The Giardia secretome disrupts gut microbiota biofilms.

This review provides a state-of-the-art update on Giardia intestinalis pathogenesis and its immunomodulatory effects during enteric coinfections. We examine mechanisms underlying abnormalities in mucus structure and glycosylation, alongside parasite-induced alterations in host immunity. Recent evidence reveals a protective role for gut microbiota biofilms and demonstrates how the Giardia secretome disrupts these communities. In particular, trophozoite-derived cysteine proteases and extracellular vesicles, along with their small RNA cargo, remodel microbiota biofilms and drive the conversion of commensal bacteria into invasive pathobionts. Collectively, these findings establish Giardia as a central regulator of gut microbial ecology and intestinal barrier function, highlighting its value as a model for developing novel therapeutic strategies against enteric disease.