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Étude de la prolifération d'Acanthamoeba castellanii suite à l'infection par Legionella pneumophila

Abstract : Acanthamoeba castellanii is an ubiquitous free-living amoeba of the environment. This amoeba feeds mainly on micro-organisms by phagocytosis. However, some micro-organisms have acquired resistances that allow them to escape digestion and even multiply inside amoebae. This is the case of Legionella pneumophila, the bacterium responsible for legionellosis. Legionella pneumophila, through its Dot/Icm secretion system, injects several effectors into its host. These effectors interact with the proteins of the host, and induce a modification of the physiology of its host, to its advantage. During my phD, we were interested in the effects of Legionella pneumophila infection on the proliferation of its amoebic host. We showed that Legionella pneumophila prevents the proliferation of Acanthamoeba castellanii. This phenotype was associated with a modification of the shape, a loss of adhesion and a decrease in motility of the amoeba. On the molecular level, Legionella pneumophila induces a decrease in the expression of the cdc2b gene, which share similarities with the cdk1 (cyclin dependent kinase) gene, coding for the major CDK of the mammalian cells cycle. The arrest of proliferation of Acanthamoeba castellanii, which involves a reduction in expression of cdc2b, is certainly induced by one or more effector(s) of Legionella pneumophila, because the mutant ΔdotA of L. pneumophila, defective in the Dot/Icm secretion apparatus, does not induce proliferation arrest of Acanthamoeba castellanii.
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Submitted on : Monday, August 20, 2018 - 3:06:07 PM
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Luce Laétitia Mengue Assoumou Louma. Étude de la prolifération d'Acanthamoeba castellanii suite à l'infection par Legionella pneumophila. Biochimie, Biologie Moléculaire. Université de Poitiers, 2017. Français. ⟨NNT : 2017POIT2259⟩. ⟨tel-01858353⟩

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