RH Strain Research Articles

Anti-Toxoplasma gondii effects of XYP1-derived peptides and regulatory mechanisms of XYP1

BackgroundToxoplasmosis, caused by Toxoplasma gondii , poses serious health issues for humans and animals. Individuals with impaired immune systems are more susceptible to severe toxoplasmosis. Pregnant women infected by T. gondii can face the possibility of birth defects and miscarriages. While pyrimethamine and sulfadiazine are commonly used drugs in clinical practice, concerns over their side effects and resistance are on the rise. A spider peptide XYP1 isolated from Lycosa coelestis had potent anti-T. gondii effects, but it had a high synthesis cost and strong cytotoxicity.MethodsThis study intended to modify XYP1 for producing derived peptides via amino acid truncation and substitution. The anti-T. gondii effect was evaluated by trypan blue staining assay and killing experiment of RH strain tachyzoites. The CCK8 and hemolysis assays were used to compare their safeties. The morphological changes of T. gondii were observed by scanning electron microscope and transmission electron microscope. In addition, the mechanism of XYP1 against T. gondii through RNA-sequencing was further explored.ResultsIn vivo and in vitro experiments revealed that XYP1-18 and XYP1-18-1 had excellent anti-T. gondii activity with lower cytotoxicity and hemolysis activity than XYP1. XYP1, XYP1-18, and XYP1-18-1 were able to disrupt the surface membrane integrity of T. gondii tachyzoites, forming pores and causing the disruption of organelles. Furthermore, RNA-sequencing analysis indicated that XYP1 could stimulate the host immune response to effectively eliminate T. gondii and lessen the host’s inflammatory reaction.ConclusionsXYP1-18 had lower cytotoxicity and hemolysis activity than XYP1, as well as significantly extending the survival time of the mice. XYP1 played a role in host inflammation and immune responses, revealing its potential mechanism. Our research provided valuable insights into the development and application of peptide-based drugs, offering novel strategies and directions for treating toxoplasmosis.Graphical

Amelioration of dextran sodium sulphate-induced colitis in mice by treatment with Lactobacillus rhamnosus and Lactobacillus reuteri: intraspecific and interspecific patterns

Lactobacillus rhamnosus (Rh) and Lactobacillus reuteri (Re) are well-known probiotic species in inflammatory bowel disease (IBD) research. The variations between these species’ efficacy against colitis, and their model of action in this regard, are intriguing and enable treatment to be individually tailored to patients. In this study, four strains each of Rh and Re were isolated from fecal samples and their draft genomes were sequenced. The anti-colitis activities of both strains involved various aspects of intestinal immune, physical, chemical, and biological barrier function. Strikingly, the tested strains exhibited considerable interspecies and intraspecies specificity in colitis amelioration. Rh strains significantly outperformed Re strains in terms of short-chain fatty acid synthesis. Nevertheless, Re strains were more effective than Rh strains in inhibiting production of inflammatory factors; promoting production of intestinal mucus, antimicrobial peptides, and tight junction proteins; and supporting the stem cell compartment. This accounts for the anti-colitis outcomes of Re strains being superior to those of Rh strains. In addition, the effective Rh and Re strains were found to express high concentrations of specific carbohydrate metabolism- and prophage-related genes, respectively. Taken together, the results of this study could assist researchers in developing effective therapies for IBD.

Functional Characterization of 11 Tentative Microneme Proteins in Type I RH Strain of Toxoplasma gondii Using the CRISPR-Cas9 System.

Toxoplasma gondii, a pathogenic apicomplexan parasite, infects approximately one third of the world's population and poses a serious threat to global public health. Microneme proteins (MICs) secreted by the microneme, an apical secretory organelle of T. gondii, play important roles in the invasion, motility, and intracellular survival of T. gondii. In this study, we selected 11 genes of interest (GOIs) of T. gondii, tentative MICs predicted to be localized in micronemes, and we used the CRISPR-Cas9 system to construct epitope tagging strains and gene knockout strains to explore the localization and function of these 11 tentative MICs. Immunofluorescence assay showed that nine tentative MICs (TGME49_243930, TGME49_200270, TGME49_273320, TGME49_287040, TGME49_261710, TGME49_205680, TGME49_304490, TGME49_245485, and TGME49_224620) were localized or partially localized in the microneme, consistent with the prediction. However, TGME49_272380 and TGME49_243790 showed different localizations from the prediction, being localized in the endoplasmic reticulum and the dense granule, respectively. Further functional characterization of the 11 RHΔGOI strains revealed that deletion of these 11 GOIs had no significant effect on plaque formation, intracellular replication, egress, invasion ability, and virulence of T. gondii. Although these 11 GOIs are not essential genes for the growth and virulence of tachyzoites of type I RH strain, they may have potential roles in other developmental stages or other genotypes of T. gondii. Thus, further research should be performed to explore the possible role of the nine mics and the other two GOIs in other life cycle stages and other genotypes of T. gondii.

Effectiveness of Miltefosine Nanoemulsion Concerning the Treatment of Acute and Chronic Toxoplasmosis: In Vivo Study.

Toxoplasma gondii is one of the most common parasites worldwide. It is of great importance to identify new potential drugs that are effective and less harmful in pregnant women and newborns. We investigated nanoemulsion miltefosine (NEM) in treating experimental acute and chronic toxoplasmosis. A combination of triacetin, Tween 80, and ethanol (1:2) was used for the development of NEM formulations. The size of NEM was calculated to be 17.463 nm by DLS and TEM. To investigate the performance of miltefosine (MLF), NEM, sulfadiazine (SDZ), and pyrimethamine (PYR) (positive control) in vivo, acute toxoplasmosis was induced in mice by an intraperitoneal injection of RH strain tachyzoites. After five days, the mice were examined for the number and condition of tachyzoites and histopathological changes in the liver and spleen. Chronic toxoplasmosis was investigated in rats and the number and size of brain cysts along with histopathological changes were assessed in different groups. The results of the in vivo assessment of drugs in acute toxoplasmosis showed the following order regarding a decrease in the number of tachyzoites and an increase in survival rate: SDZ&PYR > NEM > MLF. The effects of drugs on chronic toxoplasmosis showed a significant effect of NEM (50%) on reducing the number of cysts compared to SDZ&PYR (10%) and MLF (12%) and reducing the size of NEM brain cysts (21%) compared to SDZ&PYR (5 %) and MLF (8%). Increasing the penetration of NEM through the blood-brain barrier (BBB) and subsequently reducing the number and size of T. gondii tissue cysts is a promising new drug in treating chronic toxoplasmosis.

Antiparasitic Effects of Niosomal Formulations of Curcumin and Silymarin Against Toxoplasma gondii In Vitro.

Background: Toxoplasmosis is caused by infection with Toxoplasma gondii. No Symptoms in healthy people. Notably, very dangerous symptoms in immunocompromised, or patients with immune diseases. Previous research has shown that the parasite's resistance to drugs continues to emerge and has indicated this resistance as a cause for concern. In this context, researchers have a great responsibility to search for alternative treatments, as well as to develop existing ones. Essentially, this improves the therapeutic efficacy of drugs and prevents the emergence of resistance to them. The present study aims to evaluate antitoxoplasma effects of niosomal loaded curcumin and silymarin and their synergistic effects with clindamycin against T. gondii RH strain in vitro. Materials and Methods: Experiments were conducted on the tachyzoites of T. gondii RH-strain, based on: the free and nieosomal compounds of curcumin and silymarin, in addition to the drug clindamycin. Data were collected to estimate parasite viability during exposure to the therapeutic compounds under study using a special MTT assay ((3-(4, 5-dimethylthiazolyl-2)-2,5-diphenyltetrazolioum bromide) assay: is a colorimetric assay for measuring cellular growth) kit provided by (Bio Idea Company, Tehran, Iran). Hence, the effect of the therapeutic compounds on the parasite load was studied using the quantitative molecular technique real-time PCR. Results: The results indicate that the combination of N-silymarin and N-curcumin with clindamycin has active synergistic effects against T. gondii leading to complete elimination of the parasite. Data revealed that curcumin and silymarin in both their free and nisomal forms had inhibitory effects on the parasite, and minimal toxic effects on normal cells. Conclusions: The results highlight the successful synergistic effect of clindamycin and the niosomal compounds curcumin and silymarin in completely eradicating the T. gondii RH-strain. This finding contributes positively to the field of safe and effective treatments.

Assessment of nebivolol efficacy in experimental models of toxoplasmosis: insights into parasite burden reduction and neuronal protection.

This study investigates the efficacy of nebivolol (NBV) in experimental models of toxoplasmosis, focusing on parasite burden reduction and neuronal protection. In the acute model of experimental toxoplasmosis, Swiss mice infected with RH strain tachyzoites received oral NBV chlorhydrate doses of 2mg/kg/day and 4mg/kg/day for 8days. Treatment with NBV significantly reduced parasite burden compared to vehicle and standard drug (PYR) groups. In the chronic model of experimental toxoplasmosis, C57/BL6 mice infected with the ME49 strain received NBV chlorhydrate 41days post-infection and were evaluated after 10days of treatment. NBV chlorhydrate effectively reduced cyst number and area, as well as bradyzoite burden compared to controls. Histological analysis demonstrated that NBV chlorhydrate preserved neuronal count, with the 4mg/kg/day dose yielding counts similar to non-infected mice. Statistical analysis confirmed significant differences compared to control groups. Furthermore, immunohistochemical analysis revealed a significant reduction in iNOS labeling in the brains of mice treated with NBV chlorhydrate, indicating a decrease in nitric oxide production compared to control groups. These findings suggest NBV's potential as a promising candidate for toxoplasmosis treatment, highlighting its ability to reduce parasite burden and protect neuronal integrity. Further research is warranted to elucidate NBV's mechanisms of action and its clinical application in managing toxoplasmosis.

Functional Characterization of Six Eukaryotic Translation Initiation Factors of Toxoplasma gondii Using the CRISPR-Cas9 System.

Eukaryotic translation initiation factors (eIFs) are crucial for initiating protein translation and ensuring the correct assembly of mRNA-ribosomal subunit complexes. In this study, we investigated the effects of deleting six eIFs in the apicomplexan parasite Toxoplasma gondii using the CRISPR-Cas9 system. We determined the subcellular localization of these eIFs using C-terminal endogenous tagging and immunofluorescence analysis. Four eIFs (RH::315150-6HA, RH::286090-6HA, RH::249370-6HA, and RH::211410-6HA) were localized in the cytoplasm, while RH::224235-6HA was localized in the apicoplast. Additionally, RH::272640-6HA was found in both the basal complex and the cytoplasm of T. gondii. Functional characterization of the six RHΔeIFs strains was conducted using plaque assay, cell invasion assay, intracellular growth assay and egress assay in vitro, and virulence assay in mice. Disruption of five eIF genes (RHΔ315150, RHΔ272640, RHΔ249370, RHΔ211410, and RHΔ224235) did not affect the ability of the T. gondii RH strain to invade, replicate, form plaques and egress in vitro, or virulence in Kunming mice (p > 0.05). However, the RHΔ286090 strain showed slightly reduced invasion efficiency and virulence (p < 0.01) compared to the other five RHΔeIFs strains and the wild-type strain. The disruption of the TGGT1_286090 gene significantly impaired the ability of tachyzoites to differentiate into bradyzoites in both type I RH and type II Pru strains. These findings reveal that the eukaryotic translation initiation factor TGGT1_286090 is crucial for T. gondii bradyzoite differentiation and may serve as a potential target for drug development and an attenuated vaccine against T. gondii.

Potential Efficacy of Toxoplasma gondii Extracellular Vesicles in Protection against Acute Experimental Toxoplasmosis

Abstract Toxoplasmosis is a zoonotic disease thought to infect 1.5 billion people worldwide. It is a significant food- and water-borne illness that can lead to a major opportunistic infection in patients with impaired immune systems. As a result, there is a pressing need to provide better alternatives for effective long-term disease control, such as vaccinations, as there is no treatment that can eradicate bradyzoites within tissue cysts. Exosomes are multivesicular entities that fuses with plasma membranes to form nanograde membrane-bound vesicles that are secreted by the majority of cell types. Exosomes play important functions in intercellular communication and several of them are well described and known to have immunomodulatory capabilities. Exosomes generated from Toxoplasma gondii (T. gondii) were isolated and their protective effectiveness and immunological responses against acute T. gondii infection in mice was investigated. T. gondii exosomes were isolated and identified by transmission electron microscopy. Mice were immunized with T. gondii tachyzoites derived exosomes (100 μg, 3 doses intramuscular with 2 weeks interval) to investigate the vaccine’s efficiency by challenging the mice with T. gondii RH strain tachyzoites administered intraperitoneal. Exosomes from T. gondii were successfully isolated and characterized. T. gondii exosome-immunized mice showed a longer survival rate compared to the unimmunized group. T. gondii derived exosomes could be a promising vaccine candidate for protection against toxoplasmosis.

Protective Efficacy of a Novel DNA Vaccine with a CL264 Molecular Adjuvant against Toxoplasma gondii in a Murine Model.

Toxoplasmosis is a significant global zoonosis with devastating impacts, and an effective vaccine against toxoplasmosis for humans has not yet been developed. In this study, we designed and formulated a novel DNA vaccine encoding the inhibitor of STAT1 transcriptional activity (IST) of T. gondii utilizing the eukaryotic expression vector pEGFP-N1 for the first time, with CL264 being a molecular adjuvant. Following intramuscular injection of the vaccine into mice, the levels of antibodies and cytokines were assessed to evaluate the immune response. Additionally, mice were challenged with highly virulent RH-strain tachyzoites of T. gondii, and their survival time was observed. The results show that the levels of IgG in serum, the ratio of IgG2a/IgG1 and the levels of IFN-γ in splenocytes of mice were significantly higher in the pEGFP-TgIST group and the pEGFP-TgIST + CL264 group than in the control group. In addition, the proportion of CD4+/CD8+ T cells was higher in mice immunized with either the pEGFP-TgIST group (p < 0.001) or the pEGFP-TgIST + CL264 group (p < 0.05) compared to the three control groups. Notably, TgIST-immunized mice exhibited prolonged survival times after T. gondii RH strain infection (p < 0.05). Our findings collectively demonstrate that the TgIST DNA vaccine elicits a significant humoral and cellular immune response and offers partial protection against acute T. gondii infection in the immunized mice, which suggests that TgIST holds potential as a candidate for further development as a DNA vaccine.

A novel mechanism of resveratrol alleviates Toxoplasma gondii infection-induced pulmonary inflammation via inhibiting inflammasome activation

BackgroundInfection by Toxoplasma gondii can lead to severe pneumonia, with current treatments being highly inadequate. The NLRP3 inflammasome is one member of the NOD-like receptor family with a pyrin domain, which is crucial in the innate immune defense against T. gondii. Research has shown that resveratrol (RSV) prevents lung damage caused by this infection by inhibiting the T. gondii-derived heat shock protein 70/TLR4/NF-κB pathway, thus reducing the macrophage-driven inflammatory response. However, it should be mentioned that the participation of NLRP3 inflammasome in the immune response to the lung injuries caused by T. gondii infections is not entirely clear. PurposeThis study aims to clarify how RSV ameliorates lung damage triggered by Toxoplasma gondii infection, with a particular focus on the pathway involving TLR4, NF-κB, and the NLRP3 inflammasome. MethodsBoth in vitro and in vivo models of infection were developed by employing the RH strain of T. gondii in BALB/c mice and RAW 264.7 macrophage cell lines. The action mechanism of RSV was explored using techniques such as molecular docking, surface plasmon resonance, ELISA, Western blot, co-immunoprecipitation, and immunofluorescence staining. ResultsFindings indicate that the suppression of TLR4 or NF-κB impacts the levels of proteins associated with the NLRP3 inflammasome pathway. Additionally, a significant affinity for binding between RSV and NLRP3 was observed. Treatment with RSV led to a marked reduction in the activation and formation of the NLRP3 inflammasome within lung tissues and RAW 264.7 cells, alongside a decrease in IL-1β concentrations in the bronchoalveolar lavage fluid. These outcomes align with those seen when using the NLRP3 inhibitor CY-09. Moreover, the application of CY-09 prior to RSV negated the latter's anti-inflammatory properties. ConclusionConsidering insights from previous research alongside the outcomes of the current investigation, it appears that the TLR4/NF-κB/NLRP3 signaling pathway emerges as a promising target for immunomodulation to alleviate lung injury from T. gondii infection. The evidence gathered in this study lays the groundwork for the continued exploration and potential future clinical deployment of RSV as a therapeutic agent with anti-Toxoplasma properties and the capability to modulate the inflammatory response.

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

PurposeSearching for a novel early diagnostic biomarker for toxoplasmosis, real-time-PCR was currently used to measure the serum mmu-miR-511-5p level in male Swiss-albino mice infected with either; ME49 or RH Toxoplasma gondii (T. gondii) strains.MethodsThree mice groups were used; (GI) constituted the non-infected control group, while (GII) and (GIII) were experimentally infected with ME49 or RH strains, respectively. GII mice were orally infected using 10 or 20 ME49 cysts (ME-10 and ME-20), both were subdivided into; non-treated (ME-10-NT and ME-20-NT) and were further subdivided into; immunocompetent (ME-10-IC and ME-20-IC) [euthanized 3-days, 1, 2, 6 or 8-weeks post-infection (PI)], and immunosuppressed using two Endoxan® injections (ME-10-IS and ME-20-IS) [euthanized 6- or 8-weeks PI], and spiramycin-treated (ME-10-SP and ME-20-SP) that received daily spiramycin, for one-week before euthanasia. GIII mice individually received 2500 intraperitoneal RH strain tachyzoites, then, were subdivided into; non-treated (RH-NT) [euthanized 3 or 5-days PI], and spiramycin-treated (RH-SP) that were euthanized 5 or 10-days PI (refer to the graphical abstract).ResultsRevealed significant upregulation of mmu-miR-511-5p in GII, one-week PI, with gradually increased expression, reaching its maximum 8-weeks PI, especially in ME-20-NT group that received the higher infective dose. Immunosuppression increased the upregulation. Contrarily, treatment caused significant downregulation. GIII recorded significant upregulation 3-days PI, yet, treatment significantly decreased this expression.ConclusionSerum mmu-miR-511-5p is a sensitive biomarker for early diagnosis of ME49 and RH infection (as early as one-week and 3-days, respectively), and its expression varies according to T. gondii infective dose, duration of infection, spiramycin-treatment and host immune status.Graphical abstract

Investigating the effect of parasites (toxoplasma gondii RH strain, Leishmania major (MRHO/IR/75/ER), and hydatid cyst) antigens on Alzheimer's disease: An in vivo evaluation

This study aimed to investigate the effects of parasite antigens on Alzheimer's symptoms in animal model. Alzheimer's model was induced in Wistar rats using Amyloid-beta peptide, and treated with parasite crude antigens from T. gondii RH strain, L. major (MRHO/IR/75/ER), and HC. Spectrophotometry and real-time PCR were used to evaluate the oxidative stress levels, antioxidant enzyme activity, and gene expression of NLRP3, IL-8, IL-1β, and Caspase-1. Histological assays were performed to investigate structural changes in the hippocampus. Apoptosis was analyzed using an Annexin V Apoptosis by Flow cytometer. The levels of total oxidant, antioxidant, and SOD increased in the Alzheimer's group compared with the control group, but these factors were lower in the L. major group. The apoptosis in the treated groups was lower compared to the Alzheimer's group. IL-8 expression was significantly higher in all Alzheimer's groups, but decreased in the HC and L. major treated group compared to Alzheimer's. IL-1β and Caspase-1 expression were similarly increased in all groups compared with the control group, but decreased in the antigen-treated groups compared with Alzheimer's. NLRP3 expression was increased in all groups compared with the control group, with lower expression in HC group, but significantly decreased in L. major group compared with Alzheimer's. In histological results, only L. major group could play a therapeutic role in pathological damage of the hippocampus. The results showed that parasite antigens, specifically L. major antigens, may have neuroprotective effects that reduce oxidative stress, apoptosis, and histopathological changes in response to AD in animal model.

Evaluation of the antiplasmodial and anti-Toxoplasma activities of several Indonesian medicinal plant extracts

Ethnopharmacological relevanceMalaria, caused by Plasmodium parasites, remains a significant global health challenge, particularly in tropical and subtropical regions. At the same time, the prevalence of toxoplasmosis has been reported to be 30% worldwide. Traditional medicines have long played a vital role in discovering and developing novel drugs, and this approach is essential in the face of increasing resistance to current antimalarial and anti-Toxoplasma drugs. In Indonesian traditional medicine, various plants are used for their therapeutic properties. This study focuses on eleven medicinal plants from which nineteen extracts were obtained and screened for their potential medicinal benefits against malaria and toxoplasmosis. Aims of the studyThe aim of this study was to evaluate the efficacy of extracts from Indonesian medicinal plants to inhibit Plasmodium falciparum, a parasite responsible for malaria, and Toxoplasma gondii, an opportunistic parasite responsible for toxoplasmosis. MethodsNineteen extracts from eleven plants were subjected to in vitro screening against P. falciparum 3D7 (a chloroquine-sensitive strain) and the T. gondii RH strain. In vitro treatments were conducted on P. falciparum 3D7 and K1 (multidrug-resistant strains) using the potent extracts, and in vivo assessments were carried out with mice infected with P. yoelii 17XNL. LCMS analysis was also conducted to identify the main components of the most effective extract. ResultsSeven extracts showed significant antiplasmodial activity (>80% inhibition) at a concentration of 100 μg/ml. These extracts were obtained from Dysoxylum parasiticum (Osbeck) Kosterm., Elaeocarpus glaber (Bl.) Bijdr., Eleutherine americana Merr., Kleinhovia hospita L., Peronema canescens Jack, and Plectranthus scutellarioides (L.) R.Br. Notably, the D. parasiticum ethyl acetate extract exhibited high selectivity and efficacy both in vitro and in vivo. Herein, the key active compounds oleamide and erucamide were identified, which had IC50 values (P. falciparum 3D7/K1) of 17.49/23.63 μM and 32.49/51.59 μM, respectively. ConclusionsThe results of this study highlight the antimalarial potential of plant extracts collected from Indonesia. Particularly, extracts from D. parasiticum EtOH and EtOAc stood out for their low toxicity and strong antiplasmodial properties, with the EtOAc extract emerging as a notably promising antimalarial candidate. Key compounds identified within this extract demonstrate the complexity of extracts' action against malaria, potentially targeting both the parasite and the host. This suggests a promising approach for developing new antimalarial strategies that tackle the multifaceted challenges of drug resistance and disease management. Future investigations are necessary to unlock the full therapeutic potential of these extracts.

Humane Endpoints in Swiss Webster Mice Infected with Toxoplasma gondii RH Strain.

The highly virulent Toxoplasma gondii RH strain is maintained through successive passages in mice, but there is still a lack of studies that refine these procedures from a 3Rs perspective, where humanitarian ideals aim to minimize the stress, pain, or suffering of the animals used in the research without the loss of results. The aim of this study was to establish humane endpoints in Swiss Webster mice inoculated with the T. gondii RH strain. A total of 52 mice were infected with 5 × 106 tachyzoites/mL and monitored for periods of up to 5 days. The parameters body weight; hair condition; higher than normal body temperature; hypothermia; respiratory function; pain; soft stools or diarrhea; bloody diarrhea; tense, nervous, or in distress during handling; and ascites were recorded daily in score tables. The results showed that prominent piloerection, respiratory function, pain parameters, and ascites are important clinical signs to be used as a cut-off point for implementing euthanasia. The application of this refinement method helped to avoid animal suffering and pain without compromising the number of parasites recovered. We therefore suggest adopting these parameters in research protocols that require the maintenance of the T. gondii RH strain in murine models to avoid and reduce animal suffering.

Toxoplasma gondii suppresses proliferation and migration of breast cancer cells by regulating their transcriptome

BackgroundBreast cancer is the most common cancer in women worldwide. Toxoplasma gondii (T. gondii) has shown anticancer activity in breast cancer mouse models, and exerted beneficial effect on the survival of breast cancer patients, but the mechanism was unclear.MethodsThe effect of tachyzoites of T. gondii (RH and ME49 strains) on human breast cancer cells (MCF-7 and MDA-MB-231 cells) proliferation and migration was assessed using cell growth curve and wound healing assays. Dual RNA-seq was performed for T. gondii-infected and non-infected cells to determine the differentially expressed genes (DEGs). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Protein–Protein Interaction Networks analysis (PPI) were performed to explore the related signaling pathway and hub genes. Hub genes were validated using the Kaplan–Meier plotter database, and Pathogen Host Interaction (PHI-base) database. The results were verified by qRT-PCR.ResultsThe tachyzoites of T. gondii decreased the expression of Ki67 and increased the expression of E-cadherin, resulting in suppressing the proliferation and migration of infected human breast cancer cells. The inhibitory effect of T. gondii on breast cancer cells showed a significant dose–response relationship. Compared with the control group, 2321 genes were transcriptionally regulated in MCF-7 cells infected with T. gondii, while 169 genes were transcriptionally regulated in infected MDA-MB-231 cells. Among these genes, 698 genes in infected MCF-7 cells and 67 genes in infected MDA-MB-231 cells were validated by the publicly available database. GO and KEGG analyses suggested that several pathways were involved in anticancer function of T. gondii, such as ribosome, interleukin-17 signaling, coronavirus disease pathway, and breast cancer pathway. BRCA1, MYC and IL-6 were identified as the top three hub genes in infected-breast cancer cells based on the connectivity of PPI analysis. In addition, after interacting with breast cancer cells, the expression of ROP16 and ROP18 in T. gondii increased, while the expression of crt, TgIST, GRA15, GRA24 and MIC13 decreased.ConclusionsT. gondii transcriptionally regulates several signaling pathways by altering the hub genes such as BRCA1, MYC and IL-6, which can inhibit the breast tumor growth and migration, hinting at a potential therapeutic strategy.

Trx4, a novel thioredoxin protein, is important for Toxoplasma gondii fitness

BackgroundTo successfully replicate within the host cell, Toxoplasma gondii employs several mechanisms to overcome the host cell defenses and mitigate the harmful effects of the free radicals resulting from its own metabolic processes using effectors such as thioredoxin proteins. In this study, we characterize the location and functions of a newly identified thioredoxin in T. gondii, which was named Trx4.MethodsWe characterized the functional role of Trx4 in T. gondii Type I RH and Type II Pru strains by gene knockout and studied its subcellular localization by endogenous protein HA tagging using CRISPR-Cas9 gene editing. The enzyme-catalyzed proximity labeling technique, the TurboID system, was employed to identify the proteins in proximity to Trx4.ResultsTrx4 was identified as a dense granule protein of T. gondii predominantly expressed in the parasitophorous vacuole (PV) and was partially co-localized with GRA1 and GRA5. Functional analysis showed that deletion of trx4 markedly influenced the parasite lytic cycle, resulting in impaired host cell invasion capacity in both RH and Pru strains. Mutation of Trx domains in Trx4 in RH strain revealed that two Trx domains were important for the parasite invasion. By utilizing the TurboID system to biotinylate proteins in proximity to Trx4, we identified a substantial number of proteins, some of which are novel, and others are previously characterized, predominantly distributed in the dense granules. In addition, we uncovered three novel proteins co-localized with Trx4. Intriguingly, deletion of trx4 did not affect the localization of these three proteins. Finally, a virulence assay demonstrated that knockout of trx4 resulted in a significant attenuation of virulence and a significant reduction in brain cyst loads in mice.ConclusionsTrx4 plays an important role in T. gondii invasion and virulence in Type I RH strain and Type II Pru strain. Combining the TurboID system with CRISPR-Cas9 technique revealed many PV-localized proximity proteins associated with Trx4. These findings suggest a versatile role of Trx4 in mediating the processes that occur in this distinctive intracellular membrane-bound vacuolar compartment.Graphical

In vitro anti-Toxoplasma effects and apoptotic induction of queen bee acid (10-hydroxy-2-decenoic acid) alone and in combination with atovaquone.

Toxoplasmosis, which is caused by the Toxoplasma gondii parasite, is a parasitic, infectious disease. 10-hydroxy-2-decenoic acid (10-H2DA, queen bee acid (QBA), is one of the most prevalent fatty acids (>40%) present in royal jelly. Studies have pointed to antitumor, anti-inflammatory, antiangiogenic, and antimicrobial effects of 10-H2DA, improving the immune system. This experimental survey aimed to assess the in vitro efficacy of QBA against tachyzoites and intracellular parasites of the T. gondii RH strain. Anti-Toxoplasma effects of QBA against tachyzoites were examined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay for 30, 60, 120, and 180 min. In addition, the effect of QBA on infection rate and intracellular parasites was studied. Real-time polymerase chain reaction (Real-Time PCR) was also applied to assess the expression level of the Caspase-3 gene. The best efficiency of QBA was obtained at 100 and 50 µg/mL, whereas all tachyzoites were diminished, followed by 120- and 180-min treatment, respectively. It was also found that the best repressing efficacy of QBA in the infection rate and the load of parasites into the Vero cells was indicated at 100 µg/mL (P<0.001). Nonetheless, the combination of QBA (12.5 µg/mL) along with atovaquone 30 µg/mL displayed the most marked effect on the infection rate and a load of parasites into the Vero cells in the infected Vero cells. The expression level of the Caspase-3 gene was dose-dependently increased after the exposure of tachyzoites to QBA, mainly at ½ IC50 and IC50 compared to normal saline. The obtained findings exhibited the high in vitro potency of QBA, especially in combination with atovaquone against T. gondii RH strain tachyzoites. Although apoptosis induction can be suggested as one of the principle mechanisms, more studies are required to elucidate its accurate mechanisms, as well as its efficacy and safety in animal models and clinical settings.

Evaluation of In Vitro Cytotoxic and Apoptotic Effects of Miltefosine on the Toxoplasma gondii RH Strain.

We aimed to investigate the cytotoxic and apoptotic effects of miltefosine on Toxoplasma gondii RH strain by various techniques. The study was conducted at the Department of Parasitology and Mycology, Urmia University of Medical Sciences, Iran in 2020. Four groups of five BALB/c mice were selected. The cytotoxicity test was conducted by adding miltefosine to T. gondii tachyzoites; control tachyzoites received PBS and MTT assay was done on each suspension. For evaluating the Th1-type immune responses, the serum levels of IFN-γ and nitric oxide (NO) were assessed in mice after injecting tachyzoites and miltefosine, respectively. The flow cytometry technique was performed on T. gondii tachyzoites challenged with IC50 and IC90 doses of miltefosine and unchallenged cells. DNA fragments in T. gondii tachyzoites were detected by Terminal dUTPnick-end labeling (TUNEL) method. Overall, 256, 64, 32, and 16 μg concentrations of miltefosine, respectively could kill more than 50% of viable T. gondii tachyzoites. The infected mice group, treated with miltefosine, significantly produced more IFN-γ relative to other groups (P< 0.001). Moreover, a significant difference was found in inducible NO synthase between the experimental and control groups (P<0.05). The flow cytometry results demonstrated a concentration-dependent apoptosis rate in tachyzoites incubated with miltefosine, though the necrosis rate was non-significant. DNA fragmentation analysis indicated oligonucleotides (18-200 bp) in tachyzoites treated with 11μg of miltefosine for 24, 48 and 72 h. However, this pattern was not observed in untreated control microorganisms. Miltefosine could be a favorable candidate for use as a new treatment for toxoplasmosis.

Toxoplasma gondii infection-induced host cellular DNA damage is strain-dependent and leads to the activation of the ATM-dependent homologous recombination pathway.

Toxoplasma gondii is a globally occurring apicomplexan parasite that infects humans and animals. Globally, different typical and atypical haplotypes of T. gondii induce varying pathologies in hosts. As an obligate intracellular protozoon, T. gondii was shown to interfere with host cell cycle progression, leading to mitotic spindle alteration, chromosome segregation errors and cytokinesis failure which all may reflect chromosomal instability. Referring to strain-dependent virulence, we here studied the potential of different T. gondii strains (RH, Me49 and NED) to drive DNA damage in primary endothelial host cells. Utilizing microscopic analyses, comet assays and γ-H2AX quantification, we demonstrated a strain-dependent induction of binucleated host cells, DNA damage and DNA double strand breaks, respectively, in T. gondii-infected cells with the RH strain driving the most prominent effects. Interestingly, only the NED strain significantly triggered micronuclei formation in T. gondii-infected cells. Focusing on the RH strain, we furthermore demonstrated that T. gondii-infected primary host cells showed a DNA damage response by activating the ATM-dependent homologous recombination (HR) pathway. In contrast, key molecules of the nonhomologous DNA end joining (NHEJ) pathway were either not affected or downregulated in RH-infected host cells, suggesting that this pathway is not activated by infection. In conclusion, current finding suggests that T. gondii infection affects the host cell genome integrity in a strain-dependent manner by causing DNA damage and chromosomal instability.

Detection and Sequence Analysis of Toxoplasma Gondii B1 Gene in Tissues of Some Bird Species in Plateau State, Nigeria

Abstract Toxoplasma gondii is a single-cell parasite capable of infecting almost all homeotherms posing a grave public health risk globally. There is limited available literature on the T. gondii strains circulating in bird species in the Plateau State, of Nigeria. Consequently, this study was carried out to identify and confirm T. gondii infection and also determine the relationship of the DNA sequences with those of bird species in other parts of the world. To achieve this, brain and heart tissues of 25 bird species were sampled and a nested polymerase chain reaction (nPCR) and sequence analyses of the B1 gene were carried out. The DNA of T. gondii was identified in the heart and brain tissues of 7/7 (100.0 %) of wild bird species, and 15/18 (83.3 %) of domestic local chickens (Gallus gallus domesticus) sampled. The evolutionary relationship among the T. gondii sequences in this study using phylogenetic tree constructed by maximum likelihood method showed the sequences shared a common ancestor with the Type I RH strain (GenBank: AF179871). The T. gondii sequences were in a cluster distinct from other sequences in the GenBank. Calculations of genetic differentiation and genetic diversity indices undertaken and collated revealed three haplotypes with higher haplotype diversity within the T. gondii sequences obtained from wild birds (0.667) compared with the sequences from local chickens (0.333). A 97–100 % homology among the aligned sequences of T. gondii in the study shows that only one strain type exists in all of the samples. This study has established the occurrence of T. gondii infection in asymptomatic bird species in the study area and portrays them as carriers, and potential sources of human infection.