Quantitative imaging and multi-scale characterization

of the mechanics of the oocyst wall of coccidian parasites

We hypothesize that the structural and biophysical properties of the oocyst wall are the key determinants of the resistance of the parasites exposed to physical and chemical conditions. To address this hypothesis, we use Eimeria parasites as coccidian models to develop innovative single-cell force measurement techniques coupled to imaging to provide a quantitative characterization of the biophysical properties of the walls of oocysts exposed to treatments. A first objective is to develop atomic force microscopy and micromanipulation techniques coupled to fluorescence microscopy to characterize (i) the mechanics of the walls of untreated oocysts and the forces required for deforming or breaking them, and (ii) the nature and duration of adhesion forces at the wall surface. A second objective is to apply these techniques to characterize the resistance of the walls of oocysts exposed to ozone disinfection and osmotic stress conditions and link it to the parasite infectivity. We believe that the new data and methodologies generated by this project will provide a quantitative description of the key biophysical parameters of the oocyst wall that determine the behaviour and infectivity of coccidian parasites exposed to adverse conditions.

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Coll. with Pierre-Henri Puech @ Marseille, Julien Husson @ Polytechnique Institute Paris, David Ferguson @ Oxford Univ, Isabelle Villena @ Reims Univ, Anne Silvestre, Mickael Riou @ INRAE Tours, and Stéphanie La Carbona @ Actalia Company

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Selected publications (click on the title to get full text)

1. Dynamics of Toxoplasma gondii oocyst phagocytosis by macrophages. Ndao O, Puech PH, Bérard C, Limozin L, Rabhi S, Azas N, Dubey JP, Dumètre A. Frontiers in Cellular and Infection Microbiology 2020; 10: 1-9

2. Structure, composition, and roles of Toxoplasma gondii oocyst and sporocyst walls. Freppel W, Ferguson DJP, Shapiro K, Dubey JP, Puech PH, Dumètre A. The Cell Surface 2019; 5:100016.

3. Macrophages facilitate the excystation and differentiation of Toxoplasma gondii sporozoites into tachyzoites following oocyst internalisation. Freppel W, Puech PH, Ferguson DJP, Azas N, Dubey JP, Dumètre A. Scientific Reports 2016; 6:33654.

4. Mechanics of the Toxoplasma gondii oocyst wall. Dumètre A, Dubey JP, Ferguson DJP, Bongrand P, Azas N, Puech PH. PNAS 2013; 110(28):11535-40

 

 

 

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Response of coccidia to food and water decontamination treatments

We study how T. gondii and C. parvum oocysts survive environmental conditions and common household and industrial inactivation treatments including chlorination and ozone. We explore the effects of such treatments on the structure, permeability, and mechanics of the parasites, and in collaboration with parasitologists and 'omics' experts, we investigate whether treatments modify the oocyst transcriptome, proteome, and infectivity. To this aim, we contribute to develop alternative approaches to assess the infectivity of native vs. treated parasites by using cell culture coupled to qPCR and surrogate models. In particular, we aim at determining whether oocysts of the chicken E. acervulina and mouse E. papillata, which are produced more easily than T. gondii oocysts, can be used as non pathogenic surrogate models of T. gondii to assess the efficacy of physical and chemical decontamination treatments.

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Coll. with Isabelle Villena & Loïc Favennec @ Reims & Rouen Univ, Stéphanie La Carbona @ Actalia Company, Jean-Michel Repérant @ANSES Ploufragan, Anne Silvestre @ INRAE Tours, Frédéric Ariey @ Cochin Instiute Paris, Christine Schaffer @Hubert Curien Institute Strasbourg, and David Ferguson @ Oxford Univ

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Selected publications (click on the title to get full text)

1. Surrogates of foodborne and waterborne protozoan parasites: a review. Augendre L, Costa D, Escoote-Binet S, Aubert D, Villena I, Dumètre A, La Carbona S. Food and Waterborne Parasitology 2023; 33:e00212.

2. Effect of household bleach on the structure of the sporocyst wall of Toxoplasma gondii. Dumètre A, Dubey JP, Ferguson DJP. Parasite 2021 28: 68

3. Toxoplasma gondii oocyst infectivity assessed using a sporocyst-based cell culture assay combined with quantitative PCR for environmental applications. Rousseau A, Escotte-Binet S, La Carbona S, Dumètre A, Chagneau S, Favennec L, Kubina S, Dubey JP, Majou D, Bigot-Clivot A, Villena I, Aubert D. Applied and Environmental Microbiology 2019; 85(20):e01189-19.

4. Evaluation of propidium monoazide-based qPCR to detect viable oocysts of Toxoplasma gondii. Rousseau A, Villena I, Dumètre A, Escotte-Binet S, Favennec L, Dubey JP, La Carbona S. Parasitology Research 2019.

5. Assessing viability and infectivity of foodborne and waterborne stages (cysts/oocysts) of Giardia duodenalis, Cryptosporidium spp., and Toxoplasma gondii: a review of methods. Rousseau A, La Carbona S, Dumètre A, Robertson LJ, Gargala G, Escotte-Binet S, Favennec L, Villena I, Gérard C, Aubert D. Parasite 2018; 25:14.

6. Simultaneous detection of the protozoan parasites Toxoplasma, Cryptosporidium and Giardia in food matrices and their persistence on basil leaves. Hohweyer J, Cazeaux C, Travaillé E, Languet E, Dumètre A, Aubert D, Terryn C, Dubey JP, Azas N, Houssin M, Favennec L, Villena I, La Carbona S. Food Microbiology 2016; 57:36-44.

7. Development of a qRT-PCR method to assess the viability of Giardia intestinalis cysts, Cryptosporidium spp., and Toxoplasma gondii oocysts. Travaillé E, La Carbona S, Gargala G, Aubert D, Guyot K, Dumètre A, Villena I, Houssin M. Food Control 2016; 59:359-65.

8. Effects of ozone and ultraviolet radiation treatments on the infectivity of Toxoplasma gondii oocysts. Dumètre A, Le Bras C, Baffet M, Meneceur P, Dubey JP, Derouin F, Duguet JP, Joyeux M, Moulin L. Veterinary Parasitology 2008; 153(3-4):209-13.

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Transport dynamics of T. gondii oocysts in soils

We study the fate and transport of oocysts in soils as a function of soil physicochemical properties and soil water chemistry properties. For this, we apply oocysts onto columns, which contain with sand, natural loamy sand soils or sandy loam soils, and subject them to artificial rainfall in absence or presence of surfactants, monovalent and divalent cations, and humic substances at different concentrations. Quantitative polymerase chain reaction (qPCR) is used to detect and numerate oocysts in soil leachates to evaluate their breakthrough and in soil matrices to examine their spatial distribution. We are interested in differences in the rate and extent of transport of oocysts as a function of physical and chemical parameters tested.

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Coll. with Christophe Darnault @ Clemson Univ, Isabelle Villena @ Reims Univ

 

Selected publications (click on the title to get full text)

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1. Detection, fate, and transport of the biohazardous agent Toxoplasma gondii in soil water systems: Influence of soil physicochemical properties, water chemistry, and surfactant. Kinsey E, Korte C, Gouasmia S, L'Ollivier C, Dubey JP, Dumètre A, Darnault CJG. Environmental Microbiology Reports 2023; 15:596-613.

2. Environmental transmission of Toxoplasma gondii: oocysts in water, soil, and food. Shapiro K, Bahia-Oliveira L, Dixon B, Dumètre A, de Wit LA, VanWormer E, Villena I. Food and Waterborne Parasitology 2019; 12:e00049.

3. Interaction forces drive the environmental transmission of pathogenic protozoa. Dumètre A, Aubert D, Puech PH, Hohweyer J, Azas N, Villena I. Applied and Environmental Microbiology 2012; 78(4):905-12.

4. Quantitative estimation of the viability of Toxoplasma gondii oocysts in soil. Lélu M, Villena I, Dardé ML, Aubert D, Geers R, Dupuis E, Marnef F, Poulle ML, Gotteland C, Dumètre A, Gilot-Fromont E. Applied and Environmental Microbiology 2012; 78(15):5127-32.

5. Development of a sensitive method for Toxoplasma gondii oocyst extraction in soil. Lélu M, Gilot-Fromont E, Aubert D, Richaume A, Afonso E, Dupuis E, Gotteland C, Marnef F, Poulle ML, Dumètre A, Thulliez P, Dardé ML, Villena I. Veterinary Parasitology 2011; 183(1-2):59-67.

6. Detection of Toxoplasma gondii oocysts in environmental soil samples using molecular methods. Lass A, Pietkiewicz H, Modzelewska E, Dumètre A, Szostakowska B, Myjak P. European Journal of Clinical Microbiology and Infectious Diseases 2009; 28(6):599-605.