Establishment Of The Model About Toxoplasma Gondii Tachyzoite-bradyzoite Interconversion In Vitro

Toxoplasma gondii is an obligate intracellular opportunistic pathogen parasite that can infect any nucleated cell of warm-blooded animals, and result in toxoplasmosis of amphixenosis. Toxoplasma invade the host cell, with the effect of host immune response, Toxoplasma gondii undergoes stage conversion, from a rapidly progenitive tachyzoite stage to a relatively non-immunogenic, dormant bradyzoite stage contained in tissue cysts in the body for a long time to resist bad environment. These bradyzoite cysts can reconvert back to tachyzoites years later serious pathology and death if a person becomes immune-compromised, in which the bad environment were removed,Such as patients with tumor,AIDS patienis,et al. With the spread of AIDS epidemic and the rise of pets, the infection of Toxoplasma gondii becomes a severe problem of public health.The interconversion between tachyzoite and bradyzoite is the key of pathogenesis of toxoplasmosis. Although a lot of and many years of research, the mechanism about the interconversion was not known. Therefore, it has become a hot spot and a difficult problem about the mechanism of the interconversion.Currently,the studying of Toxoplasma gondii induced transformation in vitrofocus on the stage conversion from tachyzoite to bradyzoite, while the reverse conversion from bradyzoites to tachyzoites reported less. In this study, by adding or removing adverse living factors of toxoplasma in vitro culture, we constructed a model about Toxoplasma gondii tachyzoite-bradyzoite interconversion in vitro.Objectives:Establisllment of the stable model about tachyzoite-bradyzoite interconversion of Toxoplasma gondii in vitro, contribute to the further study of toxoplasmosis mechanism of acute or chronic outcome.Methods:1.Conventional recovery tachyzoites of Toxoplasma gondii RH strain, then tachyzoites were inoculated into the peritoneal cavity of mouse, the purified tachyzoites were inoculated into Hela cell layer in vitro culture.2.Research on tachyzoite transformation into bradyzoite under exogenous stress conditions, Observation tachyzoite growing status with alkaline pH, high temperature, CO2starvation, and then collect parasites mixture points in time,extract total RNA of Toxoplasma gondii, SAG1、 BAG1and BSR4mRNA was detected by RT-PCR.3.Explore the bradyzoite differentiation, after removal of exogenous stress influence.Then collect parasites mixture points in time,extract total RNA of Toxoplasma gondii, SAG1、BAG1and BSR4mRNA was detected by RT-PCR.Results:1. Under the condition of43℃cells rapidly disintegrating,hard for provide a suitable environment for parasite growth; Under41℃, most of the cells can be normal growth, and can quickly induced parasite differentiation.2.We choose in alkaline pH, CO2starvation,41℃induced differentiation.In order to monitor proceeding of transformation, test stage-specific genes points in time,BAG1and BSR4mRNA transcription level gradually improve following times of the induction, SAG1gradually reduce and disappear.3.Return to normal culture conditions, collect parasites mixture points in time, the products of SAG1mRNA were raised following times of the induction.Conclusion:Establishment of the model about Toxoplasma gondii tachyzoite-bradyzoite interconversion in vitro, contributes to the further study of toxoplasmosis mechanism of acute or chronic outcome.