Elucidating pathways of Toxoplasma gondii invasion in the gastrointestinal tract: involvement of the tight junction protein occludin

Caroline Weight, Emily Jones, Nikki Horn, Nikolaus Wellner, Simon Carding

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Toxoplasma gondii is an obligate intracellular parasite infecting one third of the world’s population. The small intestine is the parasite’s primary route of infection, although the pathway of epithelium transmigration remains unclear. Using an in vitro invasion assay and live imaging we showed that T. gondii (RH) tachyzoites infect and transmigrate between adjacent intestinal epithelial cells in polarized monolayers without altering barrier integrity, despite eliciting the production of specific inflammatory mediators and chemokines. During invasion, T. gondii co-localized with occludin. Reducing the levels of endogenous cellular occludin with specific small interfering RNAs significantly reduced the ability of T. gondii to penetrate between and infect epithelial cells. Furthermore, an in vitro invasion and binding assays using recombinant occludin fragments established the capacity of the parasite to bind occludin and in particular to the extracellular loops of the protein. These findings provide evidence for occludin playing a role in the invasion of T. gondii in small intestinal epithelial cells.
Original languageEnglish
Pages (from-to)698-709
Number of pages12
JournalMicrobes and Infection
Issue number10
Early online date14 Jul 2015
Publication statusPublished - Oct 2015


  • Toxoplasma gondii
  • Occludin
  • Invasion
  • Intestinal epithelial cells

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