Thibault Allain (Canada)
University of Calgary
Department of Biological Sciences
I am currently completing my Postdoctoral fellowship in Parasitology in the Buret laboratory (Dept. Biological Sciences) at the University of Calgary. I started my Ph.D. in 2012 in France, jointly working with INRAe (team Probihote), the French National Museum of Natural History (PPL Parasites and Free-living Protists), and the Faculty of Veterinary Medicine of Alfort (Zoonotic food-borne parasites), where I studied the interactions between probiotic lactobacilli and the protozoan parasite Giardia duodenalis. I committed to further advance my understanding of parasitic infections and decided to join the Buret lab in 2016 at the University of Calgary, a world leading laboratory in the pathophysiology of intestinal parasites. My work with Dr. Buret and numerous collaborators has been instrumental in unravelling the mechanisms of parasitic infections and interactions between parasites, the gut microbiota, and the host. In particular, I have characterized the metabolomic profile of several Giardia isolates and the metabolome of host intestinal cells upon Giardia infection. I also investigated the role of the diet in the pathogenesis of giardiasis. My most recent research investigates the effects of extracellular vesicles secreted by Giardia on commensal bacteria and host cells.

Presenter of 1 Presentation

 Online Program
02. Parasites of humans

GIARDIA DUODENALIS EXTRACELLULAR VESICLES MODULATE THE GROWTH AND BEHAVIOR OF COMMENSAL BACTERIA VIA SMALL RNAS ACTIVITY (ID 1003)

Session Name
PA04-02 - GIARDIA, ENTAMOEBA, BLASTOCYSTISTOPIC: 2.3 INTESTINAL PARASITIC DISEASES
Session Type
02. Parasites of humans
Date
08/22/2022
Session Time
17:00 - 18:30
Room
Auditorium 11
Presenter
Lecture Time
18:15 - 18:20
Onsite or Pre-Recorded
Onsite

Abstract

Introduction

Extracellular vesicles (EVs) play important roles in the pathophysiology of parasites. While the protozoan parasite Giardia duodenalis can produces EVs, their exact role in the pathogenesis of giardiasis remains to be fully understood. In this study, we examined whether Giardia EVs could mediate interactions with commensal bacteria.

Methods

G. duodenalis NF EVs were isolated using Exo-Easy Kit. EVs were characterized using Nanoparticle track analysis and transmission electron microscopy. EVs Small-RNAs were characterized by RNA-Sequencing analysis. Kinetic experiments were conducted on EVs-treated E. coli HB101 and Enterobacter cloacae (human isolate). Swimming motility of EVs-treated E. coli HB101 and E. cloacae was assessed on agar. Biofilm biomass of EVs treated bacteria was investigated using the Calgary Biofilm Device. Adhesion of EVs-treated bacteria was assessed on SCBN intestinal epithelial cells.

Results

Giardia EVs exerted bacteriostatic effects on E. coli HB101 and E. cloacae (p<0.05). EVs decreased the ability of E. coli HB101 to form biofilms. Giardia EVs significantly increased the swimming motility of both E. coli HB101 and E. cloacae as well as their adhesion to the intestinal epithelial cells (p<0.05). RNase assays showed that EVs total RNAs but not proteins modulate bacterial swimming motility and biofilm formation. Small RNAs analysis revealed the presence of heat stable rRNA, miRNA, tRNA, snRNA and snoRNA.

Conclusions

This study indicates that Giardia EVs can mediate interactions with the commensal bacteria by increasing their virulence. G. duodenalis EVs, via their nucleic acid content, can trigger the formation of pathobionts, depicting a novel trans-kingdom cross-talk in the gut.

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