Induction of virulence factors in giardia duodenalis independent of host attachment

Samantha J. Emery, Mehdi Mirzaei, Daniel Vuong, Dana Pascovici, Joel M. Chick, Ernest Lacey, Paul A. Haynes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)
42 Downloads (Pure)


Giardia duodenalis is responsible for the majority of parasitic gastroenteritis in humans worldwide. Host-parasite interaction models in vitro provide insights into disease and virulence and help us to understand pathogenesis. Using HT-29 intestinal epithelial cells (IEC) as a model we have demonstrated that initial sensitisation by host secretions reduces proclivity for trophozoite attachment, while inducing virulence factors. Host soluble factors triggered up-regulation of membrane and secreted proteins, including Tenascins, Cathepsin-B precursor, cystatin, and numerous Variant-specific Surface Proteins (VSPs). By comparison, host-cell attached trophozoites up-regulated intracellular pathways for ubiquitination, reactive oxygen species (ROS) detoxification and production of pyridoxal phosphate (PLP). We reason that these results demonstrate early pathogenesis in Giardia involves two independent host-parasite interactions. Motile trophozoites respond to soluble secreted signals, which deter attachment and induce expression of virulence factors. Trophozoites attached to host cells, in contrast, respond by up-regulating intracellular pathways involved in clearance of ROS, thus anticipating the host defence response.

Original languageEnglish
Article number20765
Pages (from-to)1-16
Number of pages16
JournalScientific Reports
Publication statusPublished - 12 Feb 2016

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