Affinage · Toxoplasma gondii

GRA2

dense granule protein GRA2 · UniProt A0A125YGN4

Annotated
2026-09-08
85 papers in source corpus 32 papers cited in narrative 32 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GRA2 is a dense granule protein of Toxoplasma gondii secreted into the parasitophorous vacuole (PV), where it is the principal structural organizer of the intravacuolar network (IVN) that remodels the vacuole into a host-parasite interface (PMID:8384696, PMID:12134078). After apical dense granule exocytosis within minutes of invasion, GRA2 reaches the PV by two routes—as a soluble protein that peripherally associates with the network and within multi-lamellar vesicles released from a posterior invagination that assemble the IVN, in which GRA2 becomes an integral membrane form (PMID:8415546, PMID:7615684). Two internal amphipathic alpha-helices drive GRA2's distinctive alpha-helical oligomeric self-assembly and its stable membrane association, and their integrity is essential for inducing the nanotubular conformation of the IVN; targeting and stable membrane retention are separable functions encoded by distinct helical elements (PMID:9664038, PMID:18061598, PMID:25712518). GRA2 nucleates the network's assembly hierarchy, acting upstream of GRA6 and GRA12 localization to the posterior organizing center and forming oligomeric complexes with GRA3, GRA4, GRA5, GRA6, GRA7 and GRA12 that remodel upon membrane integration (PMID:10498186, PMID:12134078, PMID:17959262, PMID:18840447). Through the tubular network it stabilizes, GRA2 sequesters host Rab11A-positive vesicles and, in a manner strictly co-dependent on GRA6, restricts MHC class I antigen presentation of PV antigens and dampens CD8 T cell responses (PMID:26628378, PMID:29070609, PMID:31555296). GRA2 is an acute-stage virulence factor whose disruption attenuates lethality while permitting chronic infection (PMID:9712765), and in chronic infection it is a structural component of the bradyzoite cyst wall and matrix required for normal cyst development (PMID:31266861, PMID:31040239, PMID:31619500).

Mechanistic history

Synthesis pass · year-by-year structured walk · 13 steps
  1. 1993 High

    Establishing GRA2's molecular identity and predicting its membrane-interaction module framed the central question of how a soluble secreted protein engages the vacuolar network.

    Evidence cDNA cloning, protein purification and sequencing, and immuno-EM localization in tachyzoites and bradyzoites

    PMID:8384696 PMID:8415546 PMID:8344403

    Open questions at the time
    • The functional role of the predicted amphipathic helices was not yet tested
    • The mechanism distinguishing GRA2 targeting from GRA5 was unresolved
  2. 1995 High

    Discovering two secretion routes and a membrane-integral form of GRA2 answered how the protein transitions from soluble cargo to a network-building component.

    Evidence Immunolabeling and cell fractionation of infected cells

    PMID:7615684

    Open questions at the time
    • Sequence determinants driving membrane integration were not defined
    • The composition of the multi-lamellar vesicles was uncharacterized
  3. 1998 High

    Mutagenesis of the two amphipathic helices showed that membrane targeting and stable retention are separable mechanisms, and knockout established GRA2 as an in vivo acute virulence factor.

    Evidence Stable transformation of tagged deletion/point mutants with IEM, IF and fractionation; targeted RH knockout with mouse virulence challenge; glycoprotein analysis

    PMID:9664038 PMID:9712765 PMID:9879904

    Open questions at the time
    • The IVN morphology defect of Δgra2 was not yet visualized
    • The molecular basis of attenuated virulence was undefined
    • Functional relevance of O-linked glycosylation was untested
  4. 1999 High

    Identifying a GRA2–GRA4–GRA6 network complex began mapping GRA2 into a defined multiprotein assembly rather than an isolated structural protein.

    Evidence Cross-linking, fractionation, denaturing treatments and immunoprecipitation

    PMID:10498186

    Open questions at the time
    • Stoichiometry and architecture of the complex were not determined
    • It was unclear which partner nucleates assembly
  5. 2002 High

    Knockout and complementation demonstrated that GRA2 is required for the nanotubular IVN conformation and acts upstream of GRA6 posterior localization, defining GRA2 as the initiator of network assembly.

    Evidence Δgra2 knockout plus complementation with helix mutants, IF and EM; Rab6 dominant-mutant assay placing GRA2 glycosylation downstream of Golgi trafficking

    PMID:12134078 PMID:12468555

    Open questions at the time
    • The biophysical mechanism of tubulation was not shown in a defined system
    • The role of glycosylation in network function remained open
  6. 2007 High

    Affinity purification and systematic domain dissection defined GRA2's pre- and post-secretion partners and showed complex remodeling on membrane integration, and mapped the helical elements required for each function.

    Evidence HA-FLAG affinity chromatography with MS from complemented parasites; complementation with eight truncated GRA2 forms scored by IF, EM and fractionation

    PMID:17959262 PMID:18061598

    Open questions at the time
    • The trigger for partner remodeling upon membrane insertion was unknown
    • Direct versus indirect nature of each association was not resolved
  7. 2008 High

    Placing GRA12 downstream of GRA2 localization extended the assembly hierarchy in which GRA2 organizes other network proteins to the posterior organizing center.

    Evidence IF, immuno-EM and affinity chromatography in Δgra2 parasites

    PMID:18840447

    Open questions at the time
    • The physical basis of GRA2-dependent GRA12 recruitment was undefined
  8. 2015 High

    Cell-free reconstitution and biophysical characterization established that GRA2 (with GRA6) directly shapes membrane tubules and that its amphipathic helices drive oligomeric self-assembly, linking network deformation to immune evasion.

    Evidence Cell-free membrane tubulation, MHC-I presentation assays with Δgra2/Δgra6, in vivo CD8 responses; CD, DLS and TEM on recombinant full-length versus helix-truncated GRA2

    PMID:26628378 PMID:25712518

    Open questions at the time
    • High-resolution structure of the assembled tubule was not determined
    • The exact route by which network association limits GRA6 antigen access was not fully resolved
  9. 2016 High

    A systematic GRA knockout panel confirmed that GRA2 is indispensable for IVN formation and linked IVN-associated GRA2 to activation of protective host immunity.

    Evidence Targeted GRA2-9 knockouts in RH with IVN imaging and virulence assays; GRA2 deletion in a uracil-auxotroph vaccine strain with antitumor immunity readouts

    PMID:27458822 PMID:27447180

    Open questions at the time
    • The RH knockout panel found no virulence effect, contrasting the earlier acute virulence phenotype
    • The molecular signal by which IVN-associated GRA2 activates dendritic cells was not defined
  10. 2017 High

    Correlative imaging showed GRA2/GRA6-stabilized tubules sequester host Rab11A vesicles, giving the IVN a defined host-interaction function.

    Evidence Correlative light-EM and GFP-Rab11A live imaging in Δgra2, Δgra6 and double-KO infections

    PMID:29070609

    Open questions at the time
    • Whether GRA2 binds host vesicle machinery directly was not shown
    • The consequences of sequestration for parasite nutrition were not defined
  11. 2019 High

    Type II knockout, cyst-wall proteomics, dynamic localization and GRA6-dependency assays established GRA2's chronic-stage structural role in the cyst wall/matrix and its co-dependent immune-evasion function.

    Evidence Pru Δgra2 in vivo cyst assays; CST1-IP proteomics; IF tracking during bradyzoite differentiation with KO controls; MHC-I presentation with Δgra2/Δgra6 epistasis; EV proteomics of infected neurons

    PMID:31266861 PMID:31040239 PMID:31619500 PMID:31555296 PMID:40523037

    Open questions at the time
    • How GRA2 mechanically contributes to cyst wall integrity is undefined
    • The mechanism of GRA6-strict co-dependence for antigen suppression is unresolved
    • GRA2's functional role within neuronal EVs (Low confidence) is not characterized
  12. 2022 Medium

    Genetic epistasis with host Rab11A positioned GRA2 in a circuit that restrains host autophagy to support replication, extending its Rab11A-linked function beyond vesicle sequestration.

    Evidence CRISPR KO of host atg5/rab11a, RT-qPCR, autophagy assays and Δgra2 replication assays in RHΔku80

    PMID:36532461

    Open questions at the time
    • Whether GRA2 directly modulates autophagy machinery or acts via IVN structure is unclear
    • The signaling link between rab11a loss and gra2 transcription is undefined
  13. 2024 Medium

    Super-resolution U-ExM refined GRA2's spatial organization as granules spanning the cyst wall, sharpening the structural picture of its chronic-stage role.

    Evidence StcE mucinase-enhanced ultrastructure expansion microscopy in fibroblasts and neurons

    PMID:39189782

    Open questions at the time
    • The molecular interactions anchoring GRA2 within the cyst wall lattice are unknown

Open questions

Synthesis pass · forward-looking unresolved questions
  • The atomic structure of the GRA2-assembled tubule and the direct molecular mechanism by which its amphipathic helices deform membranes and select partners remain unresolved.
  • No high-resolution structure of GRA2 oligomers on membranes
  • Mechanism of GRA6-strict co-dependence for MHC-I suppression undefined
  • Direct host-factor binding partners of GRA2 not identified

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
GRA12 (GRA12A/B/D) [#12, #26]GRA3 [#10]GRA4 [#7]GRA5 [#10]GRA6 [#7, #10, #15, #23]GRA7 [#10]HEPARIN / SULFATED GLYCOSAMINOGLYCANS [#13]HOST RAB11A VESICLES [#19, #28]
Complex memberships
GRA2–GRA12 soluble PV complex [#12]GRA2–GRA3–GRA6–GRA7 soluble/pre-secretion complex; remodeled to GRA2–GRA5–GRA7 upon PV membrane integration [#10]GRA2–GRA4–GRA6 intravacuolar network complex (cross-linking) [#7]

Evidence

Reading pass · 32 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1993 GRA2 is a 28.5 kDa dense granule protein stored in dense granules of Toxoplasma tachyzoites and bradyzoites; the gene encodes a 185 amino acid polypeptide (19.8 kDa) with a 23 amino acid signal sequence, and the predicted mature polypeptide contains an internal helical domain with two amphipathic alpha-helices proposed to mediate association with the membranous network within the parasitophorous vacuole. cDNA library screening, Northern blot, primer extension, HPLC purification and amino acid sequencing, metabolic radiolabeling Molecular and biochemical parasitology High 8384696
1993 Dense granule exocytosis of GRA2 occurs at the apical area of the tachyzoite within minutes of invasion; GRA2 is first found as dense material between parasite and vacuole membranes before the vacuolar network forms, and subsequently strongly labels the vacuolar network. Immunofluorescence assay (IFA) and immunoelectron microscopy at different post-infection time points Parasitology research High 8415546
1993 In bradyzoites, GRA2 is found preferentially associated with the ground substance of the cyst wall and the tubular elements of the network of the modified host cell phagosome, indicating selective targeting distinct from GRA5 (which localizes to the delimiting membrane). Monoclonal antibody immunogold labeling and colloidal immunogold labeling by electron microscopy Experimental parasitology Medium 8344403
1995 GRA2 is secreted from dense granules via two routes: (1) as a soluble protein into the vacuole lumen, which subsequently becomes peripherally associated with the intravacuolar network; and (2) within multi-lamellar vesicles released from a specialized posterior invagination of the parasite. The multi-lamellar vesicles assemble to form the intravacuolar network, in which GRA2 exists as an integral membrane form. Immunolabeling and cell fractionation Journal of cell science High 7615684
1998 The two amphipathic alpha-helices of GRA2 are required for stable membrane association with the intravacuolar network: deletion of either helix yields secreted soluble proteins unable to stably associate with the network, and rearrangement of the first alpha-helix to a non-amphipathic pattern allows initial targeting but prevents stable membrane retention, demonstrating that targeting and stable membrane association occur by separate mechanisms. Stable transformation with HA-epitope-tagged deletion and point-mutant GRA2 constructs; immunoelectron microscopy, immunofluorescence, and cell fractionation Journal of cell science High 9664038
1998 Targeted gene disruption of GRA2 (Δgra2) in the virulent RH strain produces parasites that invade and grow normally in vitro but are significantly less virulent during acute infection in mice, while still establishing chronic infection (positive serology, brain cysts, parasite reisolation at 6 weeks). This establishes GRA2 as an important virulence factor during in vivo acute infection. Gene knockout by homologous recombination (phleomycin resistance replacement), in vitro growth assays, mouse virulence challenge, serology, immunohistochemistry, bioassay Infection and immunity High 9712765
1998 GRA2 is a glycoprotein containing O-linked oligosaccharides. Biochemical characterization (glycoprotein analysis) Molecular and biochemical parasitology Medium 9879904
1999 GRA4 and GRA6 specifically interact with GRA2 to form a multimeric complex stably associated with the intravacuolar network, as established by cross-linking experiments. GRA6 is phosphorylated and its phosphorylated form shows increased association with network membranes. The GRA2–GRA4–GRA6 complex is maintained by both protein-protein and hydrophobic interactions. Cell fractionation, denaturing agent treatment, cross-linking studies, immunoprecipitation Molecular and biochemical parasitology High 10498186
2002 GRA2 is required for the unique nanotubular conformation of the intravacuolar network: Δgra2 parasites form dramatically disorganized vacuolar compartments with the tubular network replaced by small aggregated material. Additionally, GRA6 fails to localize properly to the posterior organizing center in Δgra2 cells, demonstrating that GRA2 establishes the early conformation essential for network assembly. Complementation with GRA2 mutants showed that integrity of both amphipathic alpha-helices is required for correct network formation. Gene knockout, complementation with mutated GRA2 forms, immunofluorescence, electron microscopy Molecular biology of the cell High 12134078
2002 Toxoplasma Rab6 regulates retrograde transport from post-Golgi dense granules to the Golgi; expression of GDP-bound Rab6 mutants caused a delay in glycosylation of GRA2, placing GRA2 glycosylation downstream of Rab6-mediated Golgi trafficking. Overexpression of wild-type and dominant-negative/constitutively active Rab6 mutants; glycosylation delay assessed biochemically The Journal of biological chemistry Medium 12468555
2007 GRA2 forms high-molecular-weight oligomeric complexes within the parasite prior to secretion. Affinity purification using HA-FLAG-tagged GRA2 showed that in both the parasite and PV soluble fractions, GRA2 associates with GRA3, GRA6, and GRA7. Following insertion into PV membranes, GRA2 retains association with GRA5 and GRA7 but loses other partners, suggesting complex remodeling upon membrane integration. Affinity chromatography (HA-FLAG tag pulldown) from Δgra2 complemented parasites; conventional chromatography; mass spectrometry identification of partners Molecular and biochemical parasitology High 17959262
2007 Functional dissection of GRA2 domains by KO-complementation with eight truncated forms showed: (i) the alpha3 helix combined with N-terminal and C-terminal regions is sufficient to target GRA2 to the parasite posterior end and induce membranous vesicle formation in the vacuole; (ii) alpha1-alpha2 alone is insufficient to induce membrane tubulation; (iii) only the full NT-alpha1-alpha2-alpha3 mutant restores all biochemical and functional properties including dense granule trafficking, secretion, membrane association, MNN formation, and parasite organization within the vacuole. Δgra2-HXGPRT knockout complementation with eight truncated GRA2 forms; immunofluorescence, electron microscopy, cell fractionation phenotype analysis International journal for parasitology High 18061598
2008 GRA12 is secreted into the PV and transits to the posterior organizing center where GRA2 is located; GRA12 fails to localize at the parasite posterior end in Δgra2 parasites, placing GRA2 upstream of GRA12 localization. Within the vacuole, GRA12 is purified with the GRA2-associated complex by affinity chromatography in soluble fractions but this association is lost in the PV membranous fraction. Immunofluorescence, immuno-electron microscopy, affinity chromatography experiments in Δgra2 parasites International journal for parasitology High 18840447
2012 GRA2 and GRA6 secreted by Toxoplasma bind to sulfated heparin structures; the binding specificity and affinity of GRA2 for natural heparin and heparin oligosaccharides was determined, suggesting a role for GRA2 in interactions within the PV after secretion. Heparin-functionalized zeolites, heparin oligosaccharide microarrays, surface plasmon resonance Glycobiology Medium 22997241
2013 A polymorphism in GRA2 determines differences between RH and GT1 type I strains in evasion of the interferon-gamma response. Additionally, RH but not other type I strains recruits phosphorylated IκBα to the parasitophorous vacuole membrane, and this recruitment is partially dependent on GRA2. Whole genome sequencing (SNP identification), host transcriptional profiling, genetic epistasis using strain comparisons and GRA2 polymorphism analysis BMC genomics Medium 23837824
2015 In a cell-free minimal system, GRA2 and GRA6 together shape membrane tubules, and membrane association of GRA6 regulates its access to the MHC class I antigen presentation pathway. GRA6 association with the intravacuolar network (mediated by GRA2-dependent membrane deformation) limits GRA6 antigen presentation and curtails GRA6-specific CD8 T cell responses in mice. Cell-free reconstitution system for membrane tubulation, infected cell MHC-I antigen presentation assays, Δgra2 and Δgra6 mutant parasites, in vivo CD8 T cell response measurements Cell reports High 26628378
2015 Biophysical characterization showed that full-length recombinant GRA2 adopts an alpha-helical secondary structure (by circular dichroism) and forms two populations of particles (8–15 nm and up to 40 nm in diameter by dynamic light scattering and TEM), while GRA2 truncated of its amphipathic alpha-helices is mainly random coiled and forms only small homogenous particles (~8 nm), confirming that the AAHs drive the distinctive oligomeric/structural properties of GRA2. Circular dichroism, dynamic light scattering, transmission electron microscopy of recombinant proteins Biochemical and biophysical research communications High 25712518
2016 Δgra2 and Δgra6 single knockouts fail to form an intravacuolar network. Δgra7 exhibits hyper-formation of the IVN. All GRA2-9 single knockouts show reduced infection rate in vitro but no reduction in replication rate as single knockouts; some double knockouts (Δgra4Δgra6, Δgra3Δgra5, Δgra3Δgra7) show replication defects. None of the single or double GRA knockouts affected virulence in CD1 mice. Targeted gene knockouts at GRA2-9 loci (type I RH strain), immunofluorescence for IVN morphology, in vitro invasion and replication assays, mouse virulence challenge PloS one High 27458822
2016 Deletion of GRA2 in the intravacuolar network severely abrogated antitumor immunity induced by uracil auxotrophic Toxoplasma mutants, implicating IVN-associated GRA2 in activating host immune responses (involving CD8α+ dendritic cells and IL-12/IFN-γ TH1 axis) that drive antitumor effects. Targeted deletion of GRA2 in Δku80 vaccine strain; tumor immunity assays with dendritic cell, cytokine, and T cell readouts PLoS genetics Medium 27447180
2017 Rab11A-positive host vesicles concentrate to the intravacuolar network, but this sequestration is reduced in Δgra2 and Δgra2Δgra6 parasites, demonstrating that GRA2/GRA6-stabilized tubules contribute to host vesicle sequestration within the PV. Correlative light and electron microscopy, GFP-Rab11A live imaging in cells infected with Δgra2, Δgra6, and double-KO parasites The Journal of cell biology High 29070609
2019 Deletion of GRA2 in the type II Pru strain causes severe defects in chronic-stage cyst development in vivo without affecting parasite growth rate or in vitro cyst differentiation, establishing GRA2 as important for in vivo chronic infection. Gene knockout in type II Prugniaud strain, in vivo mouse infection (cyst burden assessment), in vitro differentiation assays mBio High 31266861
2019 GRA2 was identified as a component of the cyst wall by proteomic analysis of immunoprecipitated cyst wall fragments, establishing GRA2 as a structural component of the bradyzoite cyst wall. Percoll gradient enrichment, CST1 antibody immunoprecipitation of cyst wall fragments, LC-MS/MS proteomics mBio Medium 31040239
2019 During cyst development in vitro: GRA2 remains in the cyst matrix at day 1 post-differentiation (unlike GRA1, GRA4, GRA6, GRA9, GRA12 which localize to the cyst periphery by day 1); by day 2, GRA2 also moves to the cyst periphery. GRA2 and GRA12 co-localize in prominent cyst matrix puncta throughout cyst development and co-localize in the cyst wall by day 7. Δgra2 parasites display a defect in establishing a normal cyst matrix, and deletion of any IVN-associated GRA (except GRA1) reduces the rate of cyst wall protein accumulation at the periphery. Immunofluorescence live-cell imaging during in vitro bradyzoite differentiation; gene knockouts (Δgra2 and others); DBA lectin staining for cyst wall mSphere High 31619500
2019 GRA2 suppresses MHC class I antigen presentation of PV-localized parasite antigens to CD8+ T cells in a mechanism that is not correlated with PV disruption by IFN-γ-activated IRG effectors, and is strictly co-dependent on GRA6 protein expression. GRA2 deletion mutants; MHC-I antigen presentation assays in macrophages and dendritic cells with and without IFN-γ; IRG effector assays; double KO epistasis (Δgra2 + Δgra6) Frontiers in immunology High 31555296
2019 GRA1, GRA2, GRA7, MAG1, and MAG2 proteins from Toxoplasma were identified within extracellular vesicles (EVs) isolated from infected neurons, indicating GRA2 can be packaged into neuronal EVs during infection and potentially transferred to other cells including astrocytes. LC-MS/MS proteomics of EVs from infected primary murine cortical neurons; western blot confirmation PLoS pathogens Low 40523037
2020 The relative accumulation of s-WGA-binding (N-acetylglucosamine-decorated) molecules in the cyst wall is NOT dependent on GRA2 expression, indicating GRA2-independent mechanisms also regulate trafficking of glycosylated molecules to the cyst wall. s-WGA staining in Δgra2 parasites during in vitro cyst development; immunofluorescence mSphere Medium 32132158
2021 GRA12A, GRA12B, and GRA12D co-localize with GRA2 in the intravacuolar network of tachyzoite-stage PVs and with GRA2 in the cyst matrix and cyst wall, placing these proteins in the same structural compartment as GRA2. Immunofluorescence co-localization in tachyzoites and bradyzoites; gene knockouts of GRA12 family members mSphere Medium 33883265
2021 A GRA2 minimal promoter (core promoter region of TgGRA2) provides a 23-fold higher signal-to-noise ratio for EYFP reporter expression compared with the SAG1 minimal promoter in the TATi/Tet-Off conditional system, demonstrating that the GRA2 core promoter is a superior driver for regulated transgene expression in Toxoplasma. Stable transfection with GRA2-minimal-promoter-driven reporter constructs; quantitative fluorescence comparison to SAG1 minimal promoter Molecular and biochemical parasitology Medium 34051228
2022 Δgra2 parasites induce enhanced host autophagy in HeLa cells compared to wild-type parasites and replicate more slowly, and disruption of host rab11a increases gra2 transcription in the parasite. This positions GRA2 in a pathway where GRA2 modulates Rab11A-vesicle hijacking to limit host autophagy and support parasite replication. CRISPR/Cas9 disruption of host atg5 and rab11a; RT-qPCR for rab11a and gra2 transcript levels; autophagy assays (LC3-II, autophagosome imaging); Δgra2 RH∆ku80 parasite replication assays Frontiers in microbiology Medium 36532461
2024 Using StcE mucinase-enhanced ultrastructure expansion microscopy (U-ExM), GRA2 was localized as granules spanning across the CST1 cyst wall in bradyzoite cysts, providing super-resolution spatial organization of GRA2 within the cyst wall structure. Enzymatic mucinase (StcE) pretreatment followed by ultrastructure expansion microscopy (U-ExM) with immunofluorescence in fibroblasts and primary neuronal cultures mSphere Medium 39189782
1996 The GRA2 promoter contains critical cis-acting elements (repeated AGAGACG motifs) located in the proximal region -87 to -37 upstream of the transcription start site that are required for optimal promoter activity. Transient transformation with CAT reporter gene constructs; deletion analysis and mutation analysis of promoter sequences Molecular microbiology Medium 8858595
1997 Sporozoites within oocysts possess GRA2 mRNA and GRA2 protein in dense granules, but unlike tachyzoites, sporozoites do not exocytose GRA2 during host cell invasion and PV1 formation; GRA2 is retained within cytoplasmic granules rather than being secreted into PV1, which lacks a tubulovesicular network. Immunofluorescence and antibody staining of oocyst/sporozoite stages; comparison with tachyzoite secretion; microinjection of fluorescent dyes for PV permeability Infection and immunity Medium 9353039

Source papers

Stage 0 corpus · 85 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
1995 Regulated secretion of multi-lamellar vesicles leads to formation of a tubulo-vesicular network in host-cell vacuoles occupied by Toxoplasma gondii. Journal of cell science 170 7615684
1993 Kinetics and pattern of organelle exocytosis during Toxoplasma gondii/host-cell interaction. Parasitology research 158 8415546
2002 Biogenesis of nanotubular network in Toxoplasma parasitophorous vacuole induced by parasite proteins. Molecular biology of the cell 141 12134078
2000 Recombinant antigens to detect Toxoplasma gondii-specific immunoglobulin G and immunoglobulin M in human sera by enzyme immunoassay. Journal of clinical microbiology 132 10699010
1999 Differential membrane targeting of the secretory proteins GRA4 and GRA6 within the parasitophorous vacuole formed by Toxoplasma gondii. Molecular and biochemical parasitology 93 10498186
1995 Stable DNA transformation of Toxoplasma gondii using phleomycin selection. Gene 82 8522178
2019 Toxoplasma gondii Parasitophorous Vacuole Membrane-Associated Dense Granule Proteins Orchestrate Chronic Infection and GRA12 Underpins Resistance to Host Gamma Interferon. mBio 75 31266861
2017 The parasite Toxoplasma sequesters diverse Rab host vesicles within an intravacuolar network. The Journal of cell biology 73 29070609
2007 Evaluation of protective effect of recombinant dense granule antigens GRA2 and GRA6 formulated in monophosphoryl lipid A (MPL) adjuvant against Toxoplasma chronic infection in mice. Vaccine 67 17418457
1998 Targeted disruption of the GRA2 locus in Toxoplasma gondii decreases acute virulence in mice. Infection and immunity 67 9712765
2019 Enrichment and Proteomic Characterization of the Cyst Wall from In Vitro Toxoplasma gondii Cysts. mBio 65 31040239
1993 Molecular characterization of a dense granule antigen (Gra 2) associated with the network of the parasitophorous vacuole in Toxoplasma gondii. Molecular and biochemical parasitology 65 8384696
1999 Protective immunity in the rat model of congenital toxoplasmosis and the potential of excreted-secreted antigens as vaccine components. Parasite immunology 64 10320624
2000 T cell clones raised from chronically infected healthy humans by stimulation with Toxoplasma gondii excretory-secretory antigens cross-react with live tachyzoites: characterization of the fine antigenic specificity of the clones and implications for vaccine development. Journal of immunology (Baltimore, Md. : 1950) 58 10725733
2016 Evaluation of Immunoprotection Conferred by the Subunit Vaccines of GRA2 and GRA5 against Acute Toxoplasmosis in BALB/c Mice. Frontiers in microbiology 52 27199938
2015 Intravacuolar Membranes Regulate CD8 T Cell Recognition of Membrane-Bound Toxoplasma gondii Protective Antigen. Cell reports 51 26628378
1998 The amphipathic alpha helices of the toxoplasma protein GRA2 mediate post-secretory membrane association. Journal of cell science 51 9664038
1997 Toxoplasma gondii sporozoites form a transient parasitophorous vacuole that is impermeable and contains only a subset of dense-granule proteins. Infection and immunity 51 9353039
2008 GRA12, a Toxoplasma dense granule protein associated with the intravacuolar membranous nanotubular network. International journal for parasitology 50 18840447
2015 Toxoplasma gondii: Vaccination with a DNA vaccine encoding T- and B-cell epitopes of SAG1, GRA2, GRA7 and ROP16 elicits protection against acute toxoplasmosis in mice. Vaccine 48 26518401
2016 Secretion of Rhoptry and Dense Granule Effector Proteins by Nonreplicating Toxoplasma gondii Uracil Auxotrophs Controls the Development of Antitumor Immunity. PLoS genetics 47 27447180
1996 Common cis-acting elements critical for the expression of several genes of Toxoplasma gondii. Molecular microbiology 46 8858595
2007 The dense granule protein GRA2, a new marker for the serodiagnosis of acute Toxoplasma infection: comparison of sera collected in both France and Iran from pregnant women. Diagnostic microbiology and infectious disease 45 17509806
2007 Functional domains of the Toxoplasma GRA2 protein in the formation of the membranous nanotubular network of the parasitophorous vacuole. International journal for parasitology 45 18061598
1993 Toxoplasma gondii: differential location of antigens secreted from encysted bradyzoites. Experimental parasitology 45 8344403
1989 Cloning of cDNAs encoding a 28 kilodalton antigen of Toxoplasma gondii. Molecular and biochemical parasitology 45 2710166
2009 GRA2 and ROP1 recombinant antigens as potential markers for detection of Toxoplasma gondii-specific immunoglobulin G in humans with acute toxoplasmosis. Clinical and vaccine immunology : CVI 44 19225074
2013 Identification of differentially expressed proteins in sulfadiazine resistant and sensitive strains of Toxoplasma gondii using difference-gel electrophoresis (DIGE). International journal for parasitology. Drugs and drug resistance 42 24533291
2013 Genetic basis for phenotypic differences between different Toxoplasma gondii type I strains. BMC genomics 41 23837824
2004 GRA9, a new Toxoplasma gondii dense granule protein associated with the intravacuolar network of tubular membranes. International journal for parasitology 41 15491588
2012 Peptide microarray analysis of in silico-predicted epitopes for serological diagnosis of Toxoplasma gondii infection in humans. Clinical and vaccine immunology : CVI 40 22496494
2009 Evaluation of protective effect of multi-epitope DNA vaccine encoding six antigen segments of Toxoplasma gondii in mice. Parasitology research 39 19288132
2006 Toxoplasma gondii: expression and characterization of a recombinant protein containing SAG1 and GRA2 in Pichia pastoris. Parasitology research 38 17058109
2012 Protective immune response against Toxoplasma gondii elicited by a recombinant DNA vaccine with a novel genetic adjuvant. Vaccine 36 22240340
2008 Evaluation of the immune response elicited by multi-antigenic DNA vaccine expressing SAG1, ROP2 and GRA2 against Toxoplasma gondii. Parasitology international 36 18562245
2007 Purification of Toxoplasma dense granule proteins reveals that they are in complexes throughout the secretory pathway. Molecular and biochemical parasitology 36 17959262
2016 Phenotypes Associated with Knockouts of Eight Dense Granule Gene Loci (GRA2-9) in Virulent Toxoplasma gondii. PloS one 34 27458822
2015 Serodiagnosis of Toxoplasma gondii infection in farm animals (horses, swine, and sheep) by enzyme-linked immunosorbent assay using chimeric antigens. Parasitology international 33 25817245
2002 Toxoplasma gondii Rab6 mediates a retrograde pathway for sorting of constitutively secreted proteins to the Golgi complex. The Journal of biological chemistry 33 12468555
1999 Western blot analysis of stray cat sera against Toxoplasma gondii and the diagnostic availability of monoclonal antibodies in sandwich-ELISA. The Korean journal of parasitology 32 10634041
1997 Expression of Toxoplasma gondii genes in the closely-related apicomplexan parasite Neospora caninum. Molecular and biochemical parasitology 31 9178265
2019 Proteomic and structural characterization of self-assembled vesicles from excretion/secretion products of Toxoplasma gondii. Journal of proteomics 30 31434009
2019 Toxoplasma gondii Intravacuolar-Network-Associated Dense Granule Proteins Regulate Maturation of the Cyst Matrix and Cyst Wall. mSphere 29 31619500
1993 Multiple B-cell epitopes in a recombinant GRA2 secreted antigen of Toxoplasma gondii. Applied parasitology 29 7507769
2012 Toxoplasma gondii secretory proteins bind to sulfated heparin structures. Glycobiology 27 22997241
2016 Evaluation of recombinant antigens in combination and single formula for diagnosis of feline toxoplasmosis. Experimental parasitology 25 27876472
2018 Discovery of new Toxoplasma gondii antigenic proteins using a high throughput protein microarray approach screening sera of murine model infected orally with oocysts and tissue cysts. Parasites & vectors 24 29973272
2016 Toxoplasma gondii-Derived Synthetic Peptides Containing B- and T-Cell Epitopes from GRA2 Protein Are Able to Enhance Mice Survival in a Model of Experimental Toxoplasmosis. Frontiers in cellular and infection microbiology 22 27313992
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2012 Toxoplasma gondii antigens recognized by IgG antibodies differ between mice with and without active proliferation of tachyzoites in the brain during the chronic stage of infection. Infection and immunity 21 22851753
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2005 The Toxoplasma surface protein SAG1 triggers efficient in vitro secretion of chemokine ligand 2 (CCL2) from human fibroblasts. Microbes and infection 14 16213182
2021 A Family of Toxoplasma gondii Genes Related to GRA12 Regulate Cyst Burdens and Cyst Reactivation. mSphere 12 33883265
2015 Toxoplasma gondii: biochemical and biophysical characterization of recombinant soluble dense granule proteins GRA2 and GRA6. Biochemical and biophysical research communications 12 25712518
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2020 Succinylated Wheat Germ Agglutinin Colocalizes with the Toxoplasma gondii Cyst Wall Glycoprotein CST1. mSphere 9 32132158
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2024 The Development of Toxoplasma gondii Recombinant Trivalent Chimeric Proteins as an Alternative to Toxoplasma Lysate Antigen (TLA) in Enzyme-Linked Immunosorbent Assay (ELISA) for the Detection of Immunoglobulin G (IgG) in Small Ruminants. International journal of molecular sciences 8 38673969
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2023 Dense granule protein 3 of Toxoplasma gondii plays a crucial role in the capability of the tissue cysts of the parasite to persist in the presence of anti-cyst CD8+ T cells during the chronic stage of infection. Frontiers in immunology 4 37868957
2021 Immunogenicity and protection efficacy of enhanced fitness recombinant Salmonella Typhi monovalent and bivalent vaccine strains against acute toxoplasmosis. Pathogens and global health 4 33525974
2020 The amino-terminal region of dense granule protein 6 of Toxoplasma gondii stimulates IFN-γ production by microglia. Microbes and infection 4 31972245
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2014 High expression of water-soluble recombinant antigenic domains of Toxoplasma gondii secretory organelles. The Korean journal of parasitology 4 25246715
2025 Toxoplasma gondii infection of neurons alters the production and content of extracellular vesicles directing astrocyte phenotype and contributing to the loss of GLT-1 in the infected brain. PLoS pathogens 3 40523037
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2025 A Structural In Silico Analysis of Novel Epitopes from Toxoplasma gondii Proteins for the Serodiagnosis of Toxoplasmosis. International journal of molecular sciences 2 40429830
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