Toxoplasma gondii tachyzoite–bradyzoite interconversion

Lyons, Russell E.; McLeod, Rima; Roberts, Craig W.

doi:10.1016/s1471-4922(02)02248-1

Cited by 187 publications

(157 citation statements)

References 29 publications

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“…there are more bradyzoites under these conditions than would be expected from a simple inhibition of tachyzoite replication (Bohne et al, 1999;Weiss and Kim, 2000;Lyons et al, 2002). Temperature stress (43 °C (Soete et al, 1994)), pH stress (pH 6.8 or 8.2 (Soete et al, 1994;Weiss et al, 1995)) or chemical stress (sodium arsenite, nitric oxide, sodium nitroprusside (Bohne et al, 1993;Soete et al, 1994;Weiss et al, 1995;Soete and Dubremetz, 1996)) result in an increase in bradyzoite antigen expression and the development of cyst-like structures of T. gondii in vitro.…”

Section: Introductionmentioning

confidence: 99%

Identification and characterisation of a regulatory region in the Toxoplasma gondii hsp70 genomic locus

Fen

Zhang

Kim

et al. 2004

International Journal for Parasitology

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Toxoplasma gondii is an important human and veterinary pathogen. The induction of bradyzoite development in vitro has been linked to temperature, pH, mitochondrial inhibitors, sodium arsenite and many of the other stressors associated with heat shock protein induction. Heat shock or stress induced activation of a set of heat shock protein genes, is characteristic of almost all eukaryotic and prokaryotic cells. Studies in other organisms indicate that heat shock proteins are developmentally regulated. We have established that increases in the expression of bag1/hsp30 and hsp70 are associated with bradyzoite development. The T. gondii hsp70 gene locus was cloned and sequenced. The regulatory regions of this gene were analysed by deletion analysis using β-galactosidase expression vectors transiently transfected into RH strain T. gondii. Expression was measured at pH 7.1 and 8.1 (i.e. pH shock) and compared to the expression obtained with similar constructs using BAG1 and SAG1 promoters. A pH-regulated region of the Tg-hsp70 gene locus was identified which has some similarities to heat shock elements described in other eukaryotic systems. Green fluorescent protein expression vectors driven by the Tg-hsp70 regulatory region were constructed and stably transfected into T. gondii. Expression of green fluorescent protein in these parasites was induced by pH shock in those lines carrying the Tghsp70 regulatory constructs. Gel shift analysis was carried out using oligomers corresponding to the pH-regulated region and a putative DNA binding protein was identified. These data support the identification of a pH responsive cis-regulatory element in the T. gondii hsp70 gene locus. A model of the interaction of hsp70 and small heat shock proteins (e.g. BAG1) in development is presented.

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Section: Introductionmentioning

confidence: 99%

Identification and characterisation of a regulatory region in the Toxoplasma gondii hsp70 genomic locus

Fen

Zhang

Kim

et al. 2004

International Journal for Parasitology

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“…The maintenance of T. gondii in tissues is crucial to establish the chronic infection and also is probably responsible for toxoplasmosis reactivation. This is determined by the host immunosuppression, which leads to disruption of tissue cysts and subsequent bradyzoitetachyzoite conversion (Lyons et al 2002). A hypothesis was postulated linking the protective role of neuroglobin and myoglobin to the cytotoxic effect of nitric oxide, which is also observed during infection with Plasmodium and Trypanosoma cruzi in red blood cells and cardiomyocytes, respectively (Taylor-Robinson, 1998, Ascenzi et al 2001.…”

Section: Discussionmentioning

confidence: 99%

Interaction and cystogenesis of Toxoplasma gondii within skeletal muscle cells in vitro

Guimarães

Carvalho

Barbosa

2009

Mem. Inst. Oswaldo Cruz

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“…The unique ability of T. gondii to multiply in virtually all the nucleated cells of the host body and its subsequent encystment in the various tissues, coupled with its wide host range consisting of all the warm blooded animals including humans, makes the parasite a matter of serious concern for both animal and human health in the modern times. The reversion of tissue cysts containing bradyzoites back to rapidly dividing tachyzoites resulting into disease reactivation is a common phenomenon in immunocompromised patients (Lyons et al 2002). 100 tachyzoites are sufficient for the establishment of acute phase of infection in mice (Kumara et al 2010;Sudan et al 2014).…”

Section: Histopathologymentioning

confidence: 99%

Pathobiology of human RH strain induced experimental toxoplasmosis in murine model

et al. 2014

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Of late, toxoplasmosis has gained immense importance as an opportunist parasite in immunocompromised patients. In immunocompromised subjects, the disease is supposed to occur in acute form and causes acute toxoplasmic encephalitis. However, the exact pathogenesis of other vital organs, particularly in acute form of infection, is still a matter of debate. Therefore, an attempt was made to study the pathogenesis of acute form of toxoplasmosis using cryopreserved human RH strain of the parasite in murine models. For this, 100 tachyzoites were given to individual mice and upon the setup of acute form of infection, the mice were euthanized and the organs were processed for histopathology. Histopathology revealed tachyzoites in liver only while severe necrosis due to multiplication of tachyzoites were visible in liver, spleen, lungs and brain. Kidneys and heart appeared more or less normal. Finally, the pathology of disease in these organs is described in detail. The present research has generated some vital information regarding necrotic changes in tissues due to acute toxoplasmosis and will defiantly help the researchers in the better understanding of disease particularly in humans and putting up of suitable treatment regime for human subjects infected with acute toxoplasmosis.

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Toxoplasma gondii tachyzoite–bradyzoite interconversion

Cited by 187 publications

References 29 publications

Identification and characterisation of a regulatory region in the Toxoplasma gondii hsp70 genomic locus

Identification and characterisation of a regulatory region in the Toxoplasma gondii hsp70 genomic locus

Interaction and cystogenesis of Toxoplasma gondii within skeletal muscle cells in vitro

Pathobiology of human RH strain induced experimental toxoplasmosis in murine model

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