoplasma gondii infection on the outcome of human diseases

Evaluating the Risk Landscape of Hawaiian Monk Seal Exposure to Toxoplasma gondii

Toxoplasmosis is a disease of primary concern for Hawaiian monk seals (Neomonachus schauinslandi), due to its apparently acute lethality and especially heavy impacts on breeding female seals. The disease-causing parasite, Toxoplasma gondii, depends on cats to complete its life cycle; thus, in order to understand how this pathogen infects marine mammals, it is essential to understand aspects of the terrestrial ecosystem and land-to-sea transport. In this study, we constructed a three-tiered model to assess risk of Hawaiian monk seal exposure to T. gondii oocysts: (1) oocyst contamination as a function of cat population characteristics; (2) land-to-sea transport of oocysts as a function of island hydrology, and (3) seal exposure as a function of habitat and space use. We were able to generate risk maps highlighting watersheds contributing the most to oocyst contamination of Hawaiian monk seal habitat. Further, the model showed that free-roaming cats most associated with humans (pets or strays often supplementally fed by people) were able to achieve high densities leading to high levels of oocyst contamination and elevated risk of T. gondii exposure.

Anti-inflammatory and immunomodulatory effects of mesenchymal stem cell therapy on parasitic drug resistance

INTRODUCTION

The emergence of antiparasitic drug resistance poses a concerning threat to animals and humans. Mesenchymal Stem Cells (MSCs) have been widely used to treat infections in humans, pets, and livestock. Although this is an emerging field of study, the current review outlines possible mechanisms and examines potential synergism in combination therapies and the possible harmful effects of such an approach.

AREAS COVERED

The present study delved into the latest pre-clinical research on utilizing MSCs to treat parasitic infections. As per investigations, the introduction of MSCs to patients grappling with parasitic diseases like schistosomiasis, malaria, cystic echinococcosis, toxoplasmosis, leishmaniasis, and trypanosomiasis has shown a reduction in parasite prevalence. This intervention also alters the levels of both pro- and anti-inflammatory cytokines. Furthermore, the combined administration of MSCs and antiparasitic drugs has demonstrated enhanced efficacy in combating parasites and modulating the immune response.

EXPERT OPINION

Mesenchymal stem cells are a potential solution for addressing parasitic drug resistance. This is mainly because of their remarkable immunomodulatory abilities, which can potentially help combat parasites' resistance to drugs.

Toxoplasma gondii infection and testosterone alteration: A systematic review and meta-analyses

BACKGROUND

Toxoplasma gondii (T. gondii) is a worldwide distributed protozoan parasite which has infected a wide range of warm-blooded animals and humans. The most common form of T. gondii infection is asymptomatic (latent); nevertheless, latent toxoplasmosis can induce various alterations of sex hormones, especially testosterone, in infected humans and animals. On the other hand, testosterone is involved in behavioral traits and reproductive functions in both sexes. Hence, the purpose of this systematic review is to summarize the available evidence regarding the association between T. gondii infection and testosterone alteration.

METHODS

In the setting of a systematic review, an electronic search (any date to 10 January 2023) without language restrictions was performed using Science Direct, Web of Science, PubMed, Scopus, and Google Scholar. The PRISMA guidelines were followed. Following the initial search, a total of 12,306 titles and abstracts were screened initially; 12,281 were excluded due to the lack of eligibility criteria or duplication. Finally, 24 articles met the included criteria. A mean±standard deviation (SD) was calculated to assess the difference of testosterone between T. gondii positive and T. gondii negative humans. The possibility of publication bias was assessed using Egger's regression. P-value < 0.05 was considered statistically significant.

RESULTS

This systematic review identified 24 articles (18 studies in humans and six studies in animals). Most human studies (13 out of 19) reported an increased level of testosterone following latent toxoplasmosis in males, while three studies reported decreased levels and two studies reported an insignificant change. Eleven articles (seven datasets in males and seven datasets in females) were eligible to be included in the data synthesis. Based on the random-effects model, the pooled mean± SD of testosterone in T. gondii positive than T. gondii negative was increased by 0.73 and 0.55 units in males and females, respectively. The Egger's regression did not detect a statistically significant publication bias in males and females (p = value = 0.95 and 0.71), respectively. Three studies in male animals (rats, mice, and spotted hyenas) and two studies in female animals (mice and spotted hyenas) reported a decline in testosterone in infected compared with non-infected animals. While, one study in female rats reported no significant changes of testosterone in infected than non-infected animals. Moreover, two studies in male rats reported an increased level of testosterone in infected than non-infected animals.

CONCLUSIONS

This study provides new insights about the association between T. gondii infection and testosterone alteration and identifies relevant data gaps that can inform and encourage further studies. The consequence of increased testosterone levels following T. gondii infection could partly be associated with increased sexual behavior and sexual transmission of the parasite. On the other hand, declining testosterone levels following T. gondii infection may be associated with male reproductive impairments, which were observed in T. gondii-infected humans and animals. Furthermore, these findings suggest the great need for more epidemiological and experimental investigations in depth to understand the relationship between T. gondii infection and testosterone alteration alongside with future consequences of testosterone alteration.

Toxoplasma gondii seropositivity and cognitive functioning in older adults: an analysis of cross-sectional data of the National Health and Nutrition Examination Survey 2011-2014

OBJECTIVES

This study sought to examine the relationship between Toxoplasma gondii seropositivity and cognitive function in older adults.

DESIGN

An observational cross-sectional study.

SETTING

The National Health and Nutrition Examination Survey (NHANES) study took place at participants' homes and mobile examination centres.

PARTICIPANTS

A total of 2956 older adults aged 60 and above from the NHANES from 2011 to 2014 were included in the study. Exposure of interest: participants had serum Toxoplasma gondii antibody analysed in the laboratory. A value>33 IU/mL was categorised as seropositive for Toxoplasma gondii infection; <27 IU/mL was categorised as seronegative for Toxoplasma gondii infection.

PRIMARY AND SECONDARY OUTCOME MEASURES

Cognitive tests included the Consortium to Establish a Registry for Alzheimer's Disease Word Learning subtest (CERAD-WL) for immediate and delayed memory, the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test (DSST).

RESULTS

About half of the 2956 participants (mean age 70.0) were female (51.0%), non-Hispanic White (48.3%), and completed some college or above (48.3%). A total of 703 participants were positive for Toxoplasma gondii infection (23.8%). Adjusted linear regression showed that compared with participants with negative Toxoplasma gondii infection, those with positive Toxoplasma gondii infection had lower CERAD-WL immediate memory (beta (β) -0.16, 95% CI -0.25 to -0.07), CERAD-WL delayed memory (β -0.15, 95% CI -0.24 to -0.06), AFT (β -0.15, 95% CI -0.24 to -0.06), DSST (β -0.34, 95% CI -0.43 to -0.26), and global cognition (β -0.24, 95% CI -0.32 to -0.16) z-scores after controlling for the covariates.

CONCLUSIONS

Toxoplasma gondii seropositivity is associated with worse immediate and delayed verbal learning, language proficiency, executive functioning, processing speed, sustained attention, working memory, as well as global cognition in older adults. Public health measures aiming at preventing Toxoplasma gondii infection may help preserve cognitive functioning in older adults.

Molecular Detection of Toxoplasma gondii Oocytes in Soil Samples from Guilan Province, Northern Iran

Background

Soil is an appropriate substrate for the storage and transmission of oocytes of Toxoplasma gondii. Ingestion of soil contaminated with T. gondii oocysts is a major transmission route of human and animal toxoplasmosis. The present study was carried out to investigate soil contamination with T. gondii oocysts in urban and rural areas of Guilan Province, northern Iran.

Methods

Overall, 208 soil samples were collected from 16 cities and villages in Guilan Province, northern Iran from Oct 2020 to Nov 2021. Soil samples were investigated using modified sucrose flotation technique. Real-time polymerase chain reaction was used to detect presence of T. gondii DNAs in the samples. Positive samples were further analyzed using nested polymerase chain reaction for GRA6 gene. Moreover, six selected positive samples were used for amplifying and sequencing of the GRA6 gene.

Results

Overall, 31 samples were positive for T. gondii with frequency of 14.9% and ranging from 10.9% in rural areas to 16.3% in urban areas. Statistical analysis showed significant differences between the seasons (P=0.003). The phylogenetic analysis illustrated that our six sequences were similar and closely related to Type I strain of T. gondii.

Conclusion

Results showed relatively high levels (14.9%) of T. gondii oocytes in soil samples of Guilan Province, northern Iran, which provided essential data for the effective prevention and control of toxoplasmosis in the region.

Diabetic Retinopathy during pregnancy in Hispanic women with latent Toxoplasma gondii infection

BACKGROUND

Retinal photography was performed in pregnancy and postpartum in pregnant Hispanic women with latent Toxoplasma gondii (TG) infection in order to screen for characteristic retinal lesions or the particular scars found in people with active T. gondii infection. A comparison group of TG negative women was included in the study but they did not have retinal photography.

OBJECTIVE

The goal of the parent study was to assess for adverse pregnancy events and evidence for parasite reactivation in TG positive (TG + ) women, through examination of the eyes for characteristic lesions. Retinal photography, usually at prenatal visits 2 (17 +/- 3.35 weeks) and 3 (26.3+/-1.75) weeks, was done on TG + women. Fifty-six of these women also (43 %) had retinal photography at the postpartum visit. Health and demographic data were obtained at the first prenatal visit for all women.

STUDY DESIGN

From the 690 recruited at the first prenatal visit, 128 TG- women and 158 TG + women were enrolled in a prospective study through pregnancy and the postpartum. All TG- women (n = 532) provided data at the first prenatal visit and throughout their pregnancy and birth through the EHR. This allowed comparison of health and outcome data for the TG + compared to a larger number of TG- Hispanic pregnant women.

RESULTS

While there was no evidence of ocular toxoplasmosis during pregnancy, there was a surprisingly large number (42 %) of TG + women with diabetic retinopathy (DR). We also observed that TG + women had a 20 % incidence of gestational diabetes mellitus (GDM) compared to 11.3 % in the TG- women (p = 0.01). At postpartum (mean 5.6 weeks), 23 of 30 women with pregnancy DR showed no DR in the postpartum.

CONCLUSIONS

No characteristic T. gondii lesions were discovered. Retinal photography serendipitously revealed DR in these T. gondii positive women. It was also found that latent TG infection was associated with increased incidence of GDM. Hispanic pregnant women's increased risk for latent TG infection, GDM and DR are underappreciated. Retinal photography may need to be considered an innovative approach to screening.

First detection of Toxoplasma gondii Africa 4 lineage in a population of carnivores from South Africa

Introduction

There have only been a few molecular studies conducted on the detection of T. gondii in tissues of carnivores in South Africa, with no data on the genetic diversity of this parasite. That is why the aim of this study was to detect and genotype T. gondii DNA in tissues of selected wild and domestic carnivores in South Africa.

Methods

Samples were collected from 80 animals of 20 species (mainly road-killed) in the four provinces of Limpopo (n=57), Mpumalanga (n=21), Gauteng (n=1) and Free State (n=1) during the period 2014-2018. Samples of brain (n=31), heart (n=4), liver (n=40), spleen (n=2) and lung (n=3) were used to detect T. gondii by real-time PCR targeting a 529 bp repeating fragment of T. gondii DNA. Samples that were positive in real-time PCR were genotyped using 15 microsatellite markers.

Results

T. gondii DNA was detected in 4 (5 %) samples: in the brain from a Black-backed Jackal (Canis mesomelas), in the liver from a African Wildcat (Felis silvestris lybica) and in the liver and heart of two Rusty-spotted Genets (Genetta maculata) respectively. The DNA sample from Black-backed Jackal was genotyped and characterized as belonging to the type Africa 4 lineage (equivalent to RFLP genotype ToxoDB#20), that is a widespread lineage in Africa.

Discussion

This is the first genetic characterization of T. gondii isolated from a wild carnivore on the African continent and the first report of T. gondii in Black-backed Jackal. The Africa 4 lineage was also confirmed in the region of Southern Africa for the first time.

Mineralization Reduces the Toxicity and Improves Stability and Protective Immune Response Induced by Toxoplasma gondii

Vaccination is an ideal strategy for the control and prevention of toxoplasmosis. However, the thermostability and effectiveness of vaccines limit their application. Here, calcium mineralization was used to fabricate Toxoplasma gondii tachyzoites as immunogenic core-shell particles with improved immune response and thermostability. In the current study, T. gondii RH particles coated with mineralized shells were fabricated by calcium mineralization. The mineralized shells could maintain the T. gondii tachyzoites structural integrity for at least 12 months and weaken the virulence. Immunization of mice with mineralized tachyzoites induced high levels of T. gondii-specific antibodies and cytokines. The immunized mice were protected with a 100% survival rate in acute and chronic infection, and brain cyst burdens were significantly reduced. This study reported for the first time the strategy of calcium mineralization on T. gondii and proved that mineralized tachyzoites could play an immune protective role, thus expanding the application of biomineralization in T. gondii vaccine delivery.

New Allele-Specific Oligonucleotide (ASO) amplifications for Toxoplasma gondii rop18 allele typing: Analysis of 86 human congenital infections in Brazil

This study aimed to detect and differentiate Toxoplasma gondii by the allele typing of its polymorphic rop18 gene. For this purpose, a novel genotyping system using allele-specific oligonucleotides (ASOs) was designed, consisting of three ASO pairs. The first and third pairs specifically amplify rop18 allele I and allele III, while the second pair amplify both allele I and II. Genomic DNA from 86 congenital infections was analyzed by ASO-PCRs, successfully typing 82 (95.35%) samples. The remaining 4 samples (4.65%) required sequencing and single nucleotide polymorphism (SNP) analysis of the amplification products. The distribution of samples according to rop18 alleles was: 39.5% of allele III, 38.4% of allele II, 19.8% of mixed rop18 alleles (I/III or II/III), and 2.3% of allele I. The six severely compromised infants exhibited the highest parasite load levels and were infected during the first and early second trimesters of pregnancy. Among these cases, two were associated with rop18 allele I parasites, two with mixed rop18 alleles (I/III), one with allele II, and one with allele III parasites. In conclusion, all severe cases of congenital toxoplasmosis were infected during early pregnancy, but they were not exclusively associated with rop18 allele I parasites, as observed in murine toxoplasmosis. Furthermore, nearly one-fifth of parasites were non-archetypal, exhibiting more than one rop18 allele, indicating a higher genetic diversity of Toxoplasma gondii in this South American sample. Overall, a robust T. gondii rop18 allele typing was developed and suggested that congenital toxoplasmosis in humans involves complex mechanisms beyond the parasite genotype.

Host-Derived Extracellular Vesicles in Blood and Tissue Human Protozoan Infections

Blood and tissue protozoan infections are responsible for an enormous burden in tropical and subtropical regions, even though they can also affect people living in high-income countries, mainly as a consequence of migration and travel. These pathologies are responsible for heavy socio-economic issues in endemic countries, where the lack of proper therapeutic interventions and effective vaccine strategies is still hampering their control. Moreover, the pathophysiological mechanisms associated with the establishment, progression and outcome of these infectious diseases are yet to be fully described. Among all the players, extracellular vesicles (EVs) have raised significant interest during the last decades due to their capacity to modulate inter-parasite and host-parasite interactions. In the present manuscript, we will review the state of the art of circulating host-derived EVs in clinical samples or in experimental models of human blood and tissue protozoan diseases (i.e., malaria, leishmaniasis, Chagas disease, human African trypanosomiasis and toxoplasmosis) to gain novel insights into the mechanisms of pathology underlying these conditions and to identify novel potential diagnostic markers.

Animal Models for Toxoplasma gondii Infection

Toxoplasma gondii is an obligate intracellular protozoan parasite that commonly infects mammals and birds throughout the world. This protocol describes murine models of acute T. gondii infection, toxoplasmic encephalitis and toxoplasma retinochoroiditis. T. gondii infection in severe combined immunodeficient (SCID) mice, deficient in T and B cells, has allowed for the study of T cell-independent mechanisms of defense against intracellular organisms, as described here. The uracil auxotroph strain cps1-1 and temperature-sensitive mutant strains of T. gondii induce protection against challenge with virulent strains of the parasite. They have allowed studies of immunization and adoptive-transfer experiments. A protocol is provided for infection with these mutant strains. The EGS strain of T. gondii has the unique feature of spontaneously forming tissue cysts in cell culture. Dual fluorescent reporter stains of this strain have allowed the study of tachyzoite to bradyzoite transitions in vitro and in vivo. A protocol for in vitro and in vivo growth of this strain and tissue cyst isolation is provided. Genetic manipulation of T. gondii and mice has led to the development of parasites that express fluorescent proteins as well as mice with fluorescently labeled leukocytes. This together with the use of T. gondii that express model antigens and transgenic mice that express the appropriate T cell receptor have facilitated the in vivo study of parasite host-interaction. In addition, parasites that express bioluminescent markers have made it possible to study the dynamics of infection in real time using bioluminescence imaging. Support protocols present methodology for evaluation of progression of infection and immune response to the parasite that includes these newer methodologies. In addition, support protocols address the maintenance of T. gondii tissue cysts and tachyzoites, as well as preparation of T. gondii lysate antigens. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Induction of acute T. gondii infection in mice Basic Protocol 2: Model of toxoplasmic encephalitis and toxoplasma retinochoroiditis in chronically infected mice Basic Protocol 3: Assessment of T. gondii invasion into neural tissue Basic Protocol 4: T. gondii infection in scid/scid (SCID) mice Basic Protocol 5: Infection with the uracil auxotroph strain CPS1-1 or the temperature-sensitive TS-4 strain of T. gondii Basic Protocol 6: In vivo and in vitro maintenance of the EGS strain of T. gondii Support Protocol 1: Assessment of progression of infection and immune response to T. gondii Support Protocol 2: Maintenance of a bank of T. gondii cysts of the ME49 strain Support Protocol 3: Maintenance of T. gondii tachyzoites using human foreskin fibroblasts Support Protocol 4: Maintenance of T. gondii tachyzoites in mice Support Protocol 5: Preparation of T. gondii lysate antigens Support Protocol 6: Isolation of T. gondii tissue cysts from brain.

Tryptophan metabolism and immune alterations in pregnant Hispanic women with chronic Toxoplasma gondii infection

PROBLEM

Pregnancy markedly modifies women's metabolism and immune functions. We hypothesized that pregnancy might alter the immune and metabolic responses to chronic Toxoplasma gondii infection in pregnancy.

METHOD OF STUDY

A population of 690 pregnant Hispanic women were screened for antibodies to T. gondii and 158 women were positive (23% positivity) with 83% showing high avidity indices. These seropositive women were followed through their pregnancies with four data collection time points and a postpartum collection at two clinics in Tampa, Florida. A T. gondii seronegative group (N = 128) was randomly selected to serve as a control group and measured along pregnancy in the same way. Serum levels of tryptophan, kynurenine, and their ratio, phenylalanine, tyrosine and their ratio, neopterin, and nitrite were measured through pregnancy and the postpartum. A plasma cytokine panel (IFN-γ, TNFα, IL-2, IL-10, IL-12, IL-6, IL-17) was analyzed in parallel.

RESULTS

The major findings suggest that indoleamine 2,3-dioxygenase (IDO-1) was less activated in T. gondii seropositive pregnant Hispanic women with chronic infection. Evidence for IDO-1 suppression was that tryptophan catabolism was less pronounced and there were lower levels of multiple inflammatory cytokines including IFN-γ, which is the major inducer of IDO-1, and higher nitrite concentration, a surrogate marker for nitric oxide, an inhibitor of IDO.

CONCLUSIONS

Latent T. gondii infection was associated with higher plasma tryptophan levels, and lower inflammatory cytokines across pregnancy, suggesting suppression of the IDO-1 enzyme, and possible T cell exhaustion during pregnancy.

Serotyping, a challenging approach for Toxoplasma gondii typing

Genotype analysis has revealed a high genetic diversity in strains of Toxoplasma gondii, isolated from a wide range of intermediate hosts and different geographic origins. Diversity is notably striking for parasites from wild hosts in South America, generally referred as non-archetypal genotypes. Those genotypes are implicated in the etiology of severe clinical disease, multivisceral toxoplasmosis, associated with high rate of mortality in immunocompetent individuals. Can we accept specific antibodies produced during T. gondii infection as biomarkers to identify infecting genotypes? Scientific evidence supports a positive response to this question; however, the genetic diversity of T. gondii genotypes organized into 16 haplogroups and collectively defined in 6 major clades, provides a reminder of the complexity and difficulty for the purpose. This review discusses serological approaches to genotyping T. gondii.

Curcumin ameliorates chronic Toxoplasma gondii infection-induced affective disorders through modulation of proinflammatory cytokines and oxidative stress

Objectives

Long-term infection with Toxoplasma gondii is associated with affective disorders (i.e., anxiety and depression) in adults. We aimed to explore the effects of curcumin (CR) on anxiety- and depressive-like behaviors in mice infected with T. gondii.

Materials and Methods

Animals were studied in five groups: Control, Model, Model + CR20, 40, and 80 (with IP injection of 20, 40, and 80 mg/kg CR). T. gondii infection was prolonged for four weeks. The animals were then treated with CR or vehicle for two weeks and evaluated by behavioral tests at the end of the study. Hippocampal levels of oxidative stress biomarkers (superoxide dismutase; SOD, glutathione; GSH, and malondialdehyde; MDA) and gene expression and protein levels of hippocampal proinflammatory mediators (interleukin-1β; IL-1β, IL-6, IL-18, and tumor necrosis factor- α; TNF-α) were determined.

Results

Behavioral tests confirmed that long-term infection with T. gondii led to anxiety- and depressive-like behaviors. Antidepressant effects of CR were linked to modulation of oxidative stress and cytokine network in the hippocampal region of infected mice. These results showed that CR reduced anxiety and depression symptoms via regulation of oxidative stress and proinflammatory cytokines in the hippocampus of T. gondii-infected mice.

Conclusion

Therefore, CR can be used as a potential antidepressant agent against T. gondii-induced affective disorders.

Coixol ameliorates Toxoplasma gondii infection-induced lung injury by interfering with T. gondii HSP70/TLR4/NF-κB signaling pathway

Toxoplasma gondii (T. gondii) is an obligate intracellular protozoan parasite that causes pulmonary toxoplasmosis, although its pathogenesis is incompletely understood. There is no cure for toxoplasmosis. Coixol, a plant polyphenol extracted from coix seeds, has a variety of biological activities. However, the effects of coixol on T. gondii infection have not been clarified. In this study, we infected a mouse macrophage cell line (RAW 264.7) and BALB/c mice with the T. gondii RH strain to establish infection models in vitro and in vivo, respectively, to explore protective effects and potential mechanisms of coixol on lung injury caused by T. gondii infection. Anti-T. gondii effects and underlying anti-inflammatory mechanisms of coixol were investigated by real-time quantitative PCR, molecular docking, localized surface plasmon resonance, co-immunoprecipitation, enzyme-linked immunosorbent assay, western blotting, and immunofluorescence microscopy. The results show that coixol inhibits T. gondii loads and T. gondii-derived heat shock protein 70 (T.g.HSP70) expression. Moreover, coixol reduced inflammatory cell recruitment and infiltration, and ameliorated pathological lung injury induced by T. gondii infection. Coixol can directly bind T.g.HSP70 or Toll-like receptor 4 (TLR4) to disrupt their interaction. Coixol prevented overexpression of inducible nitric oxide synthase, tumor necrosis factor-α, and high mobility group box 1 by inhibiting activation of the TLR4/nuclear factor (NF)-κB signaling pathway, consistent with effects of the TLR4 inhibitor CLI-095. These results indicate that coixol improves T. gondii infection-induced lung injury by interfering with T.g.HSP70-mediated TLR4/NF-κB signaling. Altogether, these findings suggest that coixol is a promising effective lead compound for the treatment of toxoplasmosis.

Adverse pregnancy outcomes in Toxoplasma gondii seropositive Hispanic women

AIMS

Chronic Toxoplasma gondii infection is not thought to affect pregnancy or birth outcomes, but there are few prospective studies. The study aims were T. gondii immunoglobulin G measurement and relationship of chronic T. gondii infection with gestational age at birth and adverse pregnancy outcomes in 690 Hispanic women in Tampa, Florida.

METHODS

Hispanic women, born either in the United States or in Latin America or the Caribbean had a venous blood sample drawn to measure T. gondii IgG and T. gondii serotype at the first prenatal visit, along with collection of demographic and health-related measures. Seropositive and seronegative women were followed throughout their pregnancy. Gestational age, infant weights, and adverse pregnancy outcomes (miscarriages, preterm births) were compared in the two groups.

RESULTS

There were 740 women of self-reported Hispanic ethnicity screened and enrolled in Tampa, Florida, with 690 having birth data extracted from the electronic health record (538 T. gondii negative and 152 T. gondii seropositive). T. gondii seropositivity was 22.4% and the majority (83%) had high avidity titers, indicating chronic infection. Compared to T. gondii seronegative Hispanic women, seroseropositive women had more smaller for gestational age infants and higher prevalences of miscarriages and preterm birth.

CONCLUSION

This is one of the largest longitudinal cohort studies of women with chronic T. gondii infection followed through pregnancy. There was a higher percentages of adverse pregnancy outcomes in this group compared to T. gondii seronegative controls. The mechanism for this is unknown and warrants reexamination of the dogma that chronic T. gondii infection in pregnant women has no significant clinical consequences.

Overview of Apoptosis, Autophagy, and Inflammatory Processes in Toxoplasma gondii Infected Cells

Toxoplasma gondii (T. gondii) is an obligate intracellular parasite. During the parasitic invasion, T. gondii creates a parasitophorous vacuole, which enables the modulation of cell functions, allowing its replication and host infection. It has effective strategies to escape the immune response and reach privileged immune sites and remain inactive in a controlled environment in tissue cysts. This current review presents the factors that affect host cells and the parasite, as well as changes in the immune system during host cell infection. The secretory organelles of T. gondii (dense granules, micronemes, and rhoptries) are responsible for these processes. They are involved with proteins secreted by micronemes and rhoptries (MIC, AMA, and RONs) that mediate the recognition and entry into host cells. Effector proteins (ROP and GRA) that modify the STAT signal or GTPases in immune cells determine their toxicity. Interference byhost autonomous cells during parasitic infection, gene expression, and production of microbicidal molecules such as reactive oxygen species (ROS) and nitric oxide (NO), result in the regulation of cell death. The high level of complexity in host cell mechanisms prevents cell death in its various pathways. Many of these abilities play an important role in escaping host immune responses, particularly by manipulating the expression of genes involved in apoptosis, necrosis, autophagy, and inflammation. Here we present recent works that define the mechanisms by which T. gondii interacts with these processes in infected host cells.

Toxoplasma gondii SAG2, SAG3 and GRA6 alleles and single nucleotide polymorphism in congenital infections with known parasite load and clinical outcome

Amniotic fluid DNA samples were genotyped by multilocus-nested-PCR-RFLP, but only three of 11 markers amplified 113 of 122 (92.6%) samples, resulting in 12 untyped and 101 partial non-archetypal genotypes. The 101 typed samples were subdivided into four groups: G1 with 73 samples (5'and 3' SAG2 allele I + SAG3 allele III + GRA6 allele III), 53 had parasite load ≤ 102 parasites/mL (43 asymptomatic, 10 mild infections), 17 had load > 102 and ≤ 103 (one mild, 13 moderate and three severe), and three had load > 103 parasites/mL (three severe); G2 with 22 samples (5'and 3' SAG2 allele I + SAG3 allele III), all parasite load levels ≤ 102 parasites/mL (18 asymptomatic and four mild); G3 with five samples (5' and 3' SAG2 allele I + SAG3 allele II), parasite load ≤ 102 parasites/mL (three asymptomatic and two mild); G4 with one sample (5' and 3' SAG2 allele II + SAG3 allele II + GRA6 allele I), a parasite load < 102 parasites/mL in an asymptomatic infant. After DNA sequencing, restriction sites confirmed SAG2, SAG3 and GRA6 alleles in 98.7%, 100% and 100% of the cases, respectively, while single nucleotide polymorphisms confirmed 90% of 5'-SAG2 allele I; 98.7% of 3'-SAG2 allele I; 98% of SAG-3 allele III, but only 40% of GRA6 allele III results. For the moment, partial non-archetypal genotypes of parasites did not show any relationship with either parasite load in amniotic fluid samples or clinical outcome of infants at the age of 12 months.

TZD-Based Hybrid Molecules Act as Dual Anti-Mycobacterium tuberculosis and Anti-Toxoplasma gondii Agents

Two distinct intracellular pathogens, namely Mycobacterium tuberculosis (Mtb) and Toxoplasma gondii (Tg), cause major public health problems worldwide. In addition, serious and challenging health problems of co-infections of Tg with Mtb have been recorded, especially in developing countries. Due to this fact, as well as the frequent cases of resistance to the current drugs, novel anti-infectious therapeutics, especially those with dual (anti-Tg and anti-Mtb) modes of action, are needed. To address this issue, we explored the anti-Tg potential of thiazolidinedione-based (TZD-based) hybrid molecules with proven anti-Mtb potency. Several TZD hybrids with pyridine-4-carbohydrazone (PCH) or thiosemicarbazone (TSC) structural scaffolds were more effective and more selective than sulfadiazine (SDZ) and trimethoprim (TRI). Furthermore, all of these molecules were more selective than pyrimethamine (PYR). Further studies for the most potent TZD-TSC hybrids 7, 8 and 10 and TZD-PCH hybrid molecule 2 proved that these compounds are non-cytotoxic, non-genotoxic and non-hemolytic. Moreover, they could cross the blood-brain barrier (BBB), which is a critical factor linked with ideal anti-Tg drug development. Finally, since a possible link between Tg infection and the risk of glioblastoma has recently been reported, the cytotoxic potential of TZD hybrids against human glioblastoma cells was also evaluated. TZD-PCH hybrid molecule 2 was found to be the most effective, with an IC₅₀ of 19.36 ± 1.13 µg/mL against T98G cells.

Is the incidence of congenital toxoplasmosis declining?

Prenatal infection with the protozoan parasite Toxoplasma gondii can cause congenital toxoplasmosis (CT), an often fatal or lifelong-disabling condition. Several studies of human populations have reported temporal decreases in seroprevalence, suggesting declining CT incidence. However, the consistency of this trend among diverse populations remains unclear, as does its implication for prenatal screening programmes, the major intervention against CT. Using temporally resolved data on the seroprevalence of T. gondii in various countries, we discuss how the parasite's changing epidemiology may affect trends in CT incidence in varying and counterintuitive ways. We argue that parasite stage-specific serology could be helpful for understanding underlying causes of secular changes in seroprevalence. Furthermore, we highlight the importance of updating cost-effectiveness estimates of screening programmes, accounting for neuropsychiatric sequelae.

Identification and multilocus genotyping of Toxoplasma gondii isolates from congenital infection in north of Iran

Congenital toxoplasmosis can cause severe consequences in the fetus, such as spontaneous abortion which is affected by parasite strain. Also, recent studies revealed the high genetic diversity of Toxoplasma gondii. This study aims to investigate the serological status of T. gondii in pregnant women, multilocus genotyping in aborted fetuses' tissue, and archived formalin-fixed paraffin-embedded placenta. This study was performed on 100 pregnant women with spontaneous abortion and their aborted fetuses, and 250 of the archived placentae in Iran. The blood and tissue were examined for seroprevalence and genotype determination of T. gondii using ELISA and multilocus nested-PCR-RFLP, respectively. Anti-T. gondii IgG and IgM were detected in 68 samples (68%) and 1 (1%) out of 100 serums. Toxoplasma DNA was identified in 1 (1%) aborted fetuses' tissue and 32 (12.8%) placenta samples. Overall, ten positive DNA samples were successfully genotyped, and five genotypes were recognized (ToxoDB#1, #2, #10, #27, and #48). The obtained results indicated congenital toxoplasmosis is a severe risk in this region. As type I is highly pathogen and can lead to severe complications, the prevention of the infection should be considered in seronegative pregnant women.

Molecular detection and dense granule antigen 6 genotyping of feline Toxoplasma gondii in Phayao, Thailand

Background and Aim:

Globally, toxoplasmosis is an important zoonotic parasite infection of many warm-blooded animals (including humans). Toxoplasma gondii oocysts are widespread, and their contamination can be primarily attributed to the members of the Felidae family. This study aimed to estimate the prevalence and determine the dense granule antigen 6 (GRA6) genotype of T. gondii among domestic cats in the Phayao Province, Thailand.

Materials and Methods:

A total of 124 fecal samples were collected from owned cats in the Muang district, Phayao, Thailand, from January to December 2020. Fecal samples were tested for the presence of T. gondii DNA using targeted B1 gene polymerase chain reaction (PCR) amplification, and positive samples were subsequently analyzed for their T. gondii genotype through PCR-restriction fragment length polymorphism (RFLP) analysis and sequencing of the GRA6 gene.

Results:

Among the 124 samples, 46 (37.1%) were tested positive for T. gondii. Only 10 positive DNA samples were successfully amplified for the GRA6 marker. Subsequent PCR-RFLP and sequence analyses indicated that all T. gondii isolates from cats in Phayao belonged to GRA6 genotype I.

Conclusion:

Data revealed that toxoplasmosis is remarkably distributed among (studied) domestic cats in Phayao, Thailand. Moreover, the virulent GRA6 allele was found to be circulated among domestic cats in this area. However, no significant correlation was observed between infection rates and different risk factors, which indicated that pet cats of any age, gender, or breed have similar risks of being infected with T. gondii. Our results further suggested that infective oocysts of T. gondii are widely distributed and that environmental contamination with these oocysts will introduce more risks of disease transmission to humans and other animals.

Parallel Propagation of Toxoplasma gondii In Vivo, In Vitro and in Alternate Model: Towards Less Dependence on the Mice Model

Toxoplasma gondii is an obligate intracellular protozoan. In pregnant women, it can lead to severe birth defects or intrauterine death of the fetus. Most of what is currently know on cell biology of T. gondii comes from studies relying on the RH strain propagated in mice. According to the recommendations concerning the animal welfare, we assayed in vitro/in vivo procedures to replace, or at least reduce, the demanding animal model for strain propagation. We evaluated the genetic and phenotypic stability of the RH strain throughout its parallel continuous propagation in mice, in human foreskin fibroblasts (HFF) and in an alternate fashion of these two procedures. We also assessed the virulence impact on the RH strain after different periods of its long-term propagation strictly in cells. The RH strain completely lost its virulence after long-term passage in HFF. Nevertheless, we obtained a successful outcome with the alternate passaging of the parasite in HFF and in mice as this approach enabled T. gondii to maintain the evaluated phenotypic properties, mainly its virulence potential. Also, no genetic changes were observed in genes known to be highly polymorphic or involved in pathoadaptation. In conclusion, the alternate model seems to be a feasible method for T. gondii propagation and maintenance, strongly impacting the number of sacrificed mice.

Toxoplasmosis in Human and Animals Around the World. Diagnosis and Perspectives in the One Health Approach

Toxoplasmosis is a unique health disease that significantly affects the health of humans, domestic animals, wildlife and is present in ecosystems, including water, soil and food. Toxoplasma gondii is one of the best-adapted parasites in the word. This parasite is able to persist for long periods in its hosts, in different geographic regions of the word. This review summarizes the current literature of these themes, focusing on: (1) toxoplasmosis, a zoonotic infection; (2) One health approach and toxoplasmosis; (3) human toxoplasmosis; (4) animal toxoplasmosis; (5) toxoplasmosis diagnosis, as immunological, parasitological and molecular diagnosis; (6) T. gondii outbreaks caused by infected meat, milk and dairy products, as well as, vegetables and water consume; (7) studies in experimental models; (8) genetic characterization of T. gondii strains; (9) extracellular vesicles and miRNA; and (10) future perspectives on T. gondii and toxoplasmosis. The vast prevalence of toxoplasmosis in both humans and animals and the dispersion and resistence of T. gondii parasites in environment highlight the importance of the one health approach in diagnostic and control of the disease. Here the different aspects of the one health approach are presented and discussed.

The Core Human MicroRNAs Regulated by Toxoplasma gondii

BACKGROUND

Toxoplasma gondii (T. gondii) is an intracellular zoonotic protozoan parasite known to effectively modulate the host system for its survival. A large number of microRNAs (miRNAs) regulated by different strains of T. gondii in diverse types of host cells/tissues/organs have been reported across multiple studies.

OBJECTIVE

We aimed to decipher the complexity of T. gondii regulated spectrum of miRNAs to derive a set of core miRNAs central to different strains of T. gondii infection in diverse human cell lines.

METHODS

We first assembled miRNAs hat are regulated by T. gondii altered across the various assortment of infections and time points of T. gondii infection in multiple cell types. For these assembled datasets, we employed specific criteria to filter the core miRNAs regulated by T. gondii. Subsequently, accounting for the spectrum of miRNA-mRNA target combinations, we applied a novel confidence criterion to extract their core experimentally-validated mRNA targets in human cell systems.

RESULTS

This analysis resulted in the extraction of 74 core differentially regulated miRNAs and their 319 high-confidence mRNA targets. Based on these core miRNA-mRNA pairs, we derived the central biological processes perturbed by T. gondii in diverse human cell systems. Further, our analysis also resulted in the identification of novel autocrine/paracrine signalling factors that could be associated with host response modulated by T. gondii.

CONCLUSION

The current analysis derived a set of core miRNAs, their targets, and associated biological processes fine-tuned by T. gondii for its survival within the invaded cells.

The Association of Toxoplasma gondii IgG and Liver Injury in US Adults

BACKGROUND

Toxoplasma gondii (T. gondii) is a ubiquitous obligatory intracellular parasite which infects over 40 million Americans and causes toxoplasmosis. Inside the human body, T. gondii can damage tissues and invade vital organs.

METHODS

This study evaluated the association of T. gondii infection and liver disease using data from the National Health and Nutrition Examination Survey (NHANES) 2009-2010, with a sample size of 3371 participants (age 20-80 years). Toxoplasma infection was determined by the level of T. gondii IgG antibody in serum samples. Liver disease was assessed by liver injury biomarkers and the Fatty Liver Index (US-FLI). The evaluation of the association between T. gondii infection and liver disease included the calculation of the Mantel-Haenszel risk ratio (RRMH), Rho-Scott chi-square bivariate analyses, design-based t-tests, and linear and logistic regression models which were adjusted for demographic and anthropometric covariates.

RESULTS

Mean levels of aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were significantly more elevated in the T. gondii IgG-positive (IgG+) participants as compared to T. gondii-negative (IgG-) participants, p = 0.0435 and 0.0310, respectively. In linear regression analysis, exposure to T. gondii IgG+ had statistically significant positive associations with AST (p = 0.0211), alanine aminotransferase (ALT) (p = 0.0221), and gamma-glutamyl transferase (GGT) (p = 0.0258) after adjusting for BMI, age, gender, and race. T. gondii exposure was associated with an elevated relative risk of chronic liver disease (CLD) (RRMH = 1.26, 95% CI: 1.05-1.51). This association was more pronounced in certain occupations, such as construction, agriculture, forestry, and fishing, where Toxoplasma infection is more common (p = 0.0477). Moreover, Toxoplasma infection increased the odds of nonalcoholic fatty liver disease (NAFLD) (OR = 6.99, 95% CI = 1.85-26.32, p = 0.0237).

CONCLUSION

T. gondii IgG+ antibody was significantly associated with liver injury biomarkers (ALT, AST, GGT, and ALP) and an increased risk of CLD and NAFLD. Moreover, the association of Toxoplasma with CLD was more evident in specific occupations where the prevalence of Toxoplasma was high. The findings of this study provide insight into utilizing liver biomarkers and US-FLI to assess the health complications of Toxoplasma when imaging tests are not accessible.

Behavioral Changes Induced by Latent Toxoplasmosis Could Arise from CNS Inflammation and Neuropathogenesis

Chronic infection with Toxoplasma gondii, a neurotropic parasite, has been linked to multiple behavioral changes in rodents and humans. The pathogenic mechanisms underlying these correlations are not known. I discuss here from animal studies the distribution of tissue cysts, the constant immune surveillance, the critical role of cyst burden, and the time-dependent consequences, which I believe are crucial to explaining the behavioral changes. In line with the brain-wide distribution of tissue cysts and chronic neuroinflammation, infected mice displayed a broad range of behavioral phenotypes. Many studies suggest that behavioral changes in mice are directly associated with tissue cyst presence or cyst burden and the host immune response. Cyst burden may not exert direct effects; however, the mechanisms causing behavioral and neuropathological changes are potentially the consequence of cyst burden over time, such as the neuroinflammation required to control the reactivation of tissue cysts. The reduction of neuroinflammation has proven that neuropathogenesis and behavioral abnormalities can be reversed, at least partially, in infected mice. Overall, Toxoplasma-induced behavioral changes are likely to be an indirect consequence of the host immune response in a parasite burden-dependent manner.

Strain-specific pre-existing immunity: A key to understanding the role of chronic Toxoplasma infection in cognition and Alzheimer's diseases?

Toxoplasma exposure can elicit cellular and humoral immune responses. In the case of chronic Toxoplasma infection, these immune responses are long-lasting. Some studies suggest that pre-existing immunity from Toxoplasma infection can shape immune responses and resistance to other pathogens and brain insults later in life. Much evidence has been generated suggesting Toxoplasma infection may contribute to cognitive impairment in the elderly. However, there have also been studies that disagree with the conclusion. Toxoplasma has many strain types, with virulence being the most notable difference. There is also considerable variation in the outcomes following Toxoplasma exposure ranging from resolved to persistent infection. Therefore, the brain microenvironment, particularly cellular constituents, differs based on the infecting strain (virulent versus hypovirulent) and infection stage (resolved versus persistent). Such difference might play a critical role in determining the outcome of the host on subsequent challengings to the brain. The ability of Toxoplasma strains to set up distinct stages for neurodegenerative pathology through varying degrees of virulence provides unique experimental tools for characterizing these pathways.

Toxoplasma gondii infection as a risk factor for osteoporosis: a case-control study

Background

More than one-third of the total world population is infected by Toxoplasma gondii (T. gondii). T. gondii has been linked to various diseases, such as cancer, mental disorders, type 2 diabetes mellitus (T2DM), etc. However, the effects of T. gondii infection on the risk of osteoporosis are unclear. Our study aimed to uncover evidence to determine whether patients exposed to T. gondii have an increased or decreased risk of osteoporosis in people with abnormal bone mineral density (BMD) by using case–control study.

Methods

A total of 729 patients, including 316 osteopenia and 413 osteoporosis patients of Han Chinese ancestry were selected in the study. Their blood samples were collected and the levels of specific IgG antibodies against T. gondii were measured using ELISA assay. We obtained some information about the patients from the medical record that included demographic indexes and clinical data. A logistic regression analysis was used to evaluate the effects of T. gondii infection on femur osteoporosis, lumbar osteoporosis and compound osteoporosis. Potential interaction was analyzed using multifactor dimensionality reduction software 1.0.0 (MDR 1.0.0).

Results

113 positive patients with T. gondii infections have been detected, including 80 cases of osteoporosis and 33 cases of osteopenia, the infection rates of T. gondii were 19.37% (80/413) and 10.44% (33/316), respectively. The patients with T.gondii infections were at a 2.60 times higher risk of suffering from compound osteoporosis than those without T. gondii infections (OR = 2.60, 95% CI 1.54–4.39, P < 0.001), but not associated with femur osteoporosis (OR = 1.01, 95% CI 0.43–2.34, P = 0.989) and lumbar osteoporosis (OR = 0.84, 95% CI 0.34–2.07, P = 0.705) after adjusting for the covariates. Moreover, a significantly higher risk of compound osteoporosis in the individuals with all two factors (T. gondii infection, Female) was observed compared with reference group (without T. gondii infection, male) under the interaction model (OR = 11.44, 95%CI = 5.44–24.05, P < 0.001). And the individuals with all two factors (T. gondii infection, over 70 years) exhibited a 8.14-fold higher possibility of developing compound osteoporosis compared with reference group (without T. gondii infection, under 70 years) (OR = 8.14, 95% CI 3.91–16.93, P < 0.001). We further stratified by age and sex, and found that women with T. gondii infection was more likely to develop compound osteoporosis than those without infection(OR = 3.12, 95% CI  1.67–5.81, P < 0.001), but we not found the association between T. gondii infection and compound osteoporosis in males (OR = 1.36, 95% CI 0.37–4.94, P = 0.645).

Conclusions

T. gondii infection is a risk factor for osteoporosis, especially compound osteoporosis. Meanwhile, it is very necessary for patients with osteoporosis to further diagnose and treat T. gondii infection, especially women.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05257-z.

Neuroimmunology of Common Parasitic Infections in Africa

Parasitic infections of the central nervous system are an important cause of morbidity and mortality in Africa. The neurological, cognitive, and psychiatric sequelae of these infections result from a complex interplay between the parasites and the host inflammatory response. Here we review some of the diseases caused by selected parasitic organisms known to infect the nervous system including Plasmodium falciparum, Toxoplasma gondii, Trypanosoma brucei spp., and Taenia solium species. For each parasite, we describe the geographical distribution, prevalence, life cycle, and typical clinical symptoms of infection and pathogenesis. We pay particular attention to how the parasites infect the brain and the interaction between each organism and the host immune system. We describe how an understanding of these processes may guide optimal diagnostic and therapeutic strategies to treat these disorders. Finally, we highlight current gaps in our understanding of disease pathophysiology and call for increased interrogation of these often-neglected disorders of the nervous system.

Comparative Phosphoproteomic Analysis of Sporulated Oocysts and Tachyzoites of Toxoplasma gondii Reveals Stage-Specific Patterns

Toxoplasma gondii is an obligate intracellular protozoan of severe threat to humans and livestock, whose life history harbors both gamic and apogamic stages. Chinese 1 (ToxoDB#9) was a preponderant genotype epidemic in food-derived animals and humans in China, with a different pathogenesis from the strains from the other nations of the world. Posttranslational modifications (PTMs) of proteins were critical mediators of the biology, developmental transforms, and pathogenesis of protozoan parasites. The phosphoprotein profiling and the difference between the developmental phases of T. gondii, contributing to development and infectivity, remain unknown. A quantitative phosphoproteomic approach using IBT integrated with TiO₂ affinity chromatography was applied to identify and analyze the difference in the phosphoproteomes between the sporulated oocysts and the tachyzoites of the virulent ToxoDB#9 (PYS) strain of T. gondii. A total of 4058 differential phosphopeptides, consisting of 2597 upregulated and 1461 downregulated phosphopeptides, were characterized between sporulated the oocysts and tachyzoites. Twenty-one motifs extracted from the upregulated phosphopeptides contained 19 serine motifs and 2 threonine motifs (GxxTP and TP), whereas 16 motifs identified from downregulated phosphopeptides included 13 serine motifs and 3 threonine motifs (KxxT, RxxT, and TP). Beyond the traditional kinases, some infrequent classes of kinases, including Ab1, EGFR, INSR, Jak, Src and Syk, were found to be corresponding to motifs from the upregulated and downregulated phosphopeptides. Remarkable functional properties of the differentially expressed phosphoproteins were discovered by GO analysis, KEGG pathway analysis, and STRING analysis. S8GFS8 (DNMT1-RFD domain-containing protein) and S8F5G5 (Histone kinase SNF1) were the two most connected peptides in the kinase-associated network. Out of these, phosphorylated modifications in histone kinase SNF1 have functioned in mitosis and interphase of T. gondii, as well as in the regulation of gene expression relevant to differentiation. Our study discovered a remarkable difference in the abundance of phosphopeptides between the sporulated oocysts and tachyzoites of the virulent ToxoDB#9 (PYS) strain of T. gondii, which may provide a new resource for understanding stage-specific differences in PTMs and may enhance the illustration of the regulatory mechanisms contributing to the development and infectivity of T. gondii.

The Association of Toxoplasma gondii IgG Antibody and Chronic Kidney Disease Biomarkers

BACKGROUND

Toxoplasma gondii (T. gondii) is a parasite that infects more than 40 million Americans and causes toxoplasmosis. Most cases of toxoplasmosis are asymptomatic; however, T. gondii is capable of invading organs like the kidney, causing chronic infections and cell destruction.

METHODS

This study focused on evaluating the association between T. gondii exposure and chronic kidney disease (CKD) using data from the 2009-2010 National Health and Nutrition Examination Survey (NHANES). T. gondii exposure was assessed using Toxoplasma gondii IgG antibody status, and the status of CKD was assessed using the CKD biomarkers. The evaluation of risk rate and population prevalence was performed. In addition, multivariable regression models were used to further investigate this association after adjusting for sociodemographic, anthropometric, behavioral, and clinical covariates commonly associated with kidney dysfunction.

RESULTS

The positive T. gondii IgG antibody participants had significantly higher levels of CKD biomarkers, including second albumin-to-creatinine ratio (p = 0.0376), second albuminuria (p = 0.0005), and persistent albuminuria (p < 0.0001) compared to the negative participants. Furthermore, there were statistical associations between T. gondii exposure and the status of CKD (negative vs. positive) (p = 0.0001), and between T. gondii exposure and the CKD stage (negative, stage 1, …, stage 5) (p = 0.0004). Without adjusting for age, the positive T. gondii participants had a significantly higher risk (27% higher) of having CKD than the negative participants (RRcrude = 1.27, 95% CI: 1.09-1.49). The age-adjusted prevalence of CKD was higher among Toxoplasma-positive participants compared to the Toxoplasma-negative participants (10.45 vs. 8.99). T. gondii infection was significantly associated with CKD (OR = 1.40, 95% CI = 1.06-1.84, p = 0.00447) after adjusting for age, gender, race/ethnicity, and BMI. Age was positively associated with CKD (OR = 8.89, 95% CI = 6.31-12.51, p < 0.0001) with the participants 45+ years old being 8.89 times more likely to have CKD than those who are <45 years old, after adjusting for T. gondii infection, gender, race/ethnicity, and BMI. Moreover, positive T. gondii increased the odds of CKD progression (OR = 1.41, 95% CI = 1.07-1.86, p = 0.0424).

CONCLUSIONS

Positive T. gondii IgG antibody is associated with CKD and the progression of CKD stages. This association is more apparent among older people. Further investigations are needed to examine these findings in different geographical locations and among differentially exposed populations.

Soluble total antigen derived from Toxoplasma gondii RH strain prevents apoptosis, but induces anti-apoptosis in human monocyte cell line

Apoptosis plays crucial role in the pathogenesis of toxoplasmosis, as it limits further development of the disease. The current study aimed to investigate the effects of different concentrations of soluble total antigen (STAg) of Toxoplasma gondii (Nicolle et Manceaux, 1908) on the apoptotic and anti-apoptotic pathways. PMA-activated THP-1 cell line was sensed by T. gondii STAg and the expression patterns of caspase-3, -7, -8, -9, Bax, Bcl-2, and Mcl-1 genes were evaluated. The results showed statistically significant concentration-dependent overexpression of both Bcl-2 (P-value < 0.0001) and Mcl-1 (P-value = 0.0147). The cas-7 showed overexpression in all concentrations (P-value < 0.0001). The cas-3 was suppressed in concentrations 100, 80, and 40 µg, but statistically significant downregulated in concentrations 10 and 20 µg. The Bax was suppressed in concentrations 100 to 20 µg, while it slightly downregulated 1.42 fold (P-value = 0.0029) in concentration 10 µg. The expression of cas-8 and -9 was suppressed in all concentrations. Our results indicated that T. gondii STAg downregulated and suppressed apoptotic and upregulated anti-apoptotic pathways. The upregulation of cas-7 in this study may indicate the role of T. gondii STAg in activation of inflammatory responses.

New role of sertraline against Toxoplasma gondii-induced depression-like behaviours in mice

Toxoplasma gondii (T. gondii) is a neurotropic protozoan parasite, which can cause mental and behavioural disorders. The present study aimed to elucidate the effects and underlying molecular mechanisms of sertraline (SERT) on T. gondii-induced depression-like behaviours. In the present study, a mouse model and a microglial cell line (BV2 cells) model were established by infecting with the T. gondii RH strain. In in vivo and in vitro experiments, the underlying molecular mechanisms of SERT in inhibiting depression-like behaviours and cellular perturbations caused by T. gondii infection were investigated in the mouse brain and BV2 cells. The administration of SERT significantly ameliorated depression-like behaviours in T. gondii-infected mice. Furthermore, SERT inhibited T. gondii proliferation. Treatment with SERT significantly inhibited the activation of microglia and decreased levels of pro-inflammatory cytokines such as tumour necrosis factor-alpha, and interferon-gamma, by down-regulating tumour necrosis factor receptor 1/nuclear factor-kappa B signalling pathway, thereby ameliorating the depression-like behaviours induced by T. gondii infection. Our study provides insight into the underlying molecular mechanisms of the newly discovered role of SERT against T. gondii-induced depression-like behaviours.

Association between Toxoplasma gondii Infection in Brain and a History of Depression in Suicide Decedents: A Cross-Sectional Study

We assessed the association between Toxoplasma gondii (T. gondii) infection of the central nervous system and suicide correlates in suicide decedents. Eighty-seven decedents who died by suicide received in a forensic setting for medico-legal autopsies in Mexico City were studied. Two samples of brain (amygdala and prefrontal cortex) from each decedent were examined for detection of T. gondii using immunohistochemistry. Correlates of suicide including a history of previous suicide attempts, co-morbid mental disorder, consumption of alcohol or tobacco, irritability and aggression, economic problems, presence of drugs or alcohol in blood and suicide method were obtained and analyzed for their association with T. gondii infection. T. gondii immunohistochemistry was positive in prefrontal cortex sections in 6 decedents and in an amygdala section in one decedent. Thus, the prevalence of T. gondii infection in brain in suicide victims was 8.0% (7/87). Bivariate and logistic regression analysis of suicide correlates showed that only a history of depression was associated with T. gondii infection of the brain in suicide victims (OR: 12.00; 95% CI: 2.26–63.46; p = 0.003). Our results provide evidence that T. gondii infection in brain is associated with a history of depression in suicide decedents.

Association of Toxoplasma gondii Seropositivity With Cognitive Function in Healthy People: A Systematic Review and Meta-analysis

IMPORTANCE

The parasite Toxoplasma gondii has been associated with behavioral alterations and psychiatric disorders. Studies investigating neurocognition in people with T gondii infection have reported varying results. To systematically analyze these findings, a meta-analysis evaluating cognitive function in healthy people with and without T gondii seropositivity is needed.

OBJECTIVE

To assess whether and to what extent T gondii seropositivity is associated with cognitive function in otherwise healthy people.

DATA SOURCES

A systematic search was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. A systematic search of PubMed, MEDLINE, Web of Science, PsycInfo, and Embase was performed to identify studies from database inception to June 7, 2019, that analyzed cognitive function among healthy participants with available data on T gondii seropositivity. Search terms included toxoplasmosis, neurotoxoplasmosis, Toxoplasma gondii, cognition disorder, neuropsychological, and psychomotor performance.

STUDY SELECTION

Studies that performed cognitive assessment and analyzed T gondii seroprevalence among otherwise healthy participants were included.

DATA EXTRACTION AND SYNTHESIS

Two researchers independently extracted data from published articles; if needed, authors were contacted to provide additional data. Quantitative syntheses were performed in predefined cognitive domains when 4 independent data sets per domain were available. Study quality, heterogeneity, and publication bias were assessed.

MAIN OUTCOMES AND MEASURES

Performance on neuropsychological tests measuring cognitive function.

RESULTS

The systematic search yielded 1954 records. After removal of 533 duplicates, an additional 1363 records were excluded based on a review of titles and abstracts. A total of 58 full-text articles were assessed for eligibility (including reference list screening); 45 articles were excluded because they lacked important data or did not meet study inclusion or reference list criteria. The remaining 13 studies comprising 13 289 healthy participants (mean [SD] age, 46.7 [16.0] years; 6586 men [49.6%]) with and without T gondii seropositivity were included in the meta-analysis. Participants without T gondii seropositivity had favorable functioning in 4 cognitive domains: processing speed (standardized mean difference [SMD], 0.12; 95% CI, 0.05-0.19; P = .001), working memory (SMD, 0.16; 95% CI, 0.06-0.26; P = .002), short-term verbal memory (SMD, 0.18; 95% CI, 0.09-0.27; P < .001), and executive functioning (SMD, 0.15; 95% CI, 0.01-0.28; P = .03). A meta-regression analysis found a significant association between older age and executive functioning (Q = 6.17; P = .01). Little suggestion of publication bias was detected.

CONCLUSIONS AND RELEVANCE

The study's findings suggested that T gondii seropositivity was associated with mild cognitive impairment in several cognitive domains. Although effect sizes were small, given the ubiquitous prevalence of this infection globally, the association with cognitive impairment could imply a considerable adverse effect at the population level. Further research is warranted to investigate the underlying mechanisms of this association.

Genetic characterization of Toxoplasma gondii isolates from human spontaneous aborted fetuses in Jahrom, southern Iran

Toxoplasma gondii (T. gondii) is an intracellular protozoan that infects the fetus through the placenta and leads to severe complications in the fetus. One of the complications of congenital toxoplasmosis is spontaneous abortion. The prevalence of toxoplasmosis infection was investigated among spontaneously aborted fetuses (SAFs), and the genotypes of parasite isolates were determined in the present study. Placentas from 330 samples of SAFs were collected in Jahrom (Fars province) from February to September 2018. DNA was extracted from each placental tissue. The T. gondii infection was detected using nested polymerase chain reaction (Nested-PCR) assay based on a 529 bp repeat element (RE) gene. Afterward, Toxoplasma was genotyped using PCR-restriction fragment length polymorphism (PCR-RFLP) based on the GRA6 gene. The frequency of T. gondii infection was found to be 14.5% (48 out of 330 samples). Genotyping of nine T. gondii isolates revealed that all belonged to genotype II. Statistically, the prevalence of T. gondii infection was significantly correlated with the education levels of the mothers and the age of the fetus (P < 0.05). The lowest prevalence of Toxoplasma infection belonged to mothers with university education and the highest frequency of infection was observed among the fetuses in the age group of 8-9 weeks. The findings of the present study suggest a significant role for toxoplasmosis in SAFs in Jahrom city.

Promising Drug Targets and Compounds with Anti-Toxoplasma gondii Activity

Toxoplasmosis is a parasitic disease caused by the globally distributed protozoan parasite Toxoplasma gondii, which infects around one-third of the world population. This disease may result in serious complications for fetuses, newborns, and immunocompromised individuals. Current treatment options are old, limited, and possess toxic side effects. Long treatment durations are required since the current therapeutic system lacks efficiency against T. gondii tissue cysts, promoting the establishment of latent infection. This review highlights the most promising drug targets involved in anti-T. gondii drug discovery, including the mitochondrial electron transport chain, microneme secretion pathway, type II fatty acid synthesis, DNA synthesis and replication and, DNA expression as well as others. A description of some of the most promising compounds demonstrating antiparasitic activity, developed over the last decade through drug discovery and drug repurposing, is provided as a means of giving new perspectives for future research in this field.

Examining the Relationship between Toxoplasma gondii and Seropositivity and Serointensity and Depression in Adults from the United Kingdom and the United States: A Cross-Sectional Study

Infecting approximately one-third of the world’s population, the neurotropic protozoan Toxoplasma gondii has been associated with cognition and several neuropsychiatric diseases including schizophrenia and bipolar disorder. Findings have been mixed, however, about the relationship between Toxoplasma gondii and depression, with some studies reporting positive associations and others finding no associations. To further investigate the association between Toxoplasma gondii and depression, we used data from the UK Biobank and the National Health and Examination Survey (NHANES). Results from adjusted multiple-regression modeling showed no significant associations between Toxoplasma gondii and depression in either the UK Biobank or NHANES datasets. Further, we found no significant interactions between Toxoplasma gondii and age, sex, educational attainment, and income in either dataset that affected the association between Toxoplasma gondii and depression. These results from two community-based datasets suggest that in these samples, Toxoplasma gondii is not associated with depression. Differences between our findings and other findings showing an association between Toxoplasma gondii and depression could be due to several factors including differences in socioeconomic variables, differences in Toxoplasma gondii strain, and use of different covariates in statistical modeling.

Toxoplasma gondii in South America: a differentiated pattern of spread, population structure and clinical manifestations

Toxoplasma gondii is an obligate intracellular parasite belonging to the phylum Apicomplexa. It has a worldwide distribution and can infect a wide variety of intermediate hosts, including humans. In South America, toxoplasmosis shows high health impacts, and the incidence of the disease is frequently reported and more severe than in other regions, such as Europe. Although most T. gondii infections are asymptomatic, severe manifestations can occur in cases of congenital toxoplasmosis and immunocompromised individuals. In South America, the ocular disease in immunocompetent individuals is also frequently reported. Treatment for any clinical manifestation of toxoplasmosis consists of the combination of sulfadiazine (SDZ) and pyrimethamine (PYR). However, failures in the treatment of toxoplasmosis have been reported, especially in South America, suggesting the acquisition of resistance against SDZ and PYR. Another paradigm present in the literature is that once infected with T. gondii, the host is immunologically protected from further reinfections. However, some studies indicate cases of congenital transmission of T. gondii from immunocompetent pregnant women with chronic infection, suggesting the possibility of reinfection in humans. Thus, in this review, we will cover several aspects of South American T. gondii isolates, such as genetic characterization, disease manifestation, host reinfection and drug resistance.

Pathophysiological Aspects of Ocular Toxoplasmosis: Host-parasite Interactions

Purpose: This review aims to present the state of the art to understand the pathophysiology of ocular toxoplasmosis (OT), providing further foundations that would help to improve the future treatment and prognosis of this potentially blinding disease.Methods: A thorough literature search was performed in PubMed database. An additional search was made in Google Scholar to complete the collected items.Results: Toxoplasma gondii ocular infection is one of the most frequent causes of posterior uveitis. Despite the ocular barriers, the parasite reaches the eye through different mechanisms. Once inside, it remains encysted livelong within the retina, and recurrences cannot be completely avoided. The complexity of host-parasite interactions, leading to the success of this parasite, encompasses host factors such as genetic predisposition, immune status, and age; and parasite factors such as strain diversity, virulence, phylogenetic origin, and geographical distribution. These factors influence the clinical presentation, course, and progression of the disease. Additional elements, such as pregnancy, eating behavior, and environmental, social, and cultural factors may also contribute to this complex balance.Conclusions: The host-parasite interaction in OT is a complex and multifactorial relationship, with the parasite always on the driving edge of the game. There are still multiple incompletely understood fields to be investigated. Future research would permit further insight into the immune-biology of the parasite and recognition of the host-parasite interplay to improve the diagnostic and management performance.

Toxoplasma gondii in Slaughtered Sheep in High- and Low-Humidity Regions in the South of Iran: Molecular Prevalence and Genotype Identification

Toxoplasma gondii is one of the most common meat-born zoonoses that infect all warm-blooded animals and humans. Sheep (Ovis aries) is one of the main reservoirs of T. gondii worldwide, and the infections induce various sequels, such as abortion and stillbirth. The present study aimed to identify the effects of humidity on the prevalence of T. gondii in sheep in high- and low-humidity regions. Heart samples from 200 slaughtered sheep (140 samples from a high-humidity region and 60 samples from a low-humidity region) were collected from Hormozgan Province (south of Iran). The samples were tested by nested PCR targeting the RE gene. Genotyping was performed by the PCR-RFLP method using the SAG3 and GRA6 genes. Some isolates were sequenced and recorded in the GenBank. T. gondii DNA was detected in 10.71 percent of the samples from the highly humid region, whereas no positive samples were detected in the low-humidity region. Genotyping revealed that all isolates belonged to the T. gondii type III genotype. Our study indicated that humidity is an important factor for the prevalence of T. gondii in sheep. Additionally, our study also showed the dominance of type III strain of T. gondii in sheep in the south of Iran.

A systematic review of Toxoplasma gondii genotypes in Gallus gallus domesticus worldwide: The focus is Brazil

Toxoplasma gondii was initially classified in three main lineages related to its virulence: Types I, II, and III. The recombination of genes during sexual cycle in felids gut led to more than 200 genotypes, found in ToxoDB database, using 11 RFLP markers. Free-range chickens are good bioindicators of soil contamination with T. gondii oocysts. In this sense, there are systematic reviews regarding data of genetic characterization of this parasite in felines and ruminants, but not in chickens heretofore, what makes this work necessary. A systematic review of the literature was performed with papers published prior to September 21, 2020. The main inclusion criteria were the presence of T. gondii genotypes, isolated strictly from free-range chickens, in experimental works. Initially, a total of 1,343 studies related to the terms were identified on databases and 30 studies were selected to be systematically reviewed. A total of 561 isolates of T. gondii from 6,356 free-range chickens were analyzed for genotyping, revealing 190 genotypes. ToxoDB #59 and #2 were the most frequent in America, #1 was the most frequent in Africa and three atypical isolates from genotype ToxoDB #9 were found in Asia. There is no data from Europe and Oceania. The majority of studies were Brazilian (16/30). A total of 68 RFLP genotypes were recognized among the 561 isolates' DNAs analyzed from the 30 studies. Some studies showed new genotypes never described before, which reinforces the idea that in some years even more new genotypes will be identified, due to gradual genetic recombination. A large number of undefined genotypes makes it necessary to perform Nested PCR technique when genotyping. Moreover, the lack of data in Continents such as Europe, Asia, and Oceania makes it necessary to perform new isolating and genotyping studies in these places.

Toxoplasmosis among cancer patients undergoing chemotherapy: a population study based on the serological, molecular and epidemiological aspects

BACKGROUND

Toxoplasmosis is highly prevalent in northern Iran and immunocompromised individuals are more susceptible to this infection. The present study aimed to determine the seroprevalence, parasitism and genetic diversity of Toxoplasma gondii among patients with cancer undergoing chemotherapy in northern Iran.

METHODS

A total of 350 serum samples obtained from cancer patients were collected from laboratory centers in northern Iran. Immunodiagnosis and DNA detection were accomplished by ELISA and PCR. Thereafter, multiplex-nested PCR-restriction fragment length polymorphism was used for the genotyping of T. gondii.

RESULTS

In general, out of 350 patients, 264 (75.4%) and 9 (2.57%) cases were positive for anti-T. gondii IgG and IgM, respectively. Moreover, 19 (5.43%) samples contained T. gondii DNA. From 19 positive samples, 10 high-quality samples with sharp and non-smear bands were selected to determine the genotypes of T. gondii. Accordingly, the samples were classified as genotype #1 (type II clonal; n=4, 40%), genotype #2 (type III clonal; n=3, 30%), genotype #10 (type I clonal; n=2, 20%) and genotype #27 (type I variant; n=1, 10%).

CONCLUSIONS

As evidenced by the results, due to the high prevalence of T. gondii, cancer patients in northern Iran are at serious risk of severe toxoplasmosis and its complications. Therefore, oncologists need to regard this critical health problem as a matter requiring urgent attention.

Whole-genome sequencing of a Toxoplasma gondii strain from a Turkish isolate using next-generation sequencing technology

PURPOSE

Toxoplasma gondii is an intracellular parasite that can affect all vertebrae and is the causative agent of toxoplasmosis. At present, the United States CDC (Centers for Disease Control and Prevention) recognizes this infection as a neglected disease. Toxoplasma gondii infection profiles exhibit differences because of the different regional and climatic responses to these parasites in Turkey, and these protozoan infections are notably common in this country. In this study, we attempted to obtain the whole-genome sequence of T. gondii using next-generation sequencing technology.

METHODS

Toxoplasma gondii isolates were isolated from an infant with congenital toxoplasmosis by Ekmen et al. (1974) in Ankara, Turkey. Whole-genome sequencing (WGS) was performed using the Illumina HiSeq 2500 and HiSeq SBS Kit v2. A T. gondii library was created on this device in the initial stage. After the completion of the library phase, sequence analysis was begun with a next-generation sequencing device. The resulting fragments were combined using paired-end (PE) reading and converted into a single DNA fragment. Bioinformatic analysis was performed using the Geneious 2.1.

PROGRAM

RESULTS

In our study, WGS was successfully performed on T. gondii. The T. gondii whole-genome sequence has a coverage value of 50x, a size of 61,5763 Mb and a GC ratio of 52.6%. Data from this sequence were submitted to the National Center for Biotechnology Information (NCBI) GenBank (www.ncbi.nlm.nih.gov) database under the name Toxoplasma gondii TR01 (TG_TR01). The accession number of the genome obtained in this study is WOEV00000000.1. The biological sample access number is SAMN13338796. The genome of the T. gondii strain obtained in this study was compared with the reference genome, and 8312 CDSs (coding sequences), 183 tRNAs, 294 rRNAs and 8789 genes were identified. Among the 8312 CDSs, 4284 encoded hypothetical proteins (hypothetical protein CDSs/proteins of unknown function). The entire genome sequence of T gondii TR01 was compared with that of Toxoplasma gondii ME49. The results of this comparison demonstrate that the analyzed genome was 99,98% similar to the reference genome. The accession numbers of 14 chromosomes belonging to the genome sequences of T. gondii TR01 (TG_TR01) are CM019722.1, CM019723.1, CM019724.1, CM019725.1, CM019726.1, CM019727.1, CM019728.1, CM019729.1, CM019730.1, CM019731.1, CM019732.1, CM019733.1, CM019734.1, and CM019735.1.

CONCLUSION

In this study, a whole-genome sequences of T. gondii was conducted for the first time in Turkey. The analyzed strain was named T. gondii TR01. The data obtained from this study may contribute to a better understanding of T. gondii. T. gondii is an important pathogen with an unusual population structure. Although T. gondii is highly zoonotic and has a complicated life cycle, some strains of this parasite have exhibited high genetic sequence similarity, and our study supports this knowlegde. The characterization of this strain may be very useful for the scientific community of our country and may help to establish a foundation for further research investigating the genome of T. gondii.

The Association of Toxoplasma gondii IgG and Cardiovascular Biomarkers

Background: Toxoplasma gondii (T. gondii) is a protozoan parasite with high prevalence worldwide. More than 40 million individuals in the United States carry this parasite. T. gondii infection causes toxoplasmosis, which is the leading cause of death associated with foodborne diseases in the United States. T. gondii infects humans through different routes, and it is capable of invading a wide range of tissues in the human body following the infection. Methods: The main objective of this study was to investigate the prevalence of T. gondii among adults in the United States and its association with cardiovascular health using data from the National Health and Nutrition Examination Survey (NHANES 2009-2010). Considering the limitation of studies investigating the relationship between T. gondii and cardiovascular biomarkers, this study was focused on assessing the association of T. gondii to nine cardiovascular biomarkers. First, those biomarkers were investigated individually using several statistical tests and models. Second, we developed an overall cardiovascular biomarker index (OCBI) from eight critical biomarkers to better explain the T. gondii potential cumulative effect on the cardiovascular system. These analyses were adjusted for demographic, behavioral, and anthropometric factors. Results:T. gondii IgG antibody-positive participants had significantly higher systolic blood pressure (p = 0.0022), triglycerides (p = 0.0399), C-reactive protein (p = 0.0422), gamma glutamyl transferase (p = 0.0400), and fasting glucose (p = 0.0213) than the negative participants. In addition, the positive participants had significantly lower high-density lipoprotein cholesterol (p = 0.0431) than the negative participants. Adjusting for age, T. gondii positive had a significant negative association with high-density lipoprotein cholesterol (p = 0.0026) and a significant positive association with low-density lipoprotein cholesterol (p = 0.0179), triglycerides (p = 0.0154), and gamma glutamyl transferase (p = 0.0026). With the exception of the low-density lipoprotein, these associations remained statistically significant when adjusting for demographic, behavioral, and anthropometric factors. These results potentially indicate the role of T. gondii in driving cardiovascular-related biomarkers toward dysfunction. The analysis also revealed a significant difference in the OCBI among positive and negative participants (p = 0.0020), with the (cumulative) odds of positive participants having a higher level of OCBI being 0.71 times lower than the odds for negative participants (OR = 0.29). Conclusions: Positive T. gondii IgG antibody was significantly associated with adverse effects on cardiovascular-related biomarkers, including systolic blood pressure, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, and gamma glutamyl transferase. T. gondii-positive individuals were more likely to have a lower cardiovascular biomarkers index than the negative individuals. Finally, the prevalence of toxoplasmosis among U.S. adults was associated with demographic characteristics including age, ethnicity, country of birth, and occupation.

First isolation and genotyping of Toxoplasma gondii strains from domestic animals in Tunisia

The isolation and molecular typing of Toxoplasma gondii strains provide an essential basis for a better understanding of the parasite’s genetic diversity, determinants of its geographical distribution and associated risks to human health. In this study, we isolated and genetically characterized T. gondii strains from domestic animals in Southern and coastal area of Tunisia. Blood, hearts and/or brains were collected from 766 domestic animals (630 sheep and 136 free-range chickens). Strain isolation from these samples was performed using mouse bioassay and genotyping was carried out with a multiplex PCR technique using 15 microsatellite markers. Thirty viable strains of T. gondii were successfully isolated from tissues of sheep (19/142) and chickens (11/33). In addition, 3 strains could be successfully genotyped from animal tissues for which mouse bioassay was unsuccessful. A large predominance of type II strains (n = 29) was found in the sampled regions, followed by type III (n = 3) and, for the first time in Tunisia, a single isolate of Africa 4 lineage from a sheep. Analyses of population genetics showed the presence of a divergent population of type II lineage in Tunisia, supporting limited recent migrations of strains between Tunisia and other countries of the world.

1,3,4-Thiadiazoles Effectively Inhibit Proliferation of Toxoplasma gondii

Congenital and acquired toxoplasmosis caused by the food- and water-born parasite Toxoplasma gondii (T. gondii) is one of the most prevalent zoonotic infection of global importance. T. gondii is an obligate intracellular parasite with limited capacity for extracellular survival, thus a successful, efficient and robust host cell invasion process is crucial for its survival, proliferation and transmission. In this study, we screened a series of novel 1,3,4-thiadiazole-2-halophenylamines functionalized at the C5 position with the imidazole ring (1b-12b) for their effects on T. gondii host cell invasion and proliferation. To achieve this goal, these compounds were initially subjected to in vitro assays to assess their cytotoxicity on human fibroblasts and then antiparasitic efficacy. Results showed that all of them compare favorably to control drugs sulfadiazine and trimethoprim in terms of T. gondii growth inhibition (IC50) and selectivity toward the parasite, expressed as selectivity index (SI). Subsequently, the most potent of them with meta-fluoro 2b, meta-chloro 5b, meta-bromo 8b, meta-iodo 11b and para-iodo 12b substitution were tested for their efficacy in inhibition of tachyzoites invasion and subsequent proliferation by direct action on established intracellular infection. All the compounds significantly inhibited the parasite invasion and intracellular proliferation via direct action on both tachyzoites and parasitophorous vacuoles formation. The most effective was para-iodo derivative 12b that caused reduction in the percentage of infected host cells by 44% and number of tachyzoites per vacuole by 93% compared to non-treated host cells. Collectively, these studies indicate that 1,3,4-thiadiazoles 1b-12b, especially 12b with IC50 of 4.70 µg/mL and SI of 20.89, could be considered as early hit compounds for future design and synthesis of anti-Toxoplasma agents that effectively and selectively block the invasion and subsequent proliferation of T. gondii into host cells.

Dissociating direct and indirect effects: a theoretical framework of how latent toxoplasmosis affects cognitive profile across the lifespan

About one-third of the world's population has latent toxoplasmosis, which is typically most prevalent in old age due to its lifelong persistence. Most infected people do not reveal clinically relevant symptoms, but T. gondii might trigger cognitive changes in otherwise asymptomatic individuals. As intact cognitive processes are essential for various achievements and successful aging, this review focuses on the cognitive profile associated with latent toxoplasmosis across the lifespan. It could be explained by a shift in balance between direct effects (increased dopamine synthesis) and indirect effects (neurodegeneration and chronic inflammation, which can decrease dopamine levels). Based thereon, we provide a possibly comprehensive framework of how T. gondii can differently affect cognitive performance across the lifespan (i.e., from increased catecholaminergic signaling in young age to decreased signaling in old age). We outline how future studies may inform our knowledge on the role of individual differences in response to T. gondii and how longitudinal studies can help trace the temporal dynamics in the shift of the balance between direct and indirect effects.