Giardia releases extracellular vesicles which can modulate growth and behavior of commensal bacteria

INTRODUCTION Extracellular vesicles (EVs) are a heterogeneous population of secreted vesicles that have been shown to play important roles in the pathophysiology of various parasitic diseases. The protozoan parasite Giardia duodenalis , which causes diarrheal disease, also produces EVs. However, 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 the commensal bacteria. This represents a novel role of Giardia EVs that has not been studied before. AIMS The aim of this research is to characterize Giardia extracellular vesicles and examine their effects on commensal bacterial. METHODS Extracellular vesicles (EVs) of G. duodenalis (isolate NF) were isolated using Qiagen Exo‐Easy Maxi Kit . The concentration and size of EVs were assessed using Nanosight track analysis (NTA). EVs were also characterized using transmission electron microscopy (TEM). Furthermore, we conducted a proteomic analysis of EVs using liquid chromatography with tandem mass spectrometry. To examine the effects of Giardia EVs on commensal bacteria, we used E. coli HB101 (lab strain) and Enterobacter cloacae (human isolate). The bacteria were incubated with Giardia EVs and their growth kinetics were examined. The swimming motility of EVs treated bacteria was assessed on a 0.3% agar. The ability of EVs treated bacteria to adhere to epithelial cells was examined using an adhesion assay. Finally, the biofilm forming ability of EVs treated bacteria was investigated using a crystal violet for biofilm quantification. RESULTS Our findings show that Giardia trophozoites release EVs that modulate the growth and behavior of commensal bacteria. Giardia EVs exerted bacteriostatic effects on E.coli HB101and E. cloacae . Additionally, 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. Finally, Giardia EVs decreased the ability of E.coli HB101 to form biofilms. Proteomic analysis revealed that well characterized virulence factors were packaged in EVs. CONCLUSION This study indicates that Giardia EVscan mediate interactions with the commensal bacteria. EVs were shown to alter the behavior of bacteriaand increase their virulence.The presence of virulence factors in EVs shows thatthey have significant implications in pathophysiology .