Affinage · Toxoplasma gondii

GRA4

dense granule protein GRA4 · UniProt S8EUV6

Annotated
2026-09-08
62 papers in source corpus 15 papers cited in narrative 15 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

GRA4 is a proline-rich, 40 kDa dense granule protein of Toxoplasma gondii that is secreted into the parasitophorous vacuole (PV) after host cell invasion, where it becomes a structural component of the intravacuolar tubular network and, during bradyzoite differentiation, of the cyst wall (PMID:1362450, PMID:10498186, PMID:31619500). Its trafficking to dense granules and subsequent delivery to the intravacuolar network are governed by the short length of its single transmembrane domain—not by specific sequence motifs—and require its cytoplasmic tail; lengthening the TMD reroutes it to the Golgi and cell surface (PMID:9628889, PMID:15056659). Following secretion GRA4 is first soluble in the vacuolar lumen and only later associates with the mature network through strong protein-protein interactions, forming a multimeric complex with GRA2 (PMID:10498186). GRA4 contributes to latent infection: its trafficking to the inner cyst wall layers is GRA2-dependent, it supports cyst wall maturation, and its deletion drastically reduces brain cyst burdens in mice (PMID:21531875, PMID:31619500, PMID:32132158). Beyond its structural role, secreted GRA4 acts as an immune evasion effector that suppresses host type I interferon signaling by binding phosphorylated TBK1 and promoting TRIM27-catalyzed K48-ubiquitination of TBK1 at Lys251/Lys372, targeting it for p62-mediated autophagic degradation (PMID:39031880). GRA4 is also a recognized antigen presented via MHC-I as a subdominant CD8+ T cell epitope, and its deletion (with other GRAs) enhances MHC-I antigen presentation (PMID:31555296, PMID:18922097, PMID:23818852).

Mechanistic history

Synthesis pass · year-by-year structured walk · 15 steps
  1. 1992 High

    Establishing the molecular identity of GRA4 was the first step: cloning revealed a single-copy, intronless gene encoding a 40 kDa proline-rich dense granule protein with a signal sequence and an internal hydrophobic region, defining the protein to be studied mechanistically.

    Evidence Expression library screening, genomic cloning, sequencing, Southern and Northern blot in T. gondii

    PMID:1362450

    Open questions at the time
    • Function of the internal hydrophobic region not resolved at cloning
    • No subcellular trafficking determinants defined yet
  2. 1997 Medium

    Comparing sporozoite and tachyzoite behavior showed that GRA4 secretion is stage-regulated, as sporozoite dense granule GRA4 is retained rather than exocytosed into the first PV, indicating that secretion is not automatic across life stages.

    Evidence Immunofluorescence with anti-GRA4 antibodies on sporozoite-infected cells versus tachyzoites

    PMID:9353039

    Open questions at the time
    • Mechanism of stage-specific retention unknown
    • Single-lab localization comparison
  3. 1998 High

    To learn how GRA4 reaches dense granules and the intravacuolar network, reporter fusion experiments established that its transmembrane domain and cytoplasmic tail (but not a tyrosine-based tail motif) are the sufficient targeting/secretion determinants.

    Evidence Alkaline phosphatase–GRA4 TMD/tail chimeras, domain deletions, immunofluorescence and fractionation in transfected parasites

    PMID:9628889

    Open questions at the time
    • Which TMD feature drives targeting not yet resolved
    • Trafficking machinery reading these determinants unidentified
  4. 1998 Medium

    Mapping the antibody response defined GRA4's immunodominant B cell epitope to its last 11 C-terminal residues, recognized broadly across host species, establishing GRA4 as a humoral antigen.

    Evidence GST-fused truncated GRA4 fragments in ELISA against mouse, human, and sheep sera

    PMID:9618729

    Open questions at the time
    • Protective value of the antibody response not assessed
    • Single-lab mapping
  5. 1999 High

    Biochemistry resolved how GRA4 joins the network: it is first soluble in the vacuolar lumen and later incorporates via strong protein-protein interactions, specifically forming a multimeric complex with GRA2, defining GRA4 as a network-building partner rather than a purely membrane-embedded protein.

    Evidence Cell fractionation, denaturant treatment, chemical cross-linking, immuno-EM in T. gondii

    PMID:10498186

    Open questions at the time
    • Stoichiometry and full composition of the complex not defined
    • Interaction interface residues unmapped
  6. 2002 Medium

    Perturbing trafficking machinery placed GRA4 secretion downstream of Rab6, as GDP-locked/nucleotide-free Rab6 mutants trapped dense granule proteins in the Golgi and reduced GRA4 secretion, linking retrograde transport to GRA4 delivery.

    Evidence Overexpression of wild-type and mutant Rab6, immunofluorescence, GRA4 secretion assays

    PMID:12468555

    Open questions at the time
    • Direct versus indirect effect of Rab6 on GRA4 not distinguished
    • Single-lab overexpression study
  7. 2004 High

    Refining the targeting mechanism, systematic TMD swaps showed that it is the short LENGTH of the GRA4 TMD, not its sequence, that specifies dense granule targeting—lengthening it reroutes GRA4 to the Golgi and surface.

    Evidence TMD-swap chimeric constructs and TMD-length mutants, immunofluorescence, fractionation in transfected parasites

    PMID:15056659

    Open questions at the time
    • Molecular sensor of TMD length unidentified
    • Interplay with the cytoplasmic tail determinant not integrated
  8. 2004 Medium

    Colocalization with the newly characterized GRA9 at the tubular network corroborated GRA4's residence in this intravacuolar structure alongside GRA2 and GRA6.

    Evidence Immunofluorescence and cryo-EM colocalization with established GRA markers

    PMID:15491588

    Open questions at the time
    • Does not establish direct GRA4–GRA9 interaction
    • Structural organization of the network not resolved
  9. 2008 Medium

    Identifying an H-2L(d)-restricted GRA4 epitope with MHC-I tetramers showed that GRA4 is processed and presented to CD8+ T cells during acute infection, and its response kinetics track infection stage.

    Evidence Caged MHC-I tetramer technology and flow cytometry of T. gondii-specific CD8+ T cells across tissues in BALB/c mice

    PMID:18922097

    Open questions at the time
    • Protective contribution of GRA4-specific CD8+ T cells not established
    • Single-lab tetramer analysis
  10. 2011 High

    Clean knockout and complementation established a physiological role for GRA4 in latent infection: deletion drastically reduced brain cyst burdens and complementation restored them, moving GRA4 from a structural protein to a chronic-infection determinant.

    Evidence Targeted deletion in type II Δku80, complementation, in vivo mouse brain cyst quantification

    PMID:21531875

    Open questions at the time
    • Mechanism linking GRA4 loss to reduced cyst burden not defined at this stage
    • Restricted to type II strain
  11. 2013 Medium

    Epitope-repositioning experiments explained WHY the GRA4 CD8+ response is subdominant—immunodominance is set by C-terminal epitope position during antigen processing, and GRA4's non-terminal epitope yields a non-protective subdominant response.

    Evidence Parasites expressing epitope-repositioned antigens, MHC-I tetramer staining, parasite burden after challenge

    PMID:23818852

    Open questions at the time
    • Does not address GRA4's own function in immune evasion
    • Processing rules generalize from a comparison, not exhaustive
  12. 2019 High

    Live imaging plus deletion during cyst differentiation defined the mechanism behind the cyst phenotype: GRA4 traffics from the cyst periphery to the inner cyst wall layers and its loss slows cyst wall protein accumulation, implicating GRA4 in cyst wall maturation.

    Evidence Live and fixed immunofluorescence during in vitro differentiation, DBA lectin staining, GRA deletion mutants

    PMID:31619500

    Open questions at the time
    • GRA4-specific contribution partly confounded by multi-GRA comparison
    • Molecular target of GRA4 within the wall unknown
  13. 2019 Medium

    Deletion assays revealed that GRA4, among a set of PV/network GRAs, participates in suppressing MHC-I presentation of vacuolar antigens in an IFN-γ- and cell-type-dependent manner, extending GRA4 into active immune modulation.

    Evidence GRA deletions, macrophage/dendritic cell infection, MHC-I antigen presentation assays with CD8+ T cell readout

    PMID:31555296

    Open questions at the time
    • GRA4 tested alongside other GRAs, so its individual weight is imprecise
    • Molecular mechanism of MHC-I suppression not defined
  14. 2020 Medium

    Lectin staining in a GRA2-deletion background placed GRA4 cyst wall trafficking in the GRA2-dependent pathway, showing that distinct GRA2-dependent and GRA2-independent routes deliver cyst wall molecules.

    Evidence s-WGA and DBA lectin staining and colocalization in GRA2-deletion in vitro cysts

    PMID:32132158

    Open questions at the time
    • Whether the GRA2 dependence reflects the tachyzoite GRA2–GRA4 complex not directly tested
    • Trafficking route to the inner wall not molecularly resolved
  15. 2024 High

    A defined molecular mechanism for GRA4 immune evasion was established: secreted GRA4 binds phospho-TBK1 and drives TRIM27-mediated K48-ubiquitination at Lys251/Lys372, triggering p62-dependent autophagic degradation of TBK1 and suppressing host type I interferon responses.

    Evidence Δgra4 parasites, Co-IP with phospho-TBK1, TRIM27 ubiquitination assay, site-directed mutagenesis of Lys251/Lys372, autophagy flux and IFN-I readouts

    PMID:39031880

    Open questions at the time
    • How secreted GRA4 accesses host cytosolic TBK1 not defined
    • Relationship of this effector role to GRA4's structural/network role unresolved

Open questions

Synthesis pass · forward-looking unresolved questions
  • How GRA4's dual identity—structural network/cyst wall component versus soluble cytosolic immune effector acting on host TBK1—is reconciled mechanistically, and how it crosses the vacuolar membrane to reach host signaling machinery, remains open.
  • Route of GRA4 export from the PV to the host cytosol unknown
  • TMD-length sensor for dense granule targeting unidentified
  • Full composition and stoichiometry of the GRA2–GRA4 network complex undefined

Mechanism profile

Synthesis pass · controlled-vocabulary classification
Partners
GRA2 (NETWORK ASSOCIATION AND CYST WALL TRAFFICKING DEPENDENCE)P62 (HOST, AUTOPHAGY RECEPTOR)PHOSPHORYLATED TBK1 (HOST)TRIM27 (HOST, UBIQUITIN LIGASE)
Complex memberships
GRA2-GRA4 multimeric intravacuolar network complexIntravacuolar tubular network association with GRA2, GRA6, GRA9

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1992 GRA4 was molecularly cloned and shown to encode a 40 kDa dense granule protein of Toxoplasma gondii. The deduced amino acid sequence revealed a proline-rich (12%) product with an internal hydrophobic region of 19 amino acids, a putative N-terminal signal sequence of 20 amino acids, and a potential N-glycosylation site. The GRA4 gene is single copy with no introns, and is translated in tachyzoites to yield a single ~1900 base mRNA species. Expression library screening, genomic cloning, nucleotide sequencing, Southern blot, Northern blot Molecular and biochemical parasitology High 1362450
1998 GRA4's transmembrane domain (TMD) and cytoplasmic tail are required for its targeting to dense granules and subsequent secretion into the tuboreticular intravacuolar network. When alkaline phosphatase was fused to the GRA4 TMD and cytoplasmic tail, the chimera localized to dense granules and was secreted into the intravacuolar network in a manner dependent on the cytoplasmic tail but not on a tyrosine-based motif within the tail. Stable transfection with reporter fusion constructs (alkaline phosphatase fused to GRA4 TMD/cytoplasmic tail), immunofluorescence, subcellular fractionation The Journal of cell biology High 9628889
1999 After secretion into the parasitophorous vacuole, GRA4 is initially distributed as a soluble protein throughout the vacuolar lumen and only later associates with the mature intravacuolar network via strong protein-protein interactions (not primarily hydrophobic interactions). Cross-linking studies established that GRA4 specifically interacts with GRA2 to form a multimeric complex stably associated with the intravacuolar network membranes. Cell fractionation, denaturing agent treatment, chemical cross-linking, immunofluorescence, immunoelectron microscopy Molecular and biochemical parasitology High 10498186
1997 During sporozoite invasion of host cells, GRA4 (present in oocyst sporozoite dense granules) is NOT exocytosed into the first parasitophorous vacuole (PV1) formed, in contrast to tachyzoite behavior. GRA4 is retained within cytoplasmic granules rather than being secreted into PV1. Immunofluorescence with anti-GRA4 antibodies on sporozoite-infected cells, comparison with tachyzoite secretion Infection and immunity Medium 9353039
2002 Toxoplasma Rab6 regulates retrograde transport from post-Golgi dense granule organelles to the Golgi. Expression of GDP-bound (Rab6(T25N)) or nucleotide-free (Rab6(N124I)) mutants caused accumulation of dense granule proteins in the Golgi and reduced secretion of GRA4, placing GRA4 secretion downstream of Rab6-mediated retrograde trafficking. Overexpression of wild-type and mutant Rab6 constructs, immunofluorescence, secretion assays measuring GRA4 release The Journal of biological chemistry Medium 12468555
2004 The length of the GRA4 transmembrane domain (TMD) is a key determinant of its dense granule targeting. Replacing the GRA4 TMD with the longer TMDs of VSV-G or LDL receptor completely rerouted GRA4 to the Golgi and cell surface. Shortening the LDL receptor TMD to a length similar to GRA4 restored dense granule localization; lengthening the GRA4 TMD rerouted it to the Golgi. This effect was not due to specific TMD sequence motifs or membrane association strength. Stable transfection with TMD-swap chimeric constructs, mutational analysis of TMD length, immunofluorescence, subcellular fractionation The Journal of biological chemistry High 15056659
2004 GRA9, a newly characterized dense granule protein, colocalizes with GRA4 (and GRA2 and GRA6) at the intravacuolar network of tubular membranes within the parasitophorous vacuole, confirming GRA4's association with this structural network. Immunofluorescence, cryo-electron microscopy, colocalization with established GRA markers International journal for parasitology Medium 15491588
2011 Genetic deletion of GRA4 in type II Toxoplasma gondii drastically reduced brain tissue cyst burdens in mice, and complementation with a functional GRA4 allele significantly restored cyst burdens. This established a functional role for GRA4 in cyst development and latent infection. Targeted gene deletion via homologous recombination in type II Δku80 strain, complementation, in vivo mouse infection model measuring brain cyst burdens Eukaryotic cell High 21531875
2019 During cyst development in vitro, GRA4 localizes to the cyst periphery by day 1 post-differentiation (colocalizing with Dolichos biflorus agglutinin stain), then establishes a continuous matrix pattern inside the cyst by day 2. GRA4 ultimately localizes predominantly in the inner layers of the cyst wall. Deletion of GRA4 (along with other intravacuolar network GRA proteins except GRA1) reduced the rate of accumulation of cyst wall proteins at the cyst periphery relative to the cyst interior, indicating a role in cyst wall maturation. Live-cell and fixed immunofluorescence imaging during in vitro cyst differentiation, genetic deletion mutants, lectin staining (DBA) mSphere High 31619500
2019 Deletion of GRA4 (along with GRA2, GRA3, GRA5, GRA7, GRA12) increased MHC-I antigen presentation of parasitophorous vacuole-localized parasite antigens to CD8+ T cells in macrophages and/or dendritic cells, indicating that GRA4 participates in suppressing MHC-I antigen presentation. This suppression was cell-type and IFN-γ dependent. Genetic deletion of GRA proteins in T. gondii, infection of macrophages and dendritic cells, MHC-I antigen presentation assay with CD8+ T cell readout Frontiers in immunology Medium 31555296
2024 GRA4 functions as a negative regulator of host type I interferon (IFN-I) signaling. Mechanistically, GRA4 binds to phosphorylated TBK1 and promotes TRIM27-catalyzed K48-ubiquitination of TBK1 at Lys251 and Lys372 residues, which enhances recognition by the autophagy receptor p62, ultimately leading to autophagic degradation of TBK1 and suppressed IFN-I responses. Infection with Δgra4 mutant parasites induces stronger IFN-I responses in the host. GRA4 knockout parasites (Δgra4), co-immunoprecipitation (GRA4 binding to phospho-TBK1), ubiquitination assay (TRIM27-mediated K48-ubiquitination), autophagy flux assay (p62-dependent TBK1 degradation), site-directed mutagenesis (Lys251/Lys372), IFN-I signaling readouts Advanced science (Weinheim, Baden-Wurttemberg, Germany) High 39031880
1998 The major B cell epitope of GRA4 was mapped to the last 11 C-terminal residues (within the region 297-345), recognized by serum IgG from infected mice, milk IgA, intestinal IgA, human sera, and sheep sera. A second weaker epitope was mapped to region 318-334. The N-terminal domain (amino acids 25-276) was poorly recognized. Recombinant truncated GRA4 fragments expressed as GST fusions, ELISA with sera from infected mice, humans, and sheep Parasite immunology Medium 9618729
2008 GRA4-specific CD8+ T cells (H-2L(d)-restricted epitope from GRA4) predominate in multiple organ sources 2 weeks after T. gondii infection in BALB/c mice, indicating that GRA4 is processed and presented via MHC-I during acute infection. BALB/c animals infected with T. gondii mutants defective in establishing chronic infection showed altered levels of GRA4-specific CD8+ T cells. Caged MHC-I tetramer technology (~250 H-2L(d) tetramers), flow cytometry of T. gondii-specific CD8+ T cells from multiple tissues, infection with chronic-infection-defective mutant parasites The Journal of infectious diseases Medium 18922097
2013 The GRA4-derived subdominant CD8+ T cell epitope does not provide significant host protection against parasite burden, in contrast to the immunodominant GRA6-specific response. Immunodominance and optimal antigen processing are determined by epitope position at the C-terminus of the precursor antigen, not by peptide-MHC affinity or naive T cell precursor frequency. GRA4's epitope is not at the C-terminus, which correlates with its subdominant status. Genetically modified parasites expressing epitope-repositioned antigens, MHC-I tetramer staining, parasite burden measurement after challenge in mice PLoS pathogens Medium 23818852
2020 The accumulation of s-WGA-binding (N-acetylglucosamine-decorated) molecules at the cyst wall is not dependent on GRA4 expression (or GRA2), whereas CST1, GRA4, and GRA6 cyst wall accumulation is GRA2-dependent. This indicates GRA2-dependent and GRA2-independent mechanisms for trafficking glycosylated cyst wall molecules, with GRA4 trafficking falling in the GRA2-dependent pathway. Lectin staining (s-WGA, DBA) of in vitro cysts in GRA2-deletion mutant background, immunofluorescence colocalization with GRA4, GRA6, CST1 mSphere Medium 32132158

Source papers

Stage 0 corpus · 62 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2011 Type II Toxoplasma gondii KU80 knockout strains enable functional analysis of genes required for cyst development and latent infection. Eukaryotic cell 153 21531875
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
1998 The protozoan parasite Toxoplasma gondii targets proteins to dense granules and the vacuolar space using both conserved and unusual mechanisms. The Journal of cell biology 100 9628889
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
2008 Parasite stage-specific recognition of endogenous Toxoplasma gondii-derived CD8+ T cell epitopes. The Journal of infectious diseases 86 18922097
2005 Evaluation of protective effect of DNA vaccination with genes encoding antigens GRA4 and SAG1 associated with GM-CSF plasmid, against acute, chronical and congenital toxoplasmosis in mice. Vaccine 83 15935521
2003 The MIC3 gene of Toxoplasma gondii is a novel potent vaccine candidate against toxoplasmosis. Infection and immunity 80 14573640
2000 Induction of protective immunity against toxoplasmosis in mice by DNA immunization with a plasmid encoding Toxoplasma gondii GRA4 gene. Vaccine 75 10775785
2004 Recombinant GRA4 or ROP2 protein combined with alum or the gra4 gene provides partial protection in chronic murine models of toxoplasmosis. Clinical and diagnostic laboratory immunology 74 15242945
1992 Molecular cloning of GRA4, a Toxoplasma gondii dense granule protein, recognized by mucosal IgA antibodies. Molecular and biochemical parasitology 64 1362450
2010 Evaluation of immune responses in sheep induced by DNA immunization with genes encoding GRA1, GRA4, GRA6 and GRA7 antigens of Toxoplasma gondii. Veterinary parasitology 57 21251760
1993 Mucosal and systemic cellular immune responses induced by Toxoplasma gondii antigens in cyst orally infected mice. Immunology 54 8478024
2013 Location of the CD8 T cell epitope within the antigenic precursor determines immunogenicity and protection against the Toxoplasma gondii parasite. PLoS pathogens 51 23818852
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
2018 Bioinformatics analysis of single and multi-hybrid epitopes of GRA-1, GRA-4, GRA-6 and GRA-7 proteins to improve DNA vaccine design against Toxoplasma gondii. Journal of parasitic diseases : official organ of the Indian Society for Parasitology 46 29844632
2011 Increased survival time in mice vaccinated with a branched lysine multiple antigenic peptide containing B- and T-cell epitopes from T. gondii antigens. Vaccine 42 21939715
2004 GRA9, a new Toxoplasma gondii dense granule protein associated with the intravacuolar network of tubular membranes. International journal for parasitology 41 15491588
2013 DNA prime and peptide boost immunization protocol encoding the Toxoplasma gondii GRA4 induces strong protective immunity in BALB/c mice. BMC infectious diseases 40 24148219
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
2019 A systematic review on the role of GRA proteins of Toxoplasma gondii in host immunization. Journal of microbiological methods 38 31442457
2018 Characterization of a multi-epitope peptide with selective MHC-binding capabilities encapsulated in PLGA nanoparticles as a novel vaccine candidate against Toxoplasma gondii infection. Vaccine 38 30181047
2006 A patatin-like protein protects Toxoplasma gondii from degradation in activated macrophages. Molecular microbiology 38 17166175
2012 Toxoplasma gondii: the vaccine potential of three trivalent antigen-cocktails composed of recombinant ROP2, ROP4, GRA4 and SAG1 proteins against chronic toxoplasmosis in BALB/c mice. Experimental parasitology 36 22445587
2007 A heterologous prime-boost vaccination regime using DNA and a vaccinia virus, both expressing GRA4, induced protective immunity against Toxoplasma gondii infection in mice. Parasitology 36 17506929
2012 A chloroplast-derived Toxoplasma gondii GRA4 antigen used as an oral vaccine protects against toxoplasmosis in mice. Plant biotechnology journal 35 23020088
2011 Combination of CpG-oligodeoxynucleotides with recombinant ROP2 or GRA4 proteins induces protective immunity against Toxoplasma gondii infection. Experimental parasitology 34 21554876
2014 Comparative efficacy of a multi-epitope DNA vaccine via intranasal, peroral, and intramuscular delivery against lethal Toxoplasma gondii infection in mice. Parasites & vectors 33 24685150
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
1996 Identification of two alleles in the GRA4 locus of Toxoplasma gondii determining a differential epitope which allows discrimination of type I versus type II and III strains. Molecular and biochemical parasitology 33 8898342
2019 Toxoplasma gondii Intravacuolar-Network-Associated Dense Granule Proteins Regulate Maturation of the Cyst Matrix and Cyst Wall. mSphere 29 31619500
2014 Analyzing and identifying novel B cell epitopes within Toxoplasma gondii GRA4. Parasites & vectors 26 25301141
2004 Transmembrane domain modulates sorting of membrane proteins in Toxoplasma gondii. The Journal of biological chemistry 25 15056659
1998 Mapping of B epitopes in GRA4, a dense granule antigen of Toxoplasma gondii and protection studies using recombinant proteins administered by the oral route. Parasite immunology 25 9618729
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
2019 Rhoptry and Dense Granule Secreted Effectors Regulate CD8+ T Cell Recognition of Toxoplasma gondii Infected Host Cells. Frontiers in immunology 21 31555296
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
2014 The optimal mixture of Toxoplasma gondii recombinant antigens (GRA1, P22, ROP1) for diagnosis of ovine toxoplasmosis. Veterinary parasitology 20 25300561
2006 Kinetic analysis of the humoral immune response against 3 Toxoplasma gondii-recombinant proteins in infants with suspected congenital toxoplasmosis. Diagnostic microbiology and infectious disease 18 16713163
2012 Recombinant ROP2, ROP4, GRA4 and SAG1 antigen-cocktails as possible tools for immunoprophylaxis of toxoplasmosis: what's next? Bioengineered 15 22892593
2009 Protective effect of DNA-mediated immunization with liposome-encapsulated GRA4 against infection of Toxoplasma gondii. Journal of Zhejiang University. Science. B 15 19585669
2021 Comparative Proteomics Analysis for Elucidating the Interaction Between Host Cells and Toxoplasma gondii. Frontiers in cellular and infection microbiology 14 34055664
2018 Vaccine potential of antigen cocktails composed of recombinant Toxoplasma gondii TgPI-1, ROP2 and GRA4 proteins against chronic toxoplasmosis in C3H mice. Experimental parasitology 14 29309783
2013 TgGRA23, a novel Toxoplasma gondii dense granule protein associated with the parasitophorous vacuole membrane and intravacuolar network. Parasitology international 13 23583316
2019 The dense granule protein 8 (GRA8) is a component of the sub-pellicular cytoskeleton in Toxoplasma gondii. Parasitology research 11 30949853
2024 The Toxoplasma Effector GRA4 Hijacks Host TBK1 to Oppositely Regulate Anti-T. Gondii Immunity and Tumor Immunotherapy. Advanced science (Weinheim, Baden-Wurttemberg, Germany) 9 39031880
2020 Succinylated Wheat Germ Agglutinin Colocalizes with the Toxoplasma gondii Cyst Wall Glycoprotein CST1. mSphere 9 32132158
2020 Construction of A Synthetic Gene Encoding the Multi-Epitope of Toxoplasma gondii and Demonstration of the Relevant Recombinant Protein Production: A Vaccine Candidate. Galen medical journal 9 34466573
2008 Efficient expression of a Toxoplasma gondii dense granule Gra4 antigen in tobacco leaves. Experimental parasitology 9 18588877
1997 Detection of a novel 40,000 MW excretory Toxoplasma gondii antigen by murine Th1 clone which induces toxoplasmacidal activity when exposed to infected macrophages. Immunology 8 9415038
2010 Cloning and expression of Toxoplasma gondii dense granular protein 4 (GRA4) in Pichia pastoris. Tropical biomedicine 7 21399595
2025 Immunization with plant-based vaccine expressing Toxoplasma gondii SAG1 fused to plant HSP90 elicits protective immune response in lambs. Acta tropica 6 39894243
2021 Characterization and evaluation of a recombinant multiepitope peptide antigen MAG in the serological diagnosis of Toxoplasma gondii infection in pigs. Parasites & vectors 6 34404476
2013 Molecular cloning, sequencing, and biological characterization of GRA4 gene of Toxoplasma gondii. Parasitology research 6 23572047
2020 Cloning and expression of Toxoplasma gondii GRA-4 recombinant protein as a toxoplasmosis diagnostic kit candidate. Veterinary world 5 33281340
2018 Expression of Plasmid Encoded GRA4 Gene of Toxoplasma gondii RH Strain in CHO Eukaryotic Cells. Iranian journal of parasitology 5 30483330
2015 Interferon-Gamma Release Assay: An Effective Tool to Detect Early Toxoplasma gondii Infection in Mice. PloS one 5 26378802
2019 Heat treatment alleviates the growth and photosynthetic impairment of transplastomic plants expressing Leishmania infantum Hsp83-Toxoplasma gondii SAG1 fusion protein. Plant science : an international journal of experimental plant biology 2 31084864
2025 A comprehensive multi-epitope recombinant protein strategy for accurate serological detection of Toxoplasma gondii infection. Medical microbiology and immunology 0 41428119
2025 Characterization of the immune response to recombinant GRA-4 protein (rGRA-4) of Toxoplasma gondii in Balb/c strain mice. Open veterinary journal 0 41036004
2007 [Study on immuno-effect with GRA4 or SAG2 gene recombinant BCG vaccine of Toxoplasma gondii]. Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases 0 18038782
2005 [Expression and purification of Toxoplasma gondii GRA4 gene in prokaryotic system]. Zhongguo ji sheng chong xue yu ji sheng chong bing za zhi = Chinese journal of parasitology & parasitic diseases 0 16566210