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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 104, No. 2, 2009, pp. 196-200
Bioline Code: oc09035
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 104, No. 2, 2009, pp. 196-200

 en Spontaneous stage differentiation of mouse-virulent Toxoplasma gondii check for this species in other resources RH parasites in skeletal muscle cells: an ultrastructural evaluation
Ferreira-da-Silva, Marialice da Fonseca; Rodrigues, Renata Mendonça; de Andrade, Elisabete Ferreira; de Carvalho, Laís; Gross, Uwe; Lüder, Carsten G.K. & Barbosa, Helene Santos

Abstract

Although the predilection for Toxoplasma gondii check for this species in other resources to form cysts in the nervous system and skeletal and heart muscles has been described for more than fifty years, skeletal muscle cells (SkMCs) have not been explored as a host cell type to study the Toxoplasma-host cell interaction and investigate the intracellular development of the parasite. Morphological aspects of the initial events in the Toxoplasma-SkMC interaction were analysed and suggest that there are different processes of protozoan adhesion and invasion and of the subsequent fate of the parasite inside the parasitophorous vacuole (PV). Using scanning electron microscopy, Toxoplasma tachyzoites from the mouse-virulent RH strain were found to be attached to SkMCs by the anterior or posterior region of the body, with or without expansion of the SkMC membrane. This suggests that different types of parasite internalization occurred. Asynchronous multiplication and differentiation of T. gondii were observed. Importantly, intracellular parasites were seen to display high amounts of amylopectin granules in their cytoplasm, indicating that tachyzoites of the RH strain were able to differentiate spontaneously into bradyzoites in SkMCs. This stage conversion occurred in approximately 3% of the PVs. This is particularly intriguing as tachyzoites of virulent Toxoplasma strains are not thought to be prone to cyst formation. We discuss whether biological differences in host cells are crucial to Toxoplasma stage conversion and suggest that important questions concerning the host cell type and its relevance in Toxoplasma differentiation are still unanswered.

Keywords
Toxoplasma gondii - stage conversion - T. gondii-host cell interaction - skeletal muscle cell - tachyzoite - bradyzoite

 
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