Toxoplasma Gondii: Patterns of Bradyzoite-Tachyzoite Interconversion In Vitro
The development of Toxoplasma gondii in the intermediate host is believed to be a balance between the parasite and the immune system of the host which leads to either of the two possible developmental stages that are tachyzoites or bradyzoites. Alteration of the balance leads to interconversion between these stages [Frenkel et al, 1975]. The relations between the immune response and the mechanism(s) of interconversion are unknown. Since analyzing these phenomena in the host is complex, we have started investigating this phenomenon in vitro. We have confirmed the previous description by others of strains producing both stages in vitro in the absence of any immunological effector [Hoff et al, 1977; Darde et al, 1989]. This system will be used to characterize the essential requirements for differentiation toward either of the two stages. The strategy developed towards this goal is as follows: first to obtain stages specific probes; second to follow spontaneous differentiation in vitro, and third to find ways of manipulating differentiation in order to define the mechanisms involved. The first two steps will be described in this report.
KeywordsTrypsin Encephalitis Toxoplasmosis
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