Toxoplasma gondii:Étude ultrastructurale des formations kystiques observées en culture de fibroblastes humains

Abstract

Toxoplasma gondii: Ultrastructure of cyst-like forms observed in human fibroblasts cell culture.SUMMARY. A strain of Toxoplasma gondii, non pathogenic to mice (Prugniaud strain) produced cyst-like stages when inoculated in human fibroblast culture. An ultrastructural study was performed in order to compare these cyst-like forms to brain cysts of the same strain and to intracellular clusters of tachyzoites observed in mice TG 180 sar coma cells.Electron microscopy confirmed the similarities between brain cysts and cysts obtained in vitro.

Development of an in vitro model of Toxoplasma gondii cyst formation

“…TEM studies have confirmed that the in vitro structures described here are comparable both to those described by previous authors [7][8][9] and cysts prepared from mouse brain. The differences in size between mouse brain and in vitro cysts may be attributable to the lack of tertiary structure in the monolayer and a limited nutrient supply; this may have a direct effect on the differentiation of the cysts.…”

“…Lindsay et al [9] described some variation in cyst-forming activity using the isolate GT-1 when different host cells were adopted. Similarly, Jones et al [8] were able to produce long-lived 331 cyst cultures by use of a slowly dividing primary astrocyte culture. In the present study, we have achieved stabilised cyst cultures by removal of parasite-laden culture supernatant and refeeding the monolayer with fresh media.…”

“…The slow division of these host cells was thought to facilitate development of the cyst which formed after 80 days; cysts were further stabilised in the presence of gamma interferon. Development of cysts in cell lines with a more rapid turnover has been described by Darde [8] and by Lindsay [9], although in these lines the cysts are unstable after approximately 2 weeks of culture. Despite the gross differences in the time course of cyst formation between astrocyte and fibroblast systems, it appears that the host cell type is not a critical factor in Toxoplasma cyst formation, although the dynamics of cyst formation may vary according to host cell type.…”

Structures ofToxoplasma gondiiTachyzoites, Bradyzoites, and Sporozoites and Biology and Development of Tissue Cysts

“…Most strains of T. gondii will spontaneously develop tissue cysts in cell culture with no manipulation (22,109,111,113,156). However, the number of tissue cysts produced spontaneously is small and manipulation of the cell culture system is needed to increase this number (11,83,155,156,178).…”

Cyst formation by Toxoplasma gondii in vivo and in brain-cell culture: a comparative morphology and immunocytochemistry study

“…It has been reported that most T. gondii isolates can be maintained in various feeder-cell cultures, where most of them form cysts (Darde et al 1989;Jones et al 1986;Lindsay et al 1993;Smith and Lewis 1992). The majority of reports suggest that the production of cysts does not depend on the host-cell type, the culture medium, or the presence of immunological factors.…”