Toxoplasmosis

Essential oil of oregano (Origanum vulgare L.) reduces infection and proliferation of Toxoplasma gondii in BeWo cells with induction of autophagy and death of tachyzoites through a mechanism similar to necrosis

Toxoplasmosis poses a global health threat, ranging from asymptomatic cases to severe, potentially fatal manifestations, especially in immunocompromised individuals and congenital transmission. Prior research suggests that oregano essential oil (OEO) exhibits diverse biological effects, including antiparasitic activity against Toxoplasma gondii. Given concerns about current treatments, exploring new compounds is important. This study was to assess the toxicity of OEO on BeWo cells and T. gondii tachyzoites, as well as to evaluate its effectiveness in in vitro infection models and determine its direct action on free tachyzoites. OEO toxicity on BeWo cells and T. gondii tachyzoites was assessed by MTT and trypan blue methods, determining cytotoxic concentration (CC50), inhibitory concentration (IC50), and selectivity index (SI). Infection and proliferation indices were analyzed. Direct assessments of the parasite included reactive oxygen species (ROS) levels, mitochondrial membrane potential, necrosis, and apoptosis, as well as electron microscopy. Oregano oil exhibited low cytotoxicity on BeWo cells (CC50: 114.8 µg/mL ± 0.01) and reduced parasite viability (IC50 12.5 ± 0.06 µg/mL), demonstrating 9.18 times greater selectivity for parasites than BeWo cells. OEO treatment significantly decreased intracellular proliferation in infected cells by 84% after 24 h with 50 μg/mL. Mechanistic investigations revealed increased ROS levels, mitochondrial depolarization, and lipid droplet formation, linked to autophagy induction and plasma membrane permeabilization. These alterations, observed through electron microscopy, suggested a necrotic process confirmed by propidium iodide labeling. OEO treatment demonstrated anti-T. gondii action through cellular and metabolic change while maintaining low toxicity to trophoblastic cells.

Toxoplasma-host endoplasmic reticulum interaction: How T. gondii activates unfolded protein response and modulates immune response

Toxoplasma gondii is a neurotropic single-celled zoonotic parasite that can infect human beings and animals. Infection with T. gondii is usually asymptomatic in immune-competent individual, however, it can cause symptomatic and life-threatening conditions in immunocompromised individuals and in developing foetuses. Although the mechanisms that allow T. gondii to persist in host cells are poorly understood, studies in animal models have greatly improved our understanding of Toxoplasma-host cell interaction and how this interaction modulates parasite proliferation and development, host immune response and virulence of the parasite. T. gondii is capable of recruiting the host endoplasmic reticulum (ER), suggesting it may influence the host ER function. Herein, we provide an overview of T. gondii infection and the role of host ER during stressed conditions. Furthermore, we highlight studies that explore T. gondii's interaction with the host ER. We delve into how this interaction activates the unfolded protein response (UPR) and ER stress-mediated apoptosis. Additionally, we examine how T. gondii exploits these pathways to its advantage.

Toxoplasma gondii in small mammals in Romania: the influence of host, season and sampling location

BACKGROUND

Toxoplasma gondii is a protozoan parasite that infects a large spectrum of warm-blooded animals, including humans. Small rodents and insectivores play an important role in the epidemiology of T. gondii and may serve as a source of infection for both, domestic and wild definitive felid hosts. Factors influencing the occurrence of T. gondii in wild small mammals are unknown, despite the fact that many intermediate host species are identified. We have used small mammals (Rodentia and Lipotyphla) captured over two years in various habitats, both in urbanised and in natural landscapes. We assessed the importance of land-use, season and host ecology on T. gondii infection.

RESULTS

We examined 471 individuals belonging to 20 small mammal species, collected at 63 locations spread over wide altitude, habitat and land-use ranges from Romania. Heart tissue samples were individually analysed by PCR targeting the 529 bp repetitive DNA fragment of T. gondii. The overall prevalence of infection was 7.3%, with nine species of rodents and two species of shrews being found to carry T. gondii DNA. Five species showed high frequency of infection, with the highest prevalence found in Myodes glareolus (35.5%), followed by Spermophilus citellus (33.3%), Sorex minutus (23.1%), S. araneus (21.7%) and Micromys minutus (11.1%). Adults seemed more often infected than young, however when controlling for season, the difference was not significant, as in spring both adults and young showed higher infection rates, but more adults were sampled. Contrary to our expectations, urban/rural areas (with their implicit high density of domestic feline presence) had no effect on infection prevalence. In addition, neither habitat, nor land-use at sampling sites was important as only geographical location and host species were contributing factors to the infection risk.

CONCLUSIONS

High prevalence of T. gondii infection showed a highly localised, patchy occurrence, with long living and higher mobility host species being the most common carriers, especially during autumn.

Application of Silver Nanoparticles in Parasite Treatment

Silver nanoparticles (AgNPs) are ultra-small silver particles with a size from 1 to 100 nanometers. Unlike bulk silver, they have unique physical and chemical properties. Numerous studies have shown that AgNPs have beneficial biological effects on various diseases, including antibacterial, anti-inflammatory, antioxidant, antiparasitic, and antiviruses. One of the most well-known applications is in the field of antibacterial applications, where AgNPs have strong abilities to kill multi-drug resistant bacteria, making them a potential candidate as an antibacterial drug. Recently, AgNPs synthesized from plant extracts have exhibited outstanding antiparasitic effects, with a shorter duration of use and enhanced ability to inhibit parasite multiplication compared to traditional antiparasitic drugs. This review summarizes the types, characteristics, and the mechanism of action of AgNPs in anti-parasitism, mainly focusing on their effects in leishmaniasis, flukes, cryptosporidiosis, toxoplasmosis, Haemonchus, Blastocystis hominis, and Strongylides. The aim is to provide a reference for the application of AgNPs in the prevention and control of parasitic diseases.

Maternal anti-Toxoplasma gondii antibodies IgG2, IgG3 and IgG1 are markers of vertical transmission and clinical evolution of toxoplasmosis in the offspring

Toxoplasma gondii can be transmitted vertically during pregnancy and may cause neurological, ocular, and even systemic damage to the offspring. Congenital toxoplasmosis (CT) can be diagnosed during gestation and/or after birth in the postnatal period. The timely diagnosis is highly relevant for efficient clinical management. The most common laboratory methods for diagnosing CT are based on Toxoplasma-specific humoral immune responses. However, these methods are of low sensitivity or specificity. In a previous study with a small number of cases, the comparison of anti-T. gondii IgG subclasses between mothers and their offspring showed promising results for CT diagnosis and prognosis. Thus, in this work, we analyzed specific IgG subclasses and IgA in 40 T. gondii-infected mothers and their children, of which 27 were congenitally infected and 13 uninfected. A higher frequency of anti-Toxoplasma IgG2, IgG3, IgG4, and IgA antibodies was observed in mothers and congenitally infected offspring. Of these, IgG2 or IgG3 were statistically the most conspicuous. In the CT group, maternal IgG3 antibodies were significantly associated with severe disease of the infants and IgG1 and IgG3 with disseminated disease. The results support that maternal anti-T. gondii IgG3, IgG2 and IgG1 are markers of congenital transmission and severity/spread of disease in the offspring.

Toxoplasma gondii dense granule protein 3 promotes endoplasmic reticulum stress-induced apoptosis by activating the PERK pathway

Background

Toxoplasma gondii is a neurotropic single-celled parasite that can infect mammals, including humans. Central nervous system infection with T. gondii infection can lead to Toxoplasma encephalitis. Toxoplasma infection can cause endoplasmic reticulum (ER) stress and unfolded protein response (UPR) activation, which ultimately can lead to apoptosis of host cells. The dense granule protein GRA3 has been identified as one of the secretory proteins that contribute to the virulence of T. gondii; however, the mechanism remains enigmatic.

Methods

The expression of the GRA3 gene in RH, ME49, Wh3, and Wh6 strains was determined using quantitative real-time polymerase chain reaction (qRT–PCR). pEGFP-GRA3_Wh6 was constructed by inserting Chinese 1 Wh6 GRA3 (GRA3_Wh6) cDNA into a plasmid encoding the enhanced GFP. Mouse neuro2a (N2a) cells were transfected with either pEGFP or pEGFP-GRA3_Wh6 (GRA3_Wh6) and incubated for 24–36 h. N2a cell apoptosis and ER stress-associated proteins were determined using flow cytometry and immunoblotting. Furthermore, N2a cells were pretreated with GSK2656157 (a PERK inhibitor) and Z-ATAD-FMK (a caspase-12 inhibitor) before GRA3_Wh6 transfection, and the effect of the inhibitors on GRA3_Wh6-induced ER stress and apoptosis were investigated.

Results

GRA3 gene expression was higher in the less virulent strains of type II ME49 and type Chinese 1 Wh6 strains compared with the virulent strains of type I RH strain and type Chinese 1 Wh3 strain. Transfection with GRA3_Wh6 plasmid induced neuronal apoptosis and increased the expression of GRP78, p-PERK, cleaved caspase-12, cleaved caspase-3, and CHOP compared with the control vector. Pretreatment with GSK2656157 and Z-ATAD-FMK decreased apoptosis in N2a cells, and similarly, ER stress- and apoptosis-associated protein levels were significantly decreased.

Conclusion

GRA3 induces neural cell apoptosis via the ER stress signaling pathway, which could play a role in toxoplasmic encephalitis.

Graphical Abstract

Formulation of Neem oil-loaded solid lipid nanoparticles and evaluation of its anti-Toxoplasma activity

BACKGROUND

Toxoplasmosis is caused by an intracellular zoonotic protozoan, Toxoplasma gondii, which could be lethal in immunocompromised patients. This study aimed to synthesize Neem oil-loaded solid lipid nanoparticles (NeO-SLNs) and to evaluate the anti-Toxoplasma activity of this component.

METHODS

The NeO-SLNs were constructed using double emulsification method, and their shape and size distribution were evaluated using transmission electron microscope (TEM) and dynamic light scattering (DLS), respectively. An MTT assay was employed to evaluate the cell toxicity of the component. The anti-Toxoplasma activity of NeO-SLNs was investigated using vital (trypan-blue) staining. Anti-intracellular Toxoplasma activity of NeO-SLNs was evaluated in T. gondii-infected Vero cells.

RESULTS

The TEM analysis represented round shape NeO-SLNs with clear and stable margins. DLS analysis showed a mean particle size 337.6 nm for SLNs, and most of nanoparticles were in range 30 to 120 nm. The cell toxicity of NeO-SLNs was directly correlated with the concentration of the component (P-value = 0.0013). The concentration of NeO-SLNs, which was toxic for at least 50% of alive T. gondii (cytotoxic concentration (CC50)), was > 10 mg/mL. The ability of NeO-SLNs to kill Toxoplasma was concentration-dependent (P-value < 0.0001), and all concentrations killed at least 70% of alive tachyzoites. Furthermore, the viability of T. gondii- infected Vero cells was inversely correlated with NeO-SLNs concentrations (P-value = 0.0317), and in the concentration 100 μg/mL at least 75% of T. gondii- infected Vero cells remained alive.

CONCLUSIONS

Overall, our findings demonstrated that the NeO-SLNs was able to kill T. gondii tachyzoites in concentration 100 μg/mL with a cell toxicity lower than 20%. Such results suggest that employing SLNs as carrier for NeO can effectively kill T. gondii tachyzoites with acceptable cell toxicity. Our findings also showed that SLNs capsulation of the NeO can lead to prolonged release of the extract, suggesting that NeO-SLNs could be also employed to clear cyst stages, which should be further investigated in animal models.

Biogenic silver nanoparticles reduce Toxoplasma gondii infection and proliferation in RAW 264.7 macrophages by inducing tumor necrosis factor-alpha and reactive oxygen species production in the cells

Owing to the serious adverse effects caused by pyrimethamine and sulfadiazine, the drugs commonly used to treat toxoplasmosis, there is a need for treatment alternatives for this disease. Nanotechnology has enabled significant advances toward this goal. This study was conducted to evaluate the activity of biogenic silver nanoparticles (AgNp-Bio) in RAW 264.7 murine macrophages infected with the RH strain of Toxoplasma gondii. The macrophages were infected with T. gondii tachyzoites and then treated with various concentrations of AgNp-Bio. The cells were evaluated by microscopy, and culture supernatants were collected for ELISA determination of their cytokine concentration. Treatment with 6 μM AgNp-Bio reduced the infection and parasite load in infected RAW 264.7 macrophages without being toxic to the cells. The treatment also induced the synthesis of reactive oxygen species and tumor necrosis factor-alpha (both pro-inflammatory mediators), which resulted in ultrastructural changes in the tachyzoites and their intramacrophagic destruction. Our findings suggest that AgNp-Bio affect T. gondii tachyzoites by activating microbicidal and pro-inflammatory mechanisms and may be a potential alternative treatment for toxoplasmosis.

In Vitro and In Vivo Anti-Toxoplasma Activities of Dracocephalum kotschyi Extract in Experimental Models of Acute Toxoplasmosis

BACKGROUND

The problem of resistance to antiparasitic drugs, associated with their side effects, suggest exploring other alternatives, including medicinal plants. Dracocephalum kotschyi (D. kotschyi), for example, from Lamiaceae family, is a plant widely used in Iran and in many countries, and to which interesting pharmacological properties have been attributed. This study aimed to investigate in vitro and in vivo anti-Toxoplasma activities of D. kotschyi extract in experimental models of acute toxoplasmosis.

METHODS

Anti-Toxoplasma activity of the extracts in vitro was performed on Vero Cell, using the MTT test. Vero cell were infected with (3 × 10⁵ tachyzoites/well) following treatment with Dichloromethane (F1), dichloromethane: methanol (F2), methanol (F3), methanol: water (F4), and deionized water (F5) extracts of D. kotschyi, and pyrimethamine and sulfadiazine (positive control). MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was used to measure cell viability. Effects of extracts on tachyzoites viability were evaluated by trypan blue exclusion method, followed by light microscopy. For in vivo test, 18 groups of 8-10-week-old Inbred Balb/c mice weighing 18-20 g, were intraperitoneally infected with 2 × 10³ tachyzoites and then treated with sterile PBS (negative control), pyrimethamine (25 mg/kg) and sulfadiazine (500 mg/kg) as positive controls, and F1 to F5 extracts (at doses 50, 100 and 200 mg/kg).

RESULTS

The 50% Inhibitory Concentration of F1 extract, F2 extract, Sulfadiazine (Positive control) and Pyrimethamine (Positive control) were 8.77 µg, 7.1 µg 391.18 µg, and 84.20 µg, respectively, while the selectivity indices were 15.667, 30.197, 1.552 and 4.064, respectively. In vivo anti-Toxoplasma activity test showed that Methanol: water (F-4) 50 extract was more active than the positive control.

CONCLUSIONS

Indeed, the extract allowed a survival rate of 10% of the mice, compared to 0% for all the other groups. D. kotschyi has the potential to be valorized in the management of toxoplasmosis.

Epigenetic Manipulation of Psychiatric Behavioral Disorders Induced by Toxoplasma gondii

Toxoplasma gondii is known to have a complex life cycle and infect almost all kinds of warm-blooded animals around the world. The brain of the host could be persistently infected by cerebral cysts, and a variety of psychiatric disorders such as schizophrenia and suicide have been reported to be related with latent toxoplasmosis. The infected animals showed fear reduction and a tendency to be preyed upon. However, the mechanism of this “parasites manipulation” effects have not been elucidated. Here, we reviewed the recent infection prevalence of toxoplasmosis and the evidence of mental and behavioral disorders induced by T. gondii and discussed the related physiological basis including dopamine dysregulation and gamma-aminobutyric acid (GABA) pathway and the controversial opinion of the necessity for cerebral cysts existence. Based on the recent advances, we speculated that the neuroendocrine programs and neurotransmitter imbalance may play a key role in this process. Simultaneously, studies in the evaluation of the expression pattern of related genes, long noncoding RNAs (lncRNAs), and mRNAs of the host provides a new point for understanding the mechanism of neurotransmitter dysfunction induced by parasite manipulation. Therefore, we summarized the animal models, T. gondii strains, and behavioral tests used in the related epigenetic studies and the responsible epigenetic processes; pinpointed opportunities and challenges in future research including the causality evidence of human psychiatric disorders, the statistical analysis for rodent-infected host to be more vulnerable preyed upon; and identified responsible genes and drug targets through epigenetics.

Molecular detection of Toxoplasma gondii in placentas of women who received therapy during gestation in a toxoplasmosis outbreak

Toxoplasmosis is a disease caused by T. gondii, a protozoa which affects humans and animals and is widely distributed worldwide. In humans, there is great concern due to the serious consequences that can occur in the infection of pregnant women and the newborn. The early diagnosis of gestational toxoplasmosis is important for treatment to be carried out in order to prevent vertical transmission or reduce damage. The diagnosis can be made through the detection of antibodies in pregnant women or neonates and PCR of amniotic fluid. Previous studies have also reported PCR of the placenta as a good diagnostic test. Our study evaluated the detection of T. gondii DNA in placenta samples from parturients seen at the University Hospital of Santa Maria, Southern Brazil and treated during the pregnancy. We performed PCR in forty samples and five were positive, representing 12.5%. When correlating the treatment time and the detection of DNA in the placentas, no significant result was found. The prevalence of positive samples was lower than in other studies in the literature. The data reaffirm the importance of carrying out the analysis of the placenta.

Biogenic silver nanoparticles (AgNp-Bio) reduce Toxoplasma gondii infection and proliferation in HeLa cells, and induce autophagy and death of tachyzoites by apoptosis-like mechanism

Toxoplasma gondii is a protozoan parasite that can cause severe and debilitating diseases, especially in immunocompromised individuals. The available treatment is based on drugs that have low efficacy, high toxicity, several adverse effects, and need long periods of treatment. Thus, the search for therapeutic alternatives is urgently needed. Biogenic silver nanoparticles (AgNp-Bio) have been associated with several biological effects, as antiproliferative, pro-apoptotic, antioxidant, antiviral, antifungal, and antiprotozoal activity. Thus, the objective was evaluating AgNp-Bio effect on HeLa cells infected with T. gondii (RH strain). First, nontoxic AgNp-Bio concentrations for HeLa cells (1.5 - 6 µM) were determined, which were tested on cells infected with T. gondii. A significant reduction in infection, proliferation, and intracellular parasitic load was observed, also an increase in ROS and IL-6. Additionally, the evaluation of the action mechanisms of the parasite showed that AgNp-Bio acts directly on tachyzoites, inducing depolarization of the mitochondrial membrane, ROS increase, and lipid bodies accumulation, as well as triggering an autophagic process, causing damage to the parasite membrane, and phosphatidylserine exposure. Based on this, it was inferred that AgNp-Bio affects T. gondii by inducing immunomodulation and microbicidal molecules produced by infected cells, and acts on parasites, by inducing autophagy and apoptosis.

Serological evidence of exposure to Toxoplasma gondii infection in wild birds and local chickens (Gallus gallus domesticus) in Plateau State, North Central Nigeria

Toxoplasma gondii, the cause of toxoplasmosis is an obligate intracellular protozoan parasite of veterinary and public health importance. Ground feeding birds play an active role in the epidemiology of the disease and are the best indicators of soil contamination with the oocysts. Thirteen (14.1%; 95% CI = 7.7-23.0) of the 92 wild birds (6 of Coliformes; 4 of Columbiformes; 67 of Passeriformes and 15 of Piciformes) captured from Shere hills and 43 (9.3%; 95%CI = 4.9-12.4) of the 460 local chickens obtained across 3 senatorial regions of Plateau State, Nigeria were positive for anti-T. gondii antibodies using enzyme linked immunosorbent assay (ELISA). Varying prevalence (16.7-100%) of anti-T. gondii antibodies were recorded across 10 of 35 wild bird species; 2 (28.6) of 7 African thrush (Turdus pelios), 2 (33.3) of 6 speckled mouse bird (Colius striatus), 1 (20.0%) of 5 speckled fronted weaver (Sporopipes frontalis), 1 (33.3%) of 3 Northern Red bishop (Euplectes franciscanus), 1 (50.0%) of 2 village weaver (Ploceus cucullatus), 2 (28.6%) of 7 common bulbul (Pycnonotus barbatus), 1 (50.0%) of 2 black crowned tchagra (Tchagra senegalus), 1 (50.0%) of 2 black billed wood dove (Turtur abyssinicus), 1 (100.0%) of 1 mocking cliff chat (Thamnolaea cinamomeiventris), 1 (16.7) of 6 vieillot's barbet (Lybius vieilloti). The prevalence did not vary significantly based on the sex (p = 0.14), feeding guild (p = 0.53) and the taxonomic order (p = 0.62) of the wild birds. Regional based prevalence among local chickens ranged between 8.0 and 11.8% across the 3 senatorial zones. The source (p = 0.513; 95% CI = 4.9-16.8) and age (p = 0.797; 95% CI = 4.9-16.8) of local chickens were not associated with T. gondii seropositivity. Seropositivity was higher in the females (95% CI = 9.1-18.3) than in the males (p = 0.004; 95% CI = 3.0-9.4). This is the first report of the serological evidence of exposure to T. gondii infection in a wide variety of wild birds and local chickens in the area. It suggest that birds in this region are important asymptomatic intermediate hosts and play a role in the maintenance of the organism in the ecosystem.

Lymphotoxin β Receptor: a Crucial Role in Innate and Adaptive Immune Responses against Toxoplasma gondii

The lymphotoxin β receptor (LTβR) plays an essential role in the initiation of immune responses to intracellular pathogens. In mice, the LTβR is crucial for surviving acute toxoplasmosis; however, until now, a functional analysis was largely incomplete. Here, we demonstrate that the LTβR is a key regulator required for the intricate balance of adaptive immune responses. Toxoplasma gondii-infected LTβR-deficient (LTβR^−/−) mice show globally altered interferon-γ (IFN-γ) regulation, reduced IFN-γ-controlled host effector molecule expression, impaired T cell functionality, and an absent anti-parasite-specific IgG response, resulting in a severe loss of immune control of the parasites. Reconstitution of LTβR^−/− mice with toxoplasma immune serum significantly prolongs survival following T. gondii infection. Notably, analysis of RNA-seq data clearly indicates a specific effect of T. gondii infection on the B cell response and isotype switching. This study uncovers the decisive role of the LTβR in cytokine regulation and adaptive immune responses to control T. gondii.

Descriptive Comparison of ELISAs for the Detection of Toxoplasma gondii Antibodies in Animals: A Systematic Review

Toxoplasma gondii is the zoonotic parasite responsible for toxoplasmosis in warm-blooded vertebrates. This systematic review compares and evaluates the available knowledge on enzyme-linked immunosorbent assays (ELISAs), their components, and performance in detecting T. gondii antibodies in animals. Four databases were searched for published scientific studies on T. gondii and ELISA, and 57 articles were included. Overall, indirect (95%) and in-house (67%) ELISAs were the most used types of test among the studies examined, but the 'ID Screen® Toxoplasmosis Indirect Multi-species' was common among commercially available tests. Varying diagnostic performance (sensitivity and specificity) and Kappa agreements were observed depending on the type of sample (serum, meat juice, milk), antigen (native, recombinant, chimeric) and antibody-binding reagents used. Combinations of recombinant and chimeric antigens resulted in better performance than native or single recombinant antigens. Protein A/G appeared to be useful in detecting IgG antibodies in a wide range of animal species due to its non-species-specific binding. One study reported cross-reactivity, with Hammondia hammondi and Eimeria spp. This is the first systematic review to descriptively compare ELISAs for the detection of T. gondii antibodies across different animal species.

Biogenic Silver Nanoparticles Can Control Toxoplasma gondii Infection in Both Human Trophoblast Cells and Villous Explants

The combination of sulfadiazine and pyrimethamine plus folinic acid is the conventional treatment for congenital toxoplasmosis. However, this classical treatment presents teratogenic effects and bone marrow suppression. In this sense, new therapeutic strategies are necessary to reduce these effects and improve the control of infection. In this context, biogenic silver nanoparticles (AgNp-Bio) appear as a promising alternative since they have antimicrobial, antiviral, and antiparasitic activity. The purpose of this study to investigate the action of AgNp-Bio in BeWo cells, HTR-8/SVneo cells and villous explants and its effects against Toxoplasma gondii infection. Both cells and villous explants were treated with different concentrations of AgNp-Bio or combination of sulfadiazine + pyrimethamine (SDZ + PYZ) in order to verify the viability. After, cells and villi were infected and treated with AgNp-Bio or SDZ + PYZ in different concentrations to ascertain the parasite proliferation and cytokine production profile. AgNp-Bio treatment did not reduce the cell viability and villous explants. Significant reduction was observed in parasite replication in both cells and villous explants treated with silver nanoparticles and classical treatment. The AgNp-Bio treatment increased of IL-4 and IL-10 by BeWo cells, while HTR8/SVneo cells produced macrophage migration inhibitory factor (MIF) and IL-4. In the presence of T. gondii, the treatment induced high levels of MIF production by BeWo cells and IL-6 by HTR8SV/neo. In villous explants, the AgNp-Bio treatment downregulated production of IL-4, IL-6, and IL-8 after infection. In conclusion, AgNp-Bio can decrease T. gondii infection in trophoblast cells and villous explants. Therefore, this treatment demonstrated the ability to reduce the T. gondii proliferation with induction of inflammatory mediators in the cells and independent of mediators in chorionic villus which we consider the use of AgNp-Bio promising in the treatment of toxoplasmosis in BeWo and HTR8/SVneo cell models and in chorionic villi.

The congenital toxoplasmosis burden in Brazil: Systematic review and meta-analysis

Congenital toxoplasmosis is a zoonosis caused by the intracellular Apicomplexa protozoan Toxoplasma gondii. This infection causes subclinical or clinical lesions, such as retinochoroiditis and central nervous system lesions. The severity of fetal infection is related to the stage of pregnancy and the efficacy of the gestational treatment on fetal infection, whether it is achieved, or if it starts early. South America is the region with the highest burden of congenital toxoplasmosis and the most pathogenic genotypes. Here, we present the results of a comprehensive systematic review and meta-analysis of the congenital toxoplasmosis in Brazil. PubMed, Web of Science, and CAPES databases were used to search for relevant studies that were published between 1 January 2007 and 31 December 2018. The final searching process yielded 21 papers. The studies accounted for 469 children with congenital toxoplasmosis. Of these, 269 (57%) had a diagnosis in the postnatal period. Concerning mothers, 209 (44.6%) underwent prenatal care, but 47 (22.5%) did not receive any drug for toxoplasmosis treatment. There were 226 (48.2%) children with retinochoroiditis; 83 (17.7%) with brain calcifications; 9 (1.9%) with neurosensory auditory dysfunction; and 2 (0.42%) with human immunodeficiency virus coinfection. A total of 460 (98%) children had a medical and multidisciplinary follow-up for at least one year and the most frequent genotype was #11(BRII), found in seven children. There was a statistical correlation between the mother's treatment and asymptomatic children. The gestational treatment seems to protects the fetus since children of mothers who received anti-T. gondii medications have a better prognosis. The retinochoroiditis was the main finding among children, followed by brain calcifications.

Review on the Current Trends of Toxoplasmosis Serodiagnosis in Humans

Toxoplasmosis is a widely distributed zoonotic infection caused by the obligate intracellular apicomplexan parasite Toxoplasma gondii. It is mainly transmitted through the ingestion of oocysts shed by an infected cat acting as its definitive host. The key to effective control and treatment of toxoplasmosis is prompt and accurate detection of T. gondii infection. Several laboratory diagnostic methods have been established, including the most commonly used serological assays such as the dye test (DT), direct or modified agglutination test (DAT/MAT), indirect hemagglutination test (IHA), latex agglutination test (LAT), indirect immunofluorescent test (IFAT), enzyme-linked immunosorbent assays (ELISA), immunochromatographic tests (ICT), and the western blot. Nonetheless, creating specific and reliable approaches for serodiagnosis of T. gondii infection, and differentiating between acute and chronic phases of infection remains a challenge. This review provides information on the current trends in the serodiagnosis of human toxoplasmosis. It highlights the advantages of the use of recombinant proteins for serological testing and provides insight into the possible future direction of these methods.

Arctigenin exhibits hepatoprotective activity in Toxoplasma gondii-infected host through HMGB1/TLR4/NF-κB pathway

Toxoplasmosis is a parasitic zoonosis with the highest incidence in humans. Severe lesions due to acute toxoplasmosis have been recorded in the visceral organs including the liver, where hepatocytes and Kupffer cells are important innate immune cells. Arctigenin (AG) is a bioactive ingredient of Arctium lappa L. and increasing evidence suggests that AG exhibits anti-oxidant, anti-inflammatory and anti-Toxoplasma gondii (T. gondii) effects. However, the role of AG in acute liver damage induced by T. gondii infection remains unclear. In this study, we analyzed the effects of AG against T. gondii-induced liver damage by establishing an in vitro infection model using a murine liver cell line (NCTC-1469 cells) and an in vivo mouse model with acute T. gondii infection of virulent RH strain. In the current study, AG effectively attenuated hepatocytes apoptosis and inhibited the reproduction of T. gondii. The results of in vitro and in vivo studies showed that AG significantly reduced alanine aminotransferase/aspartate aminotransferase activities and lessened pathological damage of liver. Moreover, AG suppressed T. gondii-induced inducible nitric oxide synthase production. AG also attenuated liver inflammation by inhibiting T. gondii-induced activation of the high-mobility group box1/toll-like receptor 4/nuclear factor-kappa B (HMGB1/TLR4/NF-κB) signaling pathway. These findings demonstrated that AG exhibited prominent hepatoprotective activities in toxoplasmic liver injury with anti-inflammatory effects by inhibiting the HMGB1/TLR4/NF-κB signaling axis. Thus, this study provides the basis for the development of new drugs to treat toxoplasmic hepatitis.

Frequency and factors associated with Toxoplasma gondii infection in pregnant women and their pets in Ilhéus, Bahia, Brazil

INTRODUCTION

Toxoplasmosis is an asymptomatic disease that can lead to systemic disease in the fetus of pregnant women with primary infection. This study aimed to determine the prevalence of toxoplasmosis, associated factors, and correlation between the serology of pregnant women and their pets, in the municipality of Ilhéus, Bahia, Brazil.

METHODS

This cross-sectional study was conducted in 196 pregnant women and their cats or dogs (n=89). Semi-structured interviews were conducted and serum samples from the pregnant women were tested to detect IgM and IgG antibodies against Toxoplasma gondii, and avidity tests were performed for IgM-positive samples. The serum collected from pets were tested for IgG antibodies, and IgM antibodies in cats. A non-conditional logistic regression analysis was performed to identify infection-associated factors.

RESULTS

IgG and IgM antibodies were detected in 67.9% (133/196) and 1.5% (3/196) samples, respectively, for women with an avidity of over 60%. Age ≥ 25 and the presence of cats in the vicinity were found to be associated with infection, while the level of education and previous orientation toward prevention of toxoplasmosis were protective factors in pregnant women. IgG antibodies were detected in 46.1% (41/89) of the animals, and cats were found to be negative for IgM. For the animals, age ≥ 1 year was a factor associated with infection. There was no correlation between serology of the pregnant women and the animals (p=0.15).

CONCLUSIONS

An elevated prevalence of toxoplasmosis was detected in the region. Therefore, the adoption of preventive measures by public healthcare bodies is recommended.

Atovaquone-proguanil exposure in pregnancy and risk for adverse fetal and infant outcomes: A retrospective analysis

BACKGROUND

Malaria in pregnancy can cause severe maternal and fetal complications. Chloroquine (CQ) and mefloquine (MQ) are recommended for chemoprophylaxis in pregnancy, but are not always suitable. Atovaquone-proguanil (AP) might be a viable option for malaria prevention in pregnancy, but more safety data are needed.

METHODS

Data for pregnancies and live births among active duty military women, 2003-2014, from the Department of Defense Birth and Infant Health Research program were linked with pharmacy data to determine antimalarial exposure. Multivariable Cox and logistic regression models were used to assess the relationship of antimalarial exposure with fetal and infant outcomes, respectively.

RESULTS

Among 198,164 pregnancies, 50 were exposed to AP, 156 to MQ, and 131 to CQ. Overall, 17.6% of unexposed pregnancies and 28.0%, 16.0%, and 6.1% of pregnancies exposed to AP, MQ, and CQ, respectively, ended in fetal loss (spontaneous abortion or stillbirth) (adjusted hazard ratios [aHR] = 1.46, 95% confidence interval [CI] 0.87-2.46; aHR = 1.06, 95% CI 0.72-1.57; and aHR = 0.47, 95% CI 0.24-0.94, respectively).

CONCLUSIONS

The small number of AP exposed pregnancies highlights the difficulty in assessing safety. While definitive conclusions are not possible, these data suggest further research of AP exposure in pregnancy and fetal loss is warranted.

TWITTER LINE

More research on fetal loss following atovaquone-proguanil exposure in pregnancy is warranted.

Parasites in brains of wild rodents (Arvicolinae and Murinae) in the city of Leipzig, Germany

Small rodents serve as intermediate or paratenic hosts for a variety of parasites and may participate in the transmission of these parasites into synanthropic cycles. Parasites with neuroinvasive stages, such as Toxoplasma gondii or Toxocara canis, can cause detrimental damage in the brain of intermediate or paratenic hosts. Therefore, the occurrence of neuroinvasive parasite stages was evaluated in brains of wild rodents captured in the city of Leipzig, Germany. In addition, a few specimens from the cities of Hanover, Germany, and Vienna, Austria were included, resulting in a total of 716 rodents collected between 2011 and 2016. Brains were investigated for parasitic stages by microscopic examination of native tissue, artificially digested tissue as well as Giemsa-stained digestion solution to verify positive results. Infective stages of zoonotic ascarids or other helminths were not detected in any sample, while coccidian cysts were found in 10.1% (95% CI: 7.9–12.5%; 72/716) of examined brains. The most abundant rodent species in the study was the bank vole (Myodes glareolus; Arvicolinae), showing an infection rate with cerebral cysts of 13.9% (95% CI: 11.0–17.8%; 62/445), while 2.7% (95% CI: 1.0–5.8%; 6/222) of yellow-necked mice (Apodemus flavicollis; Murinae) were infected. Generalized linear modelling revealed a statistically significant difference in prevalence between M. glareolus and A. flavicollis, significant local differences as well as an effect of increasing body mass on cyst prevalence. Coccidian cysts were differentiated by amplification of the 18S rRNA gene and subsequent sequencing. The majority of identifiable cysts (97.9%) were determined as Frenkelia glareoli, a coccidian species mainly circulating between M. glareolus as intermediate and buzzards (Buteo spp.) as definitive hosts. The zoonotic pathogen Toxoplasma gondii was confirmed in one M. glareolus originating from the city of Leipzig. Overall, it can be concluded that neuroinvasion of zoonotic parasites seems to be rare in M. glareolus and A. flavicollis.

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In examined rodents, neuroinvasion of zoonotic parasites seems to be rare.

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The coccidia Frenkelia glareoli was the most abundant neuroinvasive parasite.

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The zoonotic pathogen Toxoplasma gondii was identified in one Myodes glareolus brain.

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No neuroinvasive zoonotic helminth stages were detected in the rodents’ brains.

Safety of atovaquone-proguanil during pregnancy

BACKGROUND

Malaria during pregnancy increases the risk of maternal and foetal complications. There are very limited options for prophylaxis in pregnant travellers. Atovaquone-Proguanil (AP or Malarone®) is an effective and well-tolerated antimalarial medication, but is not recommended for use in pregnancy due to limited data on safety. Passively reported adverse event data may provide additional information on the safety of AP during pregnancy.

METHODS

We analysed adverse event data on pregnancy and birth outcomes following accidental exposures to AP during pregnancy, which were passively reported to GlaxoSmithKline LLC (GSK) between 13 May 1997 and 15 August 2017. Birth outcomes of interest included live birth, miscarriage, and stillbirth. Adverse outcomes of interest were defined as any of the following: small for gestational age (SGA), low birth weight (LBW, <2500 gm), congenital anomalies, and a composite 'poor live birth outcome,' including preterm birth (PTB), LBW or SGA.

RESULTS

Among 198 women who received AP during pregnancy or breastfeeding, 96.5% occurred in women taking malaria prophylaxis, and 79.8% of exposures occurred in the first trimester. Among 195 with available birth outcome data, 18.5% resulted in miscarriage and 11.8% were elective terminations. Available adverse outcomes included SGA in 3.5% (3/85), LBW in 7.0% of infants (6/86), and the composite 'poor live birth outcome' in 13.7% (14/102). Congenital anomalies were reported in 30/124 (24.2%), with no specific pattern to suggest an effect related to AP.

CONCLUSIONS

These data provide a description of outcomes in the pregnancies reported to this dataset, and it should be noted that there is likely a bias towards reporting cases resulting in poor outcomes. While there was no specific signal to suggest a teratogenic effect of AP, AP data during pregnancy were too limited to determine AP's safety with confidence. As inadvertent exposures are not infrequent, better data are needed.

Exploring protein myristoylation in Toxoplasma gondii

Toxoplasma gondii is an important human and veterinary pathogen and the causative agent of toxoplasmosis, a potentially severe disease especially in immunocompromised or congenitally infected humans. Current therapeutic compounds are not well-tolerated, present increasing resistance, limited efficacy and require long periods of treatment. On this context, searching for new therapeutic targets is crucial to drug discovery. In this sense, recent works suggest that N-myristoyltransferase (NMT), the enzyme responsible for protein myristoylation that is essential in some parasites, could be the target of new anti-parasitic compounds. However, up to date there is no information on NMT and the extent of this modification in T. gondii. In this work, we decided to explore T. gondii genome in search of elements related with the N-myristoylation process. By a bioinformatics approach it was possible to identify a putative T. gondii NMT (TgNMT). This enzyme that is homologous to other parasitic NMTs, presents activity in vitro, is expressed in both intra- and extracellular parasites and interacts with predicted TgNMT substrates. Additionally, NMT activity seems to be important for the lytic cycle of Toxoplasma gondii. In parallel, an in silico myristoylome predicts 157 proteins to be affected by this modification. Myristoylated proteins would be affecting several metabolic functions with some of them being critical for the life cycle of this parasite. Together, these data indicate that TgNMT could be an interesting target of intervention for the treatment of toxoplasmosis.

Congenital toxoplasmosis: An overview of the neurological and ocular manifestations

Toxoplasma gondii is an obligate intracellular parasite which is known to infect one-third of the total world population chronically though it is asymptomatic in immunocompetent patients. However, in an immunocompromised patient or an infected fetus, it may cause devastating effects. The parasite may cross the placenta of an infected pregnant woman and probably infect the fetus congenitally. The severity of the infection depends on the gestational age at which the infection has occurred i.e., if it has occurred in the early phase, the rate of transmission is low but the severity is high if the fetus is infected and if it has occurred in the later phase then transmission rate is higher while the severity would be low. Congenital toxoplasmosis may result in non-specific consequences like abortion, intra-uterine growth restriction, jaundice, hepatosplenomegaly or even intra-uterine death. It may also result in neurological or ocular manifestations like intracranial calcifications, hydrocephalus or retinochoroiditis. The diagnosis may be done by serological screening of anti-Toxoplasma antibodies (IgM and IgG) while PCR of the amniotic fluid or the placenta is the confirmatory test. Acute or chronic infections may be differentiated by IgG avidity tests. The treatment regimens include spiramycin to prevent congenital transmission from an infected mother, pyrimethamine, sulfadoxine and folinic acid to treat the infected fetus, CSF shunting for the treatment of hydrocephalus and a combination of pyrimethamine, azithromycin, and corticosteroids for treating ocular toxoplasmosis.

A survey on outcomes of accidental atovaquone-proguanil exposure in pregnancy

BACKGROUND

Malaria chemoprophylaxis options in pregnancy are limited, and atovaquone-proguanil (AP) is not recommended because of insufficient safety evidence. An anonymous, internet-based survey was disseminated to describe outcomes of pregnancies accidentally exposed to AP. Outcomes of interest included miscarriage (defined as pregnancy loss before 20 weeks), stillbirth (defined as pregnancy loss at or after 20 weeks), preterm birth or live birth prior to 37 weeks, and the presence of congenital anomalies.

RESULTS

A total of 487 women responded and reported on 822 pregnancies. Of the 807 pregnancies with information available on exposure and outcomes, 10 (1.2%) had atovaquone-proguanil exposure, all in the first trimester, and all resulted in term births with no birth defects.

CONCLUSIONS

Use of an anti-malarial not recommended in pregnancy is likely to occur before the woman knows of her pregnancy. This study adds to the limited evidence of the safety of AP in pregnancy. Further study on use of AP in pregnancy should be a high priority, as an alternative option for the prevention of malaria in pregnancy in non-immune travellers is urgently needed.

A mechanistic study of Toxoplasma gondii ROP18 inhibiting differentiation of C17.2 neural stem cells

Background

Congenital infection of Toxoplasma gondii is an important factor causing birth defects. The neural stem cells (NSCs) are found to be one of the target cells for the parasite during development of the brain. As a key virulence factor of the parasite that hijacks host cellular functions, ROP18 has been demonstrated to mediate the inhibition of host innate and adaptive immune responses through specific binding different host immunity related molecules. However, its pathogenic actions in NSCs remain elusive.

Results

In the present study, ROP18 recombinant adenovirus (Ad-ROP18) was constructed and used to infect C17.2 NSCs. After 3d- or 5d–culture in differentiation medium, the differentiation of C17.2 NSCs and the activity of the Wnt/β-catenin signaling pathway were detected. The results showed that the protein level of βIII-tubulin, a marker of neurons, in the Ad-ROP18-transfected C17.2 NSCs was significantly decreased, indicating that the differentiation of C17.2 NSCs was inhibited by the ROP18. The β-catenin level in the Ad-ROP18-transfected C17.2 NSCs was found to be lower than that in the Ad group. Also, neurogenin1 (Ngn1) and neurogenin2 (Ngn2) were downregulated significantly (P < 0.05) in the Ad-ROP18-transfected C17.2 NSCs compared to the Ad group. Accordingly, the TOP flash/FOP flash dual-luciferase report system showed that the transfection of Ad-ROP18 decreased the Wnt/β-catenin pathway activity in the C17.2 NSCs.

Conclusions

The inhibition effect of the ROP18 from T. gondii (TgROP18) on the neuronal differentiation of C17.2 NSCs was at least partly mediated through inhibiting the activity of the Wnt/β-catenin signaling pathway, eventually resulting in the downregulation of Ngn1 and Ngn2. The findings help to better understand potential mechanisms of brain pathology induced by TgROP18.

SAG4 DNA and Peptide Vaccination Provides Partial Protection against T. gondii Infection in BALB/c Mice

Toxoplasma gondii can lead to congenital infections in human. Surface antigen protein 4 (SAG4) of T. gondii is a potential stimulator for humoral and cellular immune responses. In the present study, a DNA vaccine encoding SAG4 from T. gondii was constructed and used to immunize BALB/c mice with peptide to evaluate the protective efficacy of the vaccine. The productions of IgG antibodies and cytokines (gamma interferon) from the vaccine (pSAG4/peptide) group were significantly higher than pSAG4 or peptide groups. After a lethal challenge by 1 × 10⁴ tachyzoites from the I strain (RH), the survival time of mice immunized by pSAG4/peptide was longer than that of pSAG4 or peptide immunized mice or control mice. Moreover, after challenging by 20 cysts of the II strain (PRU) of T. gondii, the number of brain cysts from pSAG4/peptide vaccinated mice was only 31% of the number in PBS injected mice. The findings suggested the SAG4 DNA vaccine with peptide led significant immune responses and improved the protection against T. gondii challenges.

Infectious causes of microcephaly: epidemiology, pathogenesis, diagnosis, and management

Microcephaly is an important sign of neurological malformation and a predictor of future disability. The 2015-16 outbreak of Zika virus and congenital Zika infection brought the world's attention to links between Zika infection and microcephaly. However, Zika virus is only one of the infectious causes of microcephaly and, although the contexts in which they occur vary greatly, all are of concern. In this Review, we summarise important aspects of major congenital infections that can cause microcephaly, and describe the epidemiology, transmission, clinical features, pathogenesis, management, and long-term consequences of these infections. We include infections that cause substantial impairment: cytomegalovirus, herpes simplex virus, rubella virus, Toxoplasma gondii, and Zika virus. We highlight potential issues with classification of microcephaly and show how some infants affected by congenital infection might be missed or incorrectly diagnosed. Although Zika virus has brought the attention of the world to the problem of microcephaly, prevention of all infectious causes of microcephaly and appropriately managing its consequences remain important global public health priorities.

Association of Parasite Load Levels in Amniotic Fluid With Clinical Outcome in Congenital Toxoplasmosis

OBJECTIVE

To correlate neonatal and infant clinical outcome with parasite load in amniotic fluid (AF).

METHODS

We conducted a retrospective cohort study of 122 children whose mothers had toxoplasmosis during pregnancy. The children were monitored from birth to 12 months old. Stored AF samples were obtained at maternal diagnosis and tested by quantitative polymerase chain reaction. Gestational age at maternal infection, quantitative polymerase chain reaction results, neonatal anti-Toxoplasma gondii immunoglobulin (Ig) M, and clinical outcome at 12 months were correlated.

RESULTS

Maternal infection occurred in 18 of 122 (14.7%) and 104 of 122 (85.2%) women in the first and second trimesters, respectively. At birth, IgM was present in 107 of 122 (87.7%) neonates and 36 (29.5%) were symptomatic. Of these, half occurred in the first and the other half in the second trimester and 6 of 36 had severe infections (16.7% of symptomatic, 4.9% of total), all infected in the first trimester. Parasite load levels were highly variable (median 35 parasites/mL, range 2-30,473). Logistic regression correlated symptomatic infection with gestational age (odds ratio [OR] 0.47, CI 0.31-0.73) and parasite load (OR 2.04, CI 1.23-3.37), but not with positive IgM (OR 6.81, CI 0.86-53.9). Negative correlations were found between gestational age and parasite load (rs -0.780, CI -0.843 to -0.696), gestational age and symptoms (rs -0.664, CI -0.755 to -0.547), but not gestational age and IgM (rs -0.136, CI -0.311 to 0.048). Parasite load levels distributed by percentile showed that all symptomatic patients appeared from the 75th percentile and all severe infections from the 95th percentile. Load rankings showed doubled the OR for each 20 parasite/mL increment. Parasite load was associated with symptomatic infections (area under the curve 0.959, CI 0.908-0.987) as well as gestational age (area under the curve 0.918, CI 0.855-0.960) and both parameters combined (area under the curve 0.969, CI 0.920-0.992).

CONCLUSION

Parasite load in AF is associated with the clinical outcome in congenital toxoplasmosis, irrespective of gestational age at maternal infection.

SAG5B and SAG5C combined vaccine protects mice against Toxoplasma gondii infection

Infections with the protozoan parasite Toxoplasma gondii, which are common around the world, can lead to congenital infections in humans. T. gondii surface antigen protein 5B (SAG5B) and SAG5C are potential stimulators of humoral and cellular immune responses. In this study, a multi-antigenic DNA vaccine constructed to express T. gondii SAG5B and SAG5C proteins simultaneously was used to immunize BALB/c mice to evaluate the protective efficacy of the vaccine. IgG antibody and gamma interferon (IFN-γ) cytokine production in the pSAG5B/SAG5C DNA vaccine group were significantly higher (0.853±0.103 and 915.2±106.9, respectively) than in the single DNA vaccine groups (pSAG5B, 0.667±0.109 and 598.3±74.9, respectively; pSAG5C, 0.696±0.092 and 623.7±95.5, respectively). After a lethal challenge with 1×10⁴ RH strain tachyzoites, the survival time of the mice (17days) immunized with pSAG5B/SAG5C was longer than that of the single-gene-immunized mice (12days) or the control mice (6days). Moreover, after intragastric infection with 20 T. gondii PRU (low virulence) strain cysts, the number of brain cysts in the pSAG5B/SAG5C-vaccinated mice was only 25% of the number for the PBS-injected mice. Our findings indicate that, in comparison with the other mouse groups, the multi-antigenic DNA vaccine (pSAG5B/SAG5C) significantly induced immune responses and improved the protection against challenge with T. gondii in the host animals.

Toxoplasma Effectors Targeting Host Signaling and Transcription

Early electron microscopy studies revealed the elaborate cellular features that define the unique adaptations of apicomplexan parasites. Among these were bulbous rhoptry (ROP) organelles and small, dense granules (GRAs), both of which are secreted during invasion of host cells. These early morphological studies were followed by the exploration of the cellular contents of these secretory organelles, revealing them to be comprised of highly divergent protein families with few conserved domains or predicted functions. In parallel, studies on host-pathogen interactions identified many host signaling pathways that were mysteriously altered by infection. It was only with the advent of forward and reverse genetic strategies that the connections between individual parasite effectors and the specific host pathways that they targeted finally became clear. The current repertoire of parasite effectors includes ROP kinases and pseudokinases that are secreted during invasion and that block host immune pathways. Similarly, many secretory GRA proteins alter host gene expression by activating host transcription factors, through modification of chromatin, or by inducing small noncoding RNAs. These effectors highlight novel mechanisms by which T. gondii has learned to harness host signaling to favor intracellular survival and will guide future studies designed to uncover the additional complexity of this intricate host-pathogen interaction.

Nanomedicine advances in toxoplasmosis: diagnostic, treatment, and vaccine applications

Toxoplasmosis is an infectious disease caused by the intracellular parasite Toxoplasma gondii that affects about one third of the world's population. The diagnosis of this disease is carried out by parasite isolation and host antibodies detection. However, the diagnosis presents problems in regard to test sensitivity and specificity. Currently, the most effective T. gondii treatment is a combination of pyrimethamine and sulfadiazine, although both drugs are toxic to the host. In addition to the problems that compromise the effective diagnosis and treatment of toxoplasmosis, there are no reports or indications of any vaccine capable of fully protecting against this infection. Nanomaterials, smaller than 1000 nm, are currently being investigated as an alternative tool in the management of T. gondii infection. This article reviews how recent nanotechnology advances indicate the utility of nanomaterials in toxoplasmosis diagnosis, treatment, and vaccine development.

Protective immune response in mice induced by a suicidal DNA vaccine encoding NTPase-II gene of Toxoplasma gondii

DNA-based alphaviral RNA replicon vectors, also called suicidal DNA vectors, have been employed to alleviate biosafety concerns attribution to its ability to induce apoptotic cell death of the transfected cells. Toxoplasma gondii nucleoside triphosphate hydrolase-II (TgNTPase-II), which facilitates the parasite to salvage purines from the host cell for survival and replication, have been demonstrated to be a potential vaccine candidate for toxoplasmosis. Herein, we evaluated the immunogenic potential of a suicidal DNA vaccine encoding TgNTPase-II gene, pDREP-TgNTPase-II, delivered intramuscularly in combination with electroporation. Immunization of mice with pDREP-TgNTPase-II elicited specific humoral responses, with high IgG antibody titers and a mixed IgG1/IgG2a response. The cellular immune response was associated with high level production of IFN-γ, IL-2, IL-10 cytokines and low level IL-4 production as well as the increase of the percentage of CD8+ T cells, indicating that a Th1 predominant response was elicited. Furthermore, mice vaccinated with this suicidal DNA vaccine displayed partial protection against acute infection with the virulent RH strain as well as chronic infection with PRU cyst, which shows 77.7% and 71.4% reduction in brain cyst burden in comparison to PBS and pDREP-eGFP control group, respectively. Based on the cellular and antibody responses, the suicidal DNA vaccine elicited a Th1-predominant immune response against T. gondii challenge.

Genetic Polymorphisms and Phenotypic Profiles of Sulfadiazine-Resistant and Sensitive Toxoplasma gondii Isolates Obtained from Newborns with Congenital Toxoplasmosis in Minas Gerais, Brazil

Background

Previous Toxoplasma gondii studies revealed that mutations in the dhps (dihydropteroate synthase) gene are associated with resistance to sulfonamides. Although Brazilian strains are genotypically different, very limited data are available regarding the susceptibility of strains obtained from human to sulfonamides. The aim of this study was to evaluate the efficacy of sulfadiazine (SDZ) against Brazilian isolates of T. gondii and verify whether isolates present polymorphisms in the dhps gene. We also investigated whether the virulence-phenotype and/or genotype were associated with the profile of susceptibility to SDZ.

Methods

Five T. gondii isolates obtained from newborns with congenital toxoplasmosis were used to verify susceptibility. Mice were infected with 10⁴ tachyzoites and orally treated with different doses of SDZ. The mortality curve was evaluated by the Log-rank test. The presence of polymorphisms in the dhps gene was verified using sequencing. A descriptive analysis for 11 Brazilian isolates was used to assess the association between susceptibility, genotype, and virulence-phenotype.

Results

Statistical analysis showed that TgCTBr03, 07, 08, and 16 isolates were susceptible to SDZ, whereas TgCTBr11 isolate presented a profile of resistance to SDZ. Nineteen polymorphisms were identified in dhps exons. Seven polymorphisms corresponded to non-synonymous mutations, with four being new mutations, described for the first time in this study. No association was found between the profile of susceptibility and the virulence-phenotype or genotype of the parasite.

Conclusions

There is a high variability in the susceptibilities of Brazilian T. gondii strains to SDZ, with evidence of drug resistance. Despite the large number of polymorphisms identified, the profile of susceptibility to SDZ was not associated with any of the dhps variants identified in this study. Other genetic factors, not yet determined, may be associated with the resistance to SDZ; thus, further studies are needed as a basis for a more adequate toxoplasmosis treatment.

Seroepidemiological study of toxoplasmosis in southern districts of Tamil Nadu

The current study was conducted with the objectives of estimating the seroprevalence of Toxoplasma gondii and associated socio-demographic, clinical and behavioural characteristics in and around Tirunelveli. Serum samples from 175 immunodeficient and 175 immunocompetent patients were collected and were analyzed by in-house enzyme linked immunosorbent assay (ELISA). A questionnaire survey was administered for all study participants to gather information on risk factors. The present study revealed that anti- T. gondii IgG antibodies were detected in 13.14 % which constitutes 15.43 % in immunocompromised and 10.86 % in immunocompetent patients. There was a significant difference between sex of the study population and drinking water source. Seroprevalence was increased in the male (19.12 %, p = 0.0075, OR 2.316, 95 % CI 1.2362-4.3405) than the female and with river water consumption other than bore water (12.5 %, p = 0.0483, OR 0.857, 95 % CI 0.1853-3.4641). No significant relations were observed between anti-Toxoplasma IgG antibodies and age, residence, diet and animal contact in the study population. Toxoplasmosis will remain a problem, mainly in risk groups such as pregnant women and immunocompromised patients. Improvement can only be attained by increasing prevention and reducing the risk factors.

Toxoplasma gondii inhibits differentiation of C17.2 neural stem cells through Wnt/β-catenin signaling pathway

Toxoplasma gondii is a major cause of congenital brain disease. T. gondii infection in the developing fetus frequently results in major neural developmental damage; however, the effects of the parasite infection on the neural stem cells, the key players in fetal brain development, still remain elusive. This study is aiming to explore the role of T. gondii infection on differentiation of neural stem cells (NSCs) and elucidate the underlying molecular mechanisms that regulate the inhibited differentiation of NSCs induced by the infection. Using a differentiation medium, i.e. , DMEM: F12 (1:1 mixture) supplemented with 2% N2, C17.2 neural stem cells (NSCs) were able to differentiate to neurons and astrocytes, respectively evidenced by immunofluorescence staining of differentiation markers including βIII-tubulin and glial fibrillary acidic protein (GFAP). After 5-day culture in the differentiation medium, the excreted-secreted antigens of T. gondii (Tg-ESAs) significantly down-regulated the protein levels of βIII-tubulin and GFAP in C17.2 NSCs in a dose-dependent manner. The protein level of β-catenin in the nucleus of C17.2 cells treated with both wnt3a (a key activator for Wnt/β-catenin signaling pathway) and Tg-ESAs was significantly lower than that in the cells treated with only wnt3a, but significantly higher than that in the cells treated with only Tg-ESAs. In conclusion, the ESAs of T. gondii RH blocked the differentiation of C17.2 NCSs and downregulated the expression of β-catenin, an essential component of Wnt/β-catenin signaling pathway. The findings suggest a new mechanism underlying the neuropathogenesis induced by T. gondii infection, i.e. inhibition of the differentiation of NSCs via blockade of Wnt/β-catenin signaling pathway, such as downregulation of β-catenin expression by the parasite ESAs.

Immunity in the spleen and blood of mice immunized with irradiated Toxoplasma gondii tachyzoites

Toxoplasma gondii infection induces a strong and long-lasting immune response that is able to prevent most reinfections but allows tissue cysts. Irradiated, sterilized T. gondii tachyzoites are an interesting vaccine, and they induce immunity that is similar to infection, but without cysts. In this study, we evaluated the cellular immune response in the blood and spleen of mice immunized with this preparation by mouth (v.o.) or intraperitoneally (i.p.) and analyzed the protection after challenge with viable parasites. BALB/c mice were immunized with three i.p. or v.o. doses of irradiated T. gondii tachyzoites. Oral challenge with ten cysts of the ME-49 or VEG strain at 90 days after the last dose resulted in high levels of protection with low parasite burden in the immunized animals. There were higher levels of specific IgG, IgA and IgM antibodies in the serum, and the i.p. immunized mice had higher levels of the high-affinity IgG and IgM antibodies than the orally immunized mice, which had more high-affinity IgA antibodies. B cells (CD19(+)), plasma cells (CD138(+)) and the CD4(+) and CD8(+) T cell populations were increased in both the blood and spleen. Cells from the spleen of the i.p. immunized mice also showed antigen-induced production of interleukin-10 (IL-10), interferon gamma (IFN-γ) and interleukin 4 (IL-4). The CD4(+) T cells, B cells and likely CD8(+) T cells from the spleens of the i.p. immunized mice proliferated with a specific antigen. The protection was correlated with the spleen and blood CD8(+) T cell, high-affinity IgG and IgM and antigen-induced IL-10 and IL-4 production. Immunization with irradiated T. gondii tachyzoites induces an immune response that is mediated by B cells and CD4(+) and CD8(+) T cells, with increased humoral and cellular immune responses that are necessary for host protection after infection. The vaccine is similar to natural infection, but free of tissue cysts; this immunity restrains infection at challenge and can be an attractive and efficient model for vaccine development in toxoplasmosis.

Effect of Propranolol Alone and in Combination with Pyrimethamine on Acute Murine Toxoplasmosis

Background:

Toxoplasmosis is a public health problem worldwide. This complication principally affects immunodeficient patients and pregnant women. Toxoplasma gondii is an opportunistic parasite, causing severe illness among and death of high-risk individuals and treatment is becoming increasingly difficult owing to side effects and low efficacies of drugs.

Objectives:

In this study, we investigated the anti-Toxoplasma gondii efficacy of propranolol in vivo.

Materials and Methods:

This study was performed in two separate pre-treatment and post-treatment groups. In each group, 18 female Balb/c mice in six subgroups (n = 3) were used to assess the anti-Toxoplasma effect of propranolol at 2 and 3 mg/kg/day, pyrimethamine at 50 mg/kg/day, propranolol at 2 and 3 mg/kg/day plus pyrimethamine, and phosphate-buffered saline (PBS; as negative control). Treatment was performed 4, 24, and 48 hours before and after an intraperitoneal challenge of 1 × 10³ tachyzoites of the virulent RH strain of T. gondii, in pre-treatment and post-treatment groups. Mice peritoneal exudates were collected on the seventh day after the challenge and parasite numbers were recorded as percent of growth inhibition and survival rate.

Results:

In the pre-treatment group, results showed that propranolol at 2 and 3 mg/kg combined with pyrimethamine was more effective in inhibiting growth of tachyzoites (86% and 98%, respectively) when compared with propranolol at 2 and 3 mg/kg (37% and 39%, respectively) and pyrimethamine (41%) alone. In the post-treatment group, all combined treatments significantly reduced parasite load. The growth inhibition of tachyzoites in mice receiving propranolol (2 and 3 mg/kg) was 75% and 51%, with the mean tachyzoites count being 1526 ± 171.4 and 2948 ± 1452.8, respectively, compared with pyrimethamine treatment outcome, which represents 99.9% growth inhibition.

Conclusions:

Our results demonstrated the promising prophylactic and therapeutic effects of propranolol against T. gondii infection. Propranolol also increases the efficacy of pyrimethamine in combination therapies.

A long-lasting protective immunity against chronic toxoplasmosis in mice induced by recombinant rhoptry proteins encapsulated in poly (lactide-co-glycolide) microparticles

Toxoplasma gondii infection in humans and animals is a worldwide zoonosis. Prevention and control of toxoplasmosis based on vaccination is one of the promising strategies. In the present study, recombinant T. gondii rhoptry proteins 38 and 18 (TgROP38 and TgROP18) were encapsulated into poly (lactide-co-glycolide) (PLG) (1:1), respectively, to obtain the stable water-in-oil-in-water double emulsion. Female Kunming mice were then immunized with the protein vaccines twice at a 2-week interval. Eight weeks after the second immunization, 10 mice from each group were challenged with T. gondii PRU strain (genotype II). The entrapment rates of PLG-rROP38 and PLG-rROP18 ranged from 65.5 to 77.7% and 58.1 to 72.3%, respectively. Immunization of mice with rROP38 and rROP18 proteins encapsulated into PLG microparticles elicited strongly humoral and cell-mediated responses against T. gondii, associated with relatively high levels of total IgG, IgG2a isotype, and IFN-γ, as well as the mixed Th1/Th2 immunity responses. Immunization with various protein vaccines induced significant reduction of the brain cysts after chronic infection with the T. gondii PRU strain, and the most effective protection was achieved in the PLG-rROP38-rROP18-immunized mice, with a cyst reduction of 81.3%. The findings of the present study indicated that recombinant rhoptry antigens encapsulated in PLG could maintain the protein immunogenicity in an extended period and elicit effective protection against chronic T. gondii infection, which has implications for the development of long-lasting vaccines against chronic toxoplasmosis in animals.

In Vivo Efficacy of Drugs against Toxoplasma gondii Combined with Immunomodulators

The aim of this study is to evaluate the effects of pyrimethamine (PYR) and sulfadiazine (SDZ) combined with levamisole and echinacea on the survival of mice infected with Toxoplasma gondii. For this, we used 99 specific pathogen-free BALB/c mice. All the mice were infected intraperitoneally with 10(5) T. gondii tachyzoites and were divided into 11 groups, each including 9 mice. Except for the control group, oral treatment was initiated in all groups 24 h post infection and was continued for 10 days. The treatment regimen included dual combinations of PYR (dose, 6.25 and 12.5 mg/kg/day) and SDZ (dose, 100 and 200 mg/kg/day), triple combinations of PYR + SDZ, and levamisole (dose, 2.5 mg/kg/day) or echinacea (dose, 130 and 260 mg/kg/day) and echinacea alone (dose, 130 and 260 mg/kg/day). We observed that an effective dose of the combination of PYR + SDZ and levamisole resulted in a statistically significant increase in the survival rate from 33.3% to 88.9%. Similarly, half the dose of this combination resulted an increase in the survival rate from 0% to 44.4% (p < 0.05). Survival rate also increased in the groups treated with the combinations including echinacea; however, the difference did not reach statistical significance. The triple combination of PYR-SDZ-levamisole could be an alternative treatment option in case of infections caused by T. gondii.