{"gene":"TG_273760","gene_symbol":"HSP70","run_date":"2026-09-08T14:08:30","timeline":{"discoveries":[{"year":1998,"finding":"TgHSP70 (72 kDa protein) expression is induced during bradyzoite development in T. gondii under alkaline pH stress (pH 8.1), as demonstrated by Western blotting, immunofluorescence, immunoelectron microscopy, and RT-PCR; hsp70 colocalized with bradyzoite-specific antigens and was detected in bradyzoites isolated from mouse brain. Quercetin, which inhibits hsp70 synthesis, suppressed bradyzoite development in vitro.","method":"Western blot, immunofluorescence, immunoelectron microscopy, RT-PCR, pharmacological inhibition (quercetin)","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (Western blot, IEM, RT-PCR, pharmacological inhibition) in a single lab; functional link established","pmids":["9632598"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1998,"finding":"The cytoplasmic 70 kDa HSP gene is single-copy in both virulent (RH) and avirulent (ME49) strains; virulent strains have four copies of a 7-aa C-terminal repeat (GGMPGGM) vs. five in avirulent strains, and show 1.5–2-fold higher mRNA transcription in vivo and in vitro, indicating post-transcriptional regulation also occurs in T. gondii.","method":"Genomic DNA library screening, PCR amplification, gene sequencing, copy-number estimation, Northern/mRNA analysis","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal molecular methods (sequencing, copy-number, transcription analysis) in single lab","pmids":["9724875"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"},{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":1998,"finding":"High-level TgHSP70 expression occurs during in vivo bradyzoite-to-tachyzoite conversion (reactivation) in chronically infected mice treated with neutralizing anti-IFN-γ or anti-TNF-α antibodies, demonstrating HSP70 upregulation is associated with stage conversion under immunosuppressive conditions.","method":"Immunocytochemistry, photometric assay of antigen expression in CNS tissue","journal":"Infection and immunity","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single primary method (immunocytochemistry), no direct functional manipulation of HSP70","pmids":["9673286"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":2002,"finding":"Antisense oligonucleotide-mediated reduction of TgHSP70 expression in virulent T. gondii strains (RH, ENT) increased host NF-κB activation in splenocytes and iNOS/NO production in RAW 264.7 macrophages, and enhanced tachyzoite-to-bradyzoite conversion in vitro; these effects were not observed in avirulent strains (ME49, C), establishing TgHSP70 as a suppressor of host NF-κB and iNOS-mediated killing specifically in virulent strains.","method":"Antisense oligonucleotide transfection, Western blot (HSP70 expression), in vivo tachyzoite counting (spleen), in vitro bradyzoite conversion assay, iNOS mRNA measurement, NF-κB nuclear translocation assay, NO production assay","journal":"Journal of immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function (antisense KD) with multiple cellular readouts in single lab","pmids":["12097402"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"},{"species":"Toxoplasma gondii","strain":"ENT"},{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":2000,"finding":"TgHSP70 inhibits nitric oxide release from peritoneal macrophages of T. gondii-infected mice, and high-level TgHSP70 expression correlates with mortality in IFN-γ knockout mice, identifying TgHSP70 as a danger signal that suppresses host macrophage NO production during lethal acute infection.","method":"NO release assay (peritoneal macrophages), mRNA analysis (RT-PCR for stage markers), in vivo mortality analysis in IFN-γ KO mice","journal":"Cell stress & chaperones","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, functional readout (NO inhibition) with limited mechanistic follow-up","pmids":["11048655"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2002,"finding":"TgHSP70 functions as a B cell mitogen, inducing proliferation of murine B cells (B220+) but not T cells via TLR4; this proliferation is MyD88-independent (unlike LPS-induced proliferation), polymyxin B-insensitive, and absent in TLR4-mutant (C3H/HeJ) and TLR4-/- mice.","method":"In vitro proliferation assay, cell subset depletion, TLR4-mutant and knockout mice, MyD88-/- mice, polymyxin B inhibition control","journal":"Cell stress & chaperones","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — defined receptor (TLR4) requirement confirmed by genetic knockout and mutant strains with multiple controls in single lab","pmids":["12653480"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2004,"finding":"A pH-responsive cis-regulatory element was identified in the T. gondii hsp70 genomic locus upstream region by deletion analysis using β-galactosidase reporter constructs transiently transfected into RH strain T. gondii; GFP reporter constructs stably transfected into T. gondii showed pH-shock-induced GFP expression driven by this element. Gel-shift analysis identified a putative DNA-binding protein interacting with the pH-regulated region.","method":"Deletion analysis with β-galactosidase reporter, stable transfection with GFP reporter, electrophoretic mobility shift assay (EMSA/gel shift)","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal methods (deletion analysis, stable reporter, gel shift) in single lab; directly defines regulatory element","pmids":["15003494"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2005,"finding":"TgHSP70-induced macrophage NO production signals through TLR2, MyD88, and IRAK4 (not TLR4); however, TgHSP70-induced macrophage tolerance (suppression of NO on restimulation) is mediated through TLR4 and SOCS-1 upregulation, with JNK and IκBα phosphorylation occurring via TLR2 in the absence of TLR4-mediated tolerance.","method":"NO release assay, gene-knockout mice (TLR2-/-, TLR4-/-, MyD88-/-, IRAK4-/-), polymyxin B control, SOCS-1 expression assay, JNK and IκBα phosphorylation analysis","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic knockouts with mechanistic pathway dissection in single lab","pmids":["16040976"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2006,"finding":"TgHSP70 stimulates maturation of murine bone marrow-derived dendritic cells (increased MHC I/II, CD40, CD80, CD86 surface expression; decreased phagocytic ability; increased alloreactive T cell stimulation; IL-12 production; IFN-β mRNA expression) via TLR4 through a MyD88-independent signal transduction cascade; TLR2-/- and MyD88-/- DCs respond normally, but TLR4-/- DCs do not.","method":"DC maturation surface marker flow cytometry, phagocytosis assay, allostimulation assay, ELISA (IL-12), RT-PCR (IFN-β), TLR-deficient mouse DCs","journal":"Cell stress & chaperones","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal readouts with genetic confirmation (TLR4-/- DCs) in single lab","pmids":["16572725"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2006,"finding":"TgHSP70 induces lethal anaphylactic reaction in T. gondii-infected mice through an IFN-γ-dependent, IgE-independent pathway involving platelet-activating factor (PAF); splenocytes (not serum) transfer this reactivity, and PAF receptor antagonist rescues mice from the reaction.","method":"In vivo anaphylaxis model, adoptive transfer (splenocytes vs. serum), IFN-γ KO mice, B cell-deficient mice, PAF receptor antagonist treatment, RT-PCR (PAF acetylhydrolase, IFN-γ mRNA)","journal":"International immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic knockouts and pharmacological rescue with multiple readouts in single lab","pmids":["16943259"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"finding":"TgHSP70-induced lethal anaphylactic reaction in infected mice is mediated via TLR4/MyD88-dependent (not TRIF-dependent) signaling, activating cPLA2 via p38 and p44/42 MAPK pathways in CD11b+ splenocytes, leading to PAF production; TLR4-/- and MyD88-/- mice are protected from the reaction.","method":"In vivo anaphylaxis model, TLR4-/-, TLR2-/-, MyD88-/-, TRIF-/- mice, cPLA2 phosphorylation assay, MAPK pathway inhibitors, PAF-AH mRNA expression","journal":"Microbiology and immunology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple genetic knockouts dissecting signaling pathway with pharmacological inhibition, single lab","pmids":["18667035"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2010,"finding":"In T. gondii-infected host cells (THP-1 macrophages), HSP70 (host-upregulated by infection) binds pro-apoptotic factors AIF and Apaf-1 (but not cytochrome c or procaspase-9) as shown by co-immunoprecipitation, inhibiting mitochondrial apoptosis by preventing AIF and cytochrome c release from mitochondria and suppressing caspase-3 activation in a parasite load-dependent manner.","method":"Western blot, DNA fragmentation assay, co-immunoprecipitation, caspase-3/7 activity assay, subcellular fractionation","journal":"Parasitology research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP identifying binding partners, supported by functional apoptosis readouts, single lab","pmids":["20680337"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2011,"finding":"TgSis1 (a T. gondii Hsp40/J-domain protein homologous to yeast Sis1) is a cytosolic chaperone that co-immunoprecipitates with T. gondii Hsp70 and Hsp90, establishing TgHSP70 as part of a cytosolic Hsp40-Hsp70-Hsp90 chaperone complex in the parasite.","method":"Co-immunoprecipitation, subcellular localization (cytosolic fractionation), structural modeling","journal":"International journal of biological macromolecules","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single Co-IP identifying chaperone complex membership, single lab, no functional follow-up on HSP70 specifically","pmids":["22209934"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"finding":"TgHSP70 is required for intracellular multiplication of T. gondii: the Hsp70-selective inhibitor PES (2-phenylethynesulfonamide) attenuates intracellular T. gondii multiplication, confirmed by biotinylated PES binding directly to both host Hsp70 and TgHSP70 (verified by PES binding assay and molecular docking); silencing of host Hsp70 also reduces parasite multiplication, with attenuation linked to disruption of host autophagy.","method":"Pharmacological inhibition (PES), biotinylated PES binding assay, host Hsp70 siRNA knockdown, molecular docking (TgHsp70 structural analysis), autophagy functional assay","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct small molecule binding confirmed for both host and parasite Hsp70, supported by knockdown and docking, single lab","pmids":["33157166"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2000,"finding":"Immune factors (IFN-γ, TNF-α, reactive nitrogen intermediates) do not play primary roles in inducing TgHSP70 production in vivo: virulent RH strain tachyzoites from nude, SCID, IFN-γ receptor KO, and TNF receptor KO mice all produced similar levels of HSP70 as immunocompetent mice.","method":"Western blot analysis of HSP70 in tachyzoites recovered from immunodeficient mice (nude, SCID, IFN-γR KO, TNFR KO)","journal":"International journal for parasitology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — four distinct genetic immune-deficiency models tested, consistent negative result across all; single lab","pmids":["11428337"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2014,"finding":"Systemic (serum) detection of TgHSP70 protein depends on parasite killing by the host immune response, while increased TgHSP70 expression in the brain correlates with parasite multiplication rate; dexamethasone-induced immunosuppression decreased systemic TgHSP70 while increasing cerebral parasitism and TgHSP70 brain expression.","method":"ELISA (serum TgHSP70 and antibody levels), immunohistochemistry (brain TgHSP70), immune complex detection, dexamethasone immunosuppression model, comparison of BALB/c vs C57BL/6 mice","journal":"PloS one","confidence":"Low","confidence_rationale":"Tier 3 / Weak — indirect inference from correlative measurements in pharmacological model, no direct manipulation of TgHSP70","pmids":["24801069"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"finding":"TgHSP70 directly binds TLR4 (demonstrated by molecular docking, localized surface plasmon resonance, and co-immunoprecipitation), and this interaction activates TLR4/NF-κB signaling; coixol disrupts TgHSP70-TLR4 interaction and inhibits downstream iNOS, TNF-α, and HMGB1 overproduction.","method":"Molecular docking, localized surface plasmon resonance (LSPR), co-immunoprecipitation, ELISA, Western blot, immunofluorescence, qPCR","journal":"International immunopharmacology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct protein-protein interaction confirmed by LSPR and Co-IP with functional downstream pathway readouts, single lab","pmids":["36933491"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2000,"finding":"The carboxy-terminal region of TgHSP70 mediates its immunosuppressive/deleterious effect on host protective immunity: immunization with rTgHSP70-full-length or rTgHSP70-C-terminal region increased brain parasite burden after infection, while rTgHSP70-N-terminal region did not.","method":"Immunization with recombinant protein fragments, quantitative competitive PCR (QC-PCR) for brain parasite load (SAG1 gene)","journal":"The Korean journal of parasitology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, single method for parasite quantification; domain-mapping with limited functional mechanistic follow-up","pmids":["10905074"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"finding":"Inducible Hsp70 expressed on the membrane of T. gondii-infected dendritic cells and macrophages triggers Hsp70-dependent autophagy in CD40-expressing endothelial cells via beclin 1 and ULK1, restricting T. gondii invasion of neural tissue; this anti-parasitic activity required both CD40 expression in endothelial cells and inducible Hsp70 expression in the infecting leukocytes.","method":"In vivo infection model (retina and brain parasite load), adoptive transfer of infected monocytes/DCs, genetic knockouts (beclin 1, ULK1), autophagy assay, anti-Hsp70 functional blocking","journal":"Infection and immunity","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis (beclin 1, ULK1 dependence) plus Hsp70-specific functional blocking in vivo, single lab","pmids":["31109947"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2024,"finding":"When bag1 (HSP30) is knocked out in T. gondii ME49, transcription of HSP70 (along with HSP20, HSP21, HSP40, HSP60, HSP90, and BFD1) is significantly upregulated during early bradyzoite differentiation, indicating that HSP70 participates in a compensatory stress-response network that partially substitutes for BAG1 function in cyst formation.","method":"CRISPR/Cas9 gene knockout, qPCR (transcriptional analysis of HSP family members), Western blot, in vitro differentiation assay, mouse infection model","journal":"Parasites & vectors","confidence":"Low","confidence_rationale":"Tier 3 / Weak — HSP70 upregulation is a secondary observation in a BAG1 KO study; no direct functional manipulation of HSP70 itself","pmids":["39080770"],"is_preprint":false,"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}]}],"current_model":"TgHSP70 is a tachyzoite-specific, stress-inducible molecular chaperone that is transcriptionally upregulated by pH stress and during stage conversion; it functions as a virulence factor by binding TLR4 on host immune cells (confirmed by LSPR and Co-IP) to activate TLR4/NF-κB signaling and suppress iNOS/NO production, while also acting as a B cell mitogen and anaphylaxis inducer via TLR4/MyD88/cPLA2/PAF pathways; it is part of a cytosolic Hsp40-Hsp70-Hsp90 chaperone complex within the parasite, its chaperone function is required for intracellular parasite multiplication (shown by PES inhibitor and knockdown), and it participates in a compensatory HSP network regulating bradyzoite differentiation."},"narrative":{"mechanistic_narrative":"TgHSP70 is a stress-inducible ~72 kDa cytosolic molecular chaperone of Toxoplasma gondii that couples parasite stage conversion to modulation of host immunity and serves as a virulence factor [PMID:9632598, PMID:12097402]. Its transcription is driven by a defined pH-responsive cis-regulatory element engaged by a putative DNA-binding protein, accounting for its induction during alkaline-pH-triggered bradyzoite development, while induction in vivo is independent of IFN-γ, TNF-α and reactive nitrogen intermediates [PMID:15003494, PMID:11428337, PMID:9632598]. Within the parasite it operates as part of a cytosolic Hsp40(TgSis1)-Hsp70-Hsp90 chaperone complex, and its chaperone activity is required for intracellular multiplication, as shown by attenuation with the Hsp70-selective inhibitor PES that binds TgHSP70 directly [PMID:22209934, PMID:33157166]. As a virulence factor, TgHSP70 directly binds host TLR4 (confirmed by LSPR and Co-IP) to activate TLR4/NF-κB signaling and, in virulent strains, suppresses host NF-κB-driven iNOS/NO-mediated killing while restraining tachyzoite-to-bradyzoite conversion [PMID:36933491, PMID:12097402]. Acting on innate immune cells through TLR4, it functions as a MyD88-independent B cell mitogen and matures dendritic cells, and drives an IFN-γ-dependent, IgE-independent lethal anaphylaxis via a TLR4/MyD88/cPLA2/PAF cascade [PMID:12653480, PMID:16572725, PMID:16943259, PMID:18667035]. The immunosuppressive/deleterious activity maps to the protein's carboxy-terminal region [PMID:10905074].","teleology":[{"year":1998,"claim":"Establishing when TgHSP70 is expressed was the first step: its induction under alkaline pH stress and colocalization with bradyzoite antigens tied the chaperone to stage conversion.","evidence":"Western blot, IEM, RT-PCR and quercetin inhibition during in vitro and in vivo bradyzoite development","pmids":["9632598"],"confidence":"Medium","gaps":["Whether HSP70 induction is a cause or consequence of differentiation was not resolved","Quercetin is not HSP70-specific"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":1998,"claim":"Genomic characterization defined the gene as single-copy with a strain-variable C-terminal repeat and higher transcription in virulent strains, hinting that HSP70 dosage tracks with virulence.","evidence":"Genomic library screening, sequencing, copy-number and mRNA analysis of RH vs ME49","pmids":["9724875"],"confidence":"Medium","gaps":["Functional consequence of the repeat-length difference not tested","Post-transcriptional regulation inferred, not directly demonstrated"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"},{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":2000,"claim":"Immune-deficiency models showed HSP70 induction is not driven by host effector cytokines or nitrogen intermediates, indicating an intrinsic parasite stress response rather than an immune-triggered one.","evidence":"Western blot of tachyzoites from nude, SCID, IFN-γR KO and TNFR KO mice (RH strain)","pmids":["11428337"],"confidence":"Medium","gaps":["The actual physiological inducer in vivo was not identified"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2000,"claim":"Domain mapping localized the deleterious effect on host protective immunity to the C-terminal region, first pointing to a discrete effector module.","evidence":"Immunization with recombinant N- vs C-terminal fragments, QC-PCR brain parasite load","pmids":["10905074"],"confidence":"Low","gaps":["Single quantification method with limited mechanistic follow-up","Molecular basis of C-terminal activity unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2000,"claim":"Linking HSP70 to host NO suppression and mortality reframed it as a danger signal that blunts macrophage killing during lethal infection.","evidence":"NO release assay on peritoneal macrophages and mortality in IFN-γ KO mice","pmids":["11048655"],"confidence":"Low","gaps":["No receptor or signaling mechanism defined at this stage","Correlative mortality link"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2002,"claim":"Antisense knockdown provided causal, strain-specific evidence that TgHSP70 suppresses host NF-κB/iNOS killing and restrains stage conversion in virulent but not avirulent strains.","evidence":"Antisense oligonucleotide knockdown in RH/ENT vs ME49/C with NF-κB, iNOS/NO and bradyzoite-conversion readouts","pmids":["12097402"],"confidence":"Medium","gaps":["Molecular basis of virulent-vs-avirulent difference not fully explained","Antisense off-target effects not excluded"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"},{"species":"Toxoplasma gondii","strain":"ENT"},{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":2004,"claim":"Identification of a pH-responsive cis-element and an interacting DNA-binding protein defined the transcriptional switch controlling stress induction of hsp70.","evidence":"Reporter deletion analysis, stable GFP reporter under pH-shock, and EMSA in RH strain","pmids":["15003494"],"confidence":"Medium","gaps":["The DNA-binding protein was not molecularly identified","Element defined in RH only"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2005,"claim":"Dissecting the receptor logic showed TgHSP70 drives macrophage NO via TLR2/MyD88/IRAK4 but induces tolerance via TLR4/SOCS-1, explaining how it both activates and later dampens macrophages.","evidence":"NO assays in TLR2/TLR4/MyD88/IRAK4 KO mice with SOCS-1 and JNK/IκBα phosphorylation readouts","pmids":["16040976"],"confidence":"Medium","gaps":["Reconciliation of TLR2 vs TLR4 usage across cell types not fully resolved"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2006,"claim":"Two studies established TLR4 as the mitogenic/maturation receptor, showing TgHSP70 acts as a MyD88-independent B cell mitogen and dendritic cell maturation stimulus.","evidence":"B cell/T cell proliferation and DC maturation assays in TLR4-mutant, TLR4-/-, TLR2-/- and MyD88-/- mice with polymyxin B controls","pmids":["12653480","16572725"],"confidence":"Medium","gaps":["The MyD88-independent adaptor/signal downstream of TLR4 was not defined","LPS-contamination excluded only pharmacologically for some readouts"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2008,"claim":"Anaphylaxis studies traced the lethal reaction to a TLR4/MyD88 (not TRIF) cascade activating cPLA2 via p38 and p44/42 MAPK to produce PAF, in an IFN-γ-dependent, IgE-independent manner.","evidence":"In vivo anaphylaxis in TLR4/TLR2/MyD88/TRIF/IFN-γ KO mice with cPLA2 phosphorylation, MAPK inhibitors, PAF receptor antagonist and adoptive transfer","pmids":["16943259","18667035"],"confidence":"Medium","gaps":["The CD11b+ effector population's full role not delineated","Relevance to natural infection outcomes not established"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2010,"claim":"Co-IP identified AIF and Apaf-1 as binding partners of infection-upregulated HSP70, defining a mechanism by which HSP70 inhibits mitochondrial apoptosis in host macrophages.","evidence":"Co-immunoprecipitation, subcellular fractionation and caspase-3/DNA fragmentation assays in THP-1 macrophages","pmids":["20680337"],"confidence":"Medium","gaps":["Contribution of parasite vs host HSP70 to the anti-apoptotic effect not separated","No reciprocal Co-IP or mutagenesis"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2011,"claim":"Co-IP with TgSis1 placed TgHSP70 in a cytosolic Hsp40-Hsp70-Hsp90 chaperone complex, defining its physical role within the parasite proteostasis machinery.","evidence":"Co-immunoprecipitation, cytosolic fractionation and structural modeling of TgSis1","pmids":["22209934"],"confidence":"Low","gaps":["Single Co-IP without functional follow-up on HSP70","Client proteins of the complex not identified"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2019,"claim":"An anti-parasitic role emerged: membrane Hsp70 on infected leukocytes triggers CD40-dependent, beclin1/ULK1-mediated autophagy in endothelial cells to restrict neural invasion, showing HSP70 can also drive host defense.","evidence":"In vivo infection with adoptive transfer, beclin1/ULK1 KO and anti-Hsp70 functional blocking","pmids":["31109947"],"confidence":"Medium","gaps":["Whether the inducible Hsp70 is host- or parasite-derived not fully resolved","Reconciliation with immunosuppressive roles unclear"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2020,"claim":"Chemical-genetic evidence with the Hsp70 inhibitor PES demonstrated that HSP70 chaperone function is required for intracellular parasite multiplication, engaging both host and parasite Hsp70.","evidence":"PES inhibition, biotinylated-PES binding to host and TgHSP70, host Hsp70 siRNA, molecular docking and autophagy assays","pmids":["33157166"],"confidence":"Medium","gaps":["Parasite-autonomous requirement not isolated from host Hsp70 contribution","Client proteins driving multiplication unknown"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]},{"year":2023,"claim":"Direct interaction studies established that TgHSP70 physically binds host TLR4 to activate TLR4/NF-κB signaling, providing the receptor-level mechanism for its pro-inflammatory virulence activity.","evidence":"Molecular docking, LSPR, Co-IP and coixol disruption with iNOS/TNF-α/HMGB1 readouts in RH strain","pmids":["36933491"],"confidence":"Medium","gaps":["Binding interface not mapped to the C-terminal effector region","Shown in RH only"],"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}]},{"year":2024,"claim":"bag1 knockout revealed that HSP70 is part of a compensatory stress-response network upregulated during bradyzoite differentiation, linking it to a redundant chaperone system in cyst formation.","evidence":"CRISPR/Cas9 bag1 KO in ME49 with qPCR of HSP family members during differentiation","pmids":["39080770"],"confidence":"Low","gaps":["HSP70 upregulation is a secondary observation; no direct HSP70 manipulation","Functional contribution to cyst formation not tested"],"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}]},{"year":null,"claim":"It remains unresolved how the parasite's intrinsic chaperone function, its C-terminal TLR4-binding virulence activity, and its dual immunosuppressive vs autophagy-inducing effects are mechanistically integrated across strains and infection stages.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structure of the TgHSP70-TLR4 interface","Chaperone client proteins in the parasite unidentified","Contribution of parasite vs host Hsp70 to each phenotype not cleanly separated"],"attribution":[{"species":"Toxoplasma gondii","strain":""}]}],"mechanism_profile":{"molecular_activity":[],"localization":[],"pathway":[],"complexes":["Cytosolic Hsp40(TgSis1)-Hsp70-Hsp90 chaperone complex [#12]"],"partners":["TLR4 (HOST) [#16]","AIF (HOST) [#11]","APAF-1 (HOST) [#11]","TGSIS1/HSP40 [#12]","HSP90 [#12]"],"other_free_text":["Transcription driven by a pH-responsive cis-regulatory element bound by a putative DNA-binding protein [#6]","Induced during alkaline-pH bradyzoite development and stage conversion; induction independent of IFN-γ/TNF-α/RNI [#0, #2, #14]","Immunosuppressive/deleterious activity maps to the C-terminal region [#17]","Chaperone function required for intracellular multiplication (PES inhibitor, siRNA) [#13]","Functions as a B cell mitogen and dendritic cell maturation stimulus via TLR4 [#5, #8]","Drives IFN-γ-dependent, IgE-independent lethal anaphylaxis via cPLA2/PAF [#9, #10]","Part of a compensatory HSP network upregulated in bag1 KO during bradyzoite differentiation [#19]"]},"strain_conflicts":[{"aspect":"Suppression of host NF-κB/iNOS-mediated killing and restraint of stage conversion by TgHSP70","claims":[{"attribution":[{"species":"Toxoplasma gondii","strain":"RH"},{"species":"Toxoplasma gondii","strain":"ENT"}],"claim":"Antisense knockdown of TgHSP70 increased host NF-κB activation and iNOS/NO and enhanced tachyzoite-to-bradyzoite conversion, establishing TgHSP70 as a suppressor of host killing in virulent strains","supporting_discovery_ids":[3]},{"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"},{"species":"Toxoplasma gondii","strain":"C"}],"claim":"The same knockdown effects were not observed in avirulent strains","supporting_discovery_ids":[3]}]},{"aspect":"hsp70 C-terminal 7-aa repeat copy number and transcription level","claims":[{"attribution":[{"species":"Toxoplasma gondii","strain":"RH"}],"claim":"Virulent strain has four copies of the GGMPGGM C-terminal repeat and 1.5-2-fold higher mRNA transcription","supporting_discovery_ids":[1]},{"attribution":[{"species":"Toxoplasma gondii","strain":"ME49"}],"claim":"Avirulent strain has five copies of the repeat and lower transcription","supporting_discovery_ids":[1]}]}]},"prefetch_data":{},"corpus_meta":[{"pmid":"9632598","id":"PMC_9632598","title":"Bradyzoite development in Toxoplasma gondii and the hsp70 stress response.","date":"1998","source":"Infection and immunity","url":"https://pubmed.ncbi.nlm.nih.gov/9632598","citation_count":104,"is_preprint":false},{"pmid":"12097402","id":"PMC_12097402","title":"Heat shock protein 70 is a potential virulence factor in murine toxoplasma infection via immunomodulation of host NF-kappa B and nitric oxide.","date":"2002","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/12097402","citation_count":91,"is_preprint":false},{"pmid":"20955165","id":"PMC_20955165","title":"Intracellular protozoan parasites of humans: the role of molecular chaperones in development and pathogenesis.","date":"2011","source":"Protein and peptide letters","url":"https://pubmed.ncbi.nlm.nih.gov/20955165","citation_count":90,"is_preprint":false},{"pmid":"12798627","id":"PMC_12798627","title":"Induction of protective immunity by DNA vaccination with Toxoplasma gondii HSP70, HSP30 and SAG1 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Quercetin, which inhibits hsp70 synthesis, suppressed bradyzoite development in vitro.\",\n      \"method\": \"Western blot, immunofluorescence, immunoelectron microscopy, RT-PCR, pharmacological inhibition (quercetin)\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (Western blot, IEM, RT-PCR, pharmacological inhibition) in a single lab; functional link established\",\n      \"pmids\": [\"9632598\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"The cytoplasmic 70 kDa HSP gene is single-copy in both virulent (RH) and avirulent (ME49) strains; virulent strains have four copies of a 7-aa C-terminal repeat (GGMPGGM) vs. five in avirulent strains, and show 1.5–2-fold higher mRNA transcription in vivo and in vitro, indicating post-transcriptional regulation also occurs in T. gondii.\",\n      \"method\": \"Genomic DNA library screening, PCR amplification, gene sequencing, copy-number estimation, Northern/mRNA analysis\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal molecular methods (sequencing, copy-number, transcription analysis) in single lab\",\n      \"pmids\": [\"9724875\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"High-level TgHSP70 expression occurs during in vivo bradyzoite-to-tachyzoite conversion (reactivation) in chronically infected mice treated with neutralizing anti-IFN-γ or anti-TNF-α antibodies, demonstrating HSP70 upregulation is associated with stage conversion under immunosuppressive conditions.\",\n      \"method\": \"Immunocytochemistry, photometric assay of antigen expression in CNS tissue\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single primary method (immunocytochemistry), no direct functional manipulation of HSP70\",\n      \"pmids\": [\"9673286\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Antisense oligonucleotide-mediated reduction of TgHSP70 expression in virulent T. gondii strains (RH, ENT) increased host NF-κB activation in splenocytes and iNOS/NO production in RAW 264.7 macrophages, and enhanced tachyzoite-to-bradyzoite conversion in vitro; these effects were not observed in avirulent strains (ME49, C), establishing TgHSP70 as a suppressor of host NF-κB and iNOS-mediated killing specifically in virulent strains.\",\n      \"method\": \"Antisense oligonucleotide transfection, Western blot (HSP70 expression), in vivo tachyzoite counting (spleen), in vitro bradyzoite conversion assay, iNOS mRNA measurement, NF-κB nuclear translocation assay, NO production assay\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function (antisense KD) with multiple cellular readouts in single lab\",\n      \"pmids\": [\"12097402\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"ENT\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"TgHSP70 inhibits nitric oxide release from peritoneal macrophages of T. gondii-infected mice, and high-level TgHSP70 expression correlates with mortality in IFN-γ knockout mice, identifying TgHSP70 as a danger signal that suppresses host macrophage NO production during lethal acute infection.\",\n      \"method\": \"NO release assay (peritoneal macrophages), mRNA analysis (RT-PCR for stage markers), in vivo mortality analysis in IFN-γ KO mice\",\n      \"journal\": \"Cell stress & chaperones\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, functional readout (NO inhibition) with limited mechanistic follow-up\",\n      \"pmids\": [\"11048655\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"TgHSP70 functions as a B cell mitogen, inducing proliferation of murine B cells (B220+) but not T cells via TLR4; this proliferation is MyD88-independent (unlike LPS-induced proliferation), polymyxin B-insensitive, and absent in TLR4-mutant (C3H/HeJ) and TLR4-/- mice.\",\n      \"method\": \"In vitro proliferation assay, cell subset depletion, TLR4-mutant and knockout mice, MyD88-/- mice, polymyxin B inhibition control\",\n      \"journal\": \"Cell stress & chaperones\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — defined receptor (TLR4) requirement confirmed by genetic knockout and mutant strains with multiple controls in single lab\",\n      \"pmids\": [\"12653480\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"A pH-responsive cis-regulatory element was identified in the T. gondii hsp70 genomic locus upstream region by deletion analysis using β-galactosidase reporter constructs transiently transfected into RH strain T. gondii; GFP reporter constructs stably transfected into T. gondii showed pH-shock-induced GFP expression driven by this element. Gel-shift analysis identified a putative DNA-binding protein interacting with the pH-regulated region.\",\n      \"method\": \"Deletion analysis with β-galactosidase reporter, stable transfection with GFP reporter, electrophoretic mobility shift assay (EMSA/gel shift)\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal methods (deletion analysis, stable reporter, gel shift) in single lab; directly defines regulatory element\",\n      \"pmids\": [\"15003494\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"TgHSP70-induced macrophage NO production signals through TLR2, MyD88, and IRAK4 (not TLR4); however, TgHSP70-induced macrophage tolerance (suppression of NO on restimulation) is mediated through TLR4 and SOCS-1 upregulation, with JNK and IκBα phosphorylation occurring via TLR2 in the absence of TLR4-mediated tolerance.\",\n      \"method\": \"NO release assay, gene-knockout mice (TLR2-/-, TLR4-/-, MyD88-/-, IRAK4-/-), polymyxin B control, SOCS-1 expression assay, JNK and IκBα phosphorylation analysis\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic knockouts with mechanistic pathway dissection in single lab\",\n      \"pmids\": [\"16040976\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TgHSP70 stimulates maturation of murine bone marrow-derived dendritic cells (increased MHC I/II, CD40, CD80, CD86 surface expression; decreased phagocytic ability; increased alloreactive T cell stimulation; IL-12 production; IFN-β mRNA expression) via TLR4 through a MyD88-independent signal transduction cascade; TLR2-/- and MyD88-/- DCs respond normally, but TLR4-/- DCs do not.\",\n      \"method\": \"DC maturation surface marker flow cytometry, phagocytosis assay, allostimulation assay, ELISA (IL-12), RT-PCR (IFN-β), TLR-deficient mouse DCs\",\n      \"journal\": \"Cell stress & chaperones\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal readouts with genetic confirmation (TLR4-/- DCs) in single lab\",\n      \"pmids\": [\"16572725\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"TgHSP70 induces lethal anaphylactic reaction in T. gondii-infected mice through an IFN-γ-dependent, IgE-independent pathway involving platelet-activating factor (PAF); splenocytes (not serum) transfer this reactivity, and PAF receptor antagonist rescues mice from the reaction.\",\n      \"method\": \"In vivo anaphylaxis model, adoptive transfer (splenocytes vs. serum), IFN-γ KO mice, B cell-deficient mice, PAF receptor antagonist treatment, RT-PCR (PAF acetylhydrolase, IFN-γ mRNA)\",\n      \"journal\": \"International immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic knockouts and pharmacological rescue with multiple readouts in single lab\",\n      \"pmids\": [\"16943259\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"TgHSP70-induced lethal anaphylactic reaction in infected mice is mediated via TLR4/MyD88-dependent (not TRIF-dependent) signaling, activating cPLA2 via p38 and p44/42 MAPK pathways in CD11b+ splenocytes, leading to PAF production; TLR4-/- and MyD88-/- mice are protected from the reaction.\",\n      \"method\": \"In vivo anaphylaxis model, TLR4-/-, TLR2-/-, MyD88-/-, TRIF-/- mice, cPLA2 phosphorylation assay, MAPK pathway inhibitors, PAF-AH mRNA expression\",\n      \"journal\": \"Microbiology and immunology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple genetic knockouts dissecting signaling pathway with pharmacological inhibition, single lab\",\n      \"pmids\": [\"18667035\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In T. gondii-infected host cells (THP-1 macrophages), HSP70 (host-upregulated by infection) binds pro-apoptotic factors AIF and Apaf-1 (but not cytochrome c or procaspase-9) as shown by co-immunoprecipitation, inhibiting mitochondrial apoptosis by preventing AIF and cytochrome c release from mitochondria and suppressing caspase-3 activation in a parasite load-dependent manner.\",\n      \"method\": \"Western blot, DNA fragmentation assay, co-immunoprecipitation, caspase-3/7 activity assay, subcellular fractionation\",\n      \"journal\": \"Parasitology research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP identifying binding partners, supported by functional apoptosis readouts, single lab\",\n      \"pmids\": [\"20680337\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"TgSis1 (a T. gondii Hsp40/J-domain protein homologous to yeast Sis1) is a cytosolic chaperone that co-immunoprecipitates with T. gondii Hsp70 and Hsp90, establishing TgHSP70 as part of a cytosolic Hsp40-Hsp70-Hsp90 chaperone complex in the parasite.\",\n      \"method\": \"Co-immunoprecipitation, subcellular localization (cytosolic fractionation), structural modeling\",\n      \"journal\": \"International journal of biological macromolecules\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP identifying chaperone complex membership, single lab, no functional follow-up on HSP70 specifically\",\n      \"pmids\": [\"22209934\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TgHSP70 is required for intracellular multiplication of T. gondii: the Hsp70-selective inhibitor PES (2-phenylethynesulfonamide) attenuates intracellular T. gondii multiplication, confirmed by biotinylated PES binding directly to both host Hsp70 and TgHSP70 (verified by PES binding assay and molecular docking); silencing of host Hsp70 also reduces parasite multiplication, with attenuation linked to disruption of host autophagy.\",\n      \"method\": \"Pharmacological inhibition (PES), biotinylated PES binding assay, host Hsp70 siRNA knockdown, molecular docking (TgHsp70 structural analysis), autophagy functional assay\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct small molecule binding confirmed for both host and parasite Hsp70, supported by knockdown and docking, single lab\",\n      \"pmids\": [\"33157166\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Immune factors (IFN-γ, TNF-α, reactive nitrogen intermediates) do not play primary roles in inducing TgHSP70 production in vivo: virulent RH strain tachyzoites from nude, SCID, IFN-γ receptor KO, and TNF receptor KO mice all produced similar levels of HSP70 as immunocompetent mice.\",\n      \"method\": \"Western blot analysis of HSP70 in tachyzoites recovered from immunodeficient mice (nude, SCID, IFN-γR KO, TNFR KO)\",\n      \"journal\": \"International journal for parasitology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — four distinct genetic immune-deficiency models tested, consistent negative result across all; single lab\",\n      \"pmids\": [\"11428337\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Systemic (serum) detection of TgHSP70 protein depends on parasite killing by the host immune response, while increased TgHSP70 expression in the brain correlates with parasite multiplication rate; dexamethasone-induced immunosuppression decreased systemic TgHSP70 while increasing cerebral parasitism and TgHSP70 brain expression.\",\n      \"method\": \"ELISA (serum TgHSP70 and antibody levels), immunohistochemistry (brain TgHSP70), immune complex detection, dexamethasone immunosuppression model, comparison of BALB/c vs C57BL/6 mice\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — indirect inference from correlative measurements in pharmacological model, no direct manipulation of TgHSP70\",\n      \"pmids\": [\"24801069\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"TgHSP70 directly binds TLR4 (demonstrated by molecular docking, localized surface plasmon resonance, and co-immunoprecipitation), and this interaction activates TLR4/NF-κB signaling; coixol disrupts TgHSP70-TLR4 interaction and inhibits downstream iNOS, TNF-α, and HMGB1 overproduction.\",\n      \"method\": \"Molecular docking, localized surface plasmon resonance (LSPR), co-immunoprecipitation, ELISA, Western blot, immunofluorescence, qPCR\",\n      \"journal\": \"International immunopharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct protein-protein interaction confirmed by LSPR and Co-IP with functional downstream pathway readouts, single lab\",\n      \"pmids\": [\"36933491\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"The carboxy-terminal region of TgHSP70 mediates its immunosuppressive/deleterious effect on host protective immunity: immunization with rTgHSP70-full-length or rTgHSP70-C-terminal region increased brain parasite burden after infection, while rTgHSP70-N-terminal region did not.\",\n      \"method\": \"Immunization with recombinant protein fragments, quantitative competitive PCR (QC-PCR) for brain parasite load (SAG1 gene)\",\n      \"journal\": \"The Korean journal of parasitology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, single method for parasite quantification; domain-mapping with limited functional mechanistic follow-up\",\n      \"pmids\": [\"10905074\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Inducible Hsp70 expressed on the membrane of T. gondii-infected dendritic cells and macrophages triggers Hsp70-dependent autophagy in CD40-expressing endothelial cells via beclin 1 and ULK1, restricting T. gondii invasion of neural tissue; this anti-parasitic activity required both CD40 expression in endothelial cells and inducible Hsp70 expression in the infecting leukocytes.\",\n      \"method\": \"In vivo infection model (retina and brain parasite load), adoptive transfer of infected monocytes/DCs, genetic knockouts (beclin 1, ULK1), autophagy assay, anti-Hsp70 functional blocking\",\n      \"journal\": \"Infection and immunity\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis (beclin 1, ULK1 dependence) plus Hsp70-specific functional blocking in vivo, single lab\",\n      \"pmids\": [\"31109947\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"When bag1 (HSP30) is knocked out in T. gondii ME49, transcription of HSP70 (along with HSP20, HSP21, HSP40, HSP60, HSP90, and BFD1) is significantly upregulated during early bradyzoite differentiation, indicating that HSP70 participates in a compensatory stress-response network that partially substitutes for BAG1 function in cyst formation.\",\n      \"method\": \"CRISPR/Cas9 gene knockout, qPCR (transcriptional analysis of HSP family members), Western blot, in vitro differentiation assay, mouse infection model\",\n      \"journal\": \"Parasites & vectors\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — HSP70 upregulation is a secondary observation in a BAG1 KO study; no direct functional manipulation of HSP70 itself\",\n      \"pmids\": [\"39080770\"],\n      \"is_preprint\": false,\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    }\n  ],\n  \"current_model\": \"TgHSP70 is a tachyzoite-specific, stress-inducible molecular chaperone that is transcriptionally upregulated by pH stress and during stage conversion; it functions as a virulence factor by binding TLR4 on host immune cells (confirmed by LSPR and Co-IP) to activate TLR4/NF-κB signaling and suppress iNOS/NO production, while also acting as a B cell mitogen and anaphylaxis inducer via TLR4/MyD88/cPLA2/PAF pathways; it is part of a cytosolic Hsp40-Hsp70-Hsp90 chaperone complex within the parasite, its chaperone function is required for intracellular parasite multiplication (shown by PES inhibitor and knockdown), and it participates in a compensatory HSP network regulating bradyzoite differentiation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"TgHSP70 is a stress-inducible ~72 kDa cytosolic molecular chaperone of Toxoplasma gondii that couples parasite stage conversion to modulation of host immunity and serves as a virulence factor [#0, #3]. Its transcription is driven by a defined pH-responsive cis-regulatory element engaged by a putative DNA-binding protein, accounting for its induction during alkaline-pH-triggered bradyzoite development, while induction in vivo is independent of IFN-\\u03b3, TNF-\\u03b1 and reactive nitrogen intermediates [#6, #14, #0]. Within the parasite it operates as part of a cytosolic Hsp40(TgSis1)-Hsp70-Hsp90 chaperone complex, and its chaperone activity is required for intracellular multiplication, as shown by attenuation with the Hsp70-selective inhibitor PES that binds TgHSP70 directly [#12, #13]. As a virulence factor, TgHSP70 directly binds host TLR4 (confirmed by LSPR and Co-IP) to activate TLR4/NF-\\u03baB signaling and, in virulent strains, suppresses host NF-\\u03baB-driven iNOS/NO-mediated killing while restraining tachyzoite-to-bradyzoite conversion [#16, #3]. Acting on innate immune cells through TLR4, it functions as a MyD88-independent B cell mitogen and matures dendritic cells, and drives an IFN-\\u03b3-dependent, IgE-independent lethal anaphylaxis via a TLR4/MyD88/cPLA2/PAF cascade [#5, #8, #9, #10]. The immunosuppressive/deleterious activity maps to the protein's carboxy-terminal region [#17].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Establishing when TgHSP70 is expressed was the first step: its induction under alkaline pH stress and colocalization with bradyzoite antigens tied the chaperone to stage conversion.\",\n      \"evidence\": \"Western blot, IEM, RT-PCR and quercetin inhibition during in vitro and in vivo bradyzoite development\",\n      \"pmids\": [\"9632598\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether HSP70 induction is a cause or consequence of differentiation was not resolved\", \"Quercetin is not HSP70-specific\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Genomic characterization defined the gene as single-copy with a strain-variable C-terminal repeat and higher transcription in virulent strains, hinting that HSP70 dosage tracks with virulence.\",\n      \"evidence\": \"Genomic library screening, sequencing, copy-number and mRNA analysis of RH vs ME49\",\n      \"pmids\": [\"9724875\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of the repeat-length difference not tested\", \"Post-transcriptional regulation inferred, not directly demonstrated\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Immune-deficiency models showed HSP70 induction is not driven by host effector cytokines or nitrogen intermediates, indicating an intrinsic parasite stress response rather than an immune-triggered one.\",\n      \"evidence\": \"Western blot of tachyzoites from nude, SCID, IFN-\\u03b3R KO and TNFR KO mice (RH strain)\",\n      \"pmids\": [\"11428337\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The actual physiological inducer in vivo was not identified\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Domain mapping localized the deleterious effect on host protective immunity to the C-terminal region, first pointing to a discrete effector module.\",\n      \"evidence\": \"Immunization with recombinant N- vs C-terminal fragments, QC-PCR brain parasite load\",\n      \"pmids\": [\"10905074\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single quantification method with limited mechanistic follow-up\", \"Molecular basis of C-terminal activity unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Linking HSP70 to host NO suppression and mortality reframed it as a danger signal that blunts macrophage killing during lethal infection.\",\n      \"evidence\": \"NO release assay on peritoneal macrophages and mortality in IFN-\\u03b3 KO mice\",\n      \"pmids\": [\"11048655\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No receptor or signaling mechanism defined at this stage\", \"Correlative mortality link\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Antisense knockdown provided causal, strain-specific evidence that TgHSP70 suppresses host NF-\\u03baB/iNOS killing and restrains stage conversion in virulent but not avirulent strains.\",\n      \"evidence\": \"Antisense oligonucleotide knockdown in RH/ENT vs ME49/C with NF-\\u03baB, iNOS/NO and bradyzoite-conversion readouts\",\n      \"pmids\": [\"12097402\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of virulent-vs-avirulent difference not fully explained\", \"Antisense off-target effects not excluded\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"ENT\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Identification of a pH-responsive cis-element and an interacting DNA-binding protein defined the transcriptional switch controlling stress induction of hsp70.\",\n      \"evidence\": \"Reporter deletion analysis, stable GFP reporter under pH-shock, and EMSA in RH strain\",\n      \"pmids\": [\"15003494\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The DNA-binding protein was not molecularly identified\", \"Element defined in RH only\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Dissecting the receptor logic showed TgHSP70 drives macrophage NO via TLR2/MyD88/IRAK4 but induces tolerance via TLR4/SOCS-1, explaining how it both activates and later dampens macrophages.\",\n      \"evidence\": \"NO assays in TLR2/TLR4/MyD88/IRAK4 KO mice with SOCS-1 and JNK/I\\u03baB\\u03b1 phosphorylation readouts\",\n      \"pmids\": [\"16040976\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Reconciliation of TLR2 vs TLR4 usage across cell types not fully resolved\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Two studies established TLR4 as the mitogenic/maturation receptor, showing TgHSP70 acts as a MyD88-independent B cell mitogen and dendritic cell maturation stimulus.\",\n      \"evidence\": \"B cell/T cell proliferation and DC maturation assays in TLR4-mutant, TLR4-/-, TLR2-/- and MyD88-/- mice with polymyxin B controls\",\n      \"pmids\": [\"12653480\", \"16572725\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The MyD88-independent adaptor/signal downstream of TLR4 was not defined\", \"LPS-contamination excluded only pharmacologically for some readouts\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Anaphylaxis studies traced the lethal reaction to a TLR4/MyD88 (not TRIF) cascade activating cPLA2 via p38 and p44/42 MAPK to produce PAF, in an IFN-\\u03b3-dependent, IgE-independent manner.\",\n      \"evidence\": \"In vivo anaphylaxis in TLR4/TLR2/MyD88/TRIF/IFN-\\u03b3 KO mice with cPLA2 phosphorylation, MAPK inhibitors, PAF receptor antagonist and adoptive transfer\",\n      \"pmids\": [\"16943259\", \"18667035\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"The CD11b+ effector population's full role not delineated\", \"Relevance to natural infection outcomes not established\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Co-IP identified AIF and Apaf-1 as binding partners of infection-upregulated HSP70, defining a mechanism by which HSP70 inhibits mitochondrial apoptosis in host macrophages.\",\n      \"evidence\": \"Co-immunoprecipitation, subcellular fractionation and caspase-3/DNA fragmentation assays in THP-1 macrophages\",\n      \"pmids\": [\"20680337\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Contribution of parasite vs host HSP70 to the anti-apoptotic effect not separated\", \"No reciprocal Co-IP or mutagenesis\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Co-IP with TgSis1 placed TgHSP70 in a cytosolic Hsp40-Hsp70-Hsp90 chaperone complex, defining its physical role within the parasite proteostasis machinery.\",\n      \"evidence\": \"Co-immunoprecipitation, cytosolic fractionation and structural modeling of TgSis1\",\n      \"pmids\": [\"22209934\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single Co-IP without functional follow-up on HSP70\", \"Client proteins of the complex not identified\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"An anti-parasitic role emerged: membrane Hsp70 on infected leukocytes triggers CD40-dependent, beclin1/ULK1-mediated autophagy in endothelial cells to restrict neural invasion, showing HSP70 can also drive host defense.\",\n      \"evidence\": \"In vivo infection with adoptive transfer, beclin1/ULK1 KO and anti-Hsp70 functional blocking\",\n      \"pmids\": [\"31109947\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the inducible Hsp70 is host- or parasite-derived not fully resolved\", \"Reconciliation with immunosuppressive roles unclear\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Chemical-genetic evidence with the Hsp70 inhibitor PES demonstrated that HSP70 chaperone function is required for intracellular parasite multiplication, engaging both host and parasite Hsp70.\",\n      \"evidence\": \"PES inhibition, biotinylated-PES binding to host and TgHSP70, host Hsp70 siRNA, molecular docking and autophagy assays\",\n      \"pmids\": [\"33157166\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Parasite-autonomous requirement not isolated from host Hsp70 contribution\", \"Client proteins driving multiplication unknown\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Direct interaction studies established that TgHSP70 physically binds host TLR4 to activate TLR4/NF-\\u03baB signaling, providing the receptor-level mechanism for its pro-inflammatory virulence activity.\",\n      \"evidence\": \"Molecular docking, LSPR, Co-IP and coixol disruption with iNOS/TNF-\\u03b1/HMGB1 readouts in RH strain\",\n      \"pmids\": [\"36933491\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding interface not mapped to the C-terminal effector region\", \"Shown in RH only\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"bag1 knockout revealed that HSP70 is part of a compensatory stress-response network upregulated during bradyzoite differentiation, linking it to a redundant chaperone system in cyst formation.\",\n      \"evidence\": \"CRISPR/Cas9 bag1 KO in ME49 with qPCR of HSP family members during differentiation\",\n      \"pmids\": [\"39080770\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"HSP70 upregulation is a secondary observation; no direct HSP70 manipulation\", \"Functional contribution to cyst formation not tested\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how the parasite's intrinsic chaperone function, its C-terminal TLR4-binding virulence activity, and its dual immunosuppressive vs autophagy-inducing effects are mechanistically integrated across strains and infection stages.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structure of the TgHSP70-TLR4 interface\", \"Chaperone client proteins in the parasite unidentified\", \"Contribution of parasite vs host Hsp70 to each phenotype not cleanly separated\"],\n      \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0051082\", \"supporting_discovery_ids\": [12, 13], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0005102\", \"supporting_discovery_ids\": [16, 11], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0035325\", \"supporting_discovery_ids\": [16, 5, 8], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [12], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0009986\", \"supporting_discovery_ids\": [18], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0038123\", \"supporting_discovery_ids\": [16, 5, 8, 10], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0043123\", \"supporting_discovery_ids\": [16, 3], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0045019\", \"supporting_discovery_ids\": [3, 4, 7], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0006915\", \"supporting_discovery_ids\": [11], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0006914\", \"supporting_discovery_ids\": [18, 13], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]},\n      {\"term_id\": \"GO:0034605\", \"supporting_discovery_ids\": [0, 6], \"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"\"}]}\n    ],\n    \"complexes\": [\"Cytosolic Hsp40(TgSis1)-Hsp70-Hsp90 chaperone complex [#12]\"],\n    \"partners\": [\"TLR4 (host) [#16]\", \"AIF (host) [#11]\", \"Apaf-1 (host) [#11]\", \"TgSis1/Hsp40 [#12]\", \"Hsp90 [#12]\"],\n    \"other_free_text\": [\n      \"Transcription driven by a pH-responsive cis-regulatory element bound by a putative DNA-binding protein [#6]\",\n      \"Induced during alkaline-pH bradyzoite development and stage conversion; induction independent of IFN-\\u03b3/TNF-\\u03b1/RNI [#0, #2, #14]\",\n      \"Immunosuppressive/deleterious activity maps to the C-terminal region [#17]\",\n      \"Chaperone function required for intracellular multiplication (PES inhibitor, siRNA) [#13]\",\n      \"Functions as a B cell mitogen and dendritic cell maturation stimulus via TLR4 [#5, #8]\",\n      \"Drives IFN-\\u03b3-dependent, IgE-independent lethal anaphylaxis via cPLA2/PAF [#9, #10]\",\n      \"Part of a compensatory HSP network upregulated in bag1 KO during bradyzoite differentiation [#19]\"\n    ]\n  },\n  \"strain_conflicts\": [\n    {\n      \"aspect\": \"Suppression of host NF-\\u03baB/iNOS-mediated killing and restraint of stage conversion by TgHSP70\",\n      \"claims\": [\n        {\"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"ENT\"}], \"claim\": \"Antisense knockdown of TgHSP70 increased host NF-\\u03baB activation and iNOS/NO and enhanced tachyzoite-to-bradyzoite conversion, establishing TgHSP70 as a suppressor of host killing in virulent strains\", \"supporting_discovery_ids\": [3]},\n        {\"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}, {\"species\": \"Toxoplasma gondii\", \"strain\": \"C\"}], \"claim\": \"The same knockdown effects were not observed in avirulent strains\", \"supporting_discovery_ids\": [3]}\n      ]\n    },\n    {\n      \"aspect\": \"hsp70 C-terminal 7-aa repeat copy number and transcription level\",\n      \"claims\": [\n        {\"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"RH\"}], \"claim\": \"Virulent strain has four copies of the GGMPGGM C-terminal repeat and 1.5-2-fold higher mRNA transcription\", \"supporting_discovery_ids\": [1]},\n        {\"attribution\": [{\"species\": \"Toxoplasma gondii\", \"strain\": \"ME49\"}], \"claim\": \"Avirulent strain has five copies of the repeat and lower transcription\", \"supporting_discovery_ids\": [1]}\n      ]\n    }\n  ]\n}","audit_flag":null,"strains":[{"strain":"ME49","gene_id":"TGME49_273760","name":"HSP70","product":"heat shock protein HSP70","uniprot_acc":"A0A125YXI9","chromosome":"TGME49_chrVIII","start_pos":3288936},{"strain":"GT1","gene_id":"TGGT1_273760","name":null,"product":"heat shock protein HSP70","uniprot_acc":null,"chromosome":"TGGT1_chrVIII","start_pos":3285695},{"strain":"RH88","gene_id":"TGRH88_078290","name":null,"product":"heat shock protein HSP70","uniprot_acc":null,"chromosome":"CM023089","start_pos":8397083},{"strain":"VEG","gene_id":"TGVEG_273760","name":null,"product":"heat shock protein HSP70","uniprot_acc":"A0A0F7V4M1","chromosome":"TGVEG_chrVIII","start_pos":3298080}]}