Intestinal microbiota imbalance resulted by anti-Toxoplasma gondii immune responses aggravate gut and brain injury.

BACKGROUND: Toxoplasma gondii infection affects a significant portion of the global population, leading to severe toxoplasmosis and, in immunocompromised patients, even death. During T. gondii infection, disruption of gut microbiota further exacerbates the damage to intestinal and brain barriers. Therefore, identifying imbalanced probiotics during infection and restoring their equilibrium can regulate the balance of gut microbiota metabolites, thereby alleviating tissue damage. METHODS: Vimentin gene knockout (vim-/-) mice were employed as an immunocompromised model to evaluate the influence of host immune responses on gut microbiota balance during T. gondii infection. Behavioral experiments were performed to assess changes in cognitive levels and depressive tendencies between chronically infected vim-/- and wild-type (WT) mice. Fecal samples were subjected to 16S ribosomal RNA (rRNA) sequencing, and serum metabolites were analyzed to identify potential gut probiotics and their metabolites for the treatment of T. gondii infection. RESULTS: Compared to the immunocompetent WT sv129 mice, the immunocompromised mice exhibited lower levels of neuronal apoptosis and fewer neurobehavioral abnormalities during chronic infection. 16S rRNA sequencing revealed a significant decrease in the abundance of probiotics, including several species of Lactobacillus, in WT mice. Restoring this balance through the administration of Lactobacillus murinus and Lactobacillus gasseri significantly suppressed the T. gondii burden in the intestine, liver, and brain. Moreover, transplantation of these two Lactobacillus spp. significantly improved intestinal barrier damage and alleviated inflammation and neuronal apoptosis in the central nervous system. Metabolite detection studies revealed that the levels of various Lactobacillus-related metabolites, including indole-3-lactic acid (ILA) in serum, decreased significantly after T. gondii infection. We confirmed that L. gasseri secreted much more ILA than L. murinus. Notably, ILA can activate the aromatic hydrocarbon receptor signaling pathway in intestinal epithelial cells, promoting the activation of CD8+ T cells and the secretion of interferon-gamma. CONCLUSION: Our study revealed that host immune responses against T. gondii infection severely disrupted the balance of gut microbiota, resulting in intestinal and brain damage. Lactobacillus spp. play a crucial role in immune regulation, and the metabolite ILA is a promising therapeutic compound for efficient and safe treatment of T. gondii infection.

Research progress of ubiquitin and ubiquitin-like signaling in Toxoplasma gondii.

Toxoplasmosis, a zoonotic parasitic disease caused by Toxoplasma gondii (T. gondii), is prevalent worldwide. The fact should be emphasized that a considerable proportion of individuals infected with T. gondii may remain asymptomatic; nevertheless, the condition can have severe implications for pregnant women or immunocompromised individuals. The current treatment of toxoplasmosis primarily relies on medication; however, traditional anti-toxoplasmosis drugs exhibit significant limitations in terms of efficacy, side effects, and drug resistance. The life cycles of T. gondii are characterized by distinct stages and its body morphology goes through dynamic alterations during the growth cycle that are intricately governed by a wide array of post-translational modifications (PTMs). Ubiquitin (Ub) signaling and ubiquitin-like (Ubl) signaling are two crucial post-translational modification pathways within cells, regulating protein function, localization, stability, or interactions by attaching Ub or ubiquitin-like proteins (Ubls) to target proteins. While these signaling mechanisms share some functional similarities, they have distinct regulatory mechanisms and effects. T. gondii possesses both Ub and Ubls and plays a significant role in regulating the parasite's life cycle and maintaining its morphology through PTMs of substrate proteins. Investigating the role and mechanism of protein ubiquitination in T. gondii will provide valuable insights for preventing and treating toxoplasmosis. This review explores the distinctive characteristics of Ub and Ubl signaling in T. gondii, with the aim of inspiring research ideas for the identification of safer and more effective drug targets against toxoplasmosis.

Evaluation of protective immunity induced by a DNA vaccine encoding SAG2 and SRS2 against Toxoplasma gondii infection in mice.

Toxoplasma gondii is an important protozoan pathogen, which can cause severe diseases in the newborns and immunocompromised individuals. Developing an effective vaccine against Toxoplasma infection is a critically important global health priority. Immunofluorescence staining analysis revealed that TgSAG2 and TgSRS2 are membrane associated and displayed on the surface of the parasite. Immunizations with pBud-SAG2, pBud-SRS2 and pBud-SAG2-SRS2 DNA vaccines significantly increased the production of specific IgG antibodies. Immunization with pBud-SAG2-SRS2 elicited cellular immune response with higher concentrations of IFN-γ and IL-4 compared to the control group. Antigen-specific lymphocyte proliferations in the pBud-SRS2 and pBud-SAG2-SRS2 groups were significantly higher compared to that in the control group. Furthermore, 30 % of mice immunized with pBud-SAG2-SRS2 survived after the challenge infection with virulent T. gondii RH tachyzoites. This study revealed that immunization with pBud-SAG2-SRS2 induced potent immune responses, and has the potential as a promising vaccine candidate for the control of T. gondii infection.

T. gondii excretory proteins promote the osteogenic differentiation of human bone mesenchymal stem cells via the BMP/Smad signaling pathway.

BACKGROUND: Bone defects, resulting from substantial bone loss that exceeds the natural self-healing capacity, pose significant challenges to current therapeutic approaches due to various limitations. In the quest for alternative therapeutic strategies, bone tissue engineering has emerged as a promising avenue. Notably, excretory proteins from Toxoplasma gondii (TgEP), recognized for their immunogenicity and broad spectrum of biological activities secreted or excreted during the parasite's lifecycle, have been identified as potential facilitators of osteogenic differentiation in human bone marrow mesenchymal stem cells (hBMSCs). Building on our previous findings that TgEP can enhance osteogenic differentiation, this study investigated the molecular mechanisms underlying this effect and assessed its therapeutic potential in vivo. METHODS: We determined the optimum concentration of TgEP through cell cytotoxicity and cell proliferation assays. Subsequently, hBMSCs were treated with the appropriate concentration of TgEP. We assessed osteogenic protein markers, including alkaline phosphatase (ALP), Runx2, and Osx, as well as components of the BMP/Smad signaling pathway using quantitative real-time PCR (qRT-PCR), siRNA interference of hBMSCs, Western blot analysis, and other methods. Furthermore, we created a bone defect model in Sprague-Dawley (SD) male rats and filled the defect areas with the GelMa hydrogel, with or without TgEP. Microcomputed tomography (micro-CT) was employed to analyze the bone parameters of defect sites. H&E, Masson and immunohistochemical staining were used to assess the repair conditions of the defect area. RESULTS: Our results indicate that TgEP promotes the expression of key osteogenic markers, including ALP, Runx2, and Osx, as well as the activation of Smad1, BMP2, and phosphorylated Smad1/5-crucial elements of the BMP/Smad signaling pathway. Furthermore, in vivo experiments using a bone defect model in rats demonstrated that TgEP markedly promoted bone defect repair. CONCLUSION: Our results provide compelling evidence that TgEP facilitates hBMSC osteogenic differentiation through the BMP/Smad signaling pathway, highlighting its potential as a therapeutic approach for bone tissue engineering for bone defect healing.

Serological and molecular survey of Toxoplasma gondii infection and associated risk factors in urban cats in Kunming, Southwest China.

Toxoplasma gondii (T. gondii) is a worldwide zoonotic parasite that can infect almost warm-blood animals, including humans, which seriously affect the health of host. Cats are known to be the only definitive host of T. gondii and continuously excrete highly infectious oocysts. This parasite carried by the companion animals leads to a great public health risk. However, there is little information on epidemiology of T. gondii in urban cats in Kunming, Southwest China. In the present study, a total of 231 serum and fecal samples were collected in Kunming aera, and then seroprevalence of T. gondii IgG antibodies in serum and molecular investigation in feces were analyzed to elucidate T. gondii infection in urban cats. The results revealed that 168 of 231 cats (72.7%) were positive for T. gondii antibodies, and 1 of 74 cat feces (1.4%) also showed a positive PCR for T. gondii DNA. The positive fecal sample was sequenced and then phylogenetically analyzed, and the isolate of T. gondii in the present study was closely related to T. gondii strain CN. In addition, the food, water and age of cats were identified as the risk factor for seropositivity. Overall, our findings indicate the widespread occurrence of T. gondii infection in urban cats in Kunming, Southwest China and identify food, water and age are the risk factors associated with T. gondii infection, which can provide effective information for developing strategies to prevent and control this zoonosis.

In vitro and in vivo activity evaluation and mode of action of broxaldine on Toxoplasma gondii.

Toxoplasma gondii (T. gondii) is a highly successful global parasite, infecting about one-third of the world's population and significantly affecting human life and the economy. However, current drugs for toxoplasmosis treatment have considerable side effects, and there is no specific drug to meet current needs. This study aims to evaluate the anti-T. gondii activity of broxaldine (BRO) in vitro and in vivo and explore its mechanism of action. Our results showed that compared to the control group, the invasion rate of tachyzoites in the 4 µg/mL BRO group was only 14.31%, and the proliferation rate of tachyzoites in host cells was only 1.23%. Furthermore, BRO disrupted the lytic cycle of T. gondii and reduced the size and number of cysts in vitro. A mouse model of acute toxoplasmosis reported a 41.5% survival rate after BRO treatment, with reduced parasite load in tissues and blood. The subcellular structure of T. gondii was observed, including disintegration of T. gondii, mitochondrial swelling, increased liposomes, and the presence of autophagic lysosomes. Further investigation revealed enhanced autophagy, increased neutral lipids, and decreased mitochondrial membrane potential in T. gondii treated with BRO. The results also showed a significant decrease in ATP levels. Overall, BRO demonstrates good anti-T. gondii activity in vitro and in vivo; therefore, it has the potential to be used as a lead compound for anti-T. gondii treatment.

Research Progress on the Association between Schizophrenia and Toxoplasma gondii Infection.

Toxoplasma gondii( T. gondii or Tg), is an obligatory intracellular parasite with humans as its intermediate hosts. In recent years, significant correlations between T. gondii infection and schizophrenia have been reported, including the possible mediating mechanisms. Currently, mechanisms and hypotheses focus on central neurotransmitters, immunity, neuroinflammation, and epigenetics; however, the exact underlying mechanisms remain unclear. In this article, we review the studies related to T. gondii infection and schizophrenia, particularly the latest research progress. Research on dopamine (DA) and other neurotransmitters, the blood-brain barrier, inflammatory factors, disease heterogeneity, and other confounders is also discussed. In addition, we also summarized the results of some new epidemiological investigations.

Prevalence and risk factors of Toxoplasma gondii infection in dairy cattle from the Western Region of Thailand.

In total, 901 dairy cow sera and data were collected from 51 farms in Nakhon Pathom, Ratchaburi and Kanchanaburi provinces (Western Region of Thailand). Serum samples were processed via the multispecies ELISA method to detect IgG antibodies against Toxoplasma gondii infection. The results demonstrated that the calculated true prevalence was 1.48% (95% CI, 0.64-2.75%) for the individual-level and 29.41% (95% CI, 18.71-43%) for the farm-level. The univariate risk factor analysis showed that the number of total owned cats, the presence of stray cats, and the frequency of cleaning per day were significant factors (p < 0.2). These three factors were subjected to logistic regression analysis, and the results revealed that the frequency of cleaning farms per day was a potential risk factor for T. gondii-seropositive farms (OR = 2.745, 95% CI, 1.15-8.69, p = 0.02). The frequency of cleaning might increase the T. gondii oocyst distribution within the barn area, thus increasing the possibility of infection. Our findings show that T. gondii continues to circulate in the dairy cow population in the western part of Thailand. The presence of cats on farms was not found to be associated with T. gondii infection, but the high frequency of cleaning the floor was, and contributed to the potential risk of infection.

Title: Prévalence et facteurs de risque de l'infection à Toxoplasma gondii chez les bovins laitiers de la région occidentale de la Thaïlande. Abstract: Au total, 901 sérums de vaches laitières et des données ont été collectés dans 51 fermes des provinces de Nakhon Pathom, Ratchaburi et Kanchanaburi (région occidentale de la Thaïlande). Les échantillons de sérum ont été traités via la méthode ELISA multi-espèces pour détecter les anticorps IgG contre l'infection à Toxoplasma gondii. Les résultats ont démontré que la prévalence réelle calculée était de 1,48 % (IC à 95 %, 0,64­2,75 %) au niveau individuel et de 29,41 % (IC à 95 %, 18,71­43 %) au niveau des exploitations. L'analyse factorielle a montré que le nombre total de chats possédés, la présence de chats errants et la fréquence quotidienne de nettoyage étaient des facteurs significatifs (p < 0,2). Ces trois facteurs ont été soumis à une analyse de régression logistique et les résultats ont révélé que la fréquence quotidienne de nettoyage des exploitations était un facteur de risque potentiel pour les exploitations séropositives à T. gondii (OR = 2,745, IC à 95 % = 1,15­8,69, p = 0,02). La fréquence du nettoyage pourrait favoriser la répartition des oocystes de T. gondii dans les étables, augmentant ainsi le risque d'infection. Nos résultats indiquent que T. gondii continue de circuler dans la population de vaches laitières de l'ouest de la Thaïlande. La présence de chats dans les fermes n'a pas été associée à l'infection à T. gondii, mais la fréquence élevée du nettoyage du sol l'était et contribuait au risque potentiel d'infection.

4D label-free proteomic analysis reveals key potential pathways of Toxoplasma invasion into the central nervous system.

Toxoplasma gondii is a successful parasite capable of infecting a wide range of warm-blooded animals, including people, livestock, and wildlife. In individuals with intact immune function, T. gondii can invade the host brain tissue by altering the blood-brain barrier permeability, leading to chronic infection. Proteins play crucial regulatory roles in disease progression. By monitoring changes in proteins, a deeper understanding of the molecular mechanisms underlying host resistance to infection and the potential pathogenic mechanisms of pathogens can be gained. This study analyzed differential protein expression and associated signaling pathways in mouse brain tissues during acute and chronic T. gondii infection using proteomic and bioinformatics methods. The results showed that during acute and chronic T. gondii infection stages, 74 and 498 differentially expressed proteins (DEPs) were identified in mouse brain tissue, respectively. Among them, 45 and 309 were up-regulated, while 29 and 189 were down-regulated. GO and KEGG analyses revealed that some of these DEPs were implicated in host immunity, pathogen immune evasion, and T. gondii invasion of the central nervous system, particularly interleukin production and secretion, complement system activation, and alterations in tight junction pathways. Notably, the upregulation of Rab13 was identified as a potential molecular mechanism for T. gondii to regulate blood-brain barrier permeability and facilitate central nervous system invasion. Our findings provided fundamental data for understanding host control of Toxoplasmosis infection and offered new insights into parasite immune evasion and invasion mechanisms within the central nervous system. These insights are crucial for developing strategies to prevent the establishment of chronic T. gondii infection.

Toxoplasma gondii infection supports the infiltration of T cells into brain tumors.

Few T cells infiltrate into primary brain tumors, fundamentally hampering the effectiveness of immunotherapy. We hypothesized that Toxoplasma gondii, a microorganism that naturally elicits a Th1 response in the brain, can promote T cell infiltration into brain tumors despite their immune suppressive microenvironment. Using a mouse genetic model for medulloblastoma, we found that T. gondii infection induced the infiltration of activatable T cells into the tumor mass and led to myeloid cell reprogramming toward a T cell-supportive state, without causing severe health issues in mice. The study provides a concrete foundation for future studies to take advantage of the immune modulatory capacity of T. gondii to facilitate brain tumor immunotherapy.

Metabolic changes in Toxoplasma gondii-infected host cells measured by autofluorescence imaging.

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular parasite that infects warm-blooded vertebrates across the world. In humans, seropositivity rates of T. gondii range from 10% to 90% across communities. Despite its prevalence, few studies address how T. gondii infection changes the metabolism of host cells. In this study, we investigate how T. gondii manipulates the host cell metabolic environment by monitoring the metabolic response over time using noninvasive autofluorescence lifetime imaging of single cells, metabolite analysis, extracellular flux analysis, and reactive oxygen species (ROS) production. Autofluorescence lifetime imaging indicates that infected host cells become more oxidized and have an increased proportion of bound NAD(P)H compared to uninfected controls. Over time, infected cells also show decreases in levels of intracellular glucose and lactate, increases in oxygen consumption, and variability in ROS production. We further examined changes associated with the pre-invasion "kiss and spit" process using autofluorescence lifetime imaging, which also showed a more oxidized host cell with an increased proportion of bound NAD(P)H over 48 hours compared to uninfected controls, suggesting that metabolic changes in host cells are induced by T. gondii kiss and spit even without invasion.IMPORTANCEThis study sheds light on previously unexplored changes in host cell metabolism induced by T. gondii infection using noninvasive, label-free autofluorescence imaging. In this study, we use optical metabolic imaging (OMI) to measure the optical redox ratio (ORR) in conjunction with fluorescence lifetime imaging microscopy (FLIM) to noninvasively monitor single host cell response to T. gondii infection over 48 hours. Collectively, our results affirm the value of using autofluorescence lifetime imaging to noninvasively monitor metabolic changes in host cells over the time course of a microbial infection. Understanding this metabolic relationship between the host cell and the parasite could uncover new treatment and prevention options for T. gondii infections worldwide.

The effect of Toxoplasma gondii infection on galectin-9 expression in decidual macrophages contributing to dysfunction of decidual NK cells during pregnancy.

BACKGROUND: Toxoplasma gondii infection causes adverse pregnancy outcomes by affecting the expression of immunotolerant molecules in decidual immune cells. Galectin-9 (Gal-9) is widely expressed in decidual macrophages (dMφ) and is crucial for maintaining normal pregnancy by interacting with the immunomodulatory protein T-cell immunoglobulin and mucin domain-containing molecule 3 (Tim-3). However, the effects of T. gondii infection on Gal-9 expression in dMφ, and the impact of altered Gal-9 expression levels on the maternal-fetal tolerance function of decidual natural killer (dNK) cells, are still unknown. METHODS: Pregnancy outcomes of T. gondii-infected C57BL/6 and Lgals9-/- pregnant mice models were recorded. Expression of Gal-9, c-Jun N-terminal kinase (JNK), phosphorylated JNK (p-JNK), and Forkhead box protein O1 (FOXO1) was detected by western blotting, flow cytometry or immunofluorescence. The binding of FOXO1 to the promoter of Lgals9 was determined by chromatin immunoprecipitation-polymerase chain reaction (ChIP-PCR). The expression of extracellular signal-regulated kinase (ERK), phosphorylated ERK (p-ERK), cAMP-response element binding protein (CREB), phosphorylated CREB (p-CREB), T-box expressed in T cells (T-bet), interleukin 10 (IL-10), and interferon gamma (IFN-γ) in dNK cells was assayed by western blotting. RESULTS: Toxoplasma gondii infection increased the expression of p-JNK and FOXO1 in dMφ, resulting in a reduction in Gal-9 due to the elevated binding of FOXO1 with Lgals9 promoter. Downregulation of Gal-9 enhanced the phosphorylation of ERK, inhibited the expression of p-CREB and IL-10, and promoted the expression of T-bet and IFN-γ in dNK cells. In the mice model, knockout of Lgals9 aggravated adverse pregnancy outcomes caused by T. gondii infection during pregnancy. CONCLUSIONS: Toxoplasma gondii infection suppressed Gal-9 expression in dMφ by activating the JNK/FOXO1 signaling pathway, and reduction of Gal-9 contributed to dysfunction of dNK via Gal-9/Tim-3 interaction. This study provides new insights for the molecular mechanisms of the adverse pregnancy outcomes caused by T. gondii.

The Effects and Mechanism of ATM Kinase Inhibitors in Toxoplasma gondii.

Toxoplasma gondii, an important opportunistic pathogen, underscores the necessity of developing novel therapeutic drugs and identifying new drug targets. Our findings indicate that the half-maximal inhibitory concentrations (IC50) of KU60019 and CP466722 (abbreviated as KU and CP) against T. gondii are 0.522 µM and 0.702 µM, respectively, with selection indices (SI) of 68 and 10. Treatment with KU and CP affects the in vitro growth of T. gondii, inducing aberrant division in the daughter parasites. Transmission electron microscopy reveals that KU and CP prompt the anomalous division of T. gondii, accompanied by cellular enlargement, nuclear shrinkage, and an increased dense granule density, suggesting potential damage to parasite vesicle transport. Subsequent investigations unveil their ability to modulate the expression of certain secreted proteins and FAS II (type II fatty acid synthesis) in T. gondii, as well as including the dot-like aggregation of the autophagy-related protein ATG8 (autophagy-related protein 8), thereby expediting programmed death. Leveraging DARTS (drug affinity responsive target stability) in conjunction with 4D-Label-free quantitative proteomics technology, we identified seven target proteins binding to KU, implicated in pivotal biological processes such as the fatty acid metabolism, mitochondrial ATP transmission, microtubule formation, and Golgi proteins transport in T. gondii. Molecular docking predicts their good binding affinity. Furthermore, KU has a slight protective effect on mice infected with T. gondii. Elucidating the function of those target proteins and their mechanism of action with ATM kinase inhibitors may potentially enhance the treatment paradigm for toxoplasmosis.

Seroprevalence of zoonotic pathogens in stray cats in an urban area of northeast Spain.

The feline population is extensive in urban areas worldwide, comprising stray and domestic cats. Cats, acting as reservoirs, can transmit various zoonotic organisms to humans, which can cause significant public health issues. We evaluated the seroprevalence of zoonotic pathogens in stray cats in an urban area of northeast Spain (the city of Zaragoza) to assess potential risks to human health. A total of 88 sampled cats (52 females and 36 males) underwent antibody evaluation using the indirect immunofluorescence technique. Seroprevalence rates were determined for IgG antibodies to Bartonella henselae (36.3%), Toxoplasma gondii (31.8%), Rickettsia felis (14.7%), Rickettsia typhi (9%), and Leishmania infantum (10.2%). Our results confirmed the presence in stray cats of antibodies against all those pathogens, indicating that they all circulate in the feline population in Zaragoza. Male cats exhibited a higher predisposition to T. gondii, whereas females showed an increased likelihood of contracting B. henselae. This difference may be attributed to distinct behaviors according to sex. Our findings underscore the importance of maintaining and intensifying surveillance coupled with preventive measures against zoonotic pathogens in cats. They highlight the need for comprehensive control strategies designed to mitigate public health risks associated with feline populations.

First report on seroprevalence of Toxoplasma gondii infection in zoo animals in Algeria.

Toxoplasma gondii is one of the world's most widespread polyxenic protozoan parasites that affect all warm-blooded animals, including humans. This survey aims to study, for the first time in Algeria, the seroprevalence of Toxoplasma infection in zoo animals. The study included eight animal species of which 54 serum samples were collected from 30 Australian goats (Capra hircus), four bulls (Bos taurus), one dromedary (Camelus dromedarius), three cuffed sheep (Ammotragus lervia), seven donkeys (Equus asinus), one pony (Equus ferus), four bearded horses (Equus ferus caballus) and four rabbits (Oryctolagus cuniculus). The presence of antibodies to T. gondii was determined using the ID Screen® Toxoplasmosis Indirect Multispecies ELISA kit (IDVet, Grabels, France). A total of 8/54 (14.8%) samples were seropositive, including 5/28 (17.9%) males and 3/26 (11.5%) females. The seroprevalence was 6.7%, 50%, 25% and 75% in Capra hircus, Bos Taurus, Equus ferus caballus, and Oryctolagus cuniculus, respectively. No cases were observed in Camelus dromedarius, Ammotragus lervia, Equus asinus, and Equus ferus. This study indicates, for the first time in Algeria, the seroprevalence of T. gondii in zoo animals.

Combination of an enzyme-linked immunosorbent assay and an indirect fluorescence assay for a nationwide sero-survey of Toxoplasma gondii infection in pig herds in Taiwan.

Toxoplasma gondii is a zoonotic pathogen that can infect farm animals, companion animals, and humans, sometimes causing public health issues. In Taiwan, the pig industry is a vital agricultural industry, with a self-sufficiency rate of 91 %, and pigs are also food-producing animal reservoirs of Toxoplasma gondii. Infected pigs are usually asymptomatic, and abortions and death may occur in severe cases. We combined an enzyme-linked immunosorbent assay (ELISA) and an indirect fluorescence assay (IFA) to investigate the seroprevalence of Toxoplasma gondii among pig populations in Taiwan. A stratified sampling approach to determine the number of sample farms proportional to the number of pig farms in each county was employed, with 15 blood samples collected at each farm between July and September 2017. With the tested results, empirical Bayesian smoothing was utilized to assess the proportion of Toxoplasma-positive farms at the county level. Bayesian mixed-effects logistic regression models, incorporating farm and county as random effects, were employed to investigate associations between Toxoplasma test results and potential risk factors. A total of 930 serum samples from 62 pig farms were collected and tested. An overall herd prevalence of 27.4 % was shown with the seroprevalence in northern Taiwan being greater than that in southern Taiwan. The sampling month and companion dog density in 2017 were significantly associated with Toxoplasma infections in pigs. With every increase in the number of companion dogs per km² at the county level, the odds of Toxoplasma infection in pigs increased by 4.7 % (95 % CI: 1.7-8.9 %). This study demonstrated that combining ELISA for screening with IFA for confirmation is a cost-effective and time-saving method for conducting a large-scale sample investigation. This was also the first nationwide, cross-sectional study in Taiwanese pig herds to investigate Toxoplasma gondii infection.

Toxoplasma gondii suppress human cord blood cell differentiation to the NK cell population.

BACKGROUND: Toxoplasma gondii is an obligate intracellular protozoan parasite that can invade all mammalian cells. It is well established that natural killer (NK) cells have critical protective roles in innate immunity during infections by intracellular pathogens. In the current study, we conducted an in vitro experiment to evaluate NK cell differentiation and activation from human umbilical cord blood mononuclear cells (UCB-MNCs) after infection with T. gondii tachyzoites. METHODS: UCB-MNCs were infected by fresh tachyzoites of type I (RH) or type II (PTG) strains of T. gondii pre-expanded in mesenchymal stem cells for 2 weeks in a medium enriched with stem cell factor, Flt3, IL-2, and IL-15. Flow cytometry analysis and western blot analysis were performed to measure the CD57+, CD56+, and Granzyme A (GZMA). RESULTS: Data revealed that incubation of UCB-MNCs with NK cell differentiation medium increased the CD57+, CD56+, and GZMA. UCB-MNCs cocultured with PTG tachyzoites showed a significant reduction of CD56+ and GZMA, but nonsignificant changes, in the levels of CD56+ compared to the control UCB-MNCs (p > .05). Noteworthy, 2-week culture of UCB-MNCs with type I (RH) tachyzoites significantly suppressed CD57+, CD56+, and GZMA, showing reduction of NK cell differentiation from cord blood cells. CONCLUSION: Our findings suggest that virulent T. gondii tachyzoites with cytopathic effects inhibit NK cell activation and eliminate innate immune responses during infection, and consequently enable the parasite to continue its survival in the host body.

The Toxoplasma secreted effector TgWIP modulates dendritic cell motility by activating host tyrosine phosphatases Shp1 and Shp2.

The obligate intracellular parasite Toxoplasma gondii causes life-threatening toxoplasmosis to immunocompromised individuals. The pathogenesis of Toxoplasma relies on its swift dissemination to the central nervous system through a 'Trojan Horse' mechanism using infected leukocytes as carriers. Previous work found TgWIP, a protein secreted from Toxoplasma, played a role in altering the actin cytoskeleton and promoting cell migration in infected dendritic cells (DCs). However, the mechanism behind these changes was unknown. Here, we report that TgWIP harbors two SH2-binding motifs that interact with tyrosine phosphatases Shp1 and Shp2, leading to phosphatase activation. DCs infected with Toxoplasma exhibited hypermigration, accompanying enhanced F-actin stress fibers and increased membrane protrusions such as filopodia and pseudopodia. By contrast, these phenotypes were abrogated in DCs infected with Toxoplasma expressing a mutant TgWIP lacking the SH2-binding motifs. We further demonstrated that the Rho-associated kinase (Rock) is involved in the induction of these phenotypes, in a TgWIP-Shp1/2 dependent manner. Collectively, the data uncover a molecular mechanism by which TgWIP modulates the migration dynamics of infected DCs in vitro.

The Toxoplasma secreted effector TgWIP modulates dendritic cell motility by activating host tyrosine phosphatases Shp1 and Shp2.

The obligate intracellular parasite Toxoplasma gondii causes life-threatening toxoplasmosis to immunocompromised individuals. The pathogenesis of Toxoplasma relies on its swift dissemination to the central nervous system through a 'Trojan Horse' mechanism using infected leukocytes as carriers. Previous work found TgWIP, a protein secreted from Toxoplasma, played a role in altering the actin cytoskeleton and promoting cell migration in infected dendritic cells (DCs). However, the mechanism behind these changes was unknown. Here, we report that TgWIP harbors two SH2-binding motifs that interact with tyrosine phosphatases Shp1 and Shp2, leading to phosphatase activation. DCs infected with Toxoplasma exhibited hypermigration, accompanying enhanced F-actin stress fibers and increased membrane protrusions such as filopodia and pseudopodia. By contrast, these phenotypes were abrogated in DCs infected with Toxoplasma expressing a mutant TgWIP lacking the SH2-binding motifs. We further demonstrated that the Rho-associated kinase (Rock) is involved in the induction of these phenotypes, in a TgWIP-Shp1/2 dependent manner. Collectively, the data uncover a molecular mechanism by which TgWIP modulates the migration dynamics of infected DCs in vitro.

Selective host autophagy is induced during the intracellular parasite Toxoplasma gondii infection controlling amino acid levels.

Toxoplasma gondii, a widespread parasite, has the ability to infect nearly any nucleated cell in warm-blooded vertebrates. It is estimated that around 2 billion people globally have been infected by this pathogen. Although most healthy individuals can effectively control parasite replication, certain parasites may evade the immune response, establishing cysts in the brain that are refractory to the immune system and resistant to available drugs. For its chronic persistence in the brain, the parasite relies on host cells' nutrients, particularly amino acids and lipids. Therefore, understanding how latent parasites persist in the brain is crucial for identifying potential drug targets against chronic forms. While shielded within parasitophorous vacuoles (PVs) or cysts, Toxoplasma exploits the host endoplasmic reticulum (ER) metabolism to sustain its persistence in the brain, resulting in host neurological alterations. In this study, we demonstrate that T. gondii disrupts the host ER homeostasis, resulting in the accumulation of unfolded protein within the host ER. The host counters this stress by initiating an autophagic pathway known as ER-phagy, which breaks down unfolded proteins into amino acids, promoting their recycling. Our findings unveil the underlying mechanisms employed by T. gondii to exploit host ER and lysosomal pathways, enhancing nutrient levels during infection. These insights provide new strategies for the treatment of toxoplasmosis. IMPORTANCE: Intracellular parasites employ several mechanisms to manipulate the cellular environment, enabling them to persist in the host. Toxoplasma gondii, a single-celled parasite, possesses the ability to infect virtually any nucleated cell of warm-blooded vertebrates, including nearly 2 billion people worldwide. Unfortunately, existing treatments and immune responses are not entirely effective in eliminating the chronic persisting forms of the parasite. This study reveals that T. gondii induces the host's autophagic pathway to boost amino acid levels in infected cells. The depletion of amino acids, in turn, influences the persistence of the parasite's chronic forms. Significantly, our investigation establishes the crucial role of host endoplasmic reticulum (ER)-phagy in the parasite's persistence within the host during latent infection.