Initial Characterization of CST1, a
            <i>Toxoplasma gondii</i>
            Cyst Wall Glycoprotein

Zhang, Yi Wei; Halonen, Sandra K.; Fen, Yan; Wittner, Murray; Weiss, Louis M.

doi:10.1128/iai.69.1.501-507.2001

Cited by 104 publications

(114 citation statements)

References 52 publications

(50 reference statements)

Supporting

Mentioning

103

Contrasting

Order By: Relevance

“…Cyst formation was monitored following treatment with FLU under normal culture conditions as detected using FITC-labeled Dolichos biflorus lectin (DBL) (Sigma) or antibodies to the cyst antigens CST1 16 or BAG1 17. Transmission electron microscopy was performed as described previously 15.…”

Section: In Vitro Differentiationmentioning

confidence: 99%

See 1 more Smart Citation

Abscisic acid controls calcium-dependent egress and development in Toxoplasma gondii

Nagamune

Hicks

Fux

et al. 2008

Nature

190

174

View full text Add to dashboard Cite

Calcium controls a number of critical events including motility, secretion, cell invasion, and egress by protozoan parasites 1. Compared to animal 2 and plant cells 3 , the molecular mechanisms that govern calcium signaling in parasites are poorly understood. Here we demonstrate that the production of the phytohormone abscisic acid (ABA) controls calcium signaling within the apicomplexan parasite Toxoplasma gondii, an important human pathogen. In plants, ABA controls a number of important events including environmental stress responses, embryo development, and seed dormancy 4 ,5 . ABA induces production of the second-messenger cyclic ADP ribose (cADPR), which controls release of intracellular calcium stores in plants 6 . cADPR also controls intracellular calcium release in the protozoan parasite T. gondii 7,8 ; however, previous studies have not revealed the molecular basis of this pathway 9 . Addition of exogenous ABA induced formation of cADPR in T. gondii, stimulated calcium-dependent protein secretion, and induced parasite egress from the infected host cell in a density-dependent manner. Production of endogenous ABA within the parasite was confirmed by HPLC purification and GC-MS analysis. Selective disruption of ABA synthesis by the inhibitor fluridone (FLU) delayed egress and induced development of the slow-growing, dormant cyst stage of the parasite. Thus, ABA-mediated calcium signaling controls the decision between lytic and chronic stage growth, a developmental switch that is central in pathogenesis and transmission. The pathway for ABA production was likely acquired with an algal endosymbiont that was retained as a non-photosynthetic plastid known as the apicoplast. The plant-like nature of this pathway may be exploited therapeutically as shown by the ability of a specific inhibitor of ABA synthesis to prevent toxoplasmosis in the mouse model.Calcium-mediated secretion in T. gondii controls both motility and cell invasion and previous studies have demonstrated that these processes utilize the second messenger cADPR, yet the signals triggering this pathway remain unresolved 7,8 . In plants 6 , hydra 10 , and sponges 11 , ABA stimulates release of intracellular calcium through elevation of the cyclic nucleotide cADPR. Addition of exogenous ABA proved to be a potent agonist of secretion in T. gondii as shown by the release of the protein MIC2, a parasite adhesin that is discharged into the supernatant in response to increases in intracellular calcium (Fig. 1A). Induction of MIC2 secretion by ABA was highly specific to (±) -ABA and was not induced by (−) -ABA, the precursor β-carotene, or retinoic acid (Fig. 1B). Treatment with ABA lead to a dose-dependent increase in the second messenger cADPR in T. gondii, suggesting ABA may be a natural agonist for calcium signaling in parasites (Fig. 1C). Finally, chelation of intracellular calcium in the parasite blocked secretion induced by ABA, confirming that it acts through release of an intracellular calcium pool (Fig. 1D). Collectively these results ind...

show abstract

Section: In Vitro Differentiationmentioning

confidence: 99%

“…4A). Tissue cysts produced by treatment with FLU were positive for several stage-specific cyst markers including DBL, the cyst antigens CST1 16 , and BAG1 17 (Fig. 4B).…”

mentioning

confidence: 99%

Abscisic acid controls calcium-dependent egress and development in Toxoplasma gondii

Nagamune

Hicks

Fux

et al. 2008

Nature

190

174

View full text Add to dashboard Cite

show abstract

“…This published method is, however, limited to b-gal transgenic parasites. Here, we used the Dolichos biflorus lectin properties to bind the N-acetylgalactosamine of the cyst wall (10) and to develop two fluorescence methods to stain cysts from any Toxoplasma strains. Before labelling brain cysts with the fluorescent Dolichos lectin agglutinin, a step of mild proteinase K digestion was added for cerebral tissue clarification without cyst wall destruction.…”

Section: Resultsmentioning

confidence: 99%

“…The method is based on the Dolichos biflorus lectin property to bind to N-acetylgalactosamine on the Toxoplasma cyst wall of any Toxoplasma strain (10). A commercial FITC-Dolichos biflorus lectin is available.…”

Section: Discussionmentioning

confidence: 99%

Development of high‐throughput methods to quantify cysts of Toxoplasma gondii

et al. 2011

View full text Add to dashboard Cite

Toxplasma is a protozoan parasite, which forms persistent cysts in tissues of chronically infected animals and humans. Cysts can reactivate leading to severe pathologies. They also contribute to the transmission of Toxoplasma infection in humans by ingestion of undercooked meat. Classically, the quantification of cyst burden in tissues uses microscopy methods, which are laborious and time consuming. Here, we have developed automated protocols to quantify cysts, based on flow cytometry or high-throughput microscopy. Brains of rodents infected with cysts of Prugniaud strain were incubated with the FITC-Dolichos biflorus lectin and analyzed by flow cytometry and high-throughput epifluorescence microscopy. The comparison of cyst counts by manual epifluorescence microscopy to flow cytometry or to highthroughput epifluorescence microscopy revealed a good correlation (r 5 0.934, r 5 0.993, P \ 0.001 respectively). High-throughput epifluorescence microscopy was found to be more specific and sensitive than flow cytometry and easier to use for large series of samples. This reliable and easy protocol allow the specific detection of Toxoplasma cysts in brain, even at low concentrations; it could be a new way to detect them in water and in contaminate food. ' 2011 International Society for Advancement of Cytometry

show abstract

“…One study in Adelaide, South Australia, suggested that seropositivity to T. gondii may be associated with the presence of meningioma (91). Zhang et al also found Toxoplasma cysts, verified by immunohistochemistry, among polygonal or round tumor cells of pituitary adenoma and reported that T. gondii infection might be involved in the development of certain cases of this cancer (92).…”

Section: Parasites and Cancermentioning

confidence: 95%