Schistosomiasis from a snail’s perspective

Le 29 Juin 2023
11h30 Hybrid - online and Salle Louis Thaler, bat 22 UM


University of Alberta, Schoool of Public Health, Canada

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The freshwater snail Biomphalaria glabrata is an intermediate host for the human parasite Schistosoma mansoni. Compatibility polymorphisms exist between unique strains of B. glabrata to a point where some strains, such as BS-90, are refractory to challenge by most strains of S. mansoni. Underpinning this resistant phenotype are specific immune processes that recognize and mark the invading parasite for encapsulating and killing by snail immune cells known as hemocytes. The humoral immune factors and processes involved in the opsonization of larval S. mansoni are analogous to many well-described mammalian immune factors/processes. However, more about hemocytes and their biology needs to be understood, particularly concerning the roles of different hemocyte subtypes in the S. mansoni-killing response. We have found evidence suggesting that a Toll-like Receptor (TLR) located on a specific subset of granulocytic hemocytes serves as a marker for hemocytes most capable of killing larval S. mansoni. These TLR+ granulocytes, when co-incubated with humoral immune factors in the presence of larval S. mansoni, generate a robust respiratory burst response that leads to parasite death. TLR+ granulocytes can be generated in vitro and in vivo using a B. glabrata-produced growth factor, granulin. When injected into B. glabrata strains typically considered S. mansoni-susceptible, granulin can induce a resistance phenotype.


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Benjamin Gourbal (UMR IHPE)