scholarly journals GABARAPL2 Is Critical for Growth Restriction of Toxoplasma gondii in HeLa Cells Treated with Gamma Interferon

2020 ◽  
Vol 88 (5) ◽  
Author(s):  
Zhaoxia Zhang ◽  
Haorong Gu ◽  
Qi Li ◽  
Jun Zheng ◽  
Shinuo Cao ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Hela Cells ◽  
Critical Role ◽  
Gamma Interferon ◽  
Growth Restriction ◽  
Membrane Structures ◽  
Content Type ◽  
Receptor Associated Protein ◽  
Ifn Γ ◽  
And Function

ABSTRACT Gamma interferon (IFN-γ)-induced innate immune responses play important roles in the inhibition of Toxoplasma gondii infection. It has been reported that IFN-γ stimulates non-acidification-dependent growth restriction of T. gondii in HeLa cells, but the mechanism remains unclear. Here, we found that γ-aminobutyric acid (GABA) receptor-associated protein-like 2 (GABARAPL2) plays a critical role in parasite restriction in IFN-γ-treated HeLa cells. GABARAPL2 is recruited to membrane structures surrounding parasitophorous vacuoles (PV). Autophagy adaptors are required for the proper localization and function of GABARAPL2 in the IFN-γ -induced immune response. These findings provide further understanding of a noncanonical autophagy pathway responsible for IFN-γ-dependent inhibition of T. gondii growth in human HeLa cells and demonstrate the critical role of GABARAPL2 in this response.

scholarly journals Complex Immune Cell Interplay in the Gamma Interferon Response during Toxoplasma gondii Infection

2014 ◽  
Vol 82 (8) ◽  
pp. 3090-3097 ◽  
Author(s):  
Carolyn R. Sturge ◽  
Felix Yarovinsky
Keyword(s):  
Toxoplasma Gondii ◽  
Immune Cell ◽  
Critical Role ◽  
Clinical Importance ◽  
Protozoan Parasite ◽  
Gamma Interferon ◽  
Interferon Response ◽  
Content Type ◽  
Effector Cells ◽  
Ifn Γ

ABSTRACTToxoplasma gondiiis an obligate intracellular parasite of clinical importance, especially in immunocompromised patients. Investigations into the immune response to the parasite found that T cells are the primary effector cells regulating gamma interferon (IFN-γ)-mediated host resistance. However, recent studies have revealed a critical role for the innate immune system in mediating host defense independently of the T cell responses to the parasite. This body of knowledge is put into perspective by the unifying theme that immunity to the protozoan parasite requires a strong IFN-γ host response. In the following review, we discuss the role of IFN-γ-producing cells and the signals that regulate IFN-γ production duringT. gondiiinfection.

scholarly journals Toxoplasma gondii Inhibits Gamma Interferon (IFN-γ)- and IFN-β-Induced Host Cell STAT1 Transcriptional Activity by Increasing the Association of STAT1 with DNA

2013 ◽  
Vol 82 (2) ◽  
pp. 706-719 ◽  
Author(s):  
Emily E. Rosowski ◽  
Quynh P. Nguyen ◽  
Ana Camejo ◽  
Eric Spooner ◽  
Jeroen P. J. Saeij
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Transcriptional Activation ◽  
Histone Deacetylases ◽  
Gamma Interferon ◽  
Host Cells ◽  
Secondary Response ◽  
Type I ◽  
Content Type ◽  
Ifn Γ

ABSTRACTThe gamma interferon (IFN-γ) response, mediated by the STAT1 transcription factor, is crucial for host defense against the intracellular pathogenToxoplasma gondii, but prior infection withToxoplasmacan inhibit this response. Recently, it was reported that theToxoplasmatype II NTE strain prevents the recruitment of chromatin remodeling complexes containing Brahma-related gene 1 (BRG-1) to promoters of IFN-γ-induced secondary response genes such asCiitaand major histocompatibility complex class II genes in murine macrophages, thereby inhibiting their expression. We report here that a type I strain ofToxoplasmainhibits the expression of primary IFN-γ response genes such asIRF1through a distinct mechanism not dependent on the activity of histone deacetylases. Instead, infection with a type I, II, or III strain ofToxoplasmainhibits the dissociation of STAT1 from DNA, preventing its recycling and further rounds of STAT1-mediated transcriptional activation. This leads to increased IFN-γ-induced binding of STAT1 at theIRF1promoter in host cells and increased global IFN-γ-induced association of STAT1 with chromatin.Toxoplasmatype I infection also inhibits IFN-β-induced interferon-stimulated gene factor 3-mediated gene expression, and this inhibition is also linked to increased association of STAT1 with chromatin. The secretion of proteins into the host cell by a type I strain ofToxoplasmawithout complete parasite invasion is not sufficient to block STAT1-mediated expression, suggesting that the effector protein responsible for this inhibition is not derived from the rhoptries.

scholarly journals Antigen-Specific CD4+T Cell-Derived Gamma Interferon Is Both Necessary and Sufficient for ClearingChlamydiafrom the Small Intestine but Not the Large Intestine

2019 ◽  
Vol 87 (6) ◽  
Author(s):  
Hui Lin ◽  
Conghui He ◽  
John J. Koprivsek ◽  
Jianlin Chen ◽  
Zhiguang Zhou ◽  
...  
Keyword(s):  
T Cells ◽  
Small Intestine ◽  
Gastrointestinal Tract ◽  
T Cell ◽  
Large Intestine ◽  
Genital Tract ◽  
Critical Role ◽  
Gamma Interferon ◽  
Content Type ◽  
Ifn Γ

ABSTRACTThe genital tract pathogenChlamydia trachomatisis frequently detected in the gastrointestinal tract, but the host immunity that regulates chlamydial colonization in the gut remains unclear. In aChlamydia muridarum-C57 mouse model, chlamydial organisms are cleared from the genital tract in ∼4 weeks, but the genital organisms can spread to the gastrointestinal tract. We found that the gastrointestinal chlamydial organisms were cleared from the small intestine by day 28, paralleling their infection course in the genital tract, but persisted in the large intestine for long periods. Mice deficient in α/β T cells or CD4+T cells but not CD8+T cells showed chlamydial persistence in the small intestine, indicating a critical role for CD4+T cells in clearingChlamydiafrom the small intestine. The CD4+T cell-dependent clearance is likely mediated by gamma interferon (IFN-γ), since mice deficient in IFN-γ but not interleukin 22 (IL-22) signaling pathways rescued chlamydial colonization in the small intestine. Furthermore, exogenous IFN-γ was sufficient for clearingChlamydiafrom the small intestine but not the large intestine. Mice deficient in developingChlamydia-specific Th1 immunity showed chlamydial persistence in the small intestine. Finally, IFN-γ-producing CD4+but not CD8+T cells from immunized donor mice were sufficient for eliminatingChlamydiafrom the small intestine but not the large intestine of recipient mice. Thus, we have demonstrated a critical role for Th1 immunity in clearingChlamydiafrom the small intestine but not the large intestine, indicating that chlamydial colonization in different regions of the gastrointestinal tract is regulated by distinct immune mechanisms.

scholarly journals Cell Death of Gamma Interferon-Stimulated Human Fibroblasts upon Toxoplasma gondii Infection Induces Early Parasite Egress and Limits Parasite Replication

2013 ◽  
Vol 81 (12) ◽  
pp. 4341-4349 ◽  
Author(s):  
Wendy Niedelman ◽  
Joris K. Sprokholt ◽  
Barbara Clough ◽  
Eva-Maria Frickel ◽  
Jeroen P. J. Saeij
Keyword(s):  
Cell Death ◽  
Toxoplasma Gondii ◽  
Human Fibroblasts ◽  
Protozoan Parasite ◽  
Resistance Mechanisms ◽  
Gamma Interferon ◽  
Content Type ◽  
Food Borne Illness ◽  
Ifn Γ ◽  
Toxoplasma Gondii Infection

ABSTRACTThe intracellular protozoan parasiteToxoplasma gondiiis a major food-borne illness and opportunistic infection for the immunosuppressed. Resistance toToxoplasmais dependent on gamma interferon (IFN-γ) activation of both hematopoietic and nonhematopoietic cells. Although IFN-γ-induced innate immunity in nonhematopoietic cells has been extensively studied in mice, it remains unclear what resistance mechanisms are relied on in nonhematopoietic human cells. Here, we report an IFN-γ-induced mechanism of resistance toToxoplasmain primary human foreskin fibroblasts (HFFs) that does not depend on the deprivation of tryptophan or iron. In addition, infection is still controlled in HFFs deficient in the p65 guanylate binding proteins GBP1 or GBP2 and the autophagic protein ATG5. Resistance is coincident with host cell death that is not dependent on the necroptosis mediator RIPK3 or caspases and is correlated with early egress of the parasite before replication. This IFN-γ-induced cell death and early egress limits replication in HFFs and could promote clearance of the parasite by immune cells.

scholarly journals Enrichment and Proteomic Characterization of the Cyst Wall from In Vitro Toxoplasma gondii Cysts

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Vincent Tu ◽  
Joshua Mayoral ◽  
Tatsuki Sugi ◽  
Tadakimi Tomita ◽  
Bing Han ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Cyst Wall ◽  
Chronic Infection ◽  
Latent Infection ◽  
Gene Knockout ◽  
Life Stage ◽  
Critical Role ◽  
Data Set ◽  
Content Type ◽  
And Function

ABSTRACT The tissue cyst of Toxoplasma gondii, found in latent infection, serves a critical role in both transmission and reactivation of this organism. Within infected cells, slowly replicating parasites (bradyzoites) are surrounded by a cyst matrix, cyst wall, and cyst membrane. The cyst wall is clearly delineated by ultrastructural analysis; however, the composition and function of this layer in host-parasite interactions are not fully understood. In order to understand the composition of the cyst wall, a proteomic analysis of purified cyst wall fragments, that were enriched with Percoll gradients and subsequently immunoprecipitated with CST1 antibody, was performed. Known cyst wall proteins, such as CST1, BPK1, MCP4, MAG1, GRA2, GRA3, and GRA5, were identified in this preparation by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, dense granule proteins (GRAs) not previously shown to associate with the cyst wall, as well as uncharacterized hypothetical proteins, were identified in this cyst wall preparation. Several of these hypothetical cyst wall (CST) proteins were epitope tagged, and immunofluorescence assays confirmed their localization as novel cyst matrix and cyst wall proteins. Expression of two of these newly identified cyst wall proteins was eliminated by gene knockout (CST2-KO and CST3-KO). CST2-KO parasites were highly attenuated in virulence and did not establish detectable cyst burdens. This targeted proteomic approach allowed the identification of new components of the cyst wall that probably have roles in the parasite/host interface. IMPORTANCE Toxoplasma gondii is a highly prevalent parasite worldwide that presents life-threatening risks to immunocompromised and pregnant individuals. Whereas the life stage responsible for acute infection can be treated, the life stage responsible for chronic infection is refractory to currently available therapeutics. Little is known about the protein composition of the cyst wall, an amorphous structure formed by parasites that is suspected to facilitate persistence within muscle and nervous tissue during chronic (latent) infection. By implementing a refined approach to selectively purify cyst wall fragments, we identified several known and novel cyst wall proteins from our sample preparations. We confirmed the localizations of several proteins from this data set and identified one that is involved in parasite virulence. These data will propel further studies on cyst wall structure and function, leading to therapeutic strategies that can eliminate the chronic infection stage.

scholarly journals ISG15 Connects Autophagy and IFN-γ-Dependent Control of Toxoplasma gondii Infection in Human Cells

mBio ◽  
2020 ◽  
Vol 11 (5) ◽  
Author(s):  
Jaya Bhushan ◽  
Joshua B. Radke ◽  
Yi-Chieh Perng ◽  
Michael Mcallaster ◽  
Deborah J. Lenschow ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Parasitophorous Vacuole ◽  
Interferon Γ ◽  
Parasite Growth ◽  
Human Cells ◽  
Growth Restriction ◽  
Intracellular Pathogens ◽  
Functional Link ◽  
Content Type ◽  
Ifn Γ

ABSTRACT The intracellular protozoan parasite Toxoplasma gondii is capable of infecting most nucleated cells, where it survives in a specially modified compartment called the parasitophorous vacuole (PV). Interferon gamma (IFN-γ) is the major cytokine involved in activating cell-autonomous immune responses to inhibit parasite growth within this intracellular niche. In HeLa cells, IFN-γ treatment leads to ubiquitination of susceptible parasite strains, recruitment of the adaptors p62 and NDP52, and engulfment in microtubule-associated protein 1 light chain 3 (LC3)-positive membranes that restrict parasite growth. IFN-γ-mediated growth restriction depends on core members of the autophagy (ATG) pathway but not the initiation or degradative steps in the process. To explore the connection between these different pathways, we used permissive biotin ligation to identify proteins that interact with ATG5 in an IFN-γ-dependent fashion. Network analysis of the ATG5 interactome identified interferon-stimulated gene 15 (ISG15), which is highly upregulated by IFN treatment, as a hub connecting the ATG complex with other IFN-γ-induced genes, suggesting that it forms a functional link between the pathways. Deletion of ISG15 resulted in impaired recruitment of p62, NDP52, and LC3 to the PV and loss of IFN-γ-restricted parasite growth. The function of ISG15 required conjugation, and a number of ISGylated targets overlapped with the IFN-γ-dependent ATG5 interactome, including the adapter p62. Collectively, our findings establish a role for ISG15 in connecting the ATG pathway with IFN-γ-dependent restriction of T. gondii in human cells. IMPORTANCE Interferon(s) provide the primary defense against intracellular pathogens, a property ascribed to their ability to upregulate interferon-stimulated genes. Due to the sequestered niche occupied by Toxoplasma gondii, the host has elaborated intricate ways to target the parasite within its vacuole. One such mechanism is the recognition by a noncanonical autophagy pathway that envelops the parasite-containing vacuole and stunts growth in human cells. Remarkably, autophagy-dependent growth restriction requires interferon-γ, yet none of the classical components of autophagy are induced by interferon. Our studies draw a connection between these pathways by demonstrating that the antiviral protein ISG15, which is normally upregulated by interferons, links the autophagy-mediated control to ubiquitination of the vacuole. These findings suggest a similar link between interferon-γ signaling and autophagy that may underlie defense against other intracellular pathogens.

scholarly journals Infection-Induced Intestinal Dysbiosis Is Mediated by Macrophage Activation and Nitrate Production

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Shuai Wang ◽  
Ayah El-Fahmawi ◽  
David A. Christian ◽  
Qun Fang ◽  
Enrico Radaelli ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Oral Infection ◽  
Nitrate Respiration ◽  
Characteristic Change ◽  
Intestinal Immunity ◽  
Parasite Control ◽  
Shotgun Metagenomics ◽  
Content Type ◽  
Distal Small Intestine ◽  
Ifn Γ

ABSTRACT Oral infection of C57BL/6J mice with Toxoplasma gondii results in a marked bacterial dysbiosis and the development of severe pathology in the distal small intestine that is dependent on CD4+ T cells and interferon gamma (IFN-γ). This dysbiosis and bacterial translocation contribute to the development of ileal pathology, but the factors that support the bloom of bacterial pathobionts are unclear. The use of microbial community profiling and shotgun metagenomics revealed that Toxoplasma infection induces a dysbiosis dominated by Enterobacteriaceae and an increased potential for nitrate respiration. In vivo experiments using bacterial metabolic mutants revealed that during this infection, host-derived nitrate supports the expansion of Enterobacteriaceae in the ileum via nitrate respiration. Additional experiments with infected mice indicate that the IFN-γ/STAT1/iNOS axis, while essential for parasite control, also supplies a pool of nitrate that serves as a source for anaerobic respiration and supports overgrowth of Enterobacteriaceae. Together, these data reveal a trade-off in intestinal immunity after oral infection of C57BL/6J mice with T. gondii, in which inducible nitric oxide synthase (iNOS) is required for parasite control, while this host enzyme is responsible for specific modification of the composition of the microbiome that contributes to pathology. IMPORTANCE Toxoplasma gondii is a protozoan parasite and a leading cause of foodborne illness. Infection is initiated when the parasite invades the intestinal epithelium, and in many host species, this leads to intense inflammation and a dramatic disruption of the normal microbial ecosystem that resides in the healthy gut (the so-called microbiome). One characteristic change in the microbiome during infection with Toxoplasma—as well as numerous other pathogens—is the overgrowth of Escherichia coli or similar bacteria and a breakdown of commensal containment leading to seeding of peripheral organs with gut bacteria and subsequent sepsis. Our findings provide one clear explanation for how this process is regulated, thereby improving our understanding of the relationship between parasite infection, inflammation, and disease. Furthermore, our results could serve as the basis for the development of novel therapeutics to reduce the potential for harmful bacteria to bloom in the gut during infection.

scholarly journals Immediate Interferon Gamma Induction Determines Murine Host Compatibility Differences between Toxoplasma gondii and Neospora caninum

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Rachel S. Coombs ◽  
Matthew L. Blank ◽  
Elizabeth D. English ◽  
Yaw Adomako-Ankomah ◽  
Ifeanyi-Chukwu Samuel Urama ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Immune Responses ◽  
Interferon Gamma ◽  
Neospora Caninum ◽  
Ectopic Expression ◽  
Parasite Burden ◽  
Interleukin 12 ◽  
Content Type ◽  
Ifn Γ ◽  
And Control

ABSTRACT Rodents are critical for the transmission of Toxoplasma gondii to the definitive feline host via predation, and this relationship has been extensively studied as a model for immune responses to parasites. Neospora caninum is a closely related coccidian parasite of ruminants and canines but is not naturally transmitted by rodents. We compared mouse innate immune responses to N. caninum and T. gondii and found marked differences in cytokine levels and parasite growth kinetics during the first 24 h postinfection (hpi). N. caninum-infected mice produced significantly higher levels of interleukin-12 (IL-12) and interferon gamma (IFN-γ) by as early as 4 hpi, but the level of IFN-γ was significantly lower or undetectable in T. gondii-infected mice during the first 24 hpi. “Immediate” IFN-γ and IL-12p40 production was not detected in MyD88−/− mice. However, unlike IL-12p40−/− and IFN-γ−/− mice, MyD88−/− mice survived N. caninum infections at the dose used in this study. Serial measures of parasite burden showed that MyD88−/− mice were more susceptible to N. caninum infections than wild-type (WT) mice, and control of parasite burdens correlated with a pulse of serum IFN-γ at 3 to 4 days postinfection in the absence of detectable IL-12. Immediate IFN-γ was partially dependent on the T. gondii mouse profilin receptor Toll-like receptor 11 (TLR11), but the ectopic expression of N. caninum profilin in T. gondii had no impact on early IFN-γ production or parasite proliferation. Our data indicate that T. gondii is capable of evading host detection during the first hours after infection, while N. caninum is not, and this is likely due to the early MyD88-dependent recognition of ligands other than profilin.

scholarly journals Persistent Chlamydia trachomatis Infection of HeLa Cells Mediates Apoptosis Resistance through a Chlamydia Protease-Like Activity Factor-Independent Mechanism and Induces High Mobility Group Box 1 Release

2011 ◽  
Vol 80 (1) ◽  
pp. 195-205 ◽  
Author(s):  
Jürgen Rödel ◽  
Christina Große ◽  
Hangxing Yu ◽  
Katharina Wolf ◽  
Gordon P. Otto ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Host Cell ◽  
Hela Cells ◽  
Persistent Infection ◽  
High Mobility ◽  
Apoptosis Resistance ◽  
Content Type ◽  
Activity Factor ◽  
Infected Cells ◽  
Ifn Γ

ABSTRACTIntracellular persistence ofChlamydia trachomatishas been implicated in the development of chronic infection that can result in pelvic inflammatory disease and tubal sterility. By inhibition of host cell apoptosis, chlamydiae have evolved a strategy to maintain the intracellular environment for replication and persistence. Both antiapoptotic host cell-derived factors and the chlamydial protease-like activity factor (CPAF) are involved inChlamydia-mediated apoptosis resistance. Here, we show that in HeLa cells infected with gamma interferon (IFN-γ)-induced persistentC. trachomatisserovar D, the expression of CPAF is downregulated, and proapoptotic protease substrates are not cleaved. Persistent infection protected HeLa cells from apoptosis when they were exposed to staurosporine. Small-interfering RNA-mediated inhibition of myeloid cell leukemia 1 (Mcl-1) protein upregulation sensitized persistently infected cells for apoptosis. The inhibitor of apoptosis protein 2 (IAP-2) seems not to be relevant in this context because IAP-2 protein was not induced in response to IFN-γ treatment. Although apoptosis was inhibited, persistent infection caused cell membrane disintegration, as measured by the increased release of cytokeratin 18 from HeLa cells. Moreover, persistently infected cells released significantly increased amounts of high mobility group box 1 (HMGB1) protein which represents a proinflammatory damage-associated pattern molecule. The data of this study suggest that cells infected with persistentC. trachomatisare protected from apoptosis independently of CPAF but may promote chronic inflammation through HMGB1 release.

scholarly journals NADPH Oxidase and Guanylate Binding Protein 5 Restrict Survival of Avirulent Type III Strains of Toxoplasma gondii in Naive Macrophages

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Sumit K. Matta ◽  
Kelley Patten ◽  
Quiling Wang ◽  
Bae-Hoon Kim ◽  
John D. MacMicking ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Nadph Oxidase ◽  
Binding Protein ◽  
Parasitic Infections ◽  
Type I ◽  
Content Type ◽  
Innate Defense ◽  
Type Iii ◽  
Ifn Γ ◽  
Guanylate Binding Protein

ABSTRACT Phagocytic cells are the first line of innate defense against intracellular pathogens, and yet Toxoplasma gondii is renowned for its ability to survive in macrophages, although this paradigm is based on virulent type I parasites. Surprisingly, we find that avirulent type III parasites are preferentially cleared in naive macrophages, independent of gamma interferon (IFN-γ) activation. The ability of naive macrophages to clear type III parasites was dependent on enhanced activity of NADPH oxidase (Nox)-generated reactive oxygen species (ROS) and induction of guanylate binding protein 5 (Gbp5). Macrophages infected with type III parasites (CTG strain) showed a time-dependent increase in intracellular ROS generation that was higher than that induced by type I parasites (GT1 strain). The absence of Nox1 or Nox2, gp91 subunit isoforms of the Nox complex, reversed ROS-mediated clearance of CTG parasites. Consistent with this finding, both Nox1−/− and Nox2−/− mice showed higher susceptibility to CTG infection than wild-type mice. Additionally, Gbp5 expression was induced upon infection and the enhanced clearance of CTG strain parasites was reversed in Gbp5−/− macrophages. Expression of a type I ROP18 allele in CTG prevented clearance in naive macrophages, suggesting that it plays a role counteracting Gbp5. Although ROS and Gbp5 have been linked to activation of the NLRP3 inflammasome, clearance of CTG parasites did not rely on induction of pyroptosis. Collectively, these findings reveal that not all strains of T. gondii are adept at avoiding clearance in macrophages and define new roles for ROS and Gbps in controlling this important intracellular pathogen. IMPORTANCE Toxoplasma infections in humans and other mammals are largely controlled by IFN-γ produced by the activated adaptive immune system. However, we still do not completely understand the role of cell-intrinsic functions in controlling Toxoplasma or other apicomplexan infections. The present work identifies intrinsic activities in naive macrophages in counteracting T. gondii infection. Using an avirulent strain of T. gondii, we highlight the importance of Nox complexes in conferring protection against parasite infection both in vitro and in vivo. We also identify Gbp5 as a novel macrophage factor involved in limiting intracellular infection by avirulent strains of T. gondii. The rarity of human infections caused by type III strains suggests that these mechanisms may also be important in controlling human toxoplasmosis. These findings further extend our understanding of host responses and defense mechanisms that act to control parasitic infections at the cellular level.

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