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Identification de protéines parasitaires et de glycanes exogènes impliqués dans l’infection des microsporidies Encephalitozoon cuniculi et Anncaliia algerae

Abstract : Microsporidia are unicellular eukaryotic parasites related to fungi and responsible for parasitosis in many host organisms including humans. Microsporidia use different strategies to adhere to and invade host cells, among which the extrusion of a polar tube harpooning and carrying the infectious form inside the host cells. To date, only a few proteins have been identified as involved in adhesion, but their neutralization by inhibition assays is not sufficient to completely eliminate infection, suggesting the involvement of other molecular actors. In this study, we combined surfomics and in silico approaches in order to identify new protein candidates potentially involved in the infection processes of two microsporidia (Encephalitozoon cuniculi and Anncaliia algerae), and to determine their role in infection by functional inhibition assays. These approaches allowed the identification of Ricin-B-like proteins, EcRBLL-1, AaRBLL-1 and AaRBLL-2, which are localized at the spore wall and/or at the polar tube of the spore. Functional inhibition assays, based on the use of recombinant proteins and antibodies associated with the 3 proteins, revealed a significant decrease in the proliferation of E. cuniculi and A. algerae, suggesting their roles in the adhesion/infection process. In parallel, the study of other proteins EcSWP7, EcSWP9, EcSWP12 and EcSWP26, identified in support of literature data and complemented by in silico analysis, led to demonstrate a parietal localization of the spore and the polar tube in E. cuniculi. Finally, the surfomics approach by SDS extraction of the spore wall proteins allowed the selection of 6 candidate proteins (AaRBLL-1, AaP6BE05, AaP13YM, AaP696T, AaP3569, AaP04039, AaP03248) in A. algerae to evaluate their role in infection. The anti-microsporidian effect of a polysaccharide from the red microalga Porphyridium marinum (PM) was also explored in order to understand the mechanisms of action involved. It seems that this compound can act on the surface of host cells and thus block the adhesion of spores to cells. In parallel, a screening of new polysaccharides was carried out to search for new anti-microsporidian molecules that could act in combination with the PM polysaccharide, in particular to treat Nosema ceranae, responsible for the nosemosis of bees. Three polysaccharides were able to significantly reduce the parasite load of infected bees.
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https://tel.archives-ouvertes.fr/tel-03621931
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Submitted on : Monday, March 28, 2022 - 4:01:31 PM
Last modification on : Tuesday, March 29, 2022 - 3:58:58 AM

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Nastasia Prybylski. Identification de protéines parasitaires et de glycanes exogènes impliqués dans l’infection des microsporidies Encephalitozoon cuniculi et Anncaliia algerae. Microbiologie et Parasitologie. Université Clermont Auvergne, 2021. Français. ⟨NNT : 2021UCFAC057⟩. ⟨tel-03621931⟩

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