In vitro anti-Toxoplasma gondii activity of Ganoderma lucidum extracts.

OBJECTIVE: Ganoderma extracts have the potential to be used as anti-cancer, anti-inflammatory, immunomodulator, and antimicrobial agents, as evaluated in numerous studies. This study was aimed to determine the lethal and inhibitory effects of aqueous, hydroalcoholic, and alcoholic extracts of Ganoderma lucidum on Toxoplasma gondii RH strain tachyzoites, in vitro. RESULTS: All three types of extracts showed toxoplasmacidal effects. The highest percentage of mortality was related to hydroalcoholic extract. The EC50 of Ganoderma extracts for tachyzoites were 76.32, 3.274, and 40.18 for aqueous, hydroalcoholic and alcoholic extracts, respectively. The selectivity index obtained for hydroalcoholic extract was 71.22, showing the highest activity compared to other extracts. According to our findings, the hydroalcoholic part was the most effective substance among the extracts. This basic study showed obvious anti-toxoplasma effect of Ganoderma lucidum extracts. These extracts can be used as candidates for further in-depth and comprehensive studies especially In vivo experiments to prevent toxoplasmosis.

Herd-level based seroprevalence and associated factors for Toxoplasma gondii in cows in the state of Paraíba, Northeastern Brazil.

We aimed to determine the herd and animal levels seroprevalence and associated factors for Toxoplasma gondii infections in cattle from the state of Paraíba, Northeastern Brazil. Herds (n = 434) and cows aged ≥ 24 months (n = 1,895) were randomly selected, and serum samples were tested with the immunofluorescence antibody test (IFAT) using as cutoff of 64. Of the 434 farms investigated, 197 had at least one seropositive cow (prevalence of 49.0%; 95% CI = 44.3%-53.8%), and the prevalence at animal level was 18.0% (95% CI = 5.3%-21.1%). The antibody titers ranged from 64 to 1024, with the most frequent titers being 64 (10.8%) and 128 (3.7%). The risk factors identified were property located in Sertão region (odds ratio [OR] = 3.07), property located in Agreste/Zona da Mata regions (OR = 2.00), animal purchasing (OR = 2.68), herd size of 34-111 animals (OR = 2.91) and herd size > 111 animals (OR = 6.97). The results suggest the wide distribution of T. gondii infections in cattle throughout the state of Paraíba, and the risk factors identified are not possible to correct.

Type I and III interferons shape the retinal cytokine network and barrier function in an in vitro model of ocular toxoplasmosis.

Introduction: The particularities of the ocular immune environment and its barrier protection in the context of infection are not well elucidated. The apicomplexan parasite Toxoplasma gondii is one of the pathogens successfully crossing this barrier and establishing chronic infection in retinal cells. Methods: As a first approach, we studied the initial cytokine network in vitro in four human cell lines: Retinal pigmented epithelial (RPE), microglial, astrocytic and Müller cells. Furthermore, we looked at the consequences of retinal infection on the integrity of the outer blood-retina barrier (oBRB). We particularly focused on the roles of type I and type III interferons, (IFN-ß and IFN-λ). Especially IFN-λ is known for its significant role in barrier defense. However, its effect on the retinal barrier or T. gondii infection remains unexplored, unlike IFN-γ, which has been extensively studied in this context. Results and Discussion: Here, we show that stimulation with type I and III interferons did not limit parasite proliferation in retinal cells we tested. However, IFN-ß and IFN-γ strongly induced inflammatory or cell-attracting cytokine production, whereas IFN-λ1 showed less inflammatory activity. Concomitant T. gondii infection influenced these cytokine patterns, distinctly depending on the parasite strain. Interestingly, all these cells could be stimulated to produce IFN-λ1. Using an in vitro oBRB model based on RPE cells, we observed that interferon stimulation strengthened membrane localization of the tight junction protein ZO-1 and enhanced their barrier function, in a STAT1-independent manner. Conclusion: Together, our model shows how T. gondii infection shapes the retinal cytokine network and barrier function, and demonstrates the role of type I and type III interferons in these processes.

A state-of-the-art methodology for high-throughput in silico vaccine discovery against protozoan parasites and exemplified with discovered candidates for Toxoplasma gondii.

Vaccine discovery against eukaryotic parasites is not trivial as highlighted by the limited number of known vaccines compared to the number of protozoal diseases that need one. Only three of 17 priority diseases have commercial vaccines. Live and attenuated vaccines have proved to be more effective than subunit vaccines but adversely pose more unacceptable risks. One promising approach for subunit vaccines is in silico vaccine discovery, which predicts protein vaccine candidates given thousands of target organism protein sequences. This approach, nonetheless, is an overarching concept with no standardised guidebook on implementation. No known subunit vaccines against protozoan parasites exist as a result of this approach, and consequently none to emulate. The study goal was to combine current in silico discovery knowledge specific to protozoan parasites and develop a workflow representing a state-of-the-art approach. This approach reflectively integrates a parasite's biology, a host's immune system defences, and importantly, bioinformatics programs needed to predict vaccine candidates. To demonstrate the workflow effectiveness, every Toxoplasma gondii protein was ranked in its capacity to provide long-term protective immunity. Although testing in animal models is required to validate these predictions, most of the top ranked candidates are supported by publications reinforcing our confidence in the approach.

MyosinA is a druggable target in the widespread protozoan parasite Toxoplasma gondii.

Toxoplasma gondii is a widespread apicomplexan parasite that can cause severe disease in its human hosts. The ability of T. gondii and other apicomplexan parasites to invade into, egress from, and move between cells of the hosts they infect is critical to parasite virulence and disease progression. An unusual and highly conserved parasite myosin motor (TgMyoA) plays a central role in T. gondii motility. The goal of this work was to determine whether the parasite's motility and lytic cycle can be disrupted through pharmacological inhibition of TgMyoA, as an approach to altering disease progression in vivo. To this end, we first sought to identify inhibitors of TgMyoA by screening a collection of 50,000 structurally diverse small molecules for inhibitors of the recombinant motor's actin-activated ATPase activity. The top hit to emerge from the screen, KNX-002, inhibited TgMyoA with little to no effect on any of the vertebrate myosins tested. KNX-002 was also active against parasites, inhibiting parasite motility and growth in culture in a dose-dependent manner. We used chemical mutagenesis, selection in KNX-002, and targeted sequencing to identify a mutation in TgMyoA (T130A) that renders the recombinant motor less sensitive to compound. Compared to wild-type parasites, parasites expressing the T130A mutation showed reduced sensitivity to KNX-002 in motility and growth assays, confirming TgMyoA as a biologically relevant target of KNX-002. Finally, we present evidence that KNX-002 can slow disease progression in mice infected with wild-type parasites, but not parasites expressing the resistance-conferring TgMyoA T130A mutation. Taken together, these data demonstrate the specificity of KNX-002 for TgMyoA, both in vitro and in vivo, and validate TgMyoA as a druggable target in infections with T. gondii. Since TgMyoA is essential for virulence, conserved in apicomplexan parasites, and distinctly different from the myosins found in humans, pharmacological inhibition of MyoA offers a promising new approach to treating the devastating diseases caused by T. gondii and other apicomplexan parasites.

Toxoplasmosis in ring-tailed lemurs (Lemur catta) and a peahen (Pavo cristatus) in a zoological collection caused by the common toxoplasma genotype in wild animals in the US.

Toxoplasmosis is caused by the ubiquitous Apicomplexan protozoan Toxoplasma gondii. This pathogen affects domestic and wildlife species, but prosimians including ring-tailed lemurs (Lemur catta) are highly susceptible to infection with high mortality rates. Avian species are considered resistant to infection and are often used in surveillance efforts to determine genotypes of T. gondii present in geographical areas. This study describes the gross and histologic lesions of an outbreak of toxoplasmosis in a university-run zoological collection involving three ring-tailed lemurs and a peahen (Pavo cristatus). DNA was extracted from the liver of the lemurs and peahen to determine the genotype of T. gondii by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP), which revealed that all samples were ToxoDB PCR-RFLP genotype #5 (haplogroup 12) that is common in wildlife in North America.

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.

Defects in immune response to Toxoplasma gondii are associated with enhanced HIV-1-related neurocognitive impairment in co-infected patients.

Human immunodeficiency virus-1 (HIV-1) and Toxoplasma gondii can invade the central nervous system and affect its functionality. Advanced HIV-1 infection has been associated with defects in immune response to T. gondii, leading to reactivation of latent infections and development of toxoplasmic encephalitis. This study evaluates relationship between changes in immune response to T. gondii and neurocognitive impairment in HIV-1/T. gondii co-infected patients, across different stages of HIV-1 infection. The study assessed the immune response to T. gondii by measuring cytokine production in response to parasite antigens, and also neurocognitive functions by performing auditory and visual P300 cognitive evoked potentials, short term memory (Sternberg) and executive function tasks (Wisconsin Card Sorting Test-WCST) in 4 groups of individuals: HIV-1/T. gondii co-infected (P2), HIV-1-infected/T. gondii-non-infected (P1), HIV-1-non-infected/T. gondii-infected (C2) and HIV-1-non-infected/T. gondii-non-infected (C1). Patients (P1 and P2) were grouped in early/asymptomatic (P1A and P2A) or late/symptomatic (P1B/C and P2B/C) according to peripheral blood CD4+ T lymphocyte counts (>350 or <350/µL, respectively). Groups were compared using T-student or U-Mann-Whitney tests as appropriate, p<0.05 was considered as significantly. For P300 waves, HIV-1-infected patients (P1) had significantly longer latencies and significantly smaller amplitudes than uninfected controls, but HIV-1/T. gondii co-infected patients (P2) had significantly longer latencies and smaller amplitude than P1. P1 patients had significantly poorer results than uninfected controls in Sternberg and WCST, but P2 had significantly worse results than P1. HIV-1 infection was associated with significantly lower production of IL-2, TNF-α and IFN-γ in response to T. gondii from early/asymptomatic stages, when comparing P2 patients to C2 controls. These findings may indicate impairment in anti-parasitic response in co-infected patients, facilitating early limited reactivation of the parasitic latent infection, therefore creating cumulative damage in the brain and affecting neurocognitive functions from asymptomatic stages of HIV-1 infection, as suggested by defects in co-infected patients in this study.

Antibacterial and anti-Toxoplasma activities of Aspergillus niger endophytic fungus isolated from Ficus retusa: in vitro and in vivo approach.

Emergent records propose that Aspergillus niger endophytic fungus is a vital source for various bioactive molecules possessing many biological properties. The current study was designed to inspect the antibacterial and anti-Toxoplasma potentials of Ficus retusa-derived endophytic fungi. After isolation and identification (using 18S rRNA gene sequencing) of A. niger endophytic fungus, LC/MS was utilized for identification and authentication of the chemical profile of the A. niger endophyte extract. Then, the fungal extract was assessed for its antibacterial and antibiofilm activities against Klebsiella pneumoniae clinical isolates. Additionally, its efficacy against Toxoplasma gondii was elucidated in vivo. The fungal extract displayed antibacterial activity against K. pneumoniae isolates with minimum inhibitory concentration values of 64-512 µg/mL. It also possessed a membrane potential dissipating effect using flow cytometry. Moreover, it formed distorted cells with rough surfaces and deformed shapes using a scanning electron microscope (SEM). Regarding its antibiofilm activity, it resulted in a dysregulation of the genes encoding biofilm formation (fimH, mrkA and mrkD) using qRT-PCR in nine K. pneumoniae isolates. The in vivo anti-Toxoplasma potential was demonstrated by decreasing the mortality rate of mice and reducing the tachyzoites' count in the peritoneal fluids and liver impression smears of mice. In addition, the deformities of the parasite decreased, as revealed by SEM and the inflammation in tissues diminished. Thus, A. niger endophytic fungi could be a valuable source of antibacterial and anti-Toxoplasma compounds.

Toxoplasma gondii infection in Egyptian domestic sheep and goats: seroprevalence and risk factors.

Toxoplasma gondii is an apicomplexan protozoan parasite that has been associated with reproductive failure in small ruminants. Although T. gondii infections in ruminants and humans have been recorded in several Egypt's governorates, but little is known about the risk factors associated with T. gondii infections. In this study, 350 sheep and 290 goat serum samples from three governorates in Egypt were examined for presence of antibodies against T. gondii, and evaluate the associate risk factors for the infection. The seroprevalence in sheep and goats was 24% and 38.28%, respectively. In sheep and goats, age, sex, the presence of cats, and hygienic conditions were identified as risk factors for T. gondii infection. In addition, the prevalence rates were significantly higher in older animals more than 2 years old, females, among animals contacted with cats, and animals living in bad hygienic condition. In conclusion, sheep and goats in the examined regions are commonly infected with T. gondii. The identification of risk variables defines the sort of actions to be implemented in order to decrease, and prevent T. gondii infection in small ruminant animals and, as a result, human infection.

Occurrence of IgG antibodies against Toxoplasma gondii, Neospora caninum, and Leptospira spp. in goats and sheep from an indigenous village in Pernambuco, Brazil.

This study aimed to determine the occurrence of anti-Toxoplasma gondii, Neospora caninum, and Leptospira spp. antibodies in sheep and goats raised in villages of the Xukuru do Ororubá indigenous community, Pernambuco, Brazil. A total of 180 serum samples from sheep and 108 serum samples from goats of both sexes and different ages were analyzed. For antibody research, indirect immunofluorescence antibody test (IFAT) were used for the protozoa T. gondii and N. caninum, and microscopic agglutination test (MAT) for Leptospira spp., with a cutoff titer of 1:64, 1:50 and 1:100, respectively. The frequency of anti-T. gondii antibodies was 16.6% (30/180) for sheep and 11.1% (12/108) for goats. The frequency of anti-N. caninum antibodies was 10.55% (19/180) for sheep, and 20.37% (22/108) for goats, while for Leptospira spp., 2.2% (4/180) of sheep and 1.85% (2/108) of goats reacted positively. The results obtained in this study are unprecedented in indigenous communities in the country and serve as an alert for monitoring goats and sheep from the Xukuru do Ororubá indigenous village regarding the occurrence and productive impact of infections by T. gondii, N. caninum, and Leptospira spp., in addition to the occurrence of the zoonosis toxoplasmosis and leptospirosis in the indigenous community.

In vitro and in vivo susceptibility to sulfadiazine and pyrimethamine of Toxoplasma gondii strains isolated from Brazilian free wild birds.

Little is known about the existence of drug-resistant Toxoplasma gondii strains and their possible impact on clinic outcomes. To expand our knowledge about the existence of natural variations on drug susceptibility of T. gondii strains in Brazil, we evaluated the in vitro and in vivo susceptibility to sulfadiazine (SDZ) and pyrimethamine (PYR) of three atypical strains (Wild2, Wild3, and Wild4) isolated from free-living wild birds. In vitro susceptibility assay showed that the three strains were equally susceptible to SDZ and PYR but variations in the susceptibility were observed to SDZ plus PYR treatment. Variations in the proliferation rates in vitro and spontaneous conversion to bradyzoites were also accessed for all strains. Wild2 showed a lower cystogenesis capacity compared to Wild3 and Wild4. The in vivo analysis showed that while Wild3 was highly susceptible to all SDZ and PYR doses, and their combination, Wild2 and Wild4 showed low susceptibility to the lower doses of SDZ or PYR. Interestingly, Wild2 presented low susceptibility to the higher doses of SDZ, PYR and their combination. Our results suggest that the variability in treatment response by T. gondii isolates could possibly be related not only to drug resistance but also to the strain cystogenesis capacity.

Toxoplasma gondii-derived antigen modifies tumor microenvironment of Ehrlich solid carcinoma murine model and enhances immunotherapeutic activity of cyclophosphamide.

Pathogen-based cancer vaccine is a promising immunotherapeutic weapon to stimulate cancer immunosuppressive state. Toxoplasma gondii is a potent immunostimulant, and low-dose infection was linked to cancer resistance. Our goal was to evaluate the therapeutic antineoplastic activity of autoclaved Toxoplasma vaccine (ATV) against Ehrlich solid carcinoma (ESC) in mice in reference to and in combination with low-dose cyclophosphamide (CP), a cancer immunomodulator. Mice inoculation with ESC was followed by applying different treatment modalities including ATV, CP, and CP/ATV. We evaluated the impact of the different treatments on liver enzymes and pathology, tumor weight, volume, and histopathological changes. Using immunohistochemistry, we evaluated CD8+ T cell, FOXP3+ Treg, CD8+/Treg outside and inside ESC, and angiogenesis. Results showed significant tumor weights and volumes reduction with all treatments with 13.3% inhibition of tumor development upon combined CP/ATV use. Significant necrosis and fibrosis were noted in ESC by all treatments with improved hepatic functions versus non-treated control. Although ATV was almost equivalent to CP in tumor gross and histopathology, it promoted an immunostimulatory activity with significant Treg cells depletion outside ESC and CD8+ T cells infiltration inside ESC with higher CD8+ T/Treg ratio inside ESC superior to CP. Combined with CP, ATV exhibited significant synergistic immunotherapeutic and antiangiogenic action compared to either treatment alone with significant Kupffer cells hyperplasia and hypertrophy. Exclusively, therapeutic antineoplastic and antiangiogenic activity of ATV against ESC was verified that boosted CP immunomodulatory action which highlights a novel biological cancer immunotherapeutic vaccine candidate.

Novel therapeutic opportunities for Toxoplasma gondii, Trichomonas vaginalis, and Giardia intestinalis infections.

INTRODUCTION: Toxoplasma gondii, Trichomonas vaginalis, and Giardia intestinalis are the causative agents of toxoplasmosis, trichomoniasis, and giardiasis, three important infections threatening human health and affecting millions of people worldwide. Although drugs and treatment are available to fight these protozoan parasites, side effects and increasing drug resistance require continuous efforts for the development of novel effective drugs. AREAS COVERED: The patents search was carried out in September/October 2022 with four official scientific databases (Espacenet, Scifinder, Reaxys, Google Patents). Treatments for toxoplasmosis, trichomoniasis, and giardiasis (2015-2022) have been grouped according to their chemotypes. In particular, novel chemical entities have been reported and investigated for their structure-activity relationship, when accessible. On the other hand, drug repurposing, extensively exploited to obtain novel antiprotozoal treatment, has been in-depth described. Finally, natural metabolites and extracts have also been reported. EXPERT OPINION: T. gondii, T. vaginalis, and G. intestinalis are protozoan infections usually controlled by immune system in immunocompetent patients; however, they could represent a threatening health for immunocompromised people. The needs of novel effective drugs, endowed with new mechanisms of actions, arises from the increasing drug resistance affecting antibiotic as well as antiprotozoal therapies. In this review different therapeutic approaches to treat protozoan infections have been reported.

Occurrence of Apicomplexa protozoa in wild birds in the Northeast region of Brazil.

Protozoa of the Apicomplexa phylum are worldwide distributed with capacity to infect endothermic animals. The study of these protozoa in wild birds in Brazil is scarce. This study aimed to evaluate the occurrence of apicomplexan protozoa in wild birds in the Northeast of Brazil. From October to December 2019, brain tissue samples were collected from 71 captive birds from the Wild Animal Screening Center of the Pernambuco State (CETRAS-Tangara) and 25 free-living birds from the Caatinga biome in Rio Grande do Norte, totaling 96 animals (41 species). Brain fragments were subjected to molecular diagnosis by nested PCR for the 18s rDNA gene of Apicomplexa parasites, followed by DNA sequencing. This gene was detected in 25% (24/96) of the samples, and it was possible to perform DNA sequencing of 14 samples, confirming three genera: Isospora, Sarcocystis and Toxoplasma from eight bird species (Amazona aestiva, Coereba flaveola, Egretta thula, Paroaria dominicana, Sporophila nigricollis, Cariama cristata, Columbina talpacoti, Crypturellus parvirostris). The occurrence these coccidia in wild birds provides important epidemiological information for the adoption of preventive measures for its conservation. Future studies are needed to better understand the consequence of Apicomplexa infection in birds in Caatinga and Atlantic Forest biomes.

Tim-3 regulates the immunosuppressive function of decidual MDSCs via the Fyn-STAT3-C/EBPß pathway during Toxoplasma gondii infection.

Myeloid-derived suppressor cells (MDSCs) play a key role in maintaining maternal-fetal tolerance for a successful pregnancy, but the role of MDSCs in abnormal pregnancy caused by Toxoplasma gondii infection is unknown. Herein, we revealed a distinct mechanism by which T-cell immunoglobulin domain and mucin domain containing protein-3 (Tim-3), an immune checkpoint receptor that balances maternal-fetal tolerance during pregnancy, contributes to the immunosuppressive function of MDSCs during T. gondii infection. The expression of Tim-3 in decidual MDSCs was significantly downregulated following T. gondii infection. The proportion of monocytic MDSCs population, the inhibitory effect of MDSCs on T-cell proliferation, the levels of STAT3 phosphorylation, and the expression of functional molecules (Arg-1 and IL-10) in MDSCs were all decreased in T. gondii-infected pregnant Tim-3 gene knockout (Tim-3KO) mice compared with infected pregnant WT mice. After treatment with Tim-3-neutralizing Ab in vitro, the expression levels of Arg-1, IL-10, C/EBPß, and p-STAT3 were decreased, the interaction between Fyn and Tim-3 or between Fyn and STAT3 was weakened, and the binding ability of C/EBPß to the promoters of ARG1 and IL10 was decreased in human decidual MDSCs with T. gondii infection, while opposite results were observed following treatment with galectin-9 (a ligand for Tim-3). Inhibitors of Fyn and STAT3 also downregulated the expression of Arg-1 and IL-10 in decidual MDSCs and exacerbated adverse pregnancy outcomes caused by T. gondii infection in mice. Therefore, our studies discovered that the decrease of Tim-3 after T. gondii infection could downregulate the functional molecules of Arg-1 and IL-10 expression in decidual MDSCs through the Fyn-STAT3-C/EBPß signaling pathway and weaken their immunosuppressive function, which eventually contribute to the development of adverse pregnancy outcomes.

ROP16-mediated activation of STAT6 enhances cyst development of type III Toxoplasma gondii in neurons.

Toxoplasma gondii establishes a long-lived latent infection in the central nervous system (CNS) of its hosts. Reactivation in immunocompromised individuals can lead to life threatening disease. Latent infection is driven by the ability of the parasite to convert from the acute-stage tachyzoite to the latent-stage bradyzoite which resides in long-lived intracellular cysts. While much work has focused on the parasitic factors that drive cyst development, the host factors that influence encystment are not well defined. Here we show that a polymorphic secreted parasite kinase (ROP16), that phosphorylates host cell proteins, mediates efficient encystment of T. gondii in a stress-induced model of encystment and primary neuronal cell cultures (PNCs) in a strain-specific manner. Using short-hairpin RNA (shRNA) knockdowns in human foreskin fibroblasts (HFFs) and PNCs from transgenic mice, we determined that ROP16's cyst enhancing abilities are mediated, in part, by phosphorylation-and therefore activation-of the host cell transcription factor STAT6. To test the role of STAT6 in vivo, we infected wild-type (WT) and STAT6KO mice, finding that, compared to WT mice, STAT6KO mice have a decrease in CNS cyst burden but not overall parasite burden or dissemination to the CNS. Finally, we found a similar ROP16-dependent encystment defect in human pluripotent stem cell-derived neurons. Together, these findings identify a host cell factor (STAT6) that T. gondii manipulates in a strain-specific manner to generate a favorable encystment environment.

Structural and regulatory insights into the glideosome-associated connector from Toxoplasma gondii.

The phylum of Apicomplexa groups intracellular parasites that employ substrate-dependent gliding motility to invade host cells, egress from the infected cells, and cross biological barriers. The glideosome-associated connector (GAC) is a conserved protein essential to this process. GAC facilitates the association of actin filaments with surface transmembrane adhesins and the efficient transmission of the force generated by myosin translocation of actin to the cell surface substrate. Here, we present the crystal structure of Toxoplasma gondii GAC and reveal a unique, supercoiled armadillo repeat region that adopts a closed ring conformation. Characterisation of the solution properties together with membrane and F-actin binding interfaces suggests that GAC adopts several conformations from closed to open and extended. A multi-conformational model for assembly and regulation of GAC within the glideosome is proposed.

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

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

Protective effect of luteoloside against Toxoplasma gondii-induced liver injury through inhibiting TLR4/NF-κB and P2X7R/NLRP3 and enhancing Nrf2/HO-1 signaling pathway.

Toxoplasma gondii (T. gondii) infection can cause liver injury by inducing inflammation and oxidative stress. The Chinese herbal extract luteoloside (Lut) has considerable anti-inflammatory and antioxidant properties, but its effects on the liver injury during T. gondii infection have not been reported. This study investigated the hepatoprotective effects of Lut by treating T. gondii-infected mice with 0-200 mg/kg doses of Lut and further examined the expression of key proteins in the inflammation and oxidative stress-related pathways in the liver to investigate the potential mechanism of the hepatoprotective effects of Lut. Results showed that Lut remarkably reduced serum ALT and AST levels, considerably decreased inflammatory factors TNF-α, IL-6, and IL-1ß, as well as oxidative products MDA, and greatly increased antioxidant enzymes SOD and GSH. The expression of key proteins TLR4, Myd88, TRAF6, p-NF-κB p65 in the TLR4/NF-κB pathway and P2X7R, NLRP3, caspase 1, IL-1ß, IL-18 in the P2X7R/NLRP3 pathway were significantly decreased in the liver. And the expression of key proteins Nrf2, HO-1, NQO-1, and GCLC in the Nrf2/HO-1 antioxidant-related pathway was significantly upregulated. In conclusion, Lut attenuated T. gondii-induced liver injury by inhibiting the inflammatory response and enhancing antioxidant capacity. The hepatoprotective mechanisms of Lut are involved in inhibiting TLR4/NF-κB and P2X7R/NLRP3 inflammatory signaling pathways, as well as enhancing the Nrf2/HO-1 antioxidant pathway. These findings not only provide some reference for further exploring the specific hepatoprotective mechanism of Lut during T. gondii infection, but also provide some theoretical basis for the future clinical application of Lut as a hepatoprotective drug in T. gondii infection.