Mechanics of the Toxoplasma gondii oocyst wall

Aurélien Dumètre (1) , Jitender P. Dubey (2) , David J.P. Ferguson (3) , Pierre Bongrand (4) , Nadine Azas (1) , Pierre-Henri Puech (4)

1 IP-TPT - Infections Parasitaires : Transmission, Physiopathologie et Thérapeutiques
2 USDA Agricultural Research Service [Beltsville, Maryland]
3 Department of Ultrastructural Morphology
4 LAI - Adhésion et Inflammation

The ability of microorganisms to survive under extreme conditions is closely related to the physicochemical properties of their wall. In the ubiquitous protozoan parasite Toxoplasma gondii, the oocyst stage possesses a bilayered wall that protects the dormant but potentially infective parasites from harsh environmental conditions until their ingestion by the host. None of the common disinfectants are effective in killing the parasite because the oocyst wall acts as a primary barrier to physical and chemical attacks. Here, we address the structure and chemistry of the wall of the T. gondii oocyst by combining wall surface treatments, fluores-cence imaging, EM, and measurements of its mechanical characteristics by using atomic force microscopy. Elasticity and indentation measurements indicated that the oocyst wall resembles common plastic materials, based on the Young moduli, E, evaluated by atomic force microscopy. Our study demonstrates that the inner layer is as robust as the bilayered wall itself. Besides wall mechanics , our results suggest important differences regarding the non-specific adhesive properties of each layer. All together, these findings suggest a key biological role for the oocyst wall mechanics in maintaining the integrity of the T. gondii oocysts in the environment or after exposure to disinfectants, and therefore their potential infectivity to humans and animals.

Mots clés: Toxoplasma infectivity; oocyst resistance; Oocyst structure; oocyst integrity; transmission

Domaines: Parasitologie

Aurélien Dumètre, Jitender P. Dubey, David J.P. Ferguson, Pierre Bongrand, Nadine Azas, et al.. Mechanics of the Toxoplasma gondii oocyst wall. Proceedings of the National Academy of Sciences of the United States of America, 2013, 110 (28), pp.11535-11540. ⟨10.1073/pnas.1308425110⟩. ⟨hal-01326568⟩